Design and application of controlled low strength materials as a structural fill

• CLSM mixtures were developed as structural fill for bridge abutments.
• Performance criteria were compressive strength and flowability.
• Higher temperatures promote early strength gain in CLSM mixtures.
• Higher temperatures lower the rate of later-age strength gain in CLSM mixtures.
• Bond strength performance of the CLSM to steel anchors was investigated.

Controlled low strength materials (CLSM) are flowable and self-compacting construction materials that have been used in a wide variety of applications. This paper describes design of an optimized CLSM mixture that was used as a structural fill for construction of a bridge abutment. The main performance criteria for selection of a potential CLSM mixture were compressive strength to support the bridge loads, excavatability and flowability to fill the entire abutment in one continuous pour. Several CLSM mixtures were developed and tested in the laboratory for engineering properties including flowability, density, compressive strength and stress–strain behavior.Since it was a critical area of concern in design of the CLSM bridge abutment, the bond strength performance of the CLSM to steel anchors was also investigated. In pullout tests, a CLSM mixture with higher compressive strength resulted in higher bond strength and more brittle slippage. A numerical simulation of pullout tests indicated that the bond strength decreases with increase in bar size and embedment length.