改性橡胶增韧再生骨料混凝土高温后抗压性能

Research on the Compressive Performance of Modified Rubber Recycled Aggregate Concrete after High Temperature

摘要:

探究了改性橡胶增韧再生骨料混凝土（MRRAC）在25℃至600℃温度区间内的质量损失、抗压强度损失及韧性等力学性能的劣化规律.通过SEM表征技术，深入分析了MRRAC在细观尺度下的高温损伤机制. 结果表明：采用10%氢氧化钠溶液对橡胶颗粒进行预处理可显著提升再生骨料混凝土的高温抗压性能和韧性，其中在450℃时抗压强度较未处理组提升58%；基于再生骨料替换率和橡胶掺量等关键参数，建立了MRRAC抗压强度残余率的预测模型；揭示了橡胶颗粒在高温环境下的作用机制，即橡胶的软化和分解在混凝土内部形成孔洞结构，有效拓宽了内部自由水和结合水的释放通道，通过降低混凝土内外压力梯度显著缓解了高温损伤.

Abstract:

This study systematically investigated the deterioration mechanisms of modified rubber recycled aggregate concrete (MRRAC) subjected to elevated temperatures ranging from 25℃ to 600℃, with particular focus on quality loss, compressive strength degradation, and toughness evolution. The thermal damage mechanisms at the microscale were comprehensively characterized through scanning electron microscopy (SEM) analysis. The experimental results demonstrated that: (1) Pretreatment of rubber particles with 10% sodium hydroxide solution significantly enhanced the post-high-temperature compressive performance and toughness of recycled aggregate concrete, with a 58% im-provement in compressive strength observed at 450℃ compared to untreated specimens; (2) A predictive model for the residual compressive strength ratio of MRRAC was developed by incorporating key parameters including the replacement rate of recycled aggregates and rubber content; (3) The fundamental mechanism underlying the improved high-temperature resistance was revealed. The softening and decomposition of rubber particles created pore structures within the concrete matrix, which effectively expanded the release channels for internal free water and bound water, thereby reducing the internal-external pressure gradient and mitigating thermal damage.