粉煤灰水泥砂浆早期断裂性能试验研究

Experimental Study on Fracture Behavior of Cement Mortar Containing Fly Ash at Early Age

摘要:

为了研究粉煤灰（FA）水泥砂浆早期断裂性能，采用粉煤灰内掺替代水泥，制作了水泥砂浆切口梁，对1~3 d龄期下的试件进行了三点弯曲试验和抗压强度试验. 试验过程中采用数字图像相关技术监测试件应变和位移，采用声发射技术记录试件内部损伤过程. 结果表明：FA导致水泥砂浆早期断裂性能、抗压性能、抗裂缝扩展能力和抗断裂能力降低，断裂过程区及内部损伤范围显著缩小；FA掺量越大，龄期越早，断裂参数降幅越显著，裂缝扩展越快；断裂参数与抗压强度之间存在线性关系.

Abstract:

In order to investigate the fracture behavior of cement mortar with fly ash（FA） at early age， cement was replaced with FA to fabricate cement mortar notched beams. Specimens at 1， 2， 3 d were subjected to three-point bending tests and compressive strength tests. Digital image correlation（DIC） technology was adopted to monitor the strain and displacement of specimens， while acoustic emission（AE） technology was used to record the occurrence and accumulation of internal damage. The results show that FA leads to an obvious decrease in the fracture behavior， compressive properties， crack propagation and fracture resistance of cement mortar at early age. It is worthwhile to note that both the fracture process zone and the internal damage range are significantly narrowed for FA cement mortar at early age. With the increase of FA content and shortening of curing age， the fracture parameters of the cement mortar decrease， while the cracks propagation accelerates. It is found that a linear relationship exists between fracture parameters and cube compressive strength.