有机防冻组分对混凝土液体防冻泵送剂性能的影响

研究了有机防冻组分甲醇(CH3OH)、乙二醇(CH2OH)2]和三乙醇胺N(CH2OH)3]对混凝土液体防冻泵送剂性能的影响.结果表明:CH3OH,(CH2OH)2及N(CH2OH)3均可增大硫酸钠(Na2SO4)在-5～5 ℃的饱和溶解度,并且CH3OH和(CH2OH)2的增溶作用大于N(CH2OH)3的.CH3OH和(CH2OH)2,特别是(CH2OH)2降低掺液体防冻泵送剂的水泥净浆初始流动度及经时保留值的程度较N(CH2OH)3的低.CH3OH和(CH2OH)2与水泥的适应性比N(CH2OH)3的好.3种有机防冻组分中,CH3OH和(CH2OH)2,特别是(CH2OH)2的防冻效果优于N(CH2OH)3的,并且N(CH2OH)3还会降低R-7 28掺防冻泵送剂的受检混凝土在-15 ℃下养护7 d,再移至(20±3) ℃及相对湿度90%以上的标准养护条件下养护28 d的抗压强度,与不掺防冻泵送剂的基准混凝土在标准养护条件下养护28 d的抗压强度之比]和R-7 56(掺防冻泵送剂的受检混凝土在-15 ℃下养护7 d,再移至标准养护条件下养护56d的抗压强度,与不掺防冻泵送剂的基准混凝土在标准养护条件下养护28d的抗压强度之比).因此,虽然N(CH2OH)3是一种有效的有机早强剂,但它并不是一种有效的有机防冻剂.

INFLUENCES OF ORGANIC ANTI-FREEZING INGREDIENTS ON PERFORMANCE OF LIQUID ANTI-FREEZING PUMPING AGENTS OF CONCRETE

Influences of organic anti-freezing ingredients such as carbinol, ethanediol and triethanolamine on the performance of liquid anti-freezing pumping agents of concrete were investigated. The experimental results showed that carbinol, ethanediol and triethanolamine can improve the saturated solubility of sodium sulfate at-5 ℃ to +5 ℃, and carbinol and ethanediol increase solubility better than triethanolamine does. The initial fluidity and fluidity retention of cement paste with liquid anti-freezing pumping agents are decreased to a greater extent by triethanolamine than by carbinol or ethanediol; they decrease the least with ethanediol. Carbinol and ethanediol are more compatible with cement than is triethanolamine. Among the three organic anti-freezing ingredients, the anti-freezing effects of carbinol and ethanediol, especially ethanediol, are stronger than that of triethanolamine, and triethanolamine can still decrease R-7+28 (the ratio of the compressive strength of concrete with anti-freezing pumping agent cured for 7 d at -15 ℃then for 28 d at standard curing conditions with (20+3) ℃ and more than 90% (relative humidity, Rh) to 28d compressive strength of concrete without anti-freezing pumping agent at standard curing conditions) and R-7+56 (the ratio of the compressive strength of concrete with anti-freezing pumping agent cured for 7 d at -15 ℃ then for 56 d at standard curing conditions to 28 d compressive strength of concrete without anti-freezing pumping agent at standard curing conditions). Although triethanolamine is an effective organic accelerating admixture, it is not an effective organic anti-freezing admixture.