水化热调控型镁质抗裂剂性能研究及应用

Study on the properties and application of magnesium anticracking agent regulated by hydration heat

研究了水化热调控型镁质抗裂剂(TM)对水泥净浆水化热、砂浆膨胀性能及混凝土力学性能、干燥收缩性能的影响,并采用XRD和SEM探究了其作用机理。结果表明:入模温度对TM的抑温作用效果有显著影响,入模温度为20℃时,净浆温峰值较空白组降低了42.6%,当入模温度升高至35℃时,TM掺量对抑温效果的影响不大,但会延长水泥的凝结时间;随养护温度升高,TM水化反应会速度加快,膨胀周期显著缩短;TM可减小混凝土的干燥收缩,养护至120 d时,收缩率较空白组减少19.1%;随TM掺量的增加,会引起混凝土试件早期(3 d)抗压强度显著降低,但不影响试件长龄期(60 d)的力学性能;TM对水泥水化历程、水化产物生成及微观结构密实程度的改变是提高混凝土抗裂性能的根本原因;外掺6%TM时,混凝土工程结构试验段温升峰值较空白段降低4.8℃、收缩值降低131.3με、裂缝数仅为1条。

The effects of the hydration heat regulated magnesium anti-cracking agent(TM)on the hydration heat,expansion properties,mechanical properties and drying shrinkage properties of the cement paste were studied,and its action mechanism was explored by XRD and SEM.The data showed that the injection temperature has a significant impact on the temperature suppression effect of TM.When the injection temperature is 20℃,the temperature inhibition rate of cement paste gradually increases to 42.6%.When the injection temperature is increased to 35℃,the difference of the content on the temperature inhibition effect is not significant,but the setting time of cement is prolonged.With the increase of curing temperature,the hydration reaction of TM will increase rapidly,and the expansion period will decrease significantly.TM can reduce the drying shrinkage of concrete.When curing to 120 d,the shrinkage rate can be reduced by 19.1%compared with the blank group.With the increase of TM content,the compressive strength of concrete specimens at early stage(3 d)will decrease significantly,but the mechanical properties of concrete specimens at long age(60 d)will not be affected.The change of cement hydration process,hydration product formation and microstructure compactness by TM is the fundamental reason for improving the crack resistance of concrete.With addition of 6%TM,the temperature rise of the test section of concrete engineering structure is reduced by 4.8℃,the shrinkage value is reduced by 131.3 micro-strain,and the number of cracks is only 1.