Experimental Temperature Measurements on a Full-Scale Reinforced Concrete Box-Segment during the Construction Stage

Abstract

A full-scale square-hollow reinforced concrete segment was constructed in an open environment to evaluate the effect of the heat produced from cement hydration and the environmental cycles of cooling and heating during the first 48 hours after concrete casting. Ten thermocouples were installed along the centreline of four walls, where the wall thickness was 500 mm, while two more thermocouples were installed at the exterior and interior wall surfaces. Three environmental sensors were also installed at the site to measure air temperature, solar radiation, and wind speed. The results showed that minor differences were recorded between the eight thermocouples during the first 24 hours, while the southwest thermocouple recorded temperatures that were slightly higher during the day and slightly lower during the night compared to the core thermocouples, revealing some sensitivity to environmental thermal loads. The comparisons of the first 48 hours' temperatures with those after 72 hours showed that the hydration heat increased the concrete temperature by approximately 26 to 32 ^oC during the first 24 hours. Additionally, the effect of hydration heat became minimal after 30 hours and diminished after 36 hours, which declares the start of the life-span state of full-dependency on solar radiation and air temperature.