超细矿粉对喷射混凝土力学性能的影响研究

Study on Influence of Ultrafine Mineral Powder on Mechanical Properties of Shotcrete

为了揭示纳米微粉改性路面粉煤灰混凝土的工作性能,推动其在路面工程中的应用,开展了不同粉煤灰取代率与纳米矿粉掺量的正交试验,对改性后的混凝土力学性能、抗冻融耐久性、干缩性及耐磨性进行了分析。研究结果表明:粉煤灰取代率的增加使得混凝土力学性能呈先上升后下降趋势,且在粉煤灰取代率为25%、矿粉掺量为0.5%时达到峰值;改性后的混凝土耐磨性、抗冻性、干缩性随着纳米矿粉掺量增加而增加,且在掺量为0.5%提升幅度最大;综合考虑各方面力学性能,粉煤灰取代率为25%、纳米矿粉掺量为0.5%,改善效果显著且经济效益高,建议该配合比作为路面混凝土的设计配合比;纳米矿粉可在混凝土颗粒中生成C—S—H凝胶体,逐渐填充混凝土内部孔隙,在孔隙中形成一道阻止裂缝扩展屏障,从而达到改善水泥基复合材料孔隙结构的目的。

In order to reveal the working performance of the nano-powder modified pavement fly ash concrete and promote its application in pavement engineering,orthogonal tests of different fly ash replacement rate and nano-powder content were carried out to analyze the mechanical properties,freeze-thaw resistance durability,dry shrinkage and wear resistance of the modified concrete.The results show that the mechanical properties of concrete increase first and then decrease with the increase of fly ash replacement rate,and reach the peak value when the fly ash replacement rate is 25%and the mineral powder content is 0.5%.The wear resistance,freeze resistance and dry shrinkage of the modified concrete increase with the increase of the content of nano-ore powder,and the improvement amplitude is the largest when the content is 0.5%.Considering the mechanical properties of all aspects,the replacement rate of fly ash is 25%,the content of nano-mineral powder is 0.5%,the improvement effect is significant and the economic benefit is high,it is recommended to be used as the design mix of pavement concrete.Nano-mineral powder can form C—S—H gel in concrete particles,gradually fill the internal pores of concrete,and form a barrier to prevent crack expansion in the pores,so as to improve the pore structure of cement-based composite materials.