Title:
Long-Term Strength Development of Controlled
Low-Strength Material
Author(s):
Charles E. Pierce, Sarah L. Gassman, and Tracey M. Richards
Publication:
Materials Journal
Volume:
99
Issue:
2
Appears on pages(s):
157-164
Keywords:
compressive strength; controlled low-strength cementitious material; curing; flowable fill; fly ash; mixing time.
DOI:
10.14359/11708
Date:
3/1/2002
Abstract:
Development of long-term compressive strength of controlled low-strength material (CLSM) was examined in a controlled experimental program. Strength development is important because minimal strengths must be met and maintained to provide adequate structural support, and maximum strengths must be limited to allow future excavation. Although strength gain with age is expected, strength loss has also been reported. This study evaluated the long-term strength development of CLSM subjected to the combined effects of prolonged mixing time and retempering, which are common concerns regarding field placement of ready-mixed CLSM. In addition, the impact of long-term exposure to a high moisture environment on strength development was investigated. The results of this study showed that limiting the mixing time of CLSM prior to placement and controlling the curing environment after placement appear to be the two most critical quality-control factors. Strength loss and softening were consistently observed for all CLSM specimens when measured after 600 days of immersion curing. It appears that long-term performance of CLSM is compromised when exposed to a saturated environment for long periods of time. Leaching of fly ash may contribute to this observation. Minimum required strengths of CLSM in high-moisture field conditions might not be maintained with time.