Synthesis, characterization and investigation of the effects of a new generation of water reduci̇ng polycarboxylate for cement applications

Considering the earthquake risk of our country, the durability of reinforced concrete buildings is of great importance. Workability of concrete is achieved by using a lower water/cement ratio. Since their discovery, polycarboxylate ether-based (PCE) superplasticizers have become widely used in the construction industry in recent years due to their advantages such as high-water reduction rates and good slump retention properties even at low dosages. The molecular weight distribution of PCEs, which are mostly synthesized by free radical polymerization, is very difficult to control. The use of controlled/living polymerization (CLRP) methods is preferred to keep the molecular weight under control. Due to its unique advantages compared to conventional techniques (controllable molecular weight, low molecular weight distribution, polymer with functional groups, etc.), its use in the production of new polymeric materials is very important. Among CLRP techniques, atom transfer radical polymerization (ATRP) is the most widely used method. While the ATRP method has many advantages, problems such as high temperature requirements and easy oxidation of the metal catalyst are encountered. Nowadays, light-activated ATRP methods have been developed to eliminate these problems. In this thesis, water reducing additives were synthesized by light-induced atom transfer radical polymerization (photo-ATRP) method. The theoretical charge density values of the synthesized polymers with repeating units and the adsorption behavior with Ca2+ ion were examined and the adsorption energies were calculated theoretically with Gaussian 09 program. As a result, it was determined that the polymer with the highest adsorption energy with the Ca2+ ion was poly(AA-co-PEGMA).The behavior of the synthesized materials on cement paste was investigated under laboratory conditions. In this context, poly(AA-co-PEGMA) was found to be the most effective additive in Marsh funnel and minislump experiments. The theoretical and experimental data are in agreement with each other. This shows that the polymer can be used as a water reducing admixture and can reduce the water/cement ratio and make concrete easier to work. The reduction in the amount of cement both contributes to reducing energy consumption and plays an important role in mitigating the effects of global warming by limiting CO₂ and greenhouse gas emissions from the production process. Keywords: Cement, Photo-ATRP, Calcium ion, Polycarboxylate