This study synthesized polycarboxylate superplasticizer (PCE) with varying carboxyl densities and main chain degrees of polymerization. The structural parameters of PCE were characterized using gel permeation chromatography and infrared spectroscopy. The study investigated the impact of PCE's diverse microstructures on cement slurry's adsorption, rheology, hydration heat, and kinetics. Microscopy was used to analyze the products' morphology. The findings indicated that an increase in carboxyl density led to an increase in molecular weight and hydrodynamic radius. A carboxyl density of 3.5 resulted in the highest flowability of cement slurry and the most considerable adsorption amount. However, the adsorption effect weakened when the carboxyl density was the highest. Decreasing the main chain degree of polymerization led to a significant reduction in the molecular weight and hydrodynamic radius. A main chain degree of 16.46 resulted in the highest flowability of slurry, and both large and small main chain degrees of polymerization exhibited single-layer adsorption. PCE samples with higher carboxyl density caused the greatest delay in the induction period, whereas PCE-3 promoted the hydration period's acceleration. Hydration kinetics model analysis indicated that PCE-4 yielded needle-shaped hydration products with a small nucleation number in the crystal nucleation and growth stage, while PCE-7's nucleation was most influenced by ion concentration. The addition of PCE improved the hydration degree after three days and facilitated the strength's later development compared to the blank sample.
Abstract At present, most of the methods for testing the amount of Water-reducing admixture adsorbed on the surface of the cement particles use the total organic carbon method (TOC method), but various literatures describe the pre-treatment of the test method as ambiguous and poor operability. In view of the above problems, this paper carried out a study on the pre-treatment conditions of the test for the adsorption of Water-reducing admixture on the surface of cement particles by total organic carbon method, and explored the effects of stirring time, standing time, and standing temperature on the adsorption of Water-reducing admixture on the surface of cement particles. The study determined the pre-treatment and test conditions of the TOC method, and provided reference for the research on the adsorption behavior of the water reducer on the surface of cement particles. The correlation coefficients of the standard curve of Water-reducing admixture obtained by this method are all greater than 0.999, the relative error of the results of the 10 parallel experiments of the method is less than 0.005%, and the relative standard deviation (RSD) is 0.7706%.
A highly adaptable polycarboxylate superplasticizer (PCE-2) was synthesized by free radical copolymerization in aqueous solution with isoprenol polyoxyethylene ether as macromonomer, acrylic acid and hydroxyethyl acrylate and 2-methacryloyloxyethyl phosphate as unsaturated monomers, mercaptopropionic acid as chain transfer agent, hydrogen peroxide - Bruggolite FF6/ferrous sulfate heptahydrate as redox initiator. The structure of the copolymer was characterized by IR and GPC. The adaptability of the copolymer to concrete was studied from four aspects, such as dosage, water consumption, temperature and clay content. The results show that adaptability of the PCE-2 is better than those of the commercially available Polycarboxylate Superplasticizer (PCE-1).
Abstract With the substantial increase in the amount of data information and the development of 5G technology, boundary computing technology based on 5G, as a real-time and efficient data processing method, has broad application prospects. The aggregation gateway further aggregates the power injection data of all electric energy storage units and sends it to the power company. The power company uses its own private key to access the aggregated data. Row decryption to obtain the total power data recovered in each time slot. The paper proposes a new solution using Lagrangian interpolation to ensure data privacy and security. The security shows that the algorithm can not only protect the privacy of the electric energy storage unit, but also realize the confidentiality and integrity of the injected data. Efficiency analysis shows that this algorithm can significantly reduce computational complexity and improve communication efficiency.
Abstract Water solution method, saturated calcium hydroxide solution method and cement solution method were used to evaluate the foam inducing and foam stabilizing properties of seven different types of air entraining agents. The evaluation results of the three methods were compared with the initial air content of concrete, the air content in 1h and the change rate of air content in 1h. The results show that the corresponding relationship between the test results of water solution method and concrete is the best.
Abstract Polycarboxylate superplasticizers with different structural parameters were synthesized by isobutylene polyoxyethylene ether, acrylic acid and ammonium persulfate as raw materials from the perspective of molecular design. The influence of polycarboxylate superplasticizer on cement adsorption was characterized by cement adsorption capacity test and fluidity test, etc. At the same time, the adsorption change of polycarboxylate superplasticizer on the surface of cement particles was also revealed. It was found that the best adsorption and dispersion properties on cement paste were obtained under the heating synthesis process when the structure of the water reducing agent was designed to have a weight average molecular weight of 55128, a macromonomer conversion rate of 84.61%, and a side chain density of 0.1725. For the normal temperature process, when the weight average molecular weight was 103920, the macromonomer conversion rate 92.03%, and the side chain density 0.3115, the best effects in cement can be achieved.
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