چكيده به لاتين
Abstract:
In order to improve the efficiency and maintain the concrete's basic properties, additives are often applied to concrete. Among these properties, concrete performance during operation and its resistance can be mentioned. The use of superplasticizers in concrete makes it easier to mold, increase ultimate strength, reduce costs and save time. Polycarboxylate superplasticizers (PCEs) are the newest type of superplasticizers that cause them to spatially and electrostatically repel in cement particles. In this project, the synthesis of acrylic acid-based polycarboxylate superplasticizers with AMPS, AAm and DAAM comonomers with side-branches of polyethylene glycol in the presence of NaOH, KOH and NH4OH as mineral cations were studied. It was attempted to examine the effect of the type and amount of comonomer groups and the length of the side chain on the behavior of the synthesized PCEs. In order to evaluate the performance of superplasticizers synthesized in cementitious systemss, fluidity tests and fluidity retention were performed to analysis the effect of the ratio of sulfone, amide and carbonyl to the carboxylate groups in the main polymer chains. It was observed that AMPS and DAAM comonomers have a better performance than the AAm comonomer. However, the DAAM comonomer has the same performance compared to the AMPS comonomers in much lower amounts. It was also observed that by decreasing side chain length, the performance increased. Retention of fluidity also increases with decreasing side chain length.We had the highest fluidity and fluidity retention in copolymers AA-co-AMPS (weight percent 85: 15) and AA-co-DAAM (weighing 97/5, 2/5), which results in higher adsorption of these chains on particles of the cement. Finally, by improving the diffusion and dispersion of cement hydrated particles, it improves cement efficiency.
Keywords: superplasticizer, polycarboxylate ,cement paste, fluidity
