Revealing the Effects of Methoxy Polyethylene Glycol Ether on the Performance of Polycarboxylate Superplasticizers and Their Desensitization Functions in Relation to Concrete

During the manufacture of high-strength concrete, its sensitivity to variations inconcrete mixing water, the poor adaptability of cement, and high hydration temperatures are often encountered. Therefore, in this paper, firstly, the esterification reaction of methoxy polyethylene glycol ether (MPEG) and methacrylic acid (MAA) was carried out. According to the different molecular weights of MPEG, three kinds of esterification products (MPEG-MAA) were synthesized. Three kinds of PCE-st were synthesized by free-radical copolymerization of three kinds of MPEG-MAA, ethylene glycol polyethylene glycol ether (EPEG), and acrylic acid (AA), and their effects on the properties of cement paste and concrete were analyzed. The results revealed that when the water-cement ratio increased from 0.25 to 0.31, PCE-st with MPEG with a molecular weight of 600 optimally reduced the water content variation sensitivity and increased the fluidity of cement pastes by only 62 mm, while PCE-st with smaller and larger molecular weights of MPEG increased the fluidity by 94 mm and 80 mm, respectively. As the molecular weight of MPEG increased from 400 to 1200, the hydration temperature decreased from 43.8 °C to 39.5 °C, and the setting time was delayed by about 30 min. Finally, the compressive strength of concrete made with PCE-st was similar to that of the concrete made with commercially available PCE-et0.