施工养生期半刚性材料结构层变形观测及其抗裂性能

Deformation observation of structural layer with semi-rigid material during curing period and its anti-cracking performance

在3种半刚性材料结构层表面钉入钢钉,观测养生期内钢钉间距的变化并由此计算观测段的应变,用应变绝对值的均值、变化范围表征结构层的变形特性.采集数据的时机包含连晴7d以上的下午及暴雨过后,结构层应变极值基本能够代表3种材料在类似气候条件地区的极端变形情况.结果表明:底面设置水泥净浆粘结层的新水泥稳定碎石(CBG-25)结构层应变范围4.9×10-6～104.9×10-6,远小于室内最大干缩应变;普通水稳碎石应变均值553×10-6,变化范围67.7×10-6～1 368.3×10-6;综合稳定细粒土应变均值104×10-6,变化范围0～772×10-6;半刚性材料结构层横向应变远大于纵向应变.以极限弯拉应变作评价指标时,CBG-25结构层抗裂性能最好,综合稳定土次之,普通水稳碎石抗裂性能最差;以最大应变作为评价指标时,综合稳定土抗裂性能优于普通水稳碎石.

By driving the nails into three kinds of structural layers, with semi-rigid materials, the strain of the layers was calculated by observing the distance changes of the nails during the curing period. The average of the absolute value of strain and its variation range were used to characterize the deformation characteristics of the layers. Timing of data acquisition was set at the afternoon after seven sunny days at least and heavy rain fall. The strain extremum of the layers could represent the extreme deformation of the three kinds of materials in the areas with similar climatic condition. The result showed that the strain vari- ation range of new cement stabilized macadam （CBG-25） layer with a cement paste adhesive underside was from 4. 9）〈10.6 to 104. 9）〈 10.6, being much less than the indoor maximum shrinkage strain. The strain mean of ordinary cement stabilized macadam was 553 X 10.6 and the variation range was 67. 7 ）〈 10.6 to 1 368. 3）〈10-6. The strain mean of composite stabilized soil was 104）〈 10-6 and the variation range was from 0 to 772）〈 10-6. The transverse strain of ordinary cement stabilized macadam and composite stabi- lized soil were much larger than the longitudinal strain. Taking ultimate bending strain as evaluation in- dex, anti-cracking performance of CBC-25 layers was the best, composite stabilized soil took the second place and ordinary cement stabilized macadam was the worst. If the maximum strain was taken as evalua- tion index, the composite stabilized soil would be better than the ordinary cement stabilized macadam.