Papers by Keyword: Polycarboxylate Superplasticizer (PCE)

Abstract: A new type of polycarboxylate superplasticizer with high dispersibility was synthesized by the method of free radical polymerization and the hydrothermal reaction. The synthetic process optimized the influencing factors of reaction had been discussed, including proportion of acid and ether, reaction temperature, initiator concentration, heat preservation time and additive. The dispersibility of new product was superior under the condition of low water/cement ratio, testing by gel permeation chromatography and C60 self-compacting concrete. The new product had already been used in Tianjin Goldin 117 Mega Tower project. The performance of C70 fresh mixed self-compacting concrete, which was added with new product, was very excellent in Tianjin Goldin 117 Mega Tower project, and was satisfied with the design code for high-strength self-compacting concrete in China. It is possible to realize industrial production.

Abstract: The synthesis process of polycarboxylate superplasticizer (PCE) by bulk polymerization was investigated. Compared with BPO as initiator, PCE prepared by using AIBN as initiator exhibited better cement paste fluidities. PCE using isopentenyl polyethylene glycol (TPEG) or isobutenyl polyethylene glycol (IPEG) as macromonomer showed excellent fluidities and retaining properties at 80°C and 75°C, respectively. The fumaric acid was more suitable to copolymerize as the third monomer than maleic anhydride. The molecular weight measurements showed that the characteristics of molecular weight and its distribution for all the synthesized samples were in accordance with their cement paste fluidities. The solid-state PCEs can be conveniently dissolved into water to prepare PCE solution with arbitrary concentration, and still with good cement application performances.

Abstract: The synthesis process of esterification products used for the preparation of polycarboxylate superplasticizier (PCE) was systematically investigated, and the influences of water dosage, the catalyst dosage, reaction time and inhibitor dosage on the esterification rate and cement paste fluidities were determined. The results showed that the esterification rate can reach more than 95% as the water-carrying agent of 70 g, catalyst-alcohol ratio of 0.07, reaction time of 7 hours, inhibitor-acrylic acid ratio of 0.03, respectively. The obtained esterification products subsequently copolymerized with macromonomer to prepare PCE, and then the application performances were tested by adding PCE to cement pastes. From the fluidity results, the cement paste fluidity and fluidity retention capacity of PCE were better than those of commercial PCE, and this was in accordance with the high esterification rate of its esterification rate.

Abstract: In this paper, the adsorption behavior of polycarboxylate superplasticizer (PC) on cement was examined. Through adsorption of PC, adsorption area of the molecule was calculated, and it is found that PC molecule would maintain curled shape when it was adsorbed on the surface of cement particles.

Abstract: In this paper, polycarboxylate superplasticizer (PC) was separated by ultrafiltration to investigate function on dispersion of various portions of PC. It is found there is a grading effect on the dispersion and adsorption of polycarboxylate superplasticizer, through fluidity and adsorption experiments.

Abstract: Polycarboxylate superplasticizer (PCE) was usually sensitive to clay in mortar or concrete. The flow properties of cement pastes and mortars for PCEs with either kaolin or bentonite were studied systematically. The results showed that bentonite had a stronger influence on PCEs performance than kaolin, even no fluidity when bentonite dosage was more than 2%. The adsorption amount of bentonite on PCE was about 5-10 times more than that of kaolin, and PCEs adsorption on clay was proportional to its sensitivity to clay. The influencing mechanism of clay on PCE was analyzed from the structures of kaolin and bentonite and their adsorption characteristics between interlayer. The result of exploring control measure showed that adding the synthesized pre-adsorbent can effectively inhibit the effect of clay on PCE and ensure its workability.

Abstract: The molecular weight and molecular weight distribution (MWD) of polycarboxylate superplasticizer (PCE) was measured by gel permeation chromatograph (GPC) which combined three different detectors, namely refractive index detector (RI), laser light scattering detector (LS) and viscosity detector (VIS). By conducting numerous experiments, what the different peak stand for in the chromatogram was verified and the best sample concentration range in the GPC experiment was also determined. Besides, based on the analysis to the RI chromatogram, the theory on using peak area ratio to denote concentration ratio was put forward. What’s more, the calculation of macromonomer reaction ratio using the peak area in the RI chromatogram was introduced.

Abstract: Using methoxy polyethylene glycol methacrylate (MPEGMA), butyl acrylate (BA), Methyl allyl sulfonate (SMAS) as the raw materials, we can compose them to multipolymer in redox system. Through analyzing the factors and adjustment of orthogonal experimental results, the optimum technology of synthesis are shown as follows: n(MPEGMA):n(BA):n(SMAS)=5:12:2, n(H2O2)/n(Vc)=6, and the reaction temperature is 30°C. When the volume of superplasticizer is 0.42%, water cement ratio is 0.3; the initial fluidity of cement paste can get to 238mm, and within 1 hour without any loss.

Abstract: The properties of polycarboxylate superplasticizers(PCs) are related to their structures. For better understanding the different properties between PCs, their structures should be examined. In this paper, three kinds of PCs are synthesized by radical copolymerization method. The structure and property of PCs are studied by means of high performance liquid chromatography, zeta potential, water reducing rate and fluidity of cement paste. The results show that the conversion rate of reaction monomers is over 97%, and the reaction monomers are fully in the polymerization. The ester-type PCs has a higher water reduction capacity than the ether-type. At the same dosage, the adsorption and dispersion ability of ester-type PCs are stronger than that of ether-type PCs, yet the ether-type PCs has better slump retention performance in the cement pastes.

Abstract: A type of slow-release polycarboxylate superplasticizer (PCE) was prepared and its application performance and mechanism were studied systematically. The experimental results of cement and concrete showed that the prepared slow-release PCE can slowly play a dispersing role and finally achieve a good dispersing effect within 120 minutes. Its adsorption behavior on the surfaces of cement particles was measured by a total organic carbon (TOC) analyzer, displaying the validity of slow adsorption. The hydrate exothermic curves showed that the slow-release PCE only delayed the hydration but did not affect the hydration heat and workability of concrete.