ABSTRACT
The constituents of Portland cement concrete include coarse aggregates (natural stone or crushed rock), fine aggregate (natural and manufactured sand), Portland cement, water, and mineral or chemical admixtures. The paste phase is made up of the Portland cement, water, and air (entrapped and entrained). The paste phase is the glue or bonding agent that holds the aggregates together. The mortar phase is the combination of paste and fine aggregate. Aggregates occupy approximately 60-75% of the total volume of the concrete. The aggregates should be well graded to efficiently utilize the paste. It is desirable that each aggregate particle is coated with paste. The quality of the concrete is therefore highly dependent on the quality of the paste, the aggregates, and the interface or bond between the two.
