石粉掺量及养护温度对机制砂混凝土性能影响研究

Research on the influence of stone powder content and curing temperature on the performance of machine-made sand concrete

以机制砂混凝土试块为试验对象,分别掺入5%、10%、15%的石粉掺量,观测其在不同养护温度下的抗压强度和孔径分布,研究石粉掺量及养护温度对混凝土强度和微观结构的影响。为更直观反映其对混凝土微观影响,采用核磁共振设备对不同掺量的混凝土试块进行测试。试验结果表明:在同一龄期时,3种石粉掺量中10%石粉掺量的混凝土抗压强度最高,同时10%石粉掺量混凝土的总孔隙率更低,最可几孔径左移,优于其他两种石粉掺量的混凝土孔径分布;相同龄期,负温养护较标准养护孔结构劣化明显,大孔较多,曲线首峰峰值较高。从机理上分析,石粉颗粒较小,促进流动性以及和易性,同时微集料作用,优化孔隙。负温养护温度接近水的冰点,水的黏滞性增大,减慢了水化速率,导致混凝土强度降低,孔隙劣化。

Take the machine-made sand concrete test block as the test object,mix 5%,10%,15%of the stone powder content respectively,observe its compressive strength and pore size distribution at different curing temperatures,and study the stone powder content and curing temperature equivalence on the impact of concrete strength and microstructure.In order to more intuitively reflect its microscopic impact on concrete,nuclear magnetic resonance equipment is used to test concrete test blocks with different dosages.The test results show that at the same age,the compressive strength of the concrete with 10%stone powder content is the highest among the three types of stone powder,and the total porosity of the concrete with 10%stone powder content is lower,and the most likely pore size is shifted to the left.Compared with the pore size distribution of the other two kinds of stone powders,the negative temperature curing is more degraded than the standard curing pore structure,with more large pores,and the first peak of the curve is higher.From the mechanism analysis,the stone powder particles are smaller,which promotes fluidity and workability,and at the same time,the micro-aggregate functions to optimize the pores.The negative curing temperature is close to the freezing point of water,and the viscosity of water increases,which slows down the rate of hydration,resulting in the decrease of concrete strength and the deterioration of pores.