GH矿粉对净浆试件收缩变形的影响

用PVC塑料管成型净浆圆柱体试件，通过连续测定试件在密闭养护环境和干燥养护环境的收缩变化，对纯水泥试件、单掺30％粉煤灰试件和复合掺10％GH超细矿粉及20％粉煤灰试件的收缩变形性能进行了对比分析。实验结果表明。GH矿粉会显著促进密闭养护环境水化初期净浆试件的化学减缩和自收缩，但若密闭养护超过7d后再进入干燥养护时。复合掺GH矿粉和粉煤灰试件的收缩总量小于纯水泥净浆试件。当养护环境由密闭养护变为自然干燥养护时。收缩速率会突然增大，成为产生干缩裂缝的危险期。延长密闭养护时间可显著减小掺混合材试件的收缩量。

Influence of GH Ultra-fine Powder on the Shrinkage of Pastes

Shrinkage development of cement pastes containing GH ultra-fine powder and fly ash were studied.The cylinder specimens were prepared by the PVC pipe mould.The shrinkage of the specimens in airtight curing condition and natural drying condition were measured continuously.Test results showed that the incorporation of GH ultra-fine powder increased the chemical reduction and self-drying shrinkage in airtight curing condition,but total shrinkage in the natural environment was smaller than control specimen when the airtight curing time was longer than 7 d.Shrinkage velocity increased abruptly when the curing condition changed from airtight condition to natural drying condition,which was a dangerous period for drying cracks.