当量碱概念及矿物掺合料对抑制ASR效用的试验研究

Test and Research on Equivalent Alkali Concept and Effects of Mineral Admixtures on Inhibiting ASR

用化学纯的NaCl、NaOH、KCl、KOH来调整水泥中当量碱含量达到1.0%,采用砂浆棒法快速判定集料的潜在碱活性;用粉煤灰和磨细矿渣粉等量取代部分硅酸盐水泥,并评价这两类矿物掺合料对抑制碱-硅酸反应的效用。试验结果表明,用分子量比值作为当量碱计算的权值得到的当量碱,不能真正反映混凝土中总碱量与ASR膨胀率之间的规律;相同掺量条件下,粉煤灰抑制ASR的作用显著优于磨细矿渣粉;为有效避免混凝土发生ASR,并尽量满足混凝土的其他性能,可采取水泥∶磨细矿渣粉∶粉煤灰=40∶40∶20的胶凝材料体系。

Equivalent alkali content（1.0%） of cement adjusted with NaCl,NaOH,KCl,KOH che mically pure is used to determine the potential alkali activity of some aggregate through Accelerated Mortar Bar Test（AMBT）.The alkali-silicate reaction（ASR） inhibition effects of fly ash and GGBS are evaluated by replacing equal content of Portland cement in the test.The results shown：（1） the weight calculated by molecular weight ratio should not be simply used to compute the equivalent alkali content which can t fully represent the relationship between the whole alkali content and ASR expansion; （2） the effects of fly ash on inhibiting ASR is much better than that of GGBS; （3） the cementitious materials component ratio such as cement ＂ GGBS ＂ fly ash=40 ： 40 ： 20 is appropriate for inhibiting ASR and some other perfor-mances of fresh and hardened concrete.