高温加热后轻骨料混凝土力学性能实验研究

Experimental study on mechanical performance of lightweight aggregate concrete after high temperature heating

本文通过对陶粒轻骨料混凝土试块进行不同温度水平的加热,待自然冷却后进行相应的加载试验,研究其抗压强度和弹性模量等力学性能参数随加热温度水平的变化规律,并与普通混凝土进行理论对比。为避免试块高温爆裂,按不同温度水平对试块分批进行阶梯升温,当试块内外温度相同后恒温保持半小时,打开炉门使试块在炉内自然冷却到常温状态,然后进行相应加载试验。试验结果表明:随加热温度的升高,陶粒混凝土棱柱体抗压强度的下降幅度大于立方体抗压强度;初始弹性模量与峰值变形模量随温度变化的拟合曲线基本接近。与普通混凝土相比,不论是立方体还是棱柱体试块,陶粒混凝土的残余抗压强度均高于普通混凝土;弹性模量随温度的下降幅度也小于普通混凝土。研究表明:如能有效解决在高温加热过程中的爆裂,陶粒轻骨料混凝土的潜在抗高温性能将明显优于普通混凝土。

After being heated at different high temperatures and naturally cooled, ceramsite lightweight aggregate concrete （LWAC） blocks were conducted loading experiments to study the mechanic performance change with heating temperatures, such as compressive strength and elastic modulus, and compare with the performance of the normal concrete （NC）. To avoid concrete spalling during heating, the temperatures were increased step-by-step, and were kept for half an hour when they approach the design temperature and are identical inside and outside the blocks. Then the test blocks in furnace were naturally cooled to normal temperature by opening the furnace door loading tests were carried out. Experiment results indicate that, （1） for ceramsite LWAC, the compressive strengths of prism blocks declines greater than cubic test blocks, the fitted decrease curves of the initial and peak deformation modulus coincide well in whole; （2） whether it is cubic block or prism block, the residual strength of ceramsite LWAC is larger than that of NC, and the decrease of the elastic modulus of LWAC is lower than that of NC. The results show that ceramsite LWAC have potentially better fire resistance performance than NC if spalling problem in high temperature is well solved.