高性能纤维混凝土微观结构及其抗压强度研究

Microstructure and Mechanical Properties of High Performance Fiber Reinforced Concrete

利用粉煤灰、硅灰、纳米二氧化硅等掺合料制备高性能纤维混凝土(HPFC),研究不同掺合料对HPFC的水化、微观结构以及抗压强度的影响。通过X射线衍射(XRD)分析HPFC水化产物的物相、水化热(TAM-Air)分析HPFC水化反应过程、孔结构(MIP)分析HPFC孔结构、扫描电子显微镜(SEM)分析HPFC微观结构、压力试验机测试HPFC试块的抗压强度。结果表明,养护28d后,加入掺合料的HPFC基体中的Ca(OH)_(2)、C_(3)S、C_(2)S数量明显减少;粉煤灰、硅灰、纳米二氧化硅加速水泥的水化反应,并降低水泥的水化热;当水泥用量为490kg/m^(3),硅灰的掺量为胶凝材料用量的10%,纳米二氧化硅的掺量为胶凝材料用量的1%时,HPFC28d抗压强度为72MPa,与素混凝土相比提高69.4%;在纳米二氧化硅和硅灰复掺的情况下,HPFC的孔隙率明显减小,最可几孔径细化至40nm。

High-performance fiber concrete is prepared mainly by mixing materials such as coal ash, silicon ash and nano-silicon dioxide, and the effects of different doping materials on the hydration, microstructure and pressure strength of high-performance fiber concrete are further studied. Through X-ray diffraction(XRD),HPFC hydration product phase, hydration heat(TAM-Air)analysis of HPFC hydration reaction process, hole structure(MIP)analysis of HPFC hole structure, scanning electron microscope(SEM)analysis of HPFC microstructure, pressure test machine testing the pressure strength of HPFC-test-block, the results showed that the number of Ca(OH)_(2),C_(3)S and C_(2)S in HPFC substations added to the doping material decreased significantly after maintenance of 28 d;Pink ash, silicon ash and nano-silicon dioxide accelerate the hydration reaction of cement and reduce the hydration heat of cement;When the amount of cement is 490 kg/m^(3),the amount of silicon ash is 10% of the amount of gel material, and the amount of nano-silicon dioxide is 1% of the amount of gel material, the pressure strength of HPFC 28 days is 72 MPa, which is 69.4% higher than that of concrete;In the case of nano-silicon dioxide and silicon ash compounding, HPFC′s porosity rate is significantly reduced, up to a few apertures can be refined to 40 nm.