341 / 2024-02-29 17:32:22

Effect of Coated-Powder Aggregate on the Performance and Microstructure of RCC

RCC,aggregate,coated-powder,micro-structure,gumming face,micro-hardness

The aggregate used for Huangdeng Hydropower Project existed the coated-powder phenomenon. In order to investigate the effect mechanism that coated-powder had on properties of concrete, and solve the engineering problems, research has been done on effect that aggregate with different content of coated-powder had on working performance, mechanical property and durability of RCC. Meanwhile, mercury porosimetry, SEM and micro-hardness tester were used to study on micro-structure of RCC. The results showed that with the increase of coated-powder content from 0.8% to 4%, the compression strength, split tensile strength, ultimate tensile strength and shear strength of RCC reduced. When the coated-powder content was more than 2%, the compression strength, split tensile strength reduced significantly. With the increase of coated-powder content, the porosity of mortar increased, and the proportion of harmless pores and less harmful pores reduced, while the proportion of harmful pores and much harmful pores increased. There was an enrichment region of elemental calcium in the gumming face of aggregate and mortar, the cement-sand ratio reduced. By changes in pore structure and the impact of the cement-sand ratio increased, the hardness values of gumming face of aggregate and mortar decreased gradually, which was consistent with the variation of the compression strength of concrete. According to the results, powder content of aggregate was set to not more than 2%.