Correlation Analysis Between Concrete Compressive Strength and Pore Structure Based on Grey System Theory

In this paper, the influence degree of concrete micro-pore structure on its own compressive strength was studied. The mercury intrusion test and compressive strength test of concrete under different water-cement ratio and sand ratio were designed. The pore structure parameters such as porosity, most probable pore size, average pore size and critical pore size are quantitatively characterized. The mechanism of concrete compressive performance changes was clarified from the perspective of micro pore structure. The influence degree of different micro-pore structure parameters on concrete compressive strength was analyzed. And an empirical relationship model between pore size distribution and porosity with compressive strength was established. The test results shown that the compressive strength of concrete with different water cement ratio and sand ratio decreases with the increase of porosity. According to the grey theory analysis, the main factors affecting the compressive strength of concrete micro-pore structure were average pore size, median pore size, harmless pore content and harmful pore content, and their grey correlation degrees were above 0.8. Further regression analysis shown that the compressive strength has a good linear relationship with the average pore diameter, median pore diameter, harmless pore content and harmful pore content in the micro-pore structure. In addition, the parametric analysis of the empirical model shown that the effect of porosity on compressive strength increased with the increase of pore size.