PRODUCTION OF RAPID HARDENING CONCRETE (RHC) USING LOCAL AGGREGATE AND SODIUM CHLORIDE (NACL) AS PARTIAL REPLACEMENT OF CEMENT

Ordinary Portland cement often causes slow strength development and construction delays. Rapid-hardening cement offers faster construction, cost-effectiveness, reduced maintenance, and improved durability, making it ideal for emergency repairs, cold weather concreting, and precast concrete production. Rapid-hardening concrete is a specialized type of concrete that gains strength at an accelerated rate, allowing for faster construction and reduce project timelines. This study focuses on the use of Table Salt (NaCl), Bama gravel, river sand, and crushed stone to produce rapid-hardening concrete. Concrete mix design was evaluated using Microsoft Excel spreadsheet (MATLAB Application) based on BS 8500 Mix Design Method. The standard cubes of 150mm × 150mm × 150mm, were produced for compressive strength tests. A total of 60 cubes were cast using mix proportions of 1:0.63:0.09:0.95:0.36 (cement: river sand: Bama gravel: crushed stone: water). The materials were mixed with up to 4% NaCl in an increment rate of 1% as a partial replacement of cement. The aggregate qualification tests revealed that the materials used are within the stipulated codes and standards. The hydration properties results showed that the percentage replacement of NaCl increases the consistency, reduces setting times, and increases early strength gain. The mix proportion adequately produced rapid-hardening concrete with a compressive strength of 33.23 N/mm2 in 1 day. However, there is a deviation of 3.83% in the target strength, though concrete with high-performance properties of 57.67 N/mm2 at 4% NaCl replacement was achieved at 28 days. Rapid-hardening concrete should be used in the construction in cold-weather, hydraulic structures like bridges, culverts, dams, drainages, and highway pavements due to rapid settings and early strength gain characteristics.