Development of an economical high early strength concrete mix for paving of provincial roads in Sri Lanka

Abstract

Rigid pavement construction has a long history. Readymixed or site mixed concrete is used for rigid pavement construction. However, conventional concrete mixtures require more than 7 days to gain adequate strength to allow for traffic. Development of high early strength concrete would be a solution to allow traffic within a reasonable time. However, use of high cement content in early strength concrete induces distress in the pavements and would not be an economical mix. A high performance concrete mix was developed for rigid pavement construction using a low cost admixture with available materials in Sri Lanka. Study has shown that 3% of commercial grade CaCl2 can be used as an accelerator to obtain required compressive strength and the flexural strength of concrete in 12 hours. Strength gain was verified by the maturity test conducted for a slab placed under field condition. Slab temperature was also measured with time and found temperature rise due to heat of hydration was insignificant. Using the mix proportion developed, concrete roads can be allowed for traffic in 12 hours and can also be used for repair works of the existing roads. Life cycle cost analysis was performed taking into account the construction cost, maintenance cost and the user cost. The study has shown that there is 26% saving by using high early strength concrete developed in this study.