Abstract:
Measuring physical properties of fresh concrete is important to understand the behavior of the
early phase of concrete. The measurement of tensile strain capacity of fresh concrete predicts the risk of
cracking due to restrained shrinkage. Fresh concrete means the concrete before the hardening phase which is
still in a semi liquid state. i.e. from right after mixing of concrete to 3 – 4 hours. Several research studies have
been conducted but complex test methods have been developed to measure both stress and strain and the average
strain was measured. The paper contains the procedure adopted to develop a simple test method to measure
the local strain along a sample. After verifying the test method, influence of cement type for early age tensile
strain capacity was studied. Ordinary Portland Cement, Fly ash blended and Portland Limestone Cement
were used. Concrete was mixed as a large quantity and kept inside the mixer and agitated every 10 minutes before
being taken out for testing. The method simulates the conditions where concrete is produced and kept inside
a truck mixer for a while before placing. Results indicate that fly ash blended concrete has a higher tensile
strain capacity than other cement types thus the mix is less vulnerable for early age cracking. Further tests
should be done to determine the influence of cement type for tensile strain capacity of undisturbed concrete.
Citation:
Weerasinghe, T.G.P.L., & Nanayakkara, S.M.A. (2015). Determination of tensile strain capacity of fresh concrete. In M.T.P. Hettiarachchi (Ed.), Proceedings of the Civil Engineering Research Symposium 2015 (pp. 5-8). Department of Civil Engineering, University of Moratuwa.