珍珠岩基相变骨料混凝土断裂特性试验与分析

Experiment and Analysis on Fracture Properties of Perlite Based Phase Changing Aggregates Concrete

关键词:  膨胀珍珠岩  相变储能混凝土  三点弯曲梁  裂缝扩展过程  临界有效裂缝长度  断裂韧度

Key words:  expanded perlite  phase changing energy storing concrete  three point bending beam  crack propagation process  critical effective crack length  fracture toughness

摘要:

先以硬脂酸丁酯为相变材料，膨胀珍珠岩为基体材料，石灰石粉末为表面改性材料制备珍珠岩基相变骨料（PBPCA），再用其等体积取代混凝土中的部分砂制备珍珠岩基相变骨料混凝土（PBPCAC）；通过三点弯曲梁试验和立方体试块拉压比，研究PBPCA掺量不同时PBPCAC的断裂特性和韧性.结果表明：PBPCAC的断裂过程分为裂缝产生、裂缝发展和裂缝失稳3个阶段；其裂缝产生阶段较普通混凝土长，裂缝失稳阶段较普通混凝土短；PBPCAC的临界有效裂缝长度、起裂断裂韧度和失稳断裂韧度与普通混凝土大致相同；PBPCA的掺加未明显改变混凝土的延性和韧性；PBPCAC具有较好的抗断裂性能.

Abstract:

Butyl stearate as phase change material was impregnated into expanded perlite, and the limestone powder was used as surface modification material to prepare perlite based phase changing aggregates(PBPCA). Then the perlite based phase changing aggregates concrete(PBPCAC) was perpared by PBPCA replacing sand. The effect of PBPCA content on fracture properties and toughness of PBPCAC was investigated through ratio of splitting tensile strength to compressive strength of concrete and fracture toughness based on three point bending beam test. Results indicate that the development of crack in PBPCAC can be defined into three stages:crack producing stage, crack stable propagation and crack unstable fracture. Compared with common concrete, PBPCAC has a longer crack producing stage and a shorter crack unstable fracture. Critical effective crack length, initial fracture toughness and unstable fracture toughness of PBPCAC are almost the same as that of common concrete. PBPCA no longer gives notable influence on concrete ductility and toughness. PBPCAC shows better fracture resistance properties.