Academic literature on the topic 'Polycarboxylate superplasticizer (PCE)'

Ultra-High Strength Concrete (UHSC) is a high-strength and highly ductile material formulated to provide compressive strengths exceeding 130MPa. UHSC materials typically have a very low water-to-cementitious ratio (w/cm), which requires the use of superplasticizers to disperse the fine particles and to make the material workable for placing, handling and consolidating. Common examples of superplasticizer compositions include Polynaphthalene Sulfonate (PNS), Polymelamine Sulfonate (PMS) and Polycarboxylate Ether (PCE) based polymers. This study focuses on assessing the impact of various superplasticizers on the compressive strength and rheological performance of a UHSC mixture. Four different types of superplasticizers were used; two different PCE based superplasticizers from a leading manufacturer, one PNS superplasticizer, and one PCE superplasticizer, both of which were provided by a local chemical provider. Specific properties assessed were the superplasticizers’ viscosity, concrete workability through the mortar-spread test, concrete rheology, and 7, 14, and 28 day compressive strengths. Two mixtures were produced with two w/cm (0.20 and 0.15), which would subsequently increase the amount of HRWRA needed, from 34.7L/m3 to 44.5L/m3. The results show that both name brand PCE superplasticizers produce a higher spread, lower viscosity, and a higher compressive strength at all ages tested up to 28 days than the two local superplasticizers. Additionally, the rheology test demonstrated that the name brand PCE superplasticizers, and UHSC produced with such superplasticizers, had a lower viscosity at all angular speeds than the local superplasticizers counterparts.

A new low air-entraining polycarboxylate superplasticizer (denoted as L-PCE) was synthesized by using oxirane/epoxypropane (denoted as EO/PO) block-polyether as one of monomers. The molecular structure of EO/PO block-polyether monomer was characterized by proton nuclear magnetic resonance spectroscopy (denoted as 1H NMR). The pore parameters, workability, and compressive strength of the concrete added with L-PCE were compared to that added with conventional polycarboxylate superplasticizer (denoted as G-PCE) or the G-PCE compounding with defoaming agent. The results demonstrate that the air entraining performance of the L-PCE has been greatly improved than the G-PCE and the G-PCE compounding with defoaming agent. Then the problems, which the workability and slumps of fresh concrete decrease when G-PCE compounding with defoaming agent are added, can be solved. What is more, the interior pore structure of concrete has been optimized. The spacing factor of hardened concrete added with the L-PCE is 27% lower than that added with the G-PCE compounding with defoaming agent. And the 28d strength of the concrete added with the L-PCE is 10% higher than that added with the G-PCE compounding with defoaming agent.

Conventional concrete does not have durability and higher strength as produced by high performance concrete (HPC). It is known that the HPC possess the following three properties which are high workability, high strength, and durability. The introduction of polycarboxylate ether (PCE) superplasticizer was proved to enhance the workability of concrete even though at a lower water to cement ratio. The study was conducted to find the optimum dosage of PCE and to compare its compressive strength, physical characteristics and morphology of the HPC. The result of the test shows that the high performance concrete (HPC) with addition of 0.5% polycarboxylate ether (PCE) superplasticizer of the cement mass have the highest compressive strength and excellent physical properties.

NanoSiO2 was widely used to modify the property of cementitious materials, however, for nanoparticles used in cement-based materials, key problem is the effective dispersion. The surface modification technology can be introduced to promote dispersion of nanoparticles in aqueous system, especially in cement pore solution, which possess high concentration of ions. In this study, at first, NanoSiO2-polycarboxylate superplasticizer (SiO2-PCE) core-shell nanoparticle was synthesized from silanized polycarboxylate superplasticizer and colloidal nanoSiO2 by the “grafting to” method, then SiO2-PCE was testified by UV-Vis, FTIR, and TGA. Additionally, stability of SiO2-PCE and its effect on cement hydration were investigated. Results shows: SiO2-PCE possess higher stability in saturated calcium hydroxide solution compared to nanoSiO2, and heat development of cement hydration can be regulated by shell structure of SiO2-PCE. The research implied a new approach for nanoSiO2 to optimize cement-based composites.