Characteristics of Different Type of Coarse Aggregate on Properties of High Performance Concrete

Abstract

The weakest links of conventional cement concrete is often occurred at the transition zone around coarse aggregate particles and the bulk of the compressive load is also borne by the cement paste. However, in special concrete such as High Strength Concrete (HSC) and High Performance Concrete (HPC) where, the water/cement ratio is low and high content of cement constitute their characteristics, the bulk compressive load is borne by the aggregate. Therefore, the failure in such concrete is mostly through the aggregate. This study discussed the characteristics of different type of coarse aggregate with distinct size range, 20-14mm and 10-5mm on properties of high performance concrete. In this project, investigation such as Slump test and Unit weight were carried out on fresh properties, and also compressive strength and water absorption on hardened properties, in which, readings were taken at curing days of 7 days, 14 days, and 28 days. The water to cement ratio used is 0.35, 1% super plasticizer of  Conplast SP-430 were added, and the dosage of meta kaolin added was  0%, 7.5% and 15%. The HPC mix, grade M40concrete is designed as per ACI method. The result of the study indicated that the compressive strength increases with an increase in percentage of Metakaolin between 0% to 15% replacements. Basalt-mixed concrete gives higher compressive strength, followed by gneiss-mixed concrete, then granite-mixed concrete. It was also discovered that larger aggregate sizes (20mm-14mm) gives high compressive strength than smaller sizes (5mm-10mm). Therefore for optimum performance up to 15% replacement of Metakaolin can be used with 20mm-14mm sizes of basalt aggregate.