不同轻骨料混凝土高温后劣化性能研究

Experimental study on mechanical properties of ALWC under low temperature environment

为改善轻骨料混凝土高温后的劣化性能以及抗爆裂性能,将玄武岩、聚丙烯纤维以单掺和混掺的形式掺入到轻骨料混凝土基体中进行试验。结果表明,聚丙烯纤维有利于轻骨料混凝土的高温抗爆裂性能,而玄武岩纤维仅可推迟而不能阻止其高温爆裂。随着温度升高,不同轻骨料混凝土的色泽和表观变化规律大致相同;其立方体抗压强度在200℃以内略有升高,但随后一直下降;而轴心抗压强度、劈裂抗拉强度和弹性模量则呈直线下降趋势,但是掺入纤维后其残余力学性能指标均大于素全轻混凝土;高温后,应力-应变曲线上的峰值应力和峰值应变明显下降右移,这些特征变化反映了随着温度的增高,混凝土内部损伤加大及逐渐劣化。

In order to improve the degradation performance and anti - bursting performance of the lightweightaggregate concrete after high temperature , the basalt and polypropylene fibers were added into the lightweight aggregate concrete matrix in the form of single addition and mixed addition , and compared with the all - light-weight concrete. The results show polypropylene fiber can improve the high temperature anti - burst perform-ance of the lightweight aggregate concrete , and the basalt fiber can only be delayed and cannot prevent thehigh temperature burst of the lightweight aggregate concrete. With the increase of temperature , the color andapparent change of concrete are similar to those of the all - lightweight concrete. The compressive strength and the splitting tensile strength increase slightly at 200C , but then decrease. The axial compressive strength and elastic modulus has been declining , and the trend of the all - lightweight concrete is the same mechanical properties of the fiber are larger than that of the all - lightweight concrete. Aftethe peak stress and peak strain on the stress - strain curve decreased obviously that the internal damage of concrete increased and deteriorated with increasing temperature.