Experimental Investigation on the Best Method of Reactivating a False/Flash Set Wet Concrete and Its Effects on the Hardened Phase

Concrete that sets too fast or incorrectly needs reactivation to meet its original strength requirements. The research intends to determine the corrective means of reactivating a false/flash-set concrete to retain its properties in wet and hardened phases. The methodology involved the experimental design of concrete mix using CP 110 to calculate the target strength parameter and determine various quantities of material components required to achieve the designed strength. However, the quantifications and combination of material components until an even mix was obtained, the concrete mix matrix was divided into 4 portions. The first portion was used to mould 12 cubes, while the other 3 portions were allowed to set falsely for 3 hours before experimentation continued. The second portion was reactivated by remixing only with a mixer, and the third portion was reactivated by adding 10% of the initial amount of water. In comparison, the fourth portion was reactivated by adding 10% of the initial amounts of water and cement, respectively. The 48 concrete cubes were cured and tested at ages 7, 14, 21, and 28 days. The results indicated that water addition reduces the design strength by 44.32%. The best technique of reactivating false/flash-set wet concrete is either by adding exact water and cement (WCG) amounts, with a mean strength value of 29.48N/mm2 or by remixing in a mixer without water (NWG), with a mean strength value 29.19N/mm2. The research recommends further study to determine the exact water and cement amounts to be added to maintain the water/cement contents in the concrete mix design.