Effect of self curing chemicals in self compacting mortars

Abstract

Aging of infrastructure necessitates the need for repair and rehabilitation of structures. In this backdrop, self compacting mortar (SCM) is preferred for repair purposes especially in reinforced concrete structures. Due to many different reasons curing is not properly done rendering the repair useless. Self curing in mortars can achieve this by the addition of curing chemicals. Polyethylene Glycol, Liquid Paraffin Wax etc can be very good alternatives to increase the performance of self compacting mortars. These chemicals internally cure the mortars leading to improved hydration and C–S–H gel formation. In the present work, two self compacting mortars 1:1 with w/c=0.34 and 1:3 with w/c=0.5 are investigated with two self curing agents (Polyethylene Glycol 4000 and 200). A comparison was made considering three curing conditions namely wet curing, self-curing and no curing. Different dosages, i.e. 0%, 0.1%, 0.5% and 1.0% mass of PEGs were attempted with the above two curing agents. Mini-slump flow and V funnel tests were done to confirm flow properties required as per the specifications. Water retention, compressive strength, sorptivity and acid durability tests were carried out on SCM specimens. A unified factor viz. Acid Durability Loss Factor is introduced to study the influence of acid in terms of loss of strength, stability and weight loss. This factor accommodates both strength and durability performance. It was concluded from the study that the use of self curing agents in self compacting mortars in optimum dosages benefited self compacting mortars in achieving better strength and durability performance.