Strength assessment of controlled low strength materials (CLSM) utilizing recycled concrete aggregate and waste paper sludge ash

This paper studies the strength development of low-strength material (CLSM) is controlled by using waste paper sludge ash (WPSA) in CLSM mixtures without adding Portland cement. Series of four (4) compounds which is the CLSM containing 5%, 10%, 20% and 30% of waste paper sludge ash (WPSA) as a substitute for Portland cement. CLSM cubes the sizes of 100mm × 100mm × 100mm compressive strength were tested at age 7, 14 and 28days. It was found that this activity contributes to strength development pozzolonic paper waste sludge ash (WPSA) depending on the percentage of the added waste paper sludge ash. So, it was found that the activity pozzolonic has been activated by the alkaline and calcium hydroxide (Ca(OH)₂) contributed from recycled concrete aggregate (RCA). In this study, the alkaline releases when soaked in water for 28days. Compressive strength of controlled low-strength materials affected by both the ratio of fine aggregate and coarse aggregate and mixture characteristics during maturation developed CLSM. Cube test results show that CLSM with a ratio of 1:2 and 1:1 RCA and 20mm recycled coarse aggregate, 30% of WPSA content expressed as mass percentage of RCA is to produce a uniform mixture with a constant high-strength (maximum strength of 6.04MPa).