Controlled Low-Strength Materials Composed Solely of By-Products

A series of low-cost controlled low-strength materials (CLSMs) mixtures were produced without cement, using only by-products, including Class C fly ash, large quantities of limestone quarry fines, and synthetic gypsum. Flow, setting time, compressive strength, elastic modulus, and freezing-and-thawing resistance of mixtures were evaluated. Results indicated that CLSM mixtures solely comprised of by-products can be designed to provide a wide range of flow, setting time, and strength values. Obtained flow values varied between 200 and 600 mm (8 and 24 in.), setting time varied between a couple of hours and a day, and strength values varied between 237.4 and 9932 kPa (34.4 and 1440.5 psi). The maximum measured mass loss after 12 freezing-and-thawing cycles was 8%. Results showed that the addition of synthetic gypsum significantly improved strength and freezing-and-thawing resistance of mixtures.