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Title: Optimization of Flowable Fill Mix Proportions

Author(s): M. E. Ayers, S. Z. Wong, and W. Zaman

Publication: Symposium Paper

Volume: 150


Appears on pages(s): 15-38

Keywords: backfilling; compressive strength; flowability; fly ash; mix proportioning; sands; slump; Materials Research

DOI: 10.14359/4326

Date: 6/1/1994

The effect of mix proportions on the compressive strength of flowable fill is investigated in this study. Flowable fill, composed of Type I cement, Class C fly ash, sand, and water, meets the requirements of ACI Committee 229 as a controlled low-strength material (CLSM) if the 28-day compressive strength is 1200 psi (8.3 MPa) or less. Extensive laboratory tests were conducted to determine the effects on the engineering properties of varying the water/cement plus fly ash, sand/cement plus fly ash, and fly ash/cement ratios. A wide range of ratios was evaluated to provide a cost-effective mix design for various material costs. Compressive strengths were determined at 1, 7, 14, and 28 days, providing an indication of the rate of strength development and ultimate compressive strength.