Determination of Tensile Strain Capacity of Fresh Concrete: A new test method

Abstract

Measuring physical properties of fresh concrete is important to understand the behaviour of the early state of concrete. Plastic shrinkage occurs at the very early stage due to evaporation of water from the concrete surface. When concrete is restrained against plastic shrinkage, tensile strain is developed and when it exceeds the tensile strain capacity, cracks occur. This phenomenon is called as plastic shrinkage cracking. In order to assess the risk of plastic shrinkage cracking tensile strain capacity of fresh concrete should be measured. Fresh concrete means the concrete before the initial setting time which is still in a semi liquid state. The paper presents a test method developed to measure the strain distribution along a fresh concrete sample. Based on this test method tensile strain capacity of a selected mix proportion with three different types of cements, i.e., Ordinary Portland Cement, Fly ash blended and Portland Limestone Cement were determined. Results indicate that concrete with fly ash blended cement has a higher tensile strain capacity than other two cement types.