Effects of Withholding Mixing Water and Retempering On Compressive Strength of Concrete

Abstract

Owing to delay in placing of concrete because of any factor like failure of any equipment, improper site conditions, inexpert handling and also due to placing at slow rate in heavy reinforcement, and difficult location and type of structure to avoid segregation, concrete may undergo loss of workability because of which it may not be fit for the desired purpose and turned into wastage. This causes loss of material, effort, time and money especially in mass concreting. Process of retempering is commonly adopted in this condition and also in hot weather concreting to restore lost workability. This study evaluates the effects on compressive strength of concrete of retempering with both withholding mixing water initially followed with later addition of the withheld mixing water and redosage with water in excess of design water-cement ratio. The effects of varying the withholding time and amount of water withheld were examined. The result of this study showed that retempering with withholding mixing water appears to have no negative effect on the compressive strength characteristics of the concrete and retempering with redosage of water results in a significant reduction in the compressive strength of the concrete.