Comparison Between High Grade Retempered Concrete [M40] and Medium Grade Retempered Concrete [M20]

As the grade of concrete is increases the quantity of cement is increases which effects on theproperties of retempered concrete. For M20 concrete we can retemper the concrete upto 120 min. but forM40 concrete retempering time is only 30 min. Adding water to a plastic mix to increase slump is an extremelycommon practice, even though it is not recommended because it increases the porosity of concrete. Concrete often arrives on site more than half an hour after initial mixing. Placement operations can take anywhere from 10 to 60 minutes, depending on the field conditions and the size of the load. When the slump decreases to an unacceptable level during the operations, water is added to the mix. Objective of this paper to study the strength characteristics of retempered concrete M20 & M40 concrete. Usually the retempering process is used with normal concrete or with ready mixed concrete; an attempt is made to check the compressive and flexural strength of normal retempered concrete with an addition of retarder in three different percentages as 0.2%, 0.4% and 0.6% at retempering time of 15 minutes to 90 minutes.