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Borja Suárez, Manuel Alejandro. "Correlación entre la resistencia real del concreto y el ensayo no destructivo de esclerometría para muestras de concreto en el departamento de Lambayeque – Perú." TecnoHumanismo 1, no. 10 (2021): 1–15. http://dx.doi.org/10.53673/th.v1i10.59.
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La presente investigación busca encontrar el nivel de correlación entre la resistencia real del concreto (kg/cm2) y el ensayo no destructivo de esclerometría, pero sobre todo determinar el nivel de confianza con el que se deberían aceptar estos resultados. Para esto se evaluaron probetas provenientes de diferentes obras de construcción en la región Lambayeque, indistintamente de sus características de diseño, y antes que sean ensayadas en la prensa de compresión, se les sometió a un examen con esclerómetro digital siguiendo el procedimiento de la NTP 339.181 (2013). Se ensayaron también probetas con diseño controlado para f’c: 175, 210 y 280 kg/cm2 y así comparar si con estas probetas se obtiene una mejor correlación respecto a las probetas provenientes al azar de diferentes obras. Para las muestra analizadas de todas las obras, se encontró una desviación estándar de 45 kg/cm2 (ligeramente alta); y para el caso de concretos de diseño controlado: 13 kg/cm2, con un coeficiente de correlación de r2 = 0.9467 (a los 28 días). Después de procesar todos los datos, se llegó a la conclusión que el ensayo de esclerometría si se puede utilizar para estimar la resistencia a la compresión del concreto pero bajo ciertas condiciones controladas y teniendo en cuenta un margen de error y confiabilidad. Finalmente, se puede concluir que para un nivel de confiabilidad del 95% la resistencia del concreto obtenida con el esclerómetro podría ser estimada con el siguiente rango de precisión: f’c ± 25 kg/cm2.
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Ruda Arias, Yuber Mauricio, and Diego Fernando Paez Moreno. "Anclajes posinstalados en concretos de alta resistencia." Ciencia e Ingeniería Neogranadina 27, no. 2 (August 1, 2017): 137–56. http://dx.doi.org/10.18359/rcin.2208.
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Hoy en día, las grandes construcciones de Colombia y el mundo, y en especial las de infraestructura vial, han fomentado el uso de concretos de alta resistencia; también ha crecido de forma simultánea el uso de los anclajes posinstalados en todas las estructuras de concreto. Por lo anterior, se desarrolló en esta investigación un procedimiento experimental para evaluar sistemas de anclaje posinstalados, basado en ensayos a tracción con probetas de concreto de alta resistencia. La evaluación considera el análisis de los resultados de los ensayos a tracción de probetas con un sistema de anclaje para tres longitudes (6, 9 y 12 veces el diámetro de la varilla) con dos diámetros de varilla (3/8” y 5/8”) en dos calidades de concreto de alta resistencia (5000Psi y 6000Psi), para determinar la longitud y carga efectiva del sistema. El análisis que se realiza al ensayo experimental es correlacionar el resultado de la carga máxima de fluencia del acero de refuerzo utilizado (fy=4200Psi) con las variables del sistema de anclaje posinstalado. Con esto se obtuvo como resultados el porcentaje de resistencia del sistema en función de la longitud de anclaje, la longitud efectiva que garantiza la fluencia del acero y las correlaciones entre el porcentaje de resistencia efectiva alcanzada para cada longitud de anclaje con el uso de concreto de alta resistencia. Con los anteriores parámetros se analizó el aporte de los concretos de alta resistencia a la eficiencia de los sistemas de anclajes posinstalados.
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Gómez, Valle, Quelmer Saldaña Núñez, and John Hilmer. "Influencia de tres aditivos acelerantes en el desarrollo de la resistencia a la compresión en un concreto fe = 175 kg/cm2 y 210 kg/cm2." Revista Científica UNTRM: Ciencias Naturales e Ingeniería 2, no. 3 (January 7, 2021): 17. http://dx.doi.org/10.25127/ucni.v2i3.599.
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<p>Con la investigación se determinó la influencia de tres aditivos acelerantes en el desarrollo de la resistencia a la compresión en un concreto fc = 175 kg/cm2 y 210 kg/cm2 en la ciudad de Chachapoyas. El diseño de investigación utilizado fue experimental, con un tipo de muestreo probabilístico, según las unidades experimentales necesarias como mínimo 3 repeticiones. Los factores evaluados fueron los aditivos Z Fragua N° 05, Chema 3 y Sika R Sem Acelerante Pe y su influencia para aumentar la resistencia inicial tanto de concreto f c=175 kg/cm2 y 210 kg/cm2. Para determinar el mejor aditivo se elaboraron probetas con 2.5%, 3% y 3.5% de aditivo respecto al volumen de la bolsa de cemento, luego se realizó la rotura de probetas a los 7, 14 y 28 días de edad y se compararon las resistencias con datos de rotura de probetas elaboradas sin aditivos. Los datos fueron procesados en el software estadístico SPSS V23.0 para el análisis de los indicadores de correlación. Se concluyó que el aditivo acelerante que mayor efecto tuvo aumentando la resistencia inicial del concreto fue es el aditivo Sika R Sem Acelerante Pe, además de ser el más económico.</p>
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Cruz Hernández, Ricardo Alfredo, Carlos Mauricio Pico Cortés, and Ludwing Pérez Bustos. "Durabilidad y acústica del concreto con escoria de cubilote como reemplazo del agregado fino." Revista Tecnura 19, no. 43 (January 15, 2015): 37. http://dx.doi.org/10.14483/udistrital.jour.tecnura.2015.1.a02.
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En este trabajo se evaluó el comportamiento del concreto con escoria de horno de cubilote (EHC), triturada en porcentajes de sustitución de arena del 0, 10, 15 y 20 %, sometido a ataques químicos acelerados de carbonatación, sulfatación y reacción álcali-agregado (RAA). Se determinaron las características de absorción del sonido del material a través del coeficiente de absorción acústica (α) y el índice de reducción de ruido (NRC). La carbonatación se evaluó por medio de una cámara cerrada con 70 % de concentración de dióxido de carbono y condiciones de humedad relativa entre 50 y 70 %. Los resultados mostraron que la profundidad de penetración de CO2 es menor mientras mayor es el porcentaje de sustitución. Para acelerar el ataque por sulfatos, se sumergieron probetas en solución acuosa de sulfato de sodio anhidro (Na2SO4) 1N con ciclos de humedecimiento y secado. Se determinó que el deterioro presentado en la pasta de concreto es directamente proporcional al porcentaje de sustitución. La aceleración de la RAA en el concreto se realizó sumergiendo probetas en una solución acuosa de hidróxido de sodio (NaOH) durante dieciséis días. Se concluyó que la inclusión de EHC no es favorable por RAA. La medición del coeficiente de absorción acústica se realizó a través del método de tubo de impedancia, relacionando valores máximos y mínimos de amplitud de onda estacionaria. Los resultados mostraron que concretos de EHC con mayores sustituciones de arena por escoria son favorables para la absorción de ruidos en las edificaciones.
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Quintero Ortiz, Luz Amparo, Ricardo Alfredo Cruz Hernández, and Deyci Yamile Peña Santos. "Efecto del contenido de agua sobre la resistencia y la velocidad de pulso ultrasónico del concreto." Revista Tecnura 18, no. 42 (October 1, 2015): 103. http://dx.doi.org/10.14483/udistrital.jour.tecnura.2014.4.a08.
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El objetivo del presente trabajo es determinar correlaciones entre el contenido de agua del concreto, la resistencia a la compresión y la velocidad de pulso ultrasónico (VPU). Se estudiaron probetas cilíndricas de concreto de 200 mm de largo x 100 mm de diámetro, elaboradas a partir de una mezcla de cemento Portland tipo I y una relación agua/cemento (a/c) de 0,5. El curado de las muestras se realizó en condiciones estándar y en condiciones ambientales bajo techo, determinando el contenido de agua en cada probeta por diferencia de pesos y sometiendo las muestras a ensayos ultrasónicos y de resistencia a la compresión durante los primeros 28 días después del fraguado. A partir de los resultados obtenidos, se encontró que un modelo de tipo logarítmico puede describir adecuadamente el comportamiento del contenido de agua, la VPU y la resistencia a la compresión en función del tiempo de curado, para cada condición estudiada. Adicionalmente, se verificó que las condiciones de curado investigadas afectan significativamente el contenido de agua del concreto y los valores de resistencia a la compresión y VPU alcanzados.
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Britez, C., P. Castro-Borges, A. Berto, and P. Helene. "Experimental evaluation of colored HSC column in fire conditions." Revista ALCONPAT 3, no. 1 (January 30, 2013): 39–54. http://dx.doi.org/10.21041/ra.v3i1.42.
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ABSTRACTIn recent times it has been common to associate high-strength concrete with a greater susceptibility to explosive type spalling, when subjected to high temperatures. In part, this doubt is a result of some experimental programs that are carried out on small unreinforced concrete samples (specimens), which could substantially influence the structural concrete behavior in fire conditions. This paper presents an experimental program, carried out in Brazil on a high strength colored reinforced concrete column (HSCC), eight years-old, fc,8years = 140MPa, basalt coarse aggregate, cross section of 700mm x 700mm, tested under no load and with three faces exposed to standard fire curve ISO 834 for 180min (3h). The results demonstrated, in this case, that HSCC maintained integrity under experimental fire and that the iron oxide pigments can work as an excellent natural thermometer, contributing to the evaluation of the structure post-fire simulation.Keywords: High-strength concrete; fire resistance; colored concrete; column in fire; iron oxide pigment. RESUMENHa sido común asociar el concreto de alta resistencia con una mayor susceptibilidad al desprendimiento por explosión (spalling) cuando se le somete a altas temperaturas. Esta duda se debe en parte a los resultados de algunos programas experimentales que se han llevado a cabo en pequeñas probetas de concreto simple sin refuerzo, lo que puede influir sustancialmente en el comportamiento del concreto en situación de incendio. Este artículo presenta un programa experimental en Brasil donde un pilar de concreto armado colorido de alta resistencia (HCAR), con ocho años de edad, fc,8años = 140MPa, árido grueso basáltico, sección cuadrada de 700mm x 700mm, fue ensayado sin carga y con tres lados expuestos al fuego (curva ISO 834) durante 180min (3h). Los resultados demostraron en este caso que el HCAR se mantuvo íntegro y que los pigmentos de óxido de hierro pueden trabajar como excelente termómetro natural, contribuyendo en la evaluación de la estructura después de la simulación de incendio.Palabras Clave: Concreto de alta resistencia; resistencia al fuego; concreto colorido; pilar sometido al fuego; pigmento de óxido de hierro.
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Acuña Pinaud, Leoncio Luis, Pedro Celino Espinoza Haro, Isabel Moromi Nakata, Ana Victoria Torre Carrillo, and Francisco García Fernandez. "CONCRETO DE ALTO RENDIMIENTO, PREDICCIÓN DE SU RESISTENCIA A LA COMPRESIÓN MEDIANTE REDES NEURONALES ARTIFICIALES." Revista Cientifica TECNIA 27, no. 1 (January 4, 2018): 51. http://dx.doi.org/10.21754/tecnia.v27i1.125.
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En las edificaciones de las viviendas modernas el concreto es un elemento fundamental que interviene. De otro lado en las construcciones de puentes, diques, túneles, esto es en la construcción de estructuras no estándares de la ingeniería civil, el concreto que se utiliza es el de alto rendimiento (CAR) que aparte de los componentes básicos como el agua, cemento, agregados finos y gruesos, contienen otros aditivos cementantes, como las microsílices. El problema es conseguir un recurso tecnológico que ayude a pronosticar la resistencia de CAR a partir de sus datos de fabricación, pero esto es imposible. Sin embargo, se tiene las redes neuronales artificiales que cumplen este papel, que luego de entrenadas se transforman en verdaderas funciones matemáticas que aproximan los valores esperados de las resistencias de las probetas de concreto. El nivel de aproximación se estima por la correlación entre la respuesta y el valor esperado de la red. Entonces resulta muy útil contar con una red neuronal que permita simular numéricamente la resistencia del concreto, incluso antes de su fabricación. En esta investigación se han obtenido diversas redes neuronales artificiales que pronostican la resistencia a compresión del CAR con correlaciones que varían entre 0.86 y 0.91. . Palabras clave.- Red Neuronal Artificial, probeta, compresión axial, aditivos. em> ABSTRACT The building of modern housing concrete is a fundamental element that intervenes. On the other hand, in the construction of bridges, dams, tunnels, this is in the construction of non‐standard civil engineering structures, the concrete that is used is the high performance (CAR) that apart from the basic components such as water, Cement, fine and coarse aggregates, contain other cementing additives, such as microsílices. The problem is to get a technological resource that helps predict the resistance of CAR from its manufacturing data, but this is impossible. However, we have artificial neural networks that fulfill this role, which after being transformed into true mathematical functions that approximate the expected values ??of the resistance of concrete specimens. The approximation level is estimated by the correlation between the response and the expected value of the network. It is then very useful to have a neural network that simulates numerically the resistance of the concrete, even before its manufacture. In this investigation, several artificial neural networks have been obtained that predict the resistance to compression of the CAR with correlations that vary between 0.86 and 0.91. Keywords.- Artificial Neural Network, test tube, axial compression, additives.
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Cañola, Hernán, and Cesar Echavarria. "Bloques de concreto con emulsión de parafina." Lámpsakos 1, no. 17 (June 28, 2017): 14. http://dx.doi.org/10.21501/21454086.2346.
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Los muros de las edificaciones presentan frecuentemente problemas de humedad como consecuencia de la exposición a la lluvia y la absorción de agua del suelo. Infortunadamente, los bloques de concreto convencionales adquiridos en el mercado tienen coeficientes de absorción capilar altos y resistencias a la penetración de agua bajas.En esta investigación, se produjeron y analizaron experimentalmente bloques y probetas cilíndricas, se fabricaron con arena de concreto lavada, cemento Portland tipo 1, emulsión de parafina y una relación agua-cemento de 0,40 en peso. Se estudiaron bloques y cilindros sin emulsión de parafina y con 10%, 20%, 30% y 40% de adición de emulsión de parafina respecto al peso del cemento. Se ejecutaron ensayos de absorción capilar, de resistencia a la penetración de agua y se realizó un análisis comparativo de los resultados obtenidos para determinar la proporción óptima de adición de emulsión de parafina.Se determinó que los bloques con emulsión de parafina presentan mejores propiedades que los bloques convencionales sin aditivos y que podrían reducir los problemas de humedad en los muros pues tienen un coeficiente de absorción capilar bajo.
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Bedoya Henao, Carlos Andrés, Jorge Iván Tobón, Juan José Monsalve Valencia, Catalina Vanegas Palacio, and Mateo Valencia Betancur. "Evaluación de patologías en el concreto usando microscopía óptica." Informador Técnico 80, no. 2 (December 22, 2016): 142. http://dx.doi.org/10.23850/22565035.491.
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Algunos ensayos tradicionales como la resistencia a la compresión, porosidad total, infiltración de agua, entre otros, resultan útiles a la hora de realizar un análisis de patologías en concretos que han sido atacados por agentes agresores, los cuales van en contra de su durabilidad. Sin embargo, estas pruebas clásicas carecen de herramientas para analizar cómo fue el cambio estructural e interno de la muestra después de ser atacada. Lo que evidencia la necesidad de pensar en otras alternativas y tener en cuenta herramientas más directas como la microscopía, la cual permite hacer un análisis completo tanto macro como micro acerca de la mineralogía, estructura y textura, observando en detalle la composición, fracturas, alteraciones, deformaciones y señales particulares de las muestras. Así,en este trabajo se presenta la aplicabilidad de la petrografía mediante microscopía óptica convencional en el estudio de la degradación del concreto producida por el ataque de agentes agresores. Se muestran resultados como el cambio de color en los agregados, distorsión entre contactos de grano, y cambios en la isotropía de la matriz cementante ante el ataque por fuego. Formación de fases secundarias producto del reemplazo de iones en la matriz que generan fracturamiento y expansión en las probetas expuestas a ataques por sulfato. La aparición de nuevas fases entre la matriz y los agregados y en las fracturas para las muestras sometidas a reacción álcali-sílice. Además, se pudo correlacionar todas estas transformaciones petrográficas con las pérdidas de desempeño mecánico de los concretos.
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Gaidis, J. M., and A. H. Rosemberg. "Nuevo ensayo para la determinación de frecuencias fundamentales longitudinales, transversales y torsionales en probetas de hormigón." Materiales de Construcción 36, no. 202 (June 30, 1986): 5–10. http://dx.doi.org/10.3989/mc.1986.v36.i202.894.
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Bustos, Arturo. "Aprovechamiento de residuos orgánicos (cáscara de almendra) para sustitución de árido grueso en la elaboración de hormigón convencional = Use of organic waste (almond shell) to replace coarse aggregate in conventional concrete processing." Anales de Edificación 2, no. 3 (December 18, 2016): 1. http://dx.doi.org/10.20868/ade.2016.3465.
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ResumenEl presente trabajo, busca conocer el posible aprovechamiento de residuos orgánicos, como es la cáscara de almendra, como sustitución de una parte de la fracción granulométrica del árido grueso para la fabricación de hormigones convencionales. Para ello, primero, caracterizamos los materiales, árido y cascara de almendra. Posteriormente, fabricamos las probetas de hormigón con distintas sustituciones (10%, 20% y 30%) de cáscara de almendra sobre la fracción gruesa del árido y procedemos a la realización de los ensayos marcados por las normas UNE, evaluando su comportamiento a compresión, tracción, flexión, penetración de agua, absorción de agua, hielo y deshielo y térmico.AbstractThe present work seeks to know the possible use of organic residues, such as the almond husk, as a substitution of a part of the granulometric fraction of the coarse aggregate for the manufacture of conventional concretes. For this, first, we characterize the materials, arid and almond husk. Subsequently, we made the concrete samples with different substitutions (10%, 20% and 30%) of almond shell on the coarse fraction of the aggregate and proceed to the tests marked by UNE standards, evaluating their behavior to compression, Traction, flexion, water penetration, water absorption, ice and melt and thermal.
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Wan Masra, Sharifah Masniah, Norsuzailina Mohamed Sutan, A. K. Keran, and N. D. Matudin. "Electrical Resistivity of Cement Based Materials." Applied Mechanics and Materials 833 (April 2016): 102–7. http://dx.doi.org/10.4028/www.scientific.net/amm.833.102.
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Electrical resistivity (ER) of cement based materials (CBM) is an important measurement that indirectly relates to the durability of CBM. This study investigates the correlation between ER of CBM namely concrete with water-to-cement (w/c). As one of CBM hydration parameters w/c is an important parameter that contributes to variations of ER. The results of this study showed that different w/c can be used as indication for the setting characteristics as well as the pore structure of the concrete. ER is obtained by applying current into the concrete and measuring the response voltage during concrete hydration period of 28 days. Two aspects were also being considered in this study: (i) test specimen size and (ii) spacing between the probes. Results show the direct correlation between ER and test specimen sizes and spacing between the probes.
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Gartner, Nina, Tadeja Kosec, and Andraž Legat. "Monitoring the Corrosion of Steel in Concrete Exposed to a Marine Environment." Materials 13, no. 2 (January 15, 2020): 407. http://dx.doi.org/10.3390/ma13020407.
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Reinforced concrete structures require continuous monitoring and maintenance to prevent corrosion of the carbon steel reinforcement. In this work, concrete columns with carbon and stainless steel reinforcements were exposed to a real marine environment. In order to monitor the corrosion processes, two types of corrosion probes were embedded in these columns at different height levels. The results from the monitoring of the probes were compared to the actual corrosion damage in the different exposure zones. Electrical resistance (ER) probes and coupled multi-electrodes (CMEs) were shown to be promising methods for long-term corrosion monitoring in concrete. Correlations between the different exposure zones and the corrosion processes of the steel in the concrete were found. Macrocell corrosion properties and the distribution of the separated anodic/cathodic places on the steel in chloride-contaminated concrete were addressed as two of the key issues for understanding the corrosion mechanisms in such environments. The specific advantages and limitations of the tested measuring techniques for long-term corrosion monitoring were also indicated. The results of the measurements and the corrosion damage evaluation clearly confirmed that the tested stainless steels (AISI 304 and AISI 304L) in a chloride-contaminated environment behave significantly better than ordinary carbon steel, with corrosion rates from 110× to 9500× lower in the most severe (tidal) exposure conditions.
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Robles, Kevin Paolo V., Jurng-Jae Yee, and Seong-Hoon Kee. "Effect of the Geometrical Constraints to the Wenner Four-Point Electrical Resistivity Test of Reinforced Concrete Slabs." Sensors 21, no. 13 (July 5, 2021): 4622. http://dx.doi.org/10.3390/s21134622.
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The main objectives of this study are to evaluate the effect of geometrical constraints of plain concrete and reinforced concrete slabs on the Wenner four-point concrete electrical resistivity (ER) test through numerical and experimental investigation and to propose measurement recommendations for laboratory and field specimens. First, a series of numerical simulations was performed using a 3D finite element model to investigate the effects of geometrical constraints (the dimension of concrete slabs, the electrode spacing and configuration, and the distance of the electrode to the edges of concrete slabs) on ER measurements of concrete. Next, a reinforced concrete slab specimen (1500 mm (width) by 1500 mm (length) by 300 mm (thickness)) was used for experimental investigation and validation of the numerical simulation results. Based on the analytical and experimental results, it is concluded that measured ER values of regularly shaped concrete elements are strongly dependent on the distance-to-spacing ratio of ER probes (i.e., distance of the electrode in ER probes to the edges and/or the bottom of the concrete slabs normalized by the electrode spacing). For the plain concrete, it is inferred that the thickness of the concrete member should be at least three times the electrode spacing. In addition, the distance should be more than twice the electrode spacing to make the edge effect almost negligible. It is observed that the findings from the plain concrete are also valid for the reinforced concrete. However, for the reinforced concrete, the ER values are also affected by the presence of reinforcing steel and saturation of concrete, which could cause disruptions in ER measurements
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Ou, Man Li, Wei Jun Cao, and Long Min Jiang. "Study on the Mechanical Property of Concrete Materials under High Temperature (Fire)." Applied Mechanics and Materials 166-169 (May 2012): 3018–22. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.3018.
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The performance of concrete materials under high temperature is more complex than that under room temperature. This paper, by analyzing the mechanical property of concrete materials under high temperature(fire), probes into the changing law of the concrete materials' compressive strength under different temperatures (16 °C-800 °C) and different static placing time and makes a comparison on the concrete materials' strength between natural cooling and water cooling; illustrates the relationships of concrete materials' compressive strength and temperature, holding time and cooling and other factors under high temperature(fire).
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Alcañiz-Martínez, Jesús Herminio, Javier Senent-Aparicio, Miguel Louis Cereceda, and Francisco José Sánchez-Medrano. "Influencia de la localización geográfica en estructuras de hormigón-Influence of geographic location in concrete structures." Revista científica 2, no. 19 (June 26, 2014): 22. http://dx.doi.org/10.14483/23448350.6491.
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Es muy importante considerar la localizacion geografica de un edificio a la hora de realizar su chequeo estructural. Para ello, en este estudio se ha utilizado la conocida técnica de chequeo estructural basada en la correlación de resultados entre la velocidad de ultrasonidos (V) y la resistencia a compresión (R), obtenidas de las probetas testigo extraídas en elementos estructurales de hormigón armado. Para analizar la influencia de la localización geográfica de la estructura, se ha realizado el presente trabajo clasificando los edificios estudiados en función de su distancia a la costa y atendiendo las indicaciones de la instrucción EHE, es decir, utilizando una distancia de referencia de 500 m que permita ordenar los casos estudiados en función de dicha distancia. Como conclusión se puede afirmar que las estructuras más cercanas a las costas marinas están mas influenciadas por el medio ambiente, lo que influye en gran manera en la calidad del hormigón de sus estructuras. Esta situación queda demostrada con el resultado de la investigacion llevada a cabo, en el que se han analizado 185 casos reales. Para los más cercanos, se justifica estadísticamente la necesidad de su reparación-refuerzo en función de los resultados que arroje este chequeo y los resultados de correlación velocidad ultrasonidos-compresión en probetas testigo.
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Li, Qiu Feng, Pang Huang, and Yin Liao. "Research on SAFT Imaging Method of Array Probes in Concrete Structures." Applied Mechanics and Materials 189 (July 2012): 265–69. http://dx.doi.org/10.4028/www.scientific.net/amm.189.265.
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Because of the need of rapid detection of internal defects and embedded object in concrete structures, a detecting method with linear array probes is presented here, which is the high-resolution and efficient imaging technique for concrete structures by combining with synthetic aperture focusing technique (SAFT). Firstly, array simulation data are processed to be amalgamated B-scan data of concrete structures according to the structural characteristics of linear array; And then the B-scan data are reconstructed in the light of geometrical relation of ultrasonic path and SAFT; At last, the structural imaging figure are calculated. It can be shown from simulation results that the method is effective, and the embedded object in model can be identified effectively.
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Halstead, J. Preston, Jerome S. O’Connor, Khuong Luu, Sreenivas Alampalli, and Amy Minser. "Fiber-Reinforced Polymer Wrapping of Deteriorated Concrete Columns." Transportation Research Record: Journal of the Transportation Research Board 1696, no. 1 (January 2000): 124–30. http://dx.doi.org/10.3141/1696-53.
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The New York State Department of Transportation initiated a fiber-reinforced polymer (FRP) Column Wrap Demonstration Project in March 1998. The purpose of this project is to investigate the effectiveness and efficiency of preserving deteriorated concrete with FRP, its possible detrimental effects, and its viability as an alternative for concrete column repair and rehabilitation without regard to seismic considerations. To the authors’ knowledge, this is the first FRP column wrap demonstration project of its kind to involve most of the FRP wrap suppliers in the United States. A 5-year condition-monitoring program was established to monitor the performance of FRP wrapping in preserving the concrete columns. A baseline condition of the piers was established through testing, including concrete cores for compressive strength, chlorides, pH, and freeze-thaw resistance; hammer soundings; and a tight-grid survey of electric potentials. Concrete spalls were repaired; however, delaminations were not. To monitor corrosion of the column reinforcing steel, corrosion probes using linear polarization technology were embedded in the concrete. Initial corrosion readings were collected before wrapping, enhancing the observed baseline condition data. In addition, concrete humidity and temperature probes were installed through the FRP wraps, and strain gauges were mounted on the FRP wraps. Data will be collected at 3-month intervals for 4 or 5 years. The wraps will be removed after monitoring, and a complete column testing program will be implemented at that time.
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Ross, Robert, Alex Stumpf, Dean Barnett, and Richard Hall. "Condition Assessment for Concrete Sewer Pipes Using Displacement Probes: A Robotic Design Case Study." Robotics 10, no. 2 (April 27, 2021): 64. http://dx.doi.org/10.3390/robotics10020064.
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Worldwide, millions of kilometres of sewers are constructed from concrete pipes. Unfortunately, concrete sewers are susceptible to corrosion from biogenic hydrogen sulphide, and, though they may pass visual inspection, their ability to hold together under load may be degraded. This paper presents the design of a teleoperated robot with a protractible probe, that allows an operator to apply a localised load to selected points within a concrete sewer pipe. We report findings from laboratory and field trials of our prototype, with initial results suggesting that this approach has the potential to contribute useful information to sewer maintenance planning.
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Hnin, Su Wai, Pakawat Sancharoen, and Somnuk Tangtermsirikul. "EFFECTS OF MIX PROPORTION ON ELECTRICAL RESISTIVITY OF CONCRETE WITH FLY ASH." ASEAN Engineering Journal 7, no. 2 (December 1, 2017): 53–65. http://dx.doi.org/10.11113/aej.v7.15492.
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The aim of this paper is to investigate the effects of mix proportion on electrical resistivity of concrete with fly ash. The electrical resistivity of concrete is measured by using four Wenner probes. The varied parameters in this study were water/binder ratio, fly ash content, and paste content. Electrical resistivity of water-saturated concrete at several different ages was studied and compared with compressive strength and rapid chloride penetration. Based on experimental results, a good relationship was obtained between results of compressive strength and rapid chloride penetration with electrical resistivity of concrete. The results of this study can be applied further to predict electrical resistivity of concrete when mix proportions are provided. According to the results, lower water/binder ratio concrete had higher resistivity than those with higher water/binder ratios. When cement was replaced at 40% by fly ash, electrical resistivity increased four times when compared to that of OPC concrete.
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Fares, Milia, Yannick Fargier, Géraldine Villain, Xavier Derobert, and Sergio Palma Lopes. "Determining the permittivity profile inside reinforced concrete using capacitive probes." NDT & E International 79 (April 2016): 150–61. http://dx.doi.org/10.1016/j.ndteint.2016.01.002.
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Egba, E. I., M. Ismail, and N. Bakhary. "Temperature Response in Hardened Concrete Subjected to Tropical Rainforest Environment." Engineering, Technology & Applied Science Research 7, no. 3 (June 12, 2017): 1623–28. http://dx.doi.org/10.48084/etasr.1076.
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The objective of this paper is to characterize concrete micro-environment temperature response to the natural climate of the tropical rainforest. The peculiar warmth, high humidity, and low pressure nature of the tropical rainforest necessitated the present study. Temperature probes were inserted into concrete specimens subjected to the sheltered and unsheltered environment to measure the micro-environment temperature of the concrete, and study the hysteresis characteristics in relation to the climate temperature. Some mathematical relationships for forecasting the internal temperature of concrete in the tropical rainforest environment were proposed and tested. The proposed relationships were found reliable. It was observed that the micro-environment temperature was lower at the crest, and higher at the trough than the climate environment temperature with a temperature difference of 1-3 oC. Also, temperature response in concrete for the unsheltered micro-environment was 1.85 times faster than the response in the sheltered micro-environment. The findings of the study may be used to assist the durability assessment of concrete.
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WOO, SANG-KYUN, YOUNG-CHUL SONG, and HONG-CHUL RHIM. "MEASUREMENT OF CRACK DEPTH LOCATED UNDER REINFORCEMENT IN REINFORCED CONCRETE SPECIMENS USING ULTRASONIC METHOD." Modern Physics Letters B 22, no. 11 (May 10, 2008): 1019–24. http://dx.doi.org/10.1142/s0217984908015772.
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The objective of this study is to determine crack depth located under reinforcement in concrete specimens using ultrasonic method. Experimental studies were performed on concrete specimens containing vertical and inclined surface-opening cracks with known depths. Experimental results have shown that the crack depth can be effectively measured when the distance between the probes is less than the crack depth. The effect of reinforcement on crack depth estimation is studied through a model by considering P-wave diffraction at the tip of crack and reinforcement. In addition, experimental results show that the ultrasonic method is one of useful methods to evaluate the crack depth in reinforced concrete.
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Mazariegos Pablos, Javier, Eduvaldo Paulo Sichieri, and Mário Sérgio de Andrade Zago. "Study for Utilization of Industrial Solid Waste, Generated by the Discharge of Casting Sand Agglomeration with Clay and of Blast Furnace Slag, in Concrete Composition." Key Engineering Materials 517 (June 2012): 611–16. http://dx.doi.org/10.4028/www.scientific.net/kem.517.611.
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This research project accomplished a study on the technical feasibility of recycling industrial solid waste generated by the discharge of casting sand agglomeration with clay and blast furnace slag. For this, the plan proposed a methodology that initially establishes a process of solid waste encapsulation, by using solidification/stabilization technique on Portland cement matrices, in which the residuals act as small and large aggregates on the composition of concrete, and later it presents the possibility of using this concrete in the manufacture of concrete pieces (concrete blocks) for paving. The results obtained in this research achieved the objective set with great success, regarding the manufacturing of concrete pieces (blocks) for paving urban roads, whenever there is special vehicle traffic or demands capable of producing accentuated abrasion effects (surpassing the 50 MPa required by the regulation), which probes the technical practicability of using waste from sand casting agglomeration with clay and blast furnace slag used in this study, unlocking usage possibilities for construction.
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Guihard, Vincent, Frédéric Taillade, Jean-Paul Balayssac, Barthélémy Steck, and Julien Sanahuja. "Permittivity measurement of cementitious materials and constituents with an open-ended coaxial probe: combination of experimental data, numerical modelling and a capacitive model." RILEM Technical Letters 4 (July 10, 2019): 39–48. http://dx.doi.org/10.21809/rilemtechlett.2019.77.
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The study presents the development of a new two-dimensional FEM numerical model describing the operation of two large open-ended coaxial probes designed to investigate the permittivity of concrete, and its constituents. This numerical simulation, combined with a capacitive approach describing the behaviour of the probes, enabled to prove the suitability of such device to determine the permittivity of dispersive dielectrics. Finding back the permittivity of a specified material by calculation of the S parameters, change of the reference plane and use of the capacitive model is the key to the proof. Measurements performed onto different materials show good similarities with the numerical simulations. Special considerations are mentioned concerning the size of the probe and its ability to measure the permittivity of heterogeneous materials made of large inclusions. Combination of such numerical tool and measuring device can be used as a non-destructive testing technique to assess the near surface permittivity of concrete structures or as a calibration technique for GPR measurements.
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Michałek, Jarosław. "Variation in Compressive Strength of Concrete aross Thickness of Placed Layer." Materials 12, no. 13 (July 5, 2019): 2162. http://dx.doi.org/10.3390/ma12132162.
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Is the variation in the compressive strength of concrete across the thickness of horizontally cast elements negligibly small or rather needs to be taken into account at the design stage? There are conflicting answers to this question. In order to determine if the compressive strength of concrete varies across the thickness of horizontally cast elements, ultrasonic tests and destructive tests were carried out on core samples taken from a 350 mm thick slab made of class C25/30 concrete. Special point-contact probes were used to measure the time taken for the longitudinal ultrasonic wave to pass through the tested sample. The correlation between the velocity of the longitudinal ultrasonic wave and the compressive strength of the concrete in the slab was determined. The structure of the concrete across the thickness of the slab was evaluated using GIMP 2.10.4. It was found that the destructively determined compressive strength varied only slightly (by 3%) across the thickness of the placed layer of concrete. Whereas the averaged ultrasonically determined strength of the concrete in the same samples does not vary across the thickness of the analyzed slab. Therefore, it was concluded that the slight increase in concrete compressive strength with depth below the top surface is a natural thing and need not be taken into account in the assessment of the strength of concrete in the structure.
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Broomfield, J. P., K. Davies, and K. Hladky. "Die Verwendung von Systemen zur dauernden Überwachung der Korrosion in neuen und bestehenden Stahlbetontragwerken / The Use of Permanent Corrosion Monitoring in New and Existing Reinforced Concrete Structures." Restoration of Buildings and Monuments 6, no. 6 (December 1, 2000): 631–46. http://dx.doi.org/10.1515/rbm-2000-5515.
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Abstract Corrosion monitoring systems consisting of linear polarisation, concrete resistivity and other probes have been installed in new structures to monitor durability and in existing structures to evaluate rehabilitation strategies such as corrosion inhibitor application and patch repairs. The types of sensors used, data collection techniques, results and interpretation are discussed.
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Cabrera, O. A., N. F. Ortega, M. I. Schierloh, and L. P. Traversa. "Influencia del curado sobre la evolución de la corrosión en vigas de hormigón armado con diferentes agregados finos." Revista ALCONPAT 2, no. 2 (May 30, 2012): 72–81. http://dx.doi.org/10.21041/ra.v2i2.28.
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RESUMENEn este trabajo se analiza cómo el tipo de curado afecta la microestructura de hormigones con diferentes agregados finos, respecto al ingreso de fluidos, que se vinculan estrechamente con el deterioro del acero. Se evaluaron de 5 grupos distintos de probetas y vigas de hormigón armado, con curados: normal, en ambiente de laboratorio, en mufla, en ambiente frío y bajo la acción del viento. Las vigas fueron sometidas a ensayos de corrosión acelerada, en presencia de cloruros. Se concluyó que la velocidad de succión capilar es muy sensible al tipo de curado. En la corrosión de las vigas, el curado defectuoso influyo fuertemente sobre el tiempo de aparición de la primera fisura, el área y el ancho máximo de fisuras.Palabras claves: arena triturada; forma y textura superficial; hormigón armado; corrosión; cloruros. ABSTRACTThis paper analyses how the type of curing affects concrete microstructures with different fine aggregates in relation to the ingress of fluids closely connected with steel deterioration. Five different groups of specimens and beams of reinforced concrete were evaluated with curing in normal conditions, at laboratory ambient, in muffle furnace, at cold ambient and under wind action. Beams were submitted to accelerated corrosion tests in the presence of chlorides. It was concluded that capillary suction is very sensitive to the type of curing. In beam corrosion, defective curing highly influenced the time of appearance of the first crack, the area and maximum wide of cracks.Keywords: crushed sand; shape and surface texture; reinforced concrete; corrosion; chlorides.
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Samson, Gabriel, Fabrice Deby, Jean-Luc Garciaz, and Jean-Louis Perrin. "Monitoring DIAMOND device for corrosion state evaluation of reinforced concrete structures." MATEC Web of Conferences 199 (2018): 04007. http://dx.doi.org/10.1051/matecconf/201819904007.
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The corrosion of steel rebars is a major issue with respect to the durability of reinforced concrete structure. Several corrosion evaluation methods exist: half-cell potential, concrete resistivity or linear polarization resistance (LPR) measurement. However, these techniques are employed at a given moment and are not suitable for continuous corrosion evaluation. This works belongs to the DIAMOND project which aims to produce a new corrosion state measurement monitoring device. The monitoring probe consists on a cylindrical probe. A ring shape counter-electrode CE is plated on the probe side. At the centre of the CE, a reference electrode (RE) is placed for potential measurement. The device is embedded in concrete at 25 mm of the inspected rebar. The instantaneous ohmic drop observed at the beginning of the polarization measurement is only linked with the concrete resistance which depends on concrete cover and resistivity. A numerical model was developed on Comsol® to create abacuses graph that link concrete resistivity and concrete resistance. Thus, the ohmic drop measure at the beginning of the polarization can now be used to determine regularly concrete average resistivity between the monitoring probe and steel rebar. Two other series of abacus graphs are then introduced in order to determine the polarization resistance of the rebar in front of the monitoring probe (the point of interest (PI)). Two monitoring probes were placed in two types of concrete (one sound concrete and one concrete with chloride). Corrosion potential, concrete resistivity and rebar corrosion rate were monitored over around 200 days. The experimental results obtained with the monitoring probe are finally compared to the results obtained with the surface DIAMOND probe (introduced in the ICCRRR 2018 paper “Alternative methodology for linear polarization resistance assessment of reinforced concrete structure [1]”).
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Habera, Łukasz, and Kamil Hebda. "Badania porównawcze liniowych ładunków kumulacyjnych." Nafta-Gaz 77, no. 6 (June 2021): 366–75. http://dx.doi.org/10.18668/ng.2021.06.02.
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The fireground tests are the best method for verifying the operation effectiveness of the entire shooting device or its component parts in real conditions. The purpose of the fireground tests presented herein was the physical verification of linear shaped charge (LSC) ability to perforate multi-layered target, reflecting the material and geometrical conditions of a borehole. The series of shooting tests included tests of three types of linear shaped charges selected for use in perfo-fracturing devices. The following shaped charges were tested: LSC in lead enclosure, having φ = 40 mm circular cross-section with shaped recess; LSC with copper liner in 20/30 mm steel trapezoid enclosure; LSC with liner made of solid copper, in 20/40 mm steel trapezoidal enclosure.During testing, the cumulative jet velocity was recorded using voltage type probes, arranged between the individual layers of a target composed of steel and concrete materials. The research method adapted for the project purposes was aimed at verification of the following thesis: whether the proposed shaped charges fulfil the technical and performance conditions for their effective application in the oil industry. The criterion adopted was the ability – or lack of ability – to perforate the multi-layered barrier in the form of two steel plates and concrete casting. The testing stand, single-use by its nature, was each time composed of concrete block having 400 mm ´ 250 mm ´ 150 mm dimensions and 20 MPa static compressive strength, on which two steel plates were placed parallel to each other with 20 mm spacing. The thickness of the plates was 5 mm and 10 mm respectively. The tested shaped charge was placed on the top steel plate at a distance of one calibre – that is the distance equal to the opening of the trapezoidal shaped charge and full diameter of circular cross-section charge. Furthermore, within media interface planes (steel/air, air/steel; steel/concrete), the set of voltage-type measuring probes was installed, in the form of single electric wires (φ = 0.25 mm). At an instant when they break (circuit break) as a result of cumulative jet operation, voltage drop in the subsequent measuring probes will act as a logical gate of start-stop type, or in other words the zero-one (0–1) type gate. The readings of individual probes breakage times allowed in addition to determine the velocity of the cumulative jet and to estimate its braking dynamics while passing through the subsequent elements of multi-layered target.
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Khanal, Shila, Susan L. Tighe, and Robert Bowers. "Pavement performance mechanics of interlocking concrete paver crosswalk designs." Canadian Journal of Civil Engineering 40, no. 7 (July 2013): 583–94. http://dx.doi.org/10.1139/cjce-2012-0222.
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This paper summarizes a research study that involved a partnership between Centre for Pavement and Transportation Technology located at University of Waterloo and Interlocking Concrete Pavement Institute. This research study involved the construction of eight crosswalks with different base and bedding materials at two test sites and was directed at defining the performance mechanics for designs with various bases and setting beds. The objective was to quantify the structural performance of four different interlocking concrete pavement designs under two loading scenarios. The Test Track typically experienced loaded garbage trucks up to 56 000 kg of maximum load. The Ring Road experienced traffic volume of a typical urban road. This research evaluated eight crosswalks of four different designs in these two locations. Sand set concrete base concrete header was one of the designs. Similarly, the combination of asphalt base, granular base, steel header, aluminum header, and concrete header were other designs of the crosswalks studied. Strain gauges, moisture probes, earth pressure cells, and thermistors were installed in the crosswalks to continuously monitor the structural and environmental impact from various loading conditions. Continued surveys were all performed as part of the research. Maximum recommended lifetime design equivalent single axle loads (ESALs) for bituminous set concrete base concrete header design was 7.5 million ESALs and sand set asphalt base asphalt header was recommended to have 1.5 million design ESALs. This paper presents the performance mechanics of the crosswalks from construction (2007–2009) to May 2010.
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Jin, Ming, Yuefeng Ma, Haoyu Zeng, Jiaping Liu, Linhua Jiang, Guo Yang, and Yue Gu. "Developing a Multi-Element Sensor to Non-Destructively Monitor Several Fundamental Parameters Related to Concrete Durability." Sensors 20, no. 19 (September 30, 2020): 5607. http://dx.doi.org/10.3390/s20195607.
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A design scheme of multi-element sensor which included electrical resistivity probes, multiple Cl− selective electrodes, and a steel corrosion monitoring system was proposed in this work. Embedding this multi-element sensor in concrete enables the real-time and non-destructive monitoring of internal electrical resistivity, free Cl− (Clf) contents in the concrete pore solution at different depths, and steel corrosion parameters. Based on the monitoring data obtained by the multi-element sensor, the freezing-thawing (F-T) damage degree, the Clf diffusion coefficient, the quantitative relation between F-T damage degree and Clf diffusion coefficient, the initiation period of steel corrosion, and the critical content related to steel corrosion are determined. To conclude, the multi-element sensor provides key durability parameters for the establishment of the Clf diffusion model, the assessment of health condition, and the prediction of service life of concrete under the coexistence of the F-T cycle and Cl−.
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Legat, A. "Monitoring of steel corrosion in concrete by electrode arrays and electrical resistance probes." Electrochimica Acta 52, no. 27 (October 2007): 7590–98. http://dx.doi.org/10.1016/j.electacta.2007.06.060.
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Liebold, F., H. G. Maas, and A. A. Heravi. "CRACK WIDTH MEASUREMENT FOR NON-PLANAR SURFACES BY TRIANGLE MESH ANALYSIS IN CIVIL ENGINEERING MATERIAL TESTING." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W18 (November 29, 2019): 107–13. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w18-107-2019.
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Abstract. This publication concentrates on the photogrammetric crack width measurement of crack patterns of concrete probes under impact loading in high-speed stereo image sequences. The presented algorithm works for non-planar specimens with deformations that only appear tangential to the surface and the method is based on triangle mesh analysis. Experiments were conducted with cylindrical specimens with an impact load affecting parallel to the main axis of the cylinder.
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Li, Lufan, Jun Xia, Chee Chin, and Steve Jones. "Fibre Distribution Characterization of Ultra-High Performance Fibre-Reinforced Concrete (UHPFRC) Plates Using Magnetic Probes." Materials 13, no. 22 (November 10, 2020): 5064. http://dx.doi.org/10.3390/ma13225064.
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Ultra-high performance fibre reinforced concrete (UHPFRC) is an innovative cement-based engineering material. The mechanical properties of UHPFRC not only depend on the properties of the concrete matrix and fibres, but also depend on the interaction between these two components. The fibre distribution is affected by many factors and previous researchers had developed different approaches to test the fibre distribution. This research adopted the non-destructive C-shape ferromagnetic probe inductive test and investigated the straight steel fibre distribution of the UHPFRC plate. A simplified characterization equation is introduced with an attenuation factor to consider the different plate thicknesses. The effective testing depth of this probe was tested to be 24 mm. By applying this method, fibre volume content and the fibre orientation angle can be calibrated for the entire plate. The fibre volume content generally fulfilled the design requirement. The fibre orientation angle followed a normal distribution, with a mean value of 45.60°. By testing small flexural specimens cut from the plates, it was found out that the mechanical performance (peak flexural strength) correlates with the product of fibre volume content and cosine fibre orientation angle.
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Root, Jenny R., Diane M. Browder, Alicia F. Saunders, and Ya-yu Lo. "Schema-Based Instruction With Concrete and Virtual Manipulatives to Teach Problem Solving to Students With Autism." Remedial and Special Education 38, no. 1 (August 2, 2016): 42–52. http://dx.doi.org/10.1177/0741932516643592.
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The current study evaluated the effects of modified schema-based instruction on the mathematical word problem solving skills of three elementary students with autism spectrum disorders and moderate intellectual disability. Participants learned to solve compare problem type with themes that related to their interests and daily experiences. In addition, researchers compared the effects of concrete and virtual manipulatives within the treatment package. Results of the multiple probes across participants with an embedded alternating treatments design showed a functional relation between modified schema-based instruction and word problem solving. Two of three participants performed more steps in the virtual condition and one participant had equal performance in both concrete and virtual conditions. When given a choice between conditions upon skill mastery, all three participants preferred the virtual condition and maintained treatment effects. Implications for practice and future research are discussed.
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Pérez Casal, O., Alfonso Cobo Escamilla, M. E. Moreno Fernández, and M. I. Prieto Barrio. "Comportamiento mecánico de secciones de hormigón y mortero = Mechanical behavior of concrete-mortar sections." Anales de Edificación 4, no. 3 (September 15, 2018): 10. http://dx.doi.org/10.20868/ade.2018.3795.
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ResumenEl objetivo del presente trabajo es comparar el comportamiento de los elementos estructurales sometidos a flexión o compresión después de haber sido reparados, mediante la sustitución del hormigón deteriorado por mortero de cemento Portland o mortero modificado con polímeros. En primer lugar, las probetas cúbicas se fabricaron con diferentes proporciones de reparación de mortero de cemento para ensayar a compresión, con los materiales colocados tanto en serie como en paralelo. Del análisis de resultados, se puede concluir que los sistemas mixtos - mortero de hormigón modificado con polímeros sometido a compresión pueden soportar cargas mayores que la reparación del mortero de cemento Portland, aunque en ningún caso pueden restaurar la capacidad de carga del hormigón. En los elementos sometidos a flexión, las vigas reparadas pueden alcanzar la resistencia inicial a la fractura de las vigas y soportar cargas aún mayores. Por lo tanto, la reparación de estructuras de cemento deterioradas con morteros de reparación es una buena alternativa, especialmente en elementos estructurales sometidos a flexión, y se realizan con morteros de cemento Portland. En las estructuras sometidas a compresión, es mejor utilizar morteros de reparación modificados con polímeros que aumentan la ductilidad cuando el mortero de reparación se ubica en serie con respecto a la carga.AbstractThe aim of the present work is to compare the behavior of structural elements subjected to bending or compression after having been repaired, by substituting the deteriorated concrete by Portland cement mortar or mortar modified with polymers. Firstly, cubic specimens were manufactured with different repair concrete-mortar proportions to be tested to compression, with the materials placed both in series and in parallel. From the results analysis, it can be concluded that mixed systems - polymer-modified concrete mortar subjected to compression can withstand greater loads than the repair Portland cement mortar, although they are in no case able to restore the load capacity of concrete. In elements subjected to bending, the repaired beams are able to achieve the initial fracture strength of the beams, and support even higher loads. Therefore, repairing deteriorated concrete structures using repair mortars is a good alternative, especially in structural elements subjected to bending, and performed using Portland cement mortars. In structures subject to compression, it is better to use repair mortars modified with polymers which increase the ductility when the repair mortar is located in series regarding the load
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Hirano, Mikio, Kazuhito Noguchi, and Toru Hosokawa. "Autobiographical Recollection and Affects of Cues in an Amnesic Patient." Psychological Reports 85, no. 3_suppl (December 1999): 1113–17. http://dx.doi.org/10.2466/pr0.1999.85.3f.1113.
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The individual described herein (Y.K.) is a pure amnesic patient with severe anterograde amnesia and a selective loss of specific personal episodes in his remote memories. In this study, we examined whether more concrete cues could elicit specificity in his autobiographical memory. It was found that the richness of his autobiographical memory under the condition with probes was significantly higher than condition without probes, although Y.K.'s performance on recalling autobiographical memory was inferior to that of control subjects under both conditions. These results and our previous findings indicate that neither the disorder at the level of the framework's thematic retrieval nor the destruction of individual traces will account for the loss of Y.K.'s autobiographical memory. We suspect that Y.K.'s loss of autobiographical memory may be due to problems in the interface between thematic retrieval frameworks and individual traces.
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Zhang, Li Feng, Jun Ying Lai, Xiao Qian Qian, and Chong Shen. "The Early-Age Drying Shrinkage of Cement-Based Materials with the same Workability after Temperature Compensation." Applied Mechanics and Materials 405-408 (September 2013): 2604–9. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.2604.
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The early age drying shrinkage of cement-based materials with same the same workability staring from the initial setting time was studied. Superplasticizers (SP) were used to get the same workability. The drying shrinkage of paste was measured by clock gauge, and CABR-NES deformation instrument was used to measure the shrinkage of concrete. Temperature probes were buried into both paste and concrete specimen cores to measure the temperature curve, and temperature deformation was considered into the early shrinkage. Results show the addition of SP increases much more shrinkage than the control group, and polycarboxylate SP increases more shrinkage than naphthalene SP. The different temperature peak time of different mixtures show that the addition of SP changes the hydration process of cement, and the shrinkage of cement-based materials after temperature compensation is bigger than the measured value in the first 6 hours, but the gap is not big.
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Tsakstara, V., T. S. Kosmas, and J. Sinatkas. "Nuclear response to supernova neutrino spectra." HNPS Proceedings 18 (November 23, 2019): 187. http://dx.doi.org/10.12681/hnps.2551.
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In current probes searching for rare event processes, appropriate nuclear targets are employed (in the COBRA double-beta decay detector the CdZnTe semiconductor is used). In this work the response of such detectors to various low-energy neutrino spectra is explored starting from state-by-state calculations of the neutrino-nucleus reactions cross sections obtained by using the quasi particle random phase approximation (QRPA) based on realistic two-body residual interactions. As a concrete example, we examine the response of 64Zn isotope to low energy supernova neutrinos.
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Lin, Xingrui, and Wenming Liu. "The application of Taiji thought in packaging design." E3S Web of Conferences 179 (2020): 02010. http://dx.doi.org/10.1051/e3sconf/202017902010.
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This article starts with the thought of Taiji, and analyzes the related contents of Taiji elements. The visual guidance sequence in packaging design was analyzed through the analysis of the human eye’s visual guidance mode. This paper probes into the symbolic elements of the shape and composition of Taiji graphics, and obtains the concrete practice way of Taiji thought and visual guidance in packaging design, by combining the traditional Chinese Taiji thought with the modern visual conduction theory, a new way of modern packaging design is obtained.
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Peccia, Jordan, Eric A. Marchand, Joann Silverstein, and Mark Hernandez. "Development and Application of Small-Subunit rRNA Probes for Assessment of Selected Thiobacillus Species and Members of the Genus Acidiphilium." Applied and Environmental Microbiology 66, no. 7 (July 1, 2000): 3065–72. http://dx.doi.org/10.1128/aem.66.7.3065-3072.2000.
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ABSTRACT Culture-dependent studies have implicated sulfur-oxidizing bacteria as the causative agents of acid mine drainage and concrete corrosion in sewers. Thiobacillus species are considered the major representatives of the acid-producing bacteria in these environments. Small-subunit rRNA genes from all of the Thiobacillus andAcidiphilium species catalogued by the Ribosomal Database Project were identified and used to design oligonucleotide DNA probes. Two oligonucleotide probes were synthesized to complement variable regions of 16S rRNA in the following acidophilic bacteria:Thiobacillus ferrooxidans and T. thiooxidans(probe Thio820) and members of the genus Acidiphilium(probe Acdp821). Using 32P radiolabels, probe specificity was characterized by hybridization dissociation temperature (Td ) with membrane-immobilized RNA extracted from a suite of 21 strains representing three groups of bacteria. Fluorochrome-conjugated probes were evaluated for use with fluorescent in situ hybridization (FISH) at the experimentally determinedTd s. FISH was used to identify and enumerate bacteria in laboratory reactors and environmental samples. Probing of laboratory reactors inoculated with a mixed culture of acidophilic bacteria validated the ability of the oligonucleotide probes to track specific cell numbers with time. Additionally, probing of sediments from an active acid mine drainage site in Colorado demonstrated the ability to identify numbers of active bacteria in natural environments that contain high concentrations of metals, associated precipitates, and other mineral debris.
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Cataldo, Andrea, Raissa Schiavoni, Antonio Masciullo, Giuseppe Cannazza, Francesco Micelli, and Egidio De Benedetto. "Combined Punctual and Diffused Monitoring of Concrete Structures Based on Dielectric Measurements." Sensors 21, no. 14 (July 16, 2021): 4872. http://dx.doi.org/10.3390/s21144872.
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This work presents a microwave reflectometry-based system for monitoring large concrete structures (during the curing process and also while the structure is in use), through the combined use of punctual and diffused sensing elements. In particular, the adoption of punctual probes on a reference concrete specimen allows the development of an innovative and accurate calibration procedure, useful to obtain the value of the water content on a larger structure made of the same material. Additionally, a wire-like diffused sensing element can be permanently embedded in buildings and used to monitor the structure along the entire length of the sensing element. The adopted diffused sensing element can be used not only to detect dielectric variation during the curing process, but also throughout the service life of the structure. The combined use of punctual and diffused sensing elements represents an important innovation from a procedural point of view, able to provide detailed and quantitative information on the health status of the structure both during and after construction.
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Zhang, Guo Rong, Xiao Dong Wang, Jian Kun Han, and Yi Xuan Han. "Relationship Study and Primary Application between Gas Permeability and Crack State on Bridge Joint Concrete." Materials Science Forum 1018 (January 2021): 153–61. http://dx.doi.org/10.4028/www.scientific.net/msf.1018.153.
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For evaluating the crack state on solid bridge joint on site, the relationship between gas permeability and crack width of joint concrete is studied both on material and structural levels in this article. In laboratory tests, gas permeability tests on concrete samples with macrocrack are performed, the relationship between the relative gas permeability rate k/k0 and the relative variation of crack width ac is established combining with regression analysis, the fitting curve equation is . when ac increases by 1.125×10-2 mm, the gas permeability increases about 10 times compared with the initial state. In field tests, “pulse tests” are performed on bridge joint based on 3 embedded pulse probes to measure the evolution of gas permeability during bridge operation. The results show, firstly, the gas permeability of joint concrete are in the order of 10-16~10-19 m2, which indicates a good compaction performance; Secondly, an order of magnitude increase of gas permeability of one probe in different ages, or the fact that the gas permeability at one position in solid joint is obviously larger than the other positions, these phenomena indicate the existence of original defects, or the possibility of macrocrack appearance from microcracks, and the crack width increases by about 0.01 mm.
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Hernandez, Mark, Eric A. Marchand, Deborah Roberts, and Jordan Peccia. "In situ assessment of active Thiobacillus species in corroding concrete sewers using fluorescent RNA probes." International Biodeterioration & Biodegradation 49, no. 4 (June 2002): 271–76. http://dx.doi.org/10.1016/s0964-8305(02)00054-9.
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FONDEVILA ANTOLÍN, Jorge. "La obligación de utilización de medios electrónicos en los procesos selectivos: ciudadanos o súbditos." RVGP 20, no. 20 (June 30, 2021): 88–111. http://dx.doi.org/10.47623/ivap-rvgp.20.2021.05.
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Laburpena: Lan honetan, gaur egun indarrean dagoen arau-esparruak (Administrazio Publikoen Administrazio Prozedura Erkideari buruzko Legeak) zer-nolako aukerak eta mugak xedatzen dituen aztertzen da, hautapen-prozesuetan herritarrak bitarteko elektronikoak erabiltzera behartzeari dagokionez. Hala, kontua behar bezala ebaluatzeko, lanak esparru juridiko horren azterketa orokorra egiten du lehenik, hautapena kudeatzeko eremuan halabeharrez aplikatu behar baita. Gero, arau-esparrua hautapen-prozeduretan eta lotura zuzenik gabeko eremu batzuetan (hala nola, hautapen-organoen funtzionamenduaren araubide juridikoan eta egin beharreko probetan edo ariketetan) nola ezartzen den aztertzen da. Azkenik, administrazioaren jarduera txar batzuk aipatzen dira, kontuaren ikuspegi bateratu eta sistematizatua eskaintzeko. Resumen: Este trabajo examina las posibilidades y límites que el actual marco normativo vigente (LPAC) permite para imponer la obligación de utilización de medios electrónicos a los ciudadanos/as en los procedimientos selectivos. Así, para una correcta evaluación de esta cuestión el trabajo realiza un previo examen general del citado marco jurídico, ya que el mismo resulta de necesaria aplicación al ámbito de la gestión de la selección. Posteriormente, se procede al estudio sobre su implementación concreta en los procedimientos selectivos y a algunos ámbitos en los que su conexión no es directa (régimen jurídico de funcionamiento de los órganos selectivos y las pruebas o ejercicios a desarrollar), finalizando con la referencia a algunas malas prácticas administrativas, de esa manera se ofrece una visión conjunta y sistematizada de la cuestión. Abstract: This work examines the possibilities and limits enabled by the current regulatory framework (LPAC) with respect to imposing the obligation to use electronic media on citizens in selection processes. Thus, for a correct evaluation of this question, the work carries out a prior general examination of the aforementioned legal framework, given its necessary application to the field of recruitment management. Subsequently, a study is carried out on its concrete implementation in selection procedures and in some areas where its connection is not direct (legal operating system of the selection bodies and the tests or exercises to be carried out), ending with the reference to certain poor administrative practices, thus offering a joint and systematized view of the issue.
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Villain, Géraldine, Amine Ihamouten, and Xavier Dérobert. "Determination of concrete water content by coupling electromagnetic methods: Coaxial/cylindrical transition line with capacitive probes." NDT & E International 88 (June 2017): 59–70. http://dx.doi.org/10.1016/j.ndteint.2017.02.004.
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Hassan, Hossam F., Thomas D. White, Rebecca McDaniel, and David Andrewski. "Indiana Subdrainage Experience and Application." Transportation Research Record: Journal of the Transportation Research Board 1519, no. 1 (January 1996): 41–50. http://dx.doi.org/10.1177/0361198196151900106.
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The applications of pavement subdrainage in the state of Indiana are presented. A recent study evaluated pavement subdrainage systems and measured and predicted moisture conditions underneath various types of pavements. Camera systems were used for internal inspection of the edge and geocomposite drains. Pavement instrumentation included moisture blocks, pressure transducers, temperature probes, rain and outflow tipping buckets, and a data acquisition system. Ongoing research using a test site on I-469 at Fort Wayne, Indiana, is aimed at finding the optimum location and layer configuration in flexible pavement; it uses those instruments as well as a TDR system, neutron probes, resistivity probe trees, and an enhanced data acquisition process. The research is a long-term project that will build on the data base of material hydraulic characteristics and performance. Indiana Department of Transportation has formed a committee to address issues related to use of subdrainage. Some of the recommendations from the committee were to abandon geocomposite drains, use bigger concrete protector walls at outlet pipes, and implement a routine inspection and maintenance program for drainage systems.
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Mills, Douglas, Paul Lambert, and Shengming Yang. "Electrochemical Noise Measurement to Assess Corrosion of Steel Reinforcement in Concrete." Materials 14, no. 18 (September 18, 2021): 5392. http://dx.doi.org/10.3390/ma14185392.
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The electrochemical noise method (ENM) has previously been employed to monitor the corrosion of steel reinforcement in concrete. The development of solid-state Ag/AgCl-based probes and dedicated monitoring technology (ProCoMeter) now offers a wider range of ENM configurations. The present study involves the laboratory investigation of three mortar samples containing steel bars and varying additions of chloride, with a view to future field application. ENM could be used to provide corrosion information on reinforcement without the need to provide direct electrical connections to the steel and without the risk or inducing or increasing corrosion. In addition to half-cell potentials, measurements were made using ENM in three different probe configurations over a total test period of 90 days. The samples were then broken open and the bars extracted and cleaned. A comparison was then made between the calculated metal thickness loss obtained from the Rn values and the actual metal thickness loss. The results showed that each configuration was able to order the results in the expected manner, with the simple single substrate (SSS) arrangement providing the best correlation with direct measurements. The study is ongoing with the intention of measurements being obtained in situ on existing reinforced concrete structures.
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Raczkiewicz, Wioletta, Artur Wójcicki, and Adam Wójcicki. "Using the galvanostatic pulse method to estimate the corrosion of reinforcement in structural elements." South Florida Journal of Development 2, no. 3 (August 9, 2021): 4865–76. http://dx.doi.org/10.46932/sfjdv2n3-080.
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ABSTRACT
Early steel bars corrosion in reinforced concrete elements is difficult to detect because of the lack of visible changes on the concrete surface. To assess reinforcement corrosion risk level without structure damage some non-destructive diagnostic methods are applied. One of them is the galvanostatic pulse method. This semi-non-destructive electrochemical method allows to determine the corrosion areas and estimate the steel bars corrosion activity. Using this method it is possible to measure some electrical parameters (corrosion current density, stationary potential and reinforcement concrete cover resistivity) that allow to indirectly estimate the reinforcement corrosion progress in concrete. So far this method has been generally applied to bridges. The article presents results of studies in which the galvanostatic pulse method was used to determine reinforcement corrosion risk in structures elements different than bridges. Two types of reinforced concrete columns were tested under different environment conditions and two groups of laboratory specimens which were subjected to freezing and thawing cycles in NaCl solution or stayed in natural air–dry conditions. The apparatus GP-5000 GalvaPulseTM was used. Based on the obtained results the conclusions were drawn. The galvanostatic pulse method allows to assess the progress of the reinforcement corrosion process in tested elements. However, it is necessary to measure simultaneously all parameters and make their complex analysis.
RESUMEN
La corrosión temprana de las barras de acero en elementos de hormigón armado es difícil de detectar debido a la falta de cambios visibles en la superficie del hormigón. Para evaluar el nivel de riesgo de corrosión de la armadura sin dañar la estructura se aplican algunos métodos de diagnóstico no destructivos. Uno de ellos es el método del pulso galvanostático. Este método electroquímico semi no destructivo permite determinar las áreas de corrosión y estimar la actividad de corrosión de las barras de acero. Utilizando este método es posible medir algunos parámetros eléctricos (densidad de corriente de corrosión, potencial estacionario y resistividad de la cubierta del hormigón de la armadura) que permiten estimar indirectamente el progreso de la corrosión de la armadura en el hormigón. Hasta ahora este método se ha aplicado generalmente a los puentes. El artículo presenta los resultados de estudios en los que se utilizó el método de impulsos galvanostáticos para determinar el riesgo de corrosión de las armaduras en elementos de estructuras diferentes a los puentes. Se ensayaron dos tipos de columnas de hormigón armado en diferentes condiciones ambientales y dos grupos de probetas de laboratorio que se sometieron a ciclos de congelación y descongelación en solución de NaCl o permanecieron en condiciones naturales de secado al aire. Se utilizó el aparato GP-5000 GalvaPulseTM. A partir de los resultados obtenidos se extrajeron las siguientes conclusiones El método de impulsos galvanostáticos permite evaluar el progreso del proceso de corrosión de la armadura en los elementos ensayados. Sin embargo, es necesario medir simultáneamente todos los parámetros y realizar su complejo análisis.