A Simpler Method for Establishing an Approximate Value of Built-in Temperature Differential in Concrete Pavement

The effective temperature differential (ETD) across the thickness of the concrete pavement slab influences the magnitude of the combined stress due to curling and the wheel load. The built-in temperature differential (BiTD) value is necessary to estimate the ETD from the temperature differential (TD) value in the concrete slab measured during the test. However, it is very difficult to establish the actual BiTD in a concrete pavement during the construction time as both the temperature differential and the moisture differential (MD) in cement concrete (CC) layer influence it. The present paper uses a simpler method for establishing the approximate BiTD value using the TD value (measured during construction) alone as the MD value does not vary significantly in the first 24 h. In the present method, the TD is measured regularly in the freshly laid CC layer at an interval of one hour and the concrete strength gain is measured using the mortar penetration resistance plunger (as per ASTM C403). The TD is measured when the penetration resistance of plunger exceeds 4000 psi. Observations made during the construction of a CC pavement in the Jharkhand state in India during January 2018 are presented here. Though the BiTD measured in this method is not the actual BiTD as the MD is not taken into account, the measured BiTD value would be close to the actual value.