机制砂石粉含量配合比优化研究

Research on Optimization of Mix Proportion of Machine-made Sand Gravel Powder Content

摘要:

当前，为实现对长江水生态的有效保护，国家相关部门出台流域重要河段的河道采砂管理规划；探索机制砂的更广泛应用，为响应国家号召，现越来越多的工程师采用机制砂对混凝土配合比进行设计，而机制砂石粉含量是混凝土配合比设计中的一个重要参考指标，结合经验法和试验法，拟定了石灰岩、凝灰岩、玄武岩三种岩性机制砂石粉含量分别为3%、5%、7%、9%、11% 5组目标掺量，开展了混凝土力学性能、工作性能、外观、氯离子扩散性系数的对比分析试验，试验结果显示混凝土抗压强度在石灰岩机制砂石粉含量为9%时抗压强度最高，混凝土强度未随着凝灰岩机制砂和玄武岩机制砂石粉含量的增加而增加；机制砂石粉含量在7%~9%时，混凝土工作性能（坍落度、棍度、黏聚性、保水性）最好；随着机制砂石粉含量的增加，混凝土的外观不断改善，结果显示当石粉含量达到11%时，混凝土的外观效果最佳；机制砂28、84 d氯离子扩散性系数（RCM10^-12 m²/s）随着石粉含量的增加呈现负相关，石粉含量在11%时，28、84 d混凝土氯离子扩散性系数（RCM10^-12 m²/s）最低。

Abstract:

Currently, in order to effectively protect the water ecology of the Yangtze River, the relevant national departments have issued the river channel dredging management planning for the important river sections. The wider application of machine-made sand is explored. In response to the call of the country, nowadays, more and more engineers use the machine-made sand to design the mix proportion of concrete, and the content of machine-made sand gravel powder is an important reference index in the design of mix proportion of concrete. Combined with the empirical method and experimental method, it is proposed that the contents of three rocky machine-made sand gravel powders of limestone, volcanic ash rock and basalt are five groups of target contents of 3%, 5%, 7%, 9% and 11% respectively. The comparative analysis experiments of the mechanical properties, working performance, appearance and chloride ion diffusion coefficient of the concrete are carried out. The experimental results show that the compressive strength of concrete is the highest when the machine-made sand gravel powder content of limestone is 9%, and the compressive strength of concrete does not increase with the increase of machine-made sand gravel powder content of volcanic ash rock and basalt. The working performances (slump, stiffness, cohesion and water retention) of concrete is the best when the content of machine-made sand gravel powder is 7%~9%. With the increase of machine-made sand gravel powder content, the appearance of concrete is constantly improved. The results show that the appearance effect of concrete is the best when the content of sand powder is 11%. The chloride ion diffusion coefficients (RCM10^-12 m²/s) of machine-made sand after 28 days and 84 days present a negative correlation with the increase of gravel powder content. The chloride ion diffusion coefficient (RCM10^-12 m²/s) of concrete after 28 days and 84 days is the lowest when the content of gravel powder is 11%.