Research on the calculation method of concrete compressive strength based on volume content of recycled coarse aggregate and fine aggregate

Abstract

In order to study the influence of physical properties and volume content of coarse aggregate on concrete strength, the effective water absorption, apparent density and crushing index of different types of coarse aggregate were tested; the contribution strength coefficient and reinforcement coefficient of coarse and fine aggregate were proposed according to the mechanics of composite materials, the optimal range of the volume content of coarse and fine aggregate was determined, the calculation equation of concrete compressive strength based on the properties of coarse aggregate and the volume content of coarse and fine aggregate was established. The results show that: the effective water absorption of recycled brick aggregate (RBA) is 8.18% and that of natural aggregate (NA) is 0.32%; the apparent density of NA is 2713 kg/m3 and that of RBA is 2100 kg/m3; the crushing index of NA is 18.07% and that of RBA is 30.59%; furthermore, the crushing value of RBA is close to that of cement mortar with water cement ratio of 0.46; NA has a greater range of strengthening the compressive strength of concrete than RBA; when sand cement ratio is between 0.3 and 2.5, both Ks’ and Ks are greater than 1; when sand cement ratio is about 0.5, Ks’ reach the maximum value; when sand cement ratio is about 0.75, Ks reach the maximum value; the calculation equation of concrete compressive strength established in this paper has a good prediction effect, which provides a new idea for the calculation method of concrete compressive strength.

Keywords

• volume content of coarse and fine aggregate
• sand cement ratio
• contribution strength coefficient
• enhancement coefficient
• calculation method of concrete strength