Investigation of Cold Concrete Joint to Determine the Optimal Angle with Calcium Oxide Additive in Secondary Concrete

One of the common problems in the construction industry is the creation of cold joints between different layers of concrete during concreting, which occurs due to delays in the concreting process. Creating cold joints in concrete structures reduces the compressive and tensile strength of concrete. In this paper, we have tried to study the concrete strength of concrete samples by examining concrete samples from different angles and time delays in the concreting stages, which has received less attention from researchers. In this paper, concrete samples at zero, 30, 35, 40, 45 degree angles are used to obtain the optimal angle. Cubic samples were used to obtain the compressive strength of concrete and cylindrical specimens were used to obtain the Brazilian tensile strength of concrete. In concrete samples, in the first layer, ordinary concrete with a specific mixing design and in the second layer, calcium oxide additive in the amount of 15% cements were used. Using this method, we witnessed an increase in the adhesion of concrete between the first and second layers and also increased the compressive and tensile strength of concrete.