The granulated blast furnace slag is classifies as a high permeable stiff material with sand size particles that when it interacts with water it shows a time dependent self-hardening behavior. The previously mentioned properties indicates that the slag is a promising material that can be effectively utilized in various geotechnical aspects where it was reported that it has been used as earth reinforcement technique in harbor construction projects. However, onshore utilization of slag material is limited. It was reported that utilizing sand compaction pile (SCP) method imposes crushing the slag particle resulting in significant education of the hydraulic permeability. This study aims at evaluating the strength development of slag material under various curing times. In order to prevent the significant drop of the hydraulic permeability as a result of early hardening of the crushed particles, the slag particles were mixed with sandy soil sand and subjected to various curing durations then were examined by evaluating the strength development of the adopted mixtures.