考虑石粉对流变性影响的自密实混凝土配合比设计

Mix Design of Self-compacting Concrete Considering the Effect of Limestone Powder on Rheology

关键词:  机制砂自密实混凝土  石粉  流变性  净浆阈值  配合比设计

Key words:  manufactured sand self-compacting concrete  limestone powder  rheology  paste rheological threshold  mix design

摘要:

以净浆流变阈值理论为基础，采用在净浆中加入石粉的试验方法确定净浆流变性，通过粉煤灰替代率不同的机制砂砂浆基准需水率试验来确定砂浆的堆积密度，进行了机制砂自密实混凝土配合比试验，研究了石粉对净浆流变参数、净浆流变阈值和混凝土自密实区域的影响.结果表明：相同的水粉比下，掺入石粉后净浆的屈服强度和塑性黏度都明显大于未掺石粉的净浆；采用堆积密度修正的净浆阈值所确定的净浆自密实区域相较于未掺石粉的净浆自密实区域向水粉比较大的方向移动，考虑石粉对净浆流变性影响后，净浆的自密实区域和机制砂混凝土的自密实区域吻合.

Abstract:

Based on the rheological threshold theory of paste， the rheology of paste was determined by paste test with limestone powder（LP） as powder and the packing density of mortar was calculated by the basic water-powder ratio of manufactured sand mortar with different fly ash（FA） contents. Through the mixing test of manufactured sand self-compacting concrete， the effects of LP on the rheological parameters， rheological threshold and self-compacting zone were studied. The results show that with the same water-powder ratio， the yield strength and plastic viscosity of the paste mixed with LP are significantly higher than those without LP. Comparing to the self-compacting zone without LP， the self-compacting zone using the rheological threshold modified by packing density moves towards the direction of higher water-powder ratio. This reveals that the self-compacting zone is consistent with that of concrete mixed by manufactured sand if considering the effect of LP on the rheological property of paste.