基于机制砂改进高性能混凝土力学和工作性能及机理研究

Improvement in Mechanical and Workability Properties of High Performance Concrete by Manufactured Sand with Mechanism Analysis

为探明机制砂掺量及其成分对地铁工程中高性能混凝土工作和力学性能的影响机理,以广东地区产机制砂为研究对象,配置不同机制砂掺量和不同石粉含量的高性能混凝土并开展相应试验,研究机制砂掺量及机制砂中石粉含量对混凝土扩展度、坍落度、新拌混凝土状态、抗压强度及抗折强度的影响规律,结合混凝土电镜微观结构揭示各因素对其性能影响机理。结果表明:机制砂掺量及其石粉含量分别为40%和5%时,机制砂混凝土施工性能和所呈现状态最优;随机制砂掺量增加,混凝土抗压和抗折强度呈先上升后下降的趋势;石粉含量对混凝土最终力学性能几乎没有影响,但混凝土早期强度会随石粉含量增加而显著增加。综上,本研究所用机制砂可部分替代天然砂,且替代率为40%时效果最佳;所配置的机制砂高性能混凝土各项工作性能良好,可满足施工性能和结构强度要求。

To investigate the influencial mechanism of manufactured sand content with its component on the workability and mechanical behavior of high-performance concrete in subway engineering,this study took manufactured sand in Guangdong district as the research object.The high-performance concrete with various volumetric fractions and stone powder content of manufactured sand were proposed.The variations of manufactured sand volumetric fractions and stone powder content on the extension degree,slump,state of fresh concrete,compressive and bending strengths were studied.Furthermore,the influential mechanism of each factors on concrete behaviors were revealed in combination with the microstructure of concrete under electron microscopy.The results show that the manufactured sand concrete exhibits excellent construction performance and state,as the manufactured sand fractions and stone powder content equaling to 40%and 5%,respectively.With the increase of manufactured sand fractions,the concrete compressive and bending strengths exhibit a trend of rise first and then fall.The stone powder content has no effect on the ultimate mechanical properties of the concrete.While,with the increase of stone powder content,the concrete early strength increases significantly.Overall,it is concluded that the manufactured sand in this study can be used partially to replace natural sand,and excellent behaviors can be obtained as its volumetric fraction equaling to 40%.The proposed manufactured sand high-performance concrete exhibits outstanding workabilities and can meet corresponding construction performance and structural strength requirements.