Preparation and properties of quaternary copolymerized TPEG-based shrinkage reducing agent for cementitious materials

The shrinkage cracking of concrete will reduce the durability and bearing capacity of the structure, accelerate the corrosion of steel bars, and affect the safety and service life of buildings. Meanwhile, traditional polyether shrinkage reducers, while reducing drying shrinkage, will have adverse effects on mechanical properties and durability. To simultaneously improve the shrinkage capacity, mechanical properties and durability of concrete, In this paper, a polyether reducing agent (SRA1) was prepared by free radical polymerization using isopentenol polyoxyethylene ether (TPEG-2400) as the large monomer of polyether and diethylene glycol monobutyl ether maleic anhydride ester (MABE), acrylic acid (AA), and sodium methylallenesulfate (SMAS) as the small monomers. Based on SRA1, the number of ether bonds was increased and hydrophilic amide groups were introduced. Polyether shrinking agent (SRA2) was prepared by the same method using polyethylene glycol methacrylate (PEGMA), N-hydroxymethylacrylamide (HAM), and sodium methylallenesulfate (SMAS) as small monomers. Based on SRA2, a hydrophobic benzene ring was introduced, and polyether shrinking agent (SRA3) was prepared by the same method using polyethylene glycol methacrylate (PEGMA), N-hydroxyethyl acrylamide (HEAA), and sodium p-styrene sulfonate (SSS) as small monomers. The molecular structures, thermal stability, and microscopic morphologies of three SRAs were characterized by FTIR, 1HNMR, GPC, XRD, TG-DTG, and SEM. The effects of the three SRAs on the properties of cement-based materials were compared and evaluated through the performance test experiments of cement materials. The experimental results of the performance of cement-based materials show that the addition of the three kinds of SRAs effectively improves the shrinkage rate, fluidity, mechanical properties and durability of the mortar. When the dosage of SRAs is 2.0% of the mass of the base material, the performance of the cement-based material with SRA3 added is the best: Compared with the blank group, the drying shrinkage rate decreased by 41.2% at 30 days, the fluidity of the clean slurry reached 230 mm, the compressive strength and flexural strength increased by 33.3% and 7.9%, respectively, at 28 days, the non-steady-state migration coefficient decreased by 52.6%, and there were better retarding and water reduction effects.