Properties of controlled low-strength materials made with wood fly ash

Controlled low-strength materials (CLSM) were made in the field using one source of wood fly ash as a major component. CLSM Mixtures S-1 and S-3 contained cement, wood fly ash (81 and 89%, respectively, by mass of cementitious materials [Cm]), and sand; whereas, Mixture S-2 contained cement, wood fly ash (11% of Cm), Class C coal fly ash (67% of Cm), and sand. Mixtures S-1, S-2, and S-3 showed respective compressive strength values of 0.8, 0.3, and 0.6 MPa at 28 d, and 1.4, 14.4, and 1.0 MPa at one year. Combination of wood and coal fly ashes might have caused the drastic increase in the strength of Mixture S-2 at late ages. The respective water permeability values of Mixtures S-2 and S-3 decreased from 68 and 33 mum/s at 63 d to 6 and 12 mum/s at 227 d due to the improvement of microstructure of these CLSM mixtures.