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1
Dondi, Giulio, Francesco Mazzotta, Claudio Lantieri, Federico Cuppi, Valeria Vignali e Celestino Sangiovanni. "Use of Steel Slag as an Alternative to Aggregate and Filler in Road Pavements". Materials 14, n. 2 (12 gennaio 2021): 345. http://dx.doi.org/10.3390/ma14020345.
Testo completoAbstract (sommario):
Today the use of Construction and Demolition Materials (CDM) can be considered as a suitable solution for the construction or the rehabilitation of road pavements. In this context, it is central to minimizing waste production, favoring the reuse through new production cycles to replace virgin natural raw materials. As illustrated in this study, steel slag has mechanical properties that justify its use as aggregate in the manufacture of bituminous mixes. In road construction, their use is focused on the substitution of fine aggregate and filler in bituminous mixtures. Mechanical characterizations, Marshall stability and indirect tensile resilient modulus (ITSM) tests were used to evaluate the laboratory performance of the mixtures. The research aims are to provide the use of these materials for the construction of the entire road pavement structure; in this study authors used these materials both in the characterization of cementitious layers and in those with bituminous conglomerate. In both cases, the use of steel slag has favored an increase of stiffness in the mixtures.
2
Soares, Roberto, Rielle Haichert, Diana Podborochynski e Curtis Berthelot. "Modeling in Situ Performance of Cement-Stabilized Granular Base Layers of Urban Roads". Transportation Research Record: Journal of the Transportation Research Board 2363, n. 1 (gennaio 2013): 88–95. http://dx.doi.org/10.3141/2363-10.
Testo completoAbstract (sommario):
This study used a three-dimensional nonlinear orthotropic computational road model to measure the performance of reclaimed and recycled portland cement concrete (PCC) aggregates and reclaimed asphalt pavement (RAP) aggregates stabilized with cement as a base layer in a typical local road structure in the city of Saskatoon, Saskatchewan, Canada. The pavement structure was composed of 45-mm hot-mix asphalt concrete on a 225-mm granular base built directly over an in situ subgrade. The cross section was analyzed with a conventional granular base layer as a baseline and PCC and RAP base layers with 2% cement stabilization. The cement-stabilized PCC and RAP base layers showed improved shear strain and horizontal strain behavior when compared with the conventional granular base layer (which was not cement stabilized). This improvement con-firmed that cement stabilization of reclaimed PCC and RAP materials provided an enhanced primary response. This study demonstrated that typical thin Saskatoon pavement structures were highly dependent on the constitutive properties of base layer material. Stabilizing the PCC and RAP base layers with 2% cement reduced the maximum shear strains at the edge of the pavement structure by 12% and 25%, respectively, compared with the unstabilized conventional granular base layer. It was believed that the increased fracture and cohesion of the residual cementitious materials inherent to recycled granular base, as well as the cementitious binder added, improved structural performance.
3
Rashidi, Mohammad, Reza S. Ashtiani, Jimmy Si, Richard P. Izzo e Mark McDaniel. "A Practical Approach for the Estimation of Strength and Resilient Properties of Cementitious Materials". Transportation Research Record: Journal of the Transportation Research Board 2672, n. 52 (14 maggio 2018): 152–63. http://dx.doi.org/10.1177/0361198118769900.
Testo completoAbstract (sommario):
Cementitious stabilization of granular soils has been proven to be a cost-saving option for the use of materials with marginal quality in the construction and rehabilitation of pavement structures. The orthogonal load distribution capacity of the Cement-Stabilized Materials (CSM) is typically characterized by Unconfined Compressive Strength (UCS), Indirect Tensile Strength (IDT), and Resilient Modulus (Mr) tests in the laboratory. The aforementioned parameters and properties are integral components of the analysis and design of pavements with stabilized layers. Time and budget constraints make it impractical for many state agencies to complete the full laboratory characterization protocols to determine all the design input parameters. Therefore, in many cases, the design engineers opt out of laboratory testing and primarily rely on past experience and engineering judgments to assign design input parameters. Such an approach compromises the reliability of the pavement life predictions, and can potentially incur unforeseen costs to the traveling public. This study was designed to bridge this gap by developing a series of statistically robust relationships between the laboratory achived data to provide an estimate of the design input parameters. To accomplish this objective, 570 stabilized cylindrical specimens were prepared and subjected to UCS, IDT, and submaximal modulus tests at three strength ratio levels. Subsequently, the relationships between the IDT, UCS, and resilient modulus at small-strain and intermediate strain levels were developed in this study. Such relationships can serve as a valuable means for the estimation of the tensile and compressive strength of the CSM for pavement design.
4
Costa, Juliana O., Paulo H. R. Borges, Flávio A. dos Santos, Augusto Cesar S. Bezerra, Wim Van den bergh e Johan Blom. "Cementitious binders and reclaimed asphalt aggregates for sustainable pavement base layers: Potential, challenges and research needs". Construction and Building Materials 265 (dicembre 2020): 120325. http://dx.doi.org/10.1016/j.conbuildmat.2020.120325.
Testo completo
5
Pan, Yang, e Chao Wu. "Experimental Study on the Impact Fatigue Behavior of GFRP Mesh Reinforced ECC for Runway Pavement Application". MATEC Web of Conferences 275 (2019): 01010. http://dx.doi.org/10.1051/matecconf/201927501010.
Testo completoAbstract (sommario):
Concrete pavement is easy to crack and generate the chunks, which may destroy the engine of the airplane and maintenance cost is very expensive. Engineered cementitious composites (ECC) is ductile with microcracks, but its strength is low. Glass Fiber Reinforced Polymer (GFRP) mesh imbedded in ECC could improve the strength. This paper investigates the impact fatigue behaviour of ECC and GFRP mesh reinforced ECC under 5 different impact pressures (1.61 MPa, 1.88 MPa, 2.10 MPa, 2.41 MPa and 3.60 MPa), the concrete specimens were also tested for comparison. The pulse velocity through the specimens was also tested to analyse the damage of the specimens. The experimental results show that GFRP mesh reinforced ECC has improved impact fatigue behaviour than ECC specimens. The concrete specimens were all broken after a few impacts, but the GFRP mesh reinforced ECC specimens were all not broken after impacted for 30000 times. The impact fatigue behaviour of ECC reinforced with two layers of GFRP mesh with a grid dimension of 10 mm was the best, which is a desirable pavement composite comparing to the ordinary concrete and ECC without reinforcements.
6
Ariyo, Adanikin, Funsho Falade e Adewale Olutaiwo. "Microstructural Analysis of Concrete Using Cow Bone Ash for Alkali-Silica Reaction (ASR) Suppression". Journal of Casting & Materials Engineering 4, n. 2 (15 luglio 2020): 34–40. http://dx.doi.org/10.7494/jcme.2020.4.2.34.
Testo completoAbstract (sommario):
Concrete pavements are prone to microstructural changes and deterioration when exposed to Alkali-Silica Reaction (ASR). ASR results in strength reduction, cracking, spalling and other defects in the concrete if left unchecked. Supplementary Cementitious Materials (SCMs) such as Cow Bone Ash (CBA) however can be used to improve concrete performance, hence its use in this study. Concrete samples were prepared at replacement levels of 0%, 5%, 10%, 15%, 20% and 30% of cement with Cow Bone Ash. The concrete samples were then subjected to petrographic and Scanning Electron Microscopy (SEM) analysis. Petrographic examination shows that the minimal and least amount of ASR gels and micro cracking were observed at 15% CBA replacement of cement in the concrete samples. Scanning Electron Microscopy (SEM) analysis shows that changes in the elemental composition of the concrete samples is related to the effect of CBA which enhances adhesion in the concrete. SEM analysis show that, in general, the change in microstructure in the concrete was mainly due to the change in the arrangement of the C-H-S compounds. The microstructure analysis indicates that CBA in concrete influences the densification of the concrete at the transition zone, resulting in a much lower porosity. This results in the concrete having a tightly bound layer that repels ingress of water and thereby inhibiting cracks and gel formation as water is a contributing factor to the ASR in concrete.
7
Li, Xiaojun, Jingan Wang, Haifang Wen e Balasingam Muhunthan. "Field Calibration of Fatigue Models of Cementitiously Stabilized Pavement Materials for Use in the Mechanistic-Empirical Pavement Design Guide". Transportation Research Record: Journal of the Transportation Research Board 2673, n. 2 (febbraio 2019): 427–35. http://dx.doi.org/10.1177/0361198118821924.
Testo completoAbstract (sommario):
The use of cementitiously stabilized materials (CSM), such as lean concrete, cement-stabilized aggregate, and soil stabilized with cement, lime, fly ash, or combinations thereof in the subgrade, sub-base, and base layers of flexible and rigid pavement structures, is a widely accepted practice by many state highway agencies. However, the bottom-up fatigue cracking models of cementitiously stabilized layers (CSL) described in the AASHTO Interim Mechanistic-Empirical Pavement Design Guide Manual of Practice (referred to as the MEPDG) have not been calibrated for CSM based on their field performance. In addition, top-compression fatigue as well as the effects of increases in the modulus and strength values of CSM over time, erosion, and freeze–thaw and wet–dry cycles on the fatigue properties of CSM are not considered in the MPEDG. To address these deficiencies, this research calibrated the bottom-up fatigue model, and developed and calibrated the top-compression fatigue model, with consideration of modulus and strength growth, erosion, and freeze–thaw and wet–dry cycles. Reasonable correlations between the predicted modulus values and measured modulus values are found for CSL. Further study is needed to refine the calibration and validate the models based on a larger population of field data that covers different material types, climatic zones, and traffic conditions.
8
Bajak, Marzena. "Mechanical characteristics of Asphalt-Cement Concrete foundations (ACC)." Budownictwo i Architektura 1, n. 1 (11 dicembre 2007): 057–86. http://dx.doi.org/10.35784/bud-arch.2302.
Testo completoAbstract (sommario):
Asphalt Cement Concrete (ACC) is a new material. On the basis of Kuhn’s paradigm, conventional methods which are proper for similar road pavement materials were applied for studying the ACC. ACC is obtained from cold mixing technology such ingredients as cement-sand mortar or cement-mineral aggregate mortar, or cement-sand-mineral aggregate mortar with recycled Asphalt Concrete (AC) mixture or with recycled Mastic Asphalt (MA) mixture. Quick setting cement (CEM I 52,5 NA) is used in all mentioned cases. Novelty of the presented material is due to existence of two internal bounds - flexibility and rigidity. Such ACC parameters as stiffness, deformability and strength in general depend on type and characteristics of cementitions grout which coats applied recycled asphalt materials and fills mixture’s air voids. ACC layer stability may be predicted using viscoelastic model parameters of constitutive relations, including Burgers model, under steady and slow loadings, finally expressed by exponential formulae. This is the research study. Its basic part consists of laboratory and field testing and obtained tests results analysis. Further, road pavements were designed with subbase of ACC with improved performance comparing to typical materials.
9
de Larrard, François, Rafael Martinez-Castillo, Thierry Sedran, Philippe Hauza e Jean-Eric Poirier. "Cementitious artificial aggregate particles for high-skid resistance pavements". Road Materials and Pavement Design 13, n. 2 (giugno 2012): 376–84. http://dx.doi.org/10.1080/14680629.2012.666642.
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Marszałek, Jan, Karolina Gulańczyk e Paweł Muzolf. "Strengthening airfield pavements with cement concrete layers". Bulletin of the Military University of Technology 67, n. 2 (29 giugno 2018): 119–32. http://dx.doi.org/10.5604/01.3001.0012.0972.
Testo completoAbstract (sommario):
The paper presents original solutions and methodology for determining the thickness of cement concrete strengthening layers for repairing and upgrading existing flexible and rigid airfield pavements. Flow diagrams and nomograms for determining edge stress were developed. These are novel solutions which have not been presented in a similar form before now. After deriving the above relations, a method for the practical utilisation of the resulting monograms depending on the parameters of existing airfield pavement and properties of the cement concrete strengthening layer is presented. Preparing calculation-based charts using the derived equations will markedly shorten the procedure of selecting the thickness of cement concrete strengthening layers for existing flexible airfield pavements that require repair depending on the degree of their wear. Keywords: rigid airfield pavement, flexible airfield pavement, pavement strengthening
11
Priddy, Lucy P., e Timothy W. Rushing. "Development of Laboratory Testing Protocol for Rapid-Setting Cementitious Material for Airfield Pavement Repairs". Transportation Research Record: Journal of the Transportation Research Board 2290, n. 1 (gennaio 2012): 89–98. http://dx.doi.org/10.3141/2290-12.
Testo completoAbstract (sommario):
Many commercial off-the-shelf products for repairing portland cement concrete (PCC) pavements provide short set times, high early strengths, and the durability to withstand aircraft traffic. Twenty-five rapid-setting cementitious materials were investigated through laboratory and field evaluations to determine their suitability for repairing critical PCC airfield pavements. Standard laboratory tests were performed to characterize the properties of the materials and provide a protocol for assessing their suitability for field repairs. Criteria for using rapid-setting cementitious materials for repairing airfield pavements were published in 2008 by the U.S. Air Force. The criteria, based on laboratory and full-scale testing, allowed users to reduce the risk of premature failure of repairs by omitting unacceptable materials from their list of potential repair materials. The American Society of Testing and Materials published a similar test protocol in 2009. On the basis of a comparison of these two certification procedures and knowledge gained through field experience, the Air Force selection protocol was further updated in 2010 to improve the material selection process. The laboratory test methods used to develop the selection protocol along with the results from the material investigations are discussed in this paper.
12
Chehab, Ghassan R., Yara S. Hamdar e Angela J. Haddad. "Investigating High-Temperature PG Grade Adjustment Recommendations for Airfield Pavements". Transportation Research Record: Journal of the Transportation Research Board 2673, n. 5 (29 marzo 2019): 365–73. http://dx.doi.org/10.1177/0361198119838259.
Testo completoAbstract (sommario):
This study aims to investigate the high-temperature performance grade (PG) adjustment (bumping) recommendations included in various international specifications and guidelines for airfield pavements, particularly for asphalt intermediate and base layers. The research was instigated following recent asphalt rutting occurrences in airport pavements. Mechanistic analysis, using the software FlexPave™, was employed to assess airfield pavement responses under hot climatic conditions and for different loading conditions. The results of the analysis pointed to three important factors that should be considered when selecting binder PG grades for airfield pavements, particularly for the asphalt intermediate and base layers: (1) deeper layers within an airfield pavement structure are subjected to considerably high compressive stresses; (2) deeper layers within an airfield pavement structure are subjected to longer loading times compared with surface layers; and (3) deeper layers within a pavement structure experience consistently high temperatures. Therefore, it is recommended that PG grade bumping be applied beyond the surface layer in airfield pavements, to the intermediate and base layers, in locations that experience very high temperatures and where rutting is a critical distress. This recommendation was supported by two case studies of airfield pavements in hot climates, where the one that applied PG grade bumping for the base layer performed well under heavy loading, while the one that did not apply PG grade bumping experienced premature rutting failure.
13
Zhang, Jun, Zhenbo Wang e Xiancun Ju. "Application of ductile fiber reinforced cementitious composite in jointless concrete pavements". Composites Part B: Engineering 50 (luglio 2013): 224–31. http://dx.doi.org/10.1016/j.compositesb.2013.02.007.
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Shoukry, Samir N., D. R. Martinelli e Olga I. Selezneva. "Dynamic Performance of Composite Pavements Under Impact". Transportation Research Record: Journal of the Transportation Research Board 1570, n. 1 (gennaio 1997): 163–71. http://dx.doi.org/10.3141/1570-19.
Testo completoAbstract (sommario):
The importance of developing a deep understanding of the behavior of pavement layers under the action of dynamic loads, and the availability of cutting-edge computational and visualization technologies, led to the study presented in this paper. Explicit finite-element analysis was used to investigate the propagation of dynamic displacements induced in pavement layers under the action of an impact load similar to the one applied in a falling weight deflectometer test. The time-dependent dynamic response of a rigid pavement with straight asphalt concrete overlay was studied for two cases of unbonded and fully bonded interfaces between different layers. Significant differences in behavior were observed. Three-dimensional computer graphics and animation of the deformed model were used to display the propagation of vertical dynamic displacements through pavement layers. It was found that in the absence of a perfect bond between all pavement layers, the displacements measured on the top surface correlated little with the deformation measured in subsequent layers. In this case, a complicated pattern of behavior took place between the asphalt overlay and the concrete. The time histories of vertical displacements at selected surface locations and on the top and bottom of every layer were plotted. The plots revealed the existence of time shifts between the maximum displacements experienced by each layer, irrespective of the type of bond assumed between the interfaces.
15
Zhang, Yang, Robert Horton, David J. White e Pavana K. R. Vennapusa. "Seasonal Frost Penetration in Pavements with Multiple Layers". Journal of Cold Regions Engineering 32, n. 2 (giugno 2018): 05018002. http://dx.doi.org/10.1061/(asce)cr.1943-5495.0000159.
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Tereshchenko, Tatiana, e Serhii Illiash. "EXPERIENCE ON DESIGN AND CONSTRUCTION OF ROAD PAVEMENTS USING THE CLAUSES OF EUROPEAN STANDARDS ON HYDRAULICALLY BOUND MATERIALS". Avtoshliakhovyk Ukrayiny, n. 3 (259) ’ 2019 (17 ottobre 2019): 42–50. http://dx.doi.org/10.33868/0365-8392-2019-3-259-42-50.
Testo completoAbstract (sommario):
Hydraulically bound mixtures (HBM) are most effectively applied in the base layers of flexible road pavements to enhance their load bearing capacity and also in the base layers of rigid road pavements in the case of weak soils of the sub-grade. The evaluation of Ukrainian standards which are identical to European standards relating HBM leads to the point of subsequent implementation of new requirements trough design and construction of motor roads in Ukraine. The by European standards stated requirements and classification of HBM provide a modelling regime closer to the performance of bound pavement layer and give the wider range of HBM designations with different strength properties. Thus, this article reviews such aspects of design and construction of road pavements with HBM layers which are distinguished from the conception approved now in Ukraine. The reviewed clauses on design and construction concern road pavements which, in accordance with the European practice, are classified as flexible pavements or semi-rigid pavements and are comprised of flexible (bitumen-bound) upper layers laid on a HBM base. The reviewed types of road pavement constructions are most eligible to emphasize the possibilities of implementation of new standard requirements in the Ukrainian road building industry. As it was concluded, the European standards state classification of HBM by compressive strength RC and classification by tensile strength in combination with elastic modulus Rt, E. These methods of classification are equivalent with no correlation intended between them and have been successfully used during design and construction of road pavement constructions comprised of bitumen-bound layers laid on a HBM base. When designing the motor roads with the above mentioned pavement construction to be loaded with high traffic, HBM of strength classes RС from С8/10 to С9/12 shall be contributed where classes of strength are determined by the type of a hydraulic binder and can be accorded to the categories by ”Rt, E” values not less than T3 (from T3 to T5). Keywords: hydraulically bound mixtures, classification by values of mechanical properties, compressive strength, base layers from hydraulically bound mixtures.
17
Bhuyan, Mohammad, Mohammad Khattak, Qian Zhang e Emilee Schlader. "Experimental Evaluation of Engineered Cementitious Composites as Reflective Crack Control Interlayer for Composite Pavements". MATEC Web of Conferences 271 (2019): 07002. http://dx.doi.org/10.1051/matecconf/201927107002.
Testo completoAbstract (sommario):
Reflective cracking at transverse joints is considered as a predominant distress in composite pavements. Various interlayers have been used previously to prevent or retard reflective cracking. Engineered cementitious composite (ECC) is a special type of high-performance fiber-reinforced cementitious material that is expected to perform better as an interlayer due to its higher tensile strength and ductility. This study aims to evaluate the effectiveness of ECC as an interlayer system experimentally. A laboratory test protocol was designed to simulate repeated traffic loads to measure the fatigue performance of ECC interlayer system using digital image correlation (DIC) technique. It was found that the composite pavement specimens with ECC interlayer provided significantly higher fatigue life as compared to the control specimens without interlayer. This result indicates that ECC could be used as a potential effective interlayer system to retard or mitigate reflective cracking.
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Madhkhan, Morteza, Armin Hamidi e Navid Salehi. "Study on the Effects of Natural Pozzolan and Limestone Powder on Mechanical Properties of Roller Compacted Concrete Pavements". Advanced Materials Research 250-253 (maggio 2011): 3619–23. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.3619.
Testo completoAbstract (sommario):
Due to high maintenance and production costs of conventional asphalt pavements in recent years, substitution of concrete pavements has been taken into account. One important factor of such pavements is the long-term performance. The substitution of pozzolanic materials with existing cement in the mixture is a common choice to improve the durability factors and to increase the long term compressive strength. Owing to this change in cementitious materials, a general anticipation of the pozzolanic behavior to be observed is that the early age compressive strength gets decreased. On the other hand, this defect will be compensated in the long-term compressive strength. Furthermore, as conventional loads of road pavements are concerned, the tensile and flexural strengths have their own importance. Regarding these two factors, the related tests were also performed and the results were analyzed. The main purpose is to find the optimum material among these 2 types of pozzolanic supplements and its percentage of substitution with the preference of having the best average strength in both long and short term performances. Altogether, the natural pozzolan had better performance than limestone powder.
19
Serin, Sercan, Muhammet Ahmet Oğuzhanoğlu e Cafer Kayadelen. "Comparative analysis of stress distributions and displacements in rigid and flexible pavements via finite element method". Revista de la construcción 20, n. 2 (agosto 2021): 321–31. http://dx.doi.org/10.7764/rdlc.20.2.321.
Testo completoAbstract (sommario):
In many countries of the world, rigid and flexible pavements are widely used. Some of the external factors such as stresses and displacements play major role in the design of pavement layers such as coating, base and sub-base. Although empirical formulas and methods were used in the calculation and design of the pavement layers, complexity of today's transportation engineering demands effectiveness of the empirical formulas were diminished. Nowadays complex problems can be easily simulated and solved thanks to the higher analysis capabilities of the computer-aided softwares. In this study, the stress distributions and displacements were examined under traffic loads in rigid and flexible pavements with different coating layer thicknesses (30 mm, 50mm, 70mm, 100 mm, and 150 mm) by using finite element method. As a result, the vertical displacement in the flexible pavements were obtained as 5% higher than the vertical displacement in the rigid pavements. Based on the stress distribution results, the stress values of flexible pavements were 60% lower than the stress values of the rigid pavements. Moreover, It was determined that the stresses in the rigid pavements remain in the coating layer, while the stresses in the flexible pavements reach the base and sub-base. In addition, regression models have been developed to predict stress and displacements by using layer thicknesses. High correlation and determination coefficient values (> 0.90) were achieved based on the regression analysis both in flexible and rigid pavements.
20
Zofka, Adam, Maciej Maliszewski, Ewa Zofka, Miglė Paliukaitė e Laura Žalimienė. "GEOGRID REINFORCEMENT OF ASPHALT PAVEMENTS". Baltic Journal of Road and Bridge Engineering 12, n. 3 (30 settembre 2017): 181–86. http://dx.doi.org/10.3846/bjrbe.2017.22.
Testo completoAbstract (sommario):
Geogrid materials applied within asphalt layers defer or prevent the occurrence of reflective cracking. The contribution of this work significantly adds to extending pavement serviceability and improving benefit/cost analysis. Since 1970s many studies have demonstrated the benefits of geogrid reinforcement in asphalt pavements, but this knowledge did not translate to their extensive usage in the actual construction practice. Among potential reasons are higher initial costs, lack of in-depth understanding of working mechanism within adjacent asphalt layers and lack of commonly standard design procedures. This paper presents a recent study, which investigated the effect of geogrid reinforcement on asphalt mixture specimens. Two types of laboratory experiments were conducted, namely monotonic (strength and fracture) testing and cyclic (fatigue and modulus) testing. The results demonstrated a significant strengthening contribution of geogrid, which was observed regarding fracture energy results and terminal deflections in the fatigue testing. This paper also presents a short example connecting pavement deflections with the allowable axle loading (also known as fatigue life) to demonstrate the practical implications of geogrid reinforcement. The undertaken analysis shows the reduction of pavement deflections due to the geogrid application, which potentially leads to a significant extension of pavement fatigue life. Paper concludes with several recommendations for further work in the area of geogrid reinforcement.
21
Wang, Jingan, Xiaojun Li, Haifang Wen e Balasingam Muhunthan. "Shrinkage cracking model for cementitiously stabilized layers for use in the mechanistic-empirical pavement design guide". Transportation Geotechnics 24 (settembre 2020): 100386. http://dx.doi.org/10.1016/j.trgeo.2020.100386.
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Heckel, Laura. "Performance Problems of Open-Graded Drainage Layers Under Continuously Reinforced Concrete Pavements in Illinois". Transportation Research Record: Journal of the Transportation Research Board 1596, n. 1 (gennaio 1997): 51–57. http://dx.doi.org/10.3141/1596-08.
Testo completoAbstract (sommario):
Illinois has constructed 14 pavements that contain open-graded drainage layers (OGDLs). The pavement types include continuously reinforced concrete pavements (CRCPs), jointed pavements, and full-depth asphalt concrete pavements. Three of the CRCPs have begun to show a higher level of distress than would be expected from pavements of that cross section and age. An in-depth investigation into the cause of the distress has begun and is expected to be completed early in 1997. The investigation includes visual distress surveys, core analysis, analysis of Shelby tube samples, deflection tests, and inspection of slabs removed in patching operations. The state has placed a moratorium on the construction of new OGDLs pending the outcome of the investigation. The investigation indicates that possible causes of the problems are the incompatibility of the OGDL and CRCP, the lack of a separation layer on two of the three sections, the cement content in the OGDL, the percentage of reinforcing steel and epoxy-coating of the steel in the slab, and the design of the CRCP and shoulders. The current maintenance plan includes patching and undersealing of problem areas. No recommendations for the future use of OGDLs can be made until the investigation narrows the possible causes.
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Papadopoulos, E., e J. C. Santamarina. "Analysis of inverted base pavements with thin-asphalt layers". International Journal of Pavement Engineering 17, n. 7 (6 febbraio 2015): 590–601. http://dx.doi.org/10.1080/10298436.2015.1007232.
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Oliveira, Victor H. S., Nairo D. T. Buitrago, Luís F. M. Ribeiro e André L. B. Cavalcante. "Steel Aggregate Swelling Potential in Layers of Road Pavements". Journal of Environmental Engineering 144, n. 9 (settembre 2018): 04018077. http://dx.doi.org/10.1061/(asce)ee.1943-7870.0001435.
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Solatifar, Nader, Mojtaba Abbasghorbani, Amir Kavussi e Henrikas Sivilevičius. "PREDICTION OF DEPTH TEMPERATURE OF ASPHALT LAYERS IN HOT CLIMATE AREA". JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 24, n. 7 (13 novembre 2018): 516–25. http://dx.doi.org/10.3846/jcem.2018.6162.
Testo completoAbstract (sommario):
In determination of flexible pavement layers moduli using Falling Weight Deflectometer (FWD), the pavement depth temperature should be determined and then the moduli should be corrected into a reference temperature. As direct measurement of pavement temperature is time consuming and is difficult to be determined in trafficked roads, some models are developed to predict temperature of asphalt layers through pavement depth, including BELLS model. The objective of this research is to determine correlation between actual measurement and prediction of temperature variations through asphalt layers with applying BELLS model. Ten new and rehabilitated pavement sites were selected in hot climate regions in Khuzestan and Kerman provinces in southern part of Iran. In typical hot summer days, pavement temperatures were measured at half and at one-third of the depth of asphalt layers and FWD testing were performed. Results indicated that a linear regression analysis of BELLS predicted temperatures versus measured values, provides very good correlation with actual field measurements of temperatures through the asphalt layers. Furthermore, predictions were more precise in rehabilitated pavements rather than in newly constructed pavements. Finally, using multi parametric linear fitting analysis, a new model was developed to accurately predict the temperature of asphalt layers in new pavements.
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Khazanovich, Lev, e Jeffery Roesler. "DIPLOBACK: Neural-Network-Based Backcalculation Program for Composite Pavements". Transportation Research Record: Journal of the Transportation Research Board 1570, n. 1 (gennaio 1997): 143–50. http://dx.doi.org/10.3141/1570-17.
Testo completoAbstract (sommario):
A neural-network-based backcalculation procedure is developed for multilayer composite pavement systems. The constructed layers are modeled as compressible elastic layers, whereas the subgrade is modeled as a Winkler foundation. The neural networks are trained to find moduli of elasticity of the constructed layers and a coefficient of subgrade reaction to accurately match a measured deflection profile. The method was verified by theoretically generated deflection profiles and falling weight deflectometer data measurements conducted at Edmonton Municipal Airport, Canada. For the theoretical deflection basins, the results of backcalculation were compared with actual elastic parameters, and excellent agreement was observed. The results of backcalculation using field test data were compared with the results obtained using WESDEF. Similar trends were observed for elastic parameters of all the pavement layers. The backcalculation procedure is implemented in a computer program called DIPLOBACK.
27
Nagórski, R. "The Classification of Mechanical Models of Road Pavements". Archives of Civil Engineering 64, n. 4 (1 dicembre 2018): 155–70. http://dx.doi.org/10.2478/ace-2018-0068.
Testo completoAbstract (sommario):
AbstractA review of mechanical models of road pavements in the form of a proposal of classification of these models is presented. It is assumed an autonomy of the following elements of pavement model: the models of structural layers, the subgrade model, the interlayer bonding models, including bonding of pavement structure with its subgrade, the models of external impacts on pavement layers, including load of heavy traffic, the models of pavement environment impacts on structural layers’ borders (lateral) and subgrade borders (including the lower one) – according to the selected criteria such as structural criterion, material criterion (physical criterion), dimension criterion and model scope (purpose) criterion − in the frame of assumptions of the classical Newtonian deterministic mechanics. The presented attempt to classify mechanical models of road pavements supports to orientate the roadmen community within a scope of the mechanistic modelling of these structures.
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Pourkhorshidi, Sajjad, Cesare Sangiorgi, Daniele Torreggiani e Patrizia Tassinari. "Using Recycled Aggregates from Construction and Demolition Waste in Unbound Layers of Pavements". Sustainability 12, n. 22 (11 novembre 2020): 9386. http://dx.doi.org/10.3390/su12229386.
Testo completoAbstract (sommario):
Pavements are an expensive part of transportation infrastructures, as their construction and maintenance require large amounts of resources and materials every year and all over the world. A sustainable solution for considering environmental concerns about roads and pavements, in general, is utilizing recycled materials for their construction. This has been shown to lower the carbon footprint of the construction sector and to result in natural resource conservation, in reduction of harmful emissions and in minimization of overall costs for pavement construction and maintenance. One of the main groups of recycled materials which has attracted much attention since the end of the last century is construction and demolition waste aggregates (CDW). This paper reviews the completed studies referring to the use of the construction and demolition waste aggregates in unbound layers of pavements and compare the in-hand results from various engineering assessments of these aggregates and mixes. A number of tests and evaluations are applied in order to enhance the required quality and durability of the pavements under given traffic volumes traffic loads and climate actions. Today, unbound recycled aggregates (RA) are mainly used in the lower layers, such as subgrade, capping, sub-base and base, but in rural roads they can be adopted also for bound layers, towards the surface of the structure and may be constituents of bound layers and of novel surfacing applications.
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Mondschein, Petr. "Reuse of Reclaimed Material in Road Construction Layers". Slovak Journal of Civil Engineering 26, n. 2 (1 giugno 2018): 40–44. http://dx.doi.org/10.2478/sjce-2018-0013.
Testo completoAbstract (sommario):
AbstractThe paper summarizes past experience in the use of reclaimed material in road construction layers according to various technologies applied in road construction. The recycling of asphalt pavements is a standard widely applied and established in road practice for many years. There is strong interest to increase the use of recycled materials in asphalt pavements for cost and environmental reasons. The paper defines the strengths and weaknesses of individual technologies and recommends where and when the use of R-material is appropriate, economically sound and technically justified. The production of new asphalt mixes with more reclaimed material is limited by more factors in the Czech Republic. They include the regulation of the quantity of reclaimed material in the standards and technical regulations. The machine equipment of contractors for recycling is not always sufficient either.
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Saxena, Priyam, Derek Tompkins, Lev Khazanovich e Jose Tadeu Balbo. "Evaluation of Characterization and Performance Modeling of Cementitiously Stabilized Layers in the Mechanistic–Empirical Pavement Design Guide". Transportation Research Record: Journal of the Transportation Research Board 2186, n. 1 (gennaio 2010): 111–19. http://dx.doi.org/10.3141/2186-12.
Testo completo
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Suraneni, Prannoy, Vahid Jafari Azad, Burkan O. Isgor e William Jason Weiss. "Calcium oxychloride formation in pastes containing supplementary cementitious materials: Thoughts on the role of cement and supplementary cementitious materials reactivity". RILEM Technical Letters 1 (29 maggio 2016): 24. http://dx.doi.org/10.21809/rilemtechlett.2016.7.
Testo completoAbstract (sommario):
Over the last decade many concrete pavements in North America have begun to show excessive damage at the joints. This damage appears to be due to two primary causes: classic freeze-thaw damage due to local saturation caused by the pooling of water at the joints, and formation of an expansive phase known as calcium oxychloride due to a reaction between chloride-based deicing salts and calcium hydroxide in concrete. This letter explores the formation of calcium oxychloride in cementitious matrices based on constituent materials and mixture compositions. Low temperature differential scanning calorimetry and thermogravimetric analysis were used to quantify the amount of calcium oxychloride and calcium hydroxide, respectively. Thermodynamic modeling was used to predict calcium hydroxide contents from the constituent material compositions. It is shown that calcium oxychloride contents are well correlated with calcium hydroxide contents in cementitious pastes. Supplementary cementitious materials, such as fly ash and slag, can reduce calcium oxychloride formation by reducing the amount of calcium hydroxide. Complexities in the determination of reactivity of supplementary cementitious materials based on their replacement level and different water-to-cement ratios are discussed. Although it is clear that supplementary cementitious materials are beneficial in reducing calcium oxychloride formation, additional analysis tools are needed to more accurately quantify the specific mechanisms (such as dilution, pozzolanic or hydraulic reaction, changes in cement hydration) that result in the beneficial aspects of each supplementary cementitious material.
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Suraneni, Prannoy, Vahid Jafari Azad, Burkan O. Isgor e William Jason Weiss. "Calcium oxychloride formation in pastes containing supplementary cementitious materials: Thoughts on the role of cement and supplementary cementitious materials reactivity". RILEM Technical Letters 1 (29 maggio 2016): 24. http://dx.doi.org/10.21809/rilemtechlett.v1.7.
Testo completoAbstract (sommario):
Over the last decade many concrete pavements in North America have begun to show excessive damage at the joints. This damage appears to be due to two primary causes: classic freeze-thaw damage due to local saturation caused by the pooling of water at the joints, and formation of an expansive phase known as calcium oxychloride due to a reaction between chloride-based deicing salts and calcium hydroxide in concrete. This letter explores the formation of calcium oxychloride in cementitious matrices based on constituent materials and mixture compositions. Low temperature differential scanning calorimetry and thermogravimetric analysis were used to quantify the amount of calcium oxychloride and calcium hydroxide, respectively. Thermodynamic modeling was used to predict calcium hydroxide contents from the constituent material compositions. It is shown that calcium oxychloride contents are well correlated with calcium hydroxide contents in cementitious pastes. Supplementary cementitious materials, such as fly ash and slag, can reduce calcium oxychloride formation by reducing the amount of calcium hydroxide. Complexities in the determination of reactivity of supplementary cementitious materials based on their replacement level and different water-to-cement ratios are discussed. Although it is clear that supplementary cementitious materials are beneficial in reducing calcium oxychloride formation, additional analysis tools are needed to more accurately quantify the specific mechanisms (such as dilution, pozzolanic or hydraulic reaction, changes in cement hydration) that result in the beneficial aspects of each supplementary cementitious material.
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Pourfalah, Saeed, e Demetrios M. Cotsovos. "Enhancing the out-of-plane behaviour of unreinforced masonry walls under impact loading through the use of partially bonded layers of engineered cementitious composite". International Journal of Protective Structures 11, n. 2 (4 agosto 2019): 209–34. http://dx.doi.org/10.1177/2041419619866457.
Testo completoAbstract (sommario):
Published experimental work reveals that the out-of-plane behaviour of unreinforced masonry walls under impact loading can be significantly enhanced through the use of engineered cementitious composite layers fully bonded to the surface of the masonry. The disadvantage of this method is associated with the localised cracking exhibited by the engineered cementitious composite layer close to the joints forming between bricks. This cracking is associated with the bond developing between the masonry and the engineered cementitious composite layer and does not allow the latter layer to achieve its full potential, thus resulting in its premature failure. In an attempt to address this problem, a series of drop-weight tests were carried on masonry prismatic specimens strengthened with a layer of engineered cementitious composite partially bonded to the surface of the masonry acting in tension. The latter prismatic specimens consist of a stack of bricks connected with mortar joints. The specimens are considered to provide a simplistic representation of a vertical strip of a masonry wall subjected to out-of-plane actions associated with impact or blast loading. Analysis of the test data reveals that under impact loading, the specimens retrofitted with partially bonded engineered cementitious composite layers can exhibit a more ductile performance compared to that exhibited by the same specimens when strengthened with fully bonded layers of engineered cementitious composite. This is attributed to the fact that along its unbonded length, the engineered cementitious composite layer is subjected to purely uniaxial tension (free from any interaction with the surface of the masonry), allowing for the development of multiple uniformly distributed fine cracks.
34
Čygas, Donatas, e Daiva Žilionienė. "DESIGN SOLUTIONS FOR LITHUANIAN GRAVEL ROAD PAVEMENTS". JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 8, n. 2 (30 giugno 2002): 138–42. http://dx.doi.org/10.3846/13923730.2002.10531266.
Testo completoAbstract (sommario):
This article deals with the design problems of gravel road pavements. Mathematical models related to geological and hydrological conditions of a location, thickness of gravel pavement and characteristics of the gravel contained in this pavement are proposed to be used for pavements. For the selection of gravel pavements for reconstruction we recommend the models developed by the method of experimental planning to calculate the equivalent deformation modulus of the gravel pavements change depending on the deformation modulus of the subgrade, thickness of the gravel pavement and the materials used for its layers. Practical applications of these models will eliminate the mistakes that are still found in road pavement design.
35
Mirzapour Mounes, Sina, Mohamed Rehan Karim, Ali Khodaii e Mohammad Hadi Almasi. "Improving Rutting Resistance of Pavement Structures Using Geosynthetics: An Overview". Scientific World Journal 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/764218.
Testo completoAbstract (sommario):
A pavement structure consists of several layers for the primary purpose of transmitting and distributing traffic loads to the subgrade. Rutting is one form of pavement distresses that may influence the performance of road pavements. Geosynthetics is one type of synthetic materials utilized for improving the performance of pavements against rutting. Various studies have been conducted on using different geosynthetic materials in pavement structures by different researchers. One of the practices is a reinforcing material in asphalt pavements. This paper intends to present and discuss the discoveries from some of the studies on utilizing geosynthetics in flexible pavements as reinforcement against permanent deformation (rutting).
36
Davids, William G. "Foundation Modeling for Jointed Concrete Pavements". Transportation Research Record: Journal of the Transportation Research Board 1730, n. 1 (gennaio 2000): 34–42. http://dx.doi.org/10.3141/1730-05.
Testo completoAbstract (sommario):
Issues related to the finite element modeling of base and subgrade materials under jointed plain concrete pavements are examined. The threedimensional finite element program EverFE, developed in conjunction with the Washington State Department of Transportation, was employed for the analyses. The relevant modeling capabilities of EverFE are detailed, including the ability to model multiple foundation layers, the incorporation of loss of contact between slab and base, and the efficient iterative solution strategies that make large three-dimensional finite element analyses possible on desktop computers. The results of parametric studies examining the effects of foundation type (layered elastic and dense liquid) and properties on the response of jointed plain concrete pavements subjected to axle and thermal loads are presented. Special attention is paid to the interactions between joint load transfer effectiveness and foundation type, and joint load transfer is shown to change significantly with different foundation models and properties. A consideration of simultaneous thermal and axle loadings indicates that the effect of foundation type and properties on critical slab stresses caused by edge loading and a positive temperature gradient is relatively small. However, the slab response is quite sensitive to foundation type for a combined negative temperature gradient and corner loading. On the basis of these results, use of an equivalent dense liquid foundation modulus in mechanistic rigid pavement analysis or design is not recommended when stiff base layers are present.
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Gomez-Ullate, E., J. R. Bayon, S. Coupe e D. Castro-Fresno. "Performance of pervious pavement parking bays storing rainwater in the north of Spain". Water Science and Technology 62, n. 3 (1 agosto 2010): 615–21. http://dx.doi.org/10.2166/wst.2010.308.
Testo completoAbstract (sommario):
Pervious pavements are drainage techniques that improve urban water management in a sustainable manner. An experimental pervious pavement parking area has been constructed in the north of Spain (Santander), with the aim of harvesting good quality rainwater. Forty-five pervious pavement structures have been designed and constructed to measure stored water quantity and quality simultaneously. Ten of these structures are specifically constructed with different geotextile layers for improving water storage within the pavements. Following the confirmation in previous laboratory experiments that the geotextile influenced on water storage, two different geosynthetics (Inbitex and a One Way evaporation control membrane) and control pervious pavements with no geotextile layers were tested in the field. Weather conditions were monitored in order to find correlations with the water storage within the pervious pavement models tested. During one year of monitoring the three different pervious pavement types tested remained at their maximum storage capacity. The heavy rain events which occurred during the experimental period caused evaporation rates within the pervious pavements to be not significant, but allowed the researchers to observe certain trends in the water storage. Temperature was the most closely correlated weather factor with the level of the water stored within the pervious pavements tested.
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Jaskuła, Piotr. "Studies and analysis on interlayer bonding in asphalt pavements". Budownictwo i Architektura 13, n. 4 (9 dicembre 2014): 117–25. http://dx.doi.org/10.35784/bud-arch.1736.
Testo completoAbstract (sommario):
The paper describes research works of interlayer bonding of asphalt layers conducted at Gdansk University of Technology. The studies included laboratory and field tests, and calculation of pavement structures with different interlayer bonding models. Laboratory tests included interlayer bonding tests using the direct shear method which evaluated the influence of selected factors on interlayer bonding: the type and the amount of the emulsion, the method and the effectiveness of compaction, vulnerability to dirt, water and repeated shear loads. Field works were focused on the impact of interlayer bonding of asphalt layers on the deflection of pavement structure and the back-calculated stiffness modulus of asphalt mixtures. The analyses of the field tests also included the impact of the asphalt layers compaction ratio on interlayer bonding. Computational analyses of asphalt pavement structures consisted of the simulation of different interlayer bonding in a multi-layered elastic half-space. Calculations were also made by using the finite element method within cohesion and friction models to simulate interlayer bonding.
39
Birgin, Hasan Borke, Simon Laflamme, Antonella D’Alessandro, Enrique Garcia-Macias e Filippo Ubertini. "A Weigh-in-Motion Characterization Algorithm for Smart Pavements Based on Conductive Cementitious Materials". Sensors 20, n. 3 (24 gennaio 2020): 659. http://dx.doi.org/10.3390/s20030659.
Testo completoAbstract (sommario):
Smart materials are promising technologies for reducing the instrumentation cost required to continuously monitor road infrastructures, by transforming roadways into multifunctional elements capable of self-sensing. This study investigates a novel algorithm empowering smart pavements with weigh-in-motion (WIM) characterization capabilities. The application domain of interest is a cementitious-based smart pavement installed on a bridge over separate sections. Each section transduces axial strain provoked by the passage of a vehicle into a measurable change in electrical resistance arising from the piezoresistive effect of the smart material. The WIM characterization algorithm is as follows. First, basis signals from axles are generated from a finite element model of the structure equipped with the smart pavement and subjected to given vehicle loads. Second, the measured signal is matched by finding the number and weights of appropriate basis signals that would minimize the error between the numerical and measured signals, yielding information on the vehicle’s number of axles and weight per axle, therefore enabling vehicle classification capabilities. Third, the temporal correlation of the measured signals are compared across smart pavement sections to determine the vehicle weight. The proposed algorithm is validated numerically using three types of trucks defined by the Eurocodes. Results demonstrate the capability of the algorithm at conducting WIM characterization, even when two different trucks are driving in different directions across the same pavement sections. Then, a noise study is conducted, and the results conclude that a given smart pavement section operating with less than 5% noise on measurements could yield good WIM characterization results.
40
Asadi, Mojtaba, e Reza S. Ashtiani. "Stability analysis of anisotropic granular base layers in flexible pavements". Transportation Geotechnics 14 (marzo 2018): 183–89. http://dx.doi.org/10.1016/j.trgeo.2018.01.001.
Testo completo
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Terrones-Saeta, Juan María, Francisco Javier Iglesias-Godino, Francisco Antonio Corpas-Iglesias e Carmen Martínez-García. "Study of the Incorporation of Ladle Furnace Slag in the Manufacture of Cold In-Place Recycling with Bitumen Emulsion". Materials 13, n. 21 (26 ottobre 2020): 4765. http://dx.doi.org/10.3390/ma13214765.
Testo completoAbstract (sommario):
Cold in-place recycling with bitumen emulsion is a good environmental option for road conservation. The technique produces lower CO2 emissions because the product is manufactured and spread in the same location as the previous infrastructure, and its mixing with bitumen emulsion occurs at room temperature. Adding materials with cementitious characteristics gives the final mixture greater resistance and durability, and incorporating an industrial by-product such as ladle furnace slag (of which cementitious characteristics have been corroborated by various authors) enables the creation of sustainable, resistant pavement. This paper describes the incorporation of ladle furnace slag in reclaimed asphalt pavements (RAP) to execute in-place asphalt pavement recycling with bitumen emulsion. Various test groups of samples with increasing percentages of emulsion were created to study both the density of the mixtures obtained, and their dry and post-immersion compressive strength. To determine these characteristics, the physical and chemical properties of the ladle furnace slag and the reclaimed asphalt pavements were analyzed, as well as compatibility with the bitumen emulsion. The aforementioned tests define an optimal combination of RAP (90%), ladle furnace slag (10%), water (2.6%), and emulsion (3.3%), which demonstrated maximum values for compressive strength of the dry and post-immersion bituminous mixture. These tests therefore demonstrate the suitability of ladle furnace slag for cold in-place recycling with bitumen emulsion.
42
Sobol, Khrystyna, Taras Markiv e Oleksii Hunyak. "Effect of mineral additives on structure and properties of concrete for pavements". Selected Scientific Papers - Journal of Civil Engineering 12, n. 2 (1 dicembre 2017): 95–100. http://dx.doi.org/10.1515/sspjce-2017-0024.
Testo completoAbstract (sommario):
Abstract Concrete pavements is an attractive alternative to asphalt pavements because of its lower cost and higher durability. Major contribution to sustainable development can be made by partial replacement of cement in concrete pavement with supplementary cementitious materials of different nature and origin. In this paper, the effect of natural zeolite and perlite additives in complex with chemical admixtures on the structure and properties of concrete for pavement was studied. Compressive and flexural strength test was used to study the mechanical behavior of designed concrete under load. Generally, the compressive strength of both control concrete and concrete containing mineral additives levels at the later ages of hardening. The microstructure analysis of concrete with mineral additives of different nature activity showed the formation of additional amount of hydration products such as tobermorite type calcium hydrosilicate which provide self-reinforcement of hardening concrete system.
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Sen, Sushobhan, e Jeffery Roesler. "Microscale Heat Island Characterization of Rigid Pavements". Transportation Research Record: Journal of the Transportation Research Board 2639, n. 1 (gennaio 2017): 73–83. http://dx.doi.org/10.3141/2639-10.
Testo completoAbstract (sommario):
Rigid pavements have an impact on the urban heat island (UHI) and hence the surrounding environment and human comfort. Currently, most studies use a mesoscale approach in UHI characterization of pavements. This study proposes a microscale approach that can be incorporated into a pavement life-cycle assessment (LCA). The heat flux of various concrete pavements containing layers of varying thermal diffusivity and inertia was simulated. The surface pavement radiative forcing (RFp) was developed as a metric for use in a pavement LCA. Additionally, the heat conducted and stored in each concrete pavement system was analyzed using an average seasonal day metric to understand the temporal pavement energetics. Of the various thermal cases, only a higher albedo surface significantly changed the RFp for a fixed climate. However, a time lag was induced by the thermal inertia of the base course, which decreased the amount of heat conducted out of the pavement at night by storing heat in the base course for a longer time, effectively reducing nighttime UHI. Diurnal variations in thermal behavior can be controlled by changing the thermal properties of subsurface layers, which can be used to partially mitigate UHI.
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Mallick, Rajib B., Animesh Das e S. Nazarian. "Fast Nondestructive Field Test Method to Determine Stiffness of Subsurface Layer in Thin Surface Hot-Mix Asphalt Pavement". Transportation Research Record: Journal of the Transportation Research Board 1905, n. 1 (gennaio 2005): 82–89. http://dx.doi.org/10.1177/0361198105190500109.
Testo completoAbstract (sommario):
The determination of the moduli of subsurface stabilized layers in pavements with unknown and variable layers and thin asphalt layers is a challenging problem. Reliable estimation of moduli cannot be obtained from backcalculation of falling weight deflectometer data. In addition, for many stabilized layers, full-depth intact cores cannot be obtained from the field, and hence, laboratory determination of the moduli is not possible. Analysis of the seismic property of a pavement is a well-known method for estimation of the surface modulus of the pavement. This paper proposes a simple methodology on how seismic data acquired on the pavement surface can be effectively used to estimate the modulus of the surface layer as well as those of the subsequent subsurface layers of a flexible pavement. A research study was conducted on three hot-mix asphalt pavements with a foamed asphalt (FA) stabilized base in Maine. These three pavements were tested with both portable seismic and falling weight deflectometer equipment. Cores were taken from the same locations and tested in the laboratory for their resilient moduli. The modulus values obtained from different tests were compared, the effect of temperature on the modulus of the FA was evaluated, and the deflections computed from layered elastic analysis by use of the predicted modulus of the FA layer were compared with the observed deflections. It is concluded that the portable seismic equipment can be used to determine accurate moduli of subsurface stabilized layers. The practical advantages of using such equipment warrant further study for refinement of the method.
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Gschwendt, Ivan. "Extending the Service Life of Pavements". Slovak Journal of Civil Engineering 26, n. 1 (1 marzo 2018): 25–32. http://dx.doi.org/10.2478/sjce-2018-0004.
Testo completoAbstract (sommario):
Abstract The cost of road construction and expenditures on the maintenance of pavements, i.e., their whole life cost, represents a lot of money. The paper describes a procedure for a pavement management system with degradation models and estimates the length of time for the rehabilitation of an asphalt pavement. Using a theory of pavement mechanics, we calculated the stresses and strains on the layers of two pavement models. High modulus asphalt concrete, an asphalt mix with a high binder content, and an asphalt mix with binder modifications are new road building materials. Prolonging the time for the rehabilitation of pavements is possible.
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Bezina, Šime, Ivica Stančerić, Josipa Domitrović e Tatjana Rukavina. "Spatial Representation of GPR Data—Accuracy of Asphalt Layers Thickness Mapping". Remote Sensing 13, n. 5 (25 febbraio 2021): 864. http://dx.doi.org/10.3390/rs13050864.
Testo completoAbstract (sommario):
Information on pavement layer thickness is very important for determining bearing capacity, estimating remaining life and strengthening planning. Ground-penetrating radar (GPR) is a nondestructive testing (NDT) method used for determining the continuous pavement layer thickness in the travel direction. The data obtained with GPR in one survey line is suitable for the needs of repair and rehabilitation planning of roads and highways, but not for wider traffic areas such as airfield pavements. Spatial representation of pavement thickness is more useful for airfield pavements but requires a 3D model. In the absence of 3D GPR, a 3D model of pavement thickness can be created by additional processing of GPR data obtained from multiple survey lines. Five 3D models of asphalt pavements were created to determine how different numbers of survey lines affect their accuracy. The distance between survey lines ranges from 1 to 5 m. The accuracy of the 3D models is determined by comparing the asphalt layer thickness on the model with the values measured on 22 cores. The results, as expected, show that the highest accuracy is achieved for the 3D model created with a distance of 1 m between survey lines, with an average relative error of up to 1.5%. The lowest accuracy was obtained for the 3D model created with a distance of 4 m between the survey lines, with an average relative error of 7.4%.
47
Girskas, Giedrius. "Zeolite Influence of Vibropressing Concrete Durability". Materials Science Forum 908 (ottobre 2017): 71–75. http://dx.doi.org/10.4028/www.scientific.net/msf.908.71.
Testo completoAbstract (sommario):
Durability is one of the main characteristics in the production of high-quality concrete paving blocks in the Baltic region climate zone. Concrete paving blocks are produced by means of vi bropressing , dimensions: 198×98×80 mm . The article describes tests with concrete paving blocks, the top layer of which contains 5% of zeolite admixture obtained from waste of aluminum fluoride production by low-temperature synthesis. The durability of concrete paving blocks was tested according to abrasion resistance, tensile splitting strength, absorption and frost resistance. The test results revealed that 5% of zeolite admixture added to the top layer of concrete paving blocks reduce the absorption, increase the tensile splitting strength and decrease abrasion. The zeolite admixture used in concrete paving blocks reduces the scaling about 4 times after 28 freeze-thaw cycles when 3% NaCl is used as the freezing solution. The test results proved that synthetic zeolite obtained from aluminum fluoride by means of low temperature synthesis can be used as a supplementary cementitious material to increase the durability of concrete pavement elements.
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Kozak, Petr, Ondrej Dasek, Radka Matuszkova e Michal Radimsky. "Low-Noise Asphalt Pavements in Urban Areas". Applied Mechanics and Materials 858 (novembre 2016): 282–86. http://dx.doi.org/10.4028/www.scientific.net/amm.858.282.
Testo completoAbstract (sommario):
Current requirements for the reduction of the noise pollution in inhabited areas are constantly increasing. Acoustic wearing courses represent the real measures how to directly mitigate sources of road traffic noise created by a tire/road contact. Directly reduced noise emissions created by a tire/road contact don't need further mitigation by expensive noise barriers. Noise emissions on two different types of wearing courses of asphalt mixtures (Asphalt concrete for very thin layers and Low-noise stone mastic asphalt) were measured using the specialized device operating on the basis of CPX (Close Proximity method) and compared with the standard mixture of Asphalt concrete. Differences were between 1 dB and 5 dB depending on the wearing course and the vehicle speed. The efficiency of the low-noise asphalt pavements was also compared with the initial costs of the pavements. The economical evaluation confirmed that the initial costs of the acoustic wearing courses are higher than the costs of the standard asphalt concrete mixture. However the noise reduction by 1 dB using the asphalt concrete for very thin layers increases the costs just by 350 USD (considering the same length and width of the road segment), which makes acoustic wearing courses the economically efficient noise reducing measure.
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Spadoni, Sara, Lorenzo Paolo Ingrassia, Giulio Paoloni, Amedeo Virgili e Francesco Canestrari. "Influence of Geocomposite Properties on the Crack Propagation and Interlayer Bonding of Asphalt Pavements". Materials 14, n. 18 (15 settembre 2021): 5310. http://dx.doi.org/10.3390/ma14185310.
Testo completoAbstract (sommario):
The application of geocomposites as reinforcement in asphalt pavements is a promising solution for the maintenance/rehabilitation of existing pavements and for the construction of new pavements, whose effectiveness strongly depends on the physical and mechanical properties of the geocomposite. This study aims at assessing the influence of four different geocomposites, obtained by combining a reinforcing geosynthetic with a bituminous membrane, on the crack propagation and interlayer bonding of asphalt pavements. First, a laboratory investigation was carried out on double-layered asphalt specimens. The crack propagation resistance under static and dynamic loads was investigated through three-point bending tests (carried out on specimens with and without notch) and reflective cracking tests respectively, whereas the interlayer shear strength was evaluated through Leutner tests. Then, a trial section was constructed along an Italian motorway and a Falling Weight Deflectometer (FWD) testing campaign was carried out. The laboratory investigation highlighted that—as compared to the unreinforced system—the geocomposites increased the crack propagation energy in the layer above the reinforcement from five to ten times, indicating that they can significantly extend the service life of the pavement by delaying bottom-up and reflective cracking. However, they also worsened the interlayer bonding between the asphalt layers (de-bonding effect). The field investigation indicated that all geocomposites decreased the stiffness of the asphalt layers with respect to the unreinforced pavement as a consequence of the de-bonding effect, thus corroborating the laboratory results. Based on the results obtained, it is desirable that the geocomposite possess a high energy dissipation capability and an upper coating ensuring good adhesion between the asphalt layers. The monitoring of the existing trial section in the future will provide useful data on the long-term field performance of reinforced pavements subjected to actual motorway traffic.
50
Mallela, Jagannath, Leslie Titus-Glover e Michael I. Darter. "Considerations for Providing Subsurface Drainage in Jointed Concrete Pavements". Transportation Research Record: Journal of the Transportation Research Board 1709, n. 1 (gennaio 2000): 1–10. http://dx.doi.org/10.3141/1709-01.
Testo completoAbstract (sommario):
Design considerations for pavement subsurface drainage in new or reconstructed jointed concrete pavements are outlined for all components of a permeable base system (permeable bases, separator layers, edgedrains, and outlets). Discussion topics—including guidelines for determining drainage needs, permeable base system components, hydraulic design of permeable base systems, structural design of permeable bases and separator layers, and economic considerations for providing drainage—are arranged to provide a comprehensive picture of the subject area. For topics with established procedures, such as the hydraulic design of permeable bases, a synthesis of information is presented. Where there is a lack of information or a clear consensus among researchers on a topic, new ideas and concepts are proposed.