具有软岩硬土性质的EPS混凝土的变形特征研究

Deformation characteristics of EPS concrete with soft rock and hard soil properties

聚苯乙烯颗粒混凝土是继发泡水泥之后的又一种新型轻质混凝土,受压时表现出明显的延性特征,这导致应力-应变全过程中可能没有明显的峰值,或者有峰值时峰值处对应的应变较大,而JG/T 266—2011《泡沫混凝土》标准和新编的2014—1259T—JC《聚苯乙烯颗粒泡沫混凝土(征求意见稿)》均未考虑这一特征,也即抗压强度是以压缩过程中的最大破坏荷载除以受压面面积,若不考虑最大破坏荷载对应的应变,会存在高估其真实抗压强度的风险。在大量压缩试验和反复加卸载试验的基础上,统计后对比发现,聚苯颗粒混凝土的峰值强度大多出现在3%应变之前,故建议将3%应变作为确定最大荷载的附加条件。当峰值出现在3%应变之前时取该峰值荷载为最大破坏荷载;反之,当峰值出现在3%应变以后时,以3%应变以内的最大荷载作为破坏荷载。轻质混凝土强度测试时用应变作为附加条件是科学合理的,实际工程中应具体情况对3%进行调整。

Polystyrene concrete is a new kind of lightweight concrete after foaming cement.It shows obvious ductile characteristics subjected compression,this may lead to the possibility that there may be no obvious peak value in the whole stress-strain process,or when it has peak but peak corresponds to the strain is larger.However,JG/T 266—2011＂foam concrete＂standard and new 2014—1259 T—JC＂polystyrene foam concrete（Draft）＂are not considered this feature.The compressive strength is the biggest failure load divided by pressure surface area in the compression process.There is a risk of overestimating the true compressive strength if without considering the strain corresponding to the maximum failure load.Find after Statistical comparison in a large number of compression test and repeated unloading experiment that the peak strength of polystyrene concrete is mostly before the 3% strain,therefore suggested that the 3% strain be used as an additional condition to determine the maximum load.When the peak value appears before the 3% strain,the peak load is taken as the maximum failure load.Conversely,when the peak value appears after 3% strain,the maximum load under the strain of 3% is used as the failure load.It is scientific and reasonable to use strain as an additional condition in the strength test of lightweight concrete.The actual project should be adjusted to the specific situation of 3%.