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首页> 外文期刊>Cement and Concrete Research >Effect of shrinkage-reducing admixtures on the properties of alkali-activated slag mortars and pastes
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Effect of shrinkage-reducing admixtures on the properties of alkali-activated slag mortars and pastes

机译：减缩剂对碱活化矿渣砂浆和浆料性能的影响

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The effect of a shrinkage-reducing admixture (SRA) based on polypropylenglycol on the dimensional stability of waterglass-activated slag mortars was studied. The analysis also showed the effect of the admixture on pore structure of the mortars as well as on the mineralogical composition and microstructure of the alkali-activated slag pastes. The SRA reduced the shrinkage by up to 85 and 50 percent when the alkali-activated slag mortar specimens were cured at relative humidities of 99 and 50 percent, respectively. The mechanism primarily involved in shrinkage reduction is the decrease in the surface tension of pore water prompted by the admixture. The SRA also modified the pore structure - under both curing conditions - increasing the percentage of pores with diameters ranging from 1.0 to 0.1 mu m. Capillary stress is much lower in these pores than in the smaller capillaries prevailing in mortars prepared without admixtures. Microstructurally, the SRA occasioned a slight increase in the proportion of Si units Q~2 in the CSH gel and a decrease in the percentage of Al replacing the Si in the gel structure. The admixture did not, however, modify the mineralogical composition of the pastes. Finally, the SRA admixture retarded the alkaline activation of the slag, more intensely at higher admixture dosages. While the admixture did not significantly alter the degree of reaction in pastes cured for 7 days at RH=99 percent, the value of this parameter dropped by 7 percent in the presence of the admixture in pastes cured at 50 percent relative humidity.
机译：研究了基于聚丙二醇的减缩剂（SRA）对水玻璃活化矿渣砂浆尺寸稳定性的影响。分析还显示了掺合料对砂浆孔隙结构以及碱活化矿渣糊的矿物学组成和微观结构的影响。当碱活化矿渣砂浆试样分别在99％和50％的相对湿度下固化时，SRA最多可将收缩率降低85％和50％。减少收缩的主要机制是混合物引起的孔隙水表面张力的降低。在两种固化条件下，SRA还修饰了孔结构，从而增加了直径范围从1.0到0.1微米的孔的百分比。在这些孔隙中，毛细管应力要比在没有掺合料的砂浆中普遍存在的较小的毛细管中要低得多。在微观结构上，SRA使CSH凝胶中的Si单元Q〜2的比例略有增加，而在凝胶结构中替代Si的Al的百分比降低。然而，该混合物没有改变糊的矿物学组成。最后，SRA混合物在较高的混合物剂量下会更强烈地阻碍炉渣的碱活化。尽管混合物在RH = 99％的条件下固化7天的糊料并没有显着改变反应程度，但是在混合物中存在相对湿度为50％的相对湿度的情况下，该参数的值下降了7％。

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