నైరూప్య

Effect of Cold Joint on Strength Of Concrete

V. R Rathi , P. K. Kolase

Delay in concreting due to various conditions as well as improper casting sequence can result in cold joints. For unusually long delays during concreting, the concrete should be kept alive by periodically re-vibrating it to keep concrete workable. However, concrete should not be over-vibrated to the point of causing loss in homogeneity. This study gives strength data simulating such improper casting sequences. To cope this problem related to improper casting sequence, which ultimately results in formation of cold joints, we have used sugar as retarding agent. To prove this we conducted experiments on three types of concrete of M25 grade, such as stained concrete, stained concrete with retarding agent and fresh concrete. The experimental results of compressive, flexural and split tensile strength with above three types of concrete shows that stained concrete with retarding agent gives improved strength as compare to stained and fresh concrete in horizontal failure plane.