掺入不同细度的粉煤灰等量取代水泥10%~30%,制备了粉煤灰高强轻骨料混凝土,采用自行设计试验和椭圆环法试验分别研究了早期自收缩变形和抗裂性能,并与基准样进行了对比分析.结果表明:随粉煤灰的掺入,混凝土早期自收缩得到抑制,且随粉煤灰掺量的增加,自收缩随之减小,粉煤灰细度越高,减缩效果越明显;而在低水胶比条件下,水胶比越低,自收缩增大越显著;另外,骨料的预湿状态对自收缩影响较大,未预湿轻骨料显著增加了早期自收缩变形.椭圆环抗裂性试验表明,粉煤灰的掺入显著改善了轻骨料混凝土抗裂性能,且粉煤灰细度越高,早期抗裂性能增强越显著.因此,在实际工程中,粉煤灰的掺入可作为减小高强轻骨料混凝土早期自收缩和提高抗裂性能的技术手段.
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