To counteract the excessive air entrainment of polycarboxylate superplasticizers (PCEs) and diminish the damage caused by the expansion of air bubbles during steam curing, defoamers were used in this study to solve the problem of high porosity and coarse pore size of the steam-cured mortars containing PCEs. The effects of mineral oil defoamer and polyol defoamer on fluidity, heat of hydration, compressive strength and pore structure were investigated at different dosages (0.03–0.09 %), and the performance differences between the two defoamers were compared in fresh and hardened mortar. The results showed that the defoamers reduced the fluidity and fluidity loss of cement and had a retarding effect on cement hydration. Besides, the defoamers increased the compressive strength due to the improvement of the pore sizes and spacing coefficients. The differences in the properties and action mechanisms of the two defoamers resulted in different effects on the mortar, especially on compressive strength, and the differences were more significant in the 28-day strength. Overall, the mineral oil defoamer was better adapted to steam curing with an optimal dosage of 0.05 %.

中文翻译：

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消泡剂对聚羧酸高效减水剂蒸养砂浆力学性能及孔结构的影响

为了抵消聚羧酸减水剂（PCE）的过量引气，减少蒸汽养护过程中气泡膨胀造成的损害，本研究使用消泡剂来解决蒸汽养护砂浆孔隙率高、孔径粗的问题。含有 PCE。研究了矿物油消泡剂和多元醇消泡剂在不同用量（0.03%~0.09%）下对流动性、水化热、抗压强度和孔结构的影响，并比较了两种消泡剂在新拌砂浆和硬化砂浆中的性能差异。结果表明，消泡剂降低了水泥的流动性和流动性损失，对水泥水化具有延缓作用。此外，消泡剂由于孔径和间距系数的改善而提高了抗压强度。两种消泡剂性能和作用机理的差异导致对砂浆的影响不同，尤其是对抗压强度的影响不同，且在28天强度上差异更为显着。总体而言，矿物油消泡剂更适合蒸汽固化，最佳用量为0.05%。