Development of Heat-Curing Cycles for Portland Cement-Fly Ash Concrete for the Precast Industry

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Title: Development of Heat-Curing Cycles for Portland Cement-Fly Ash Concrete for the Precast Industry

Author(s): G. G. Carette, V. M. Malhotra, C. Bedard, V. De Benedictis, and M. Plumat

Publication: Special Publication

Volume: 91

Issue:

Appears on pages(s): 249-272

Keywords: accelerated curing; age-strength relation; compressive strength; curing; fine aggregates; fly ash; heating; plasticizers precast concrete.

Date: 2/1/1986

Abstract:
This paper reports the results of an investigation to develop heat-curing cycles for portland cement/fly ash concrete for use in the precast industry. The fly ash was incorporated into concrete not as a replacement for cement but as a partial replacement for fine aggregate. The variables considered were temperature of curing, preset time and duration of heating. The results of the investigation indicate that portland cement concrete (W/C = 0.40) in which 18% of the fine aggregate has been replaced by fly ash can be heat-cured to accelerate strength development at ages ranging from 12 to 24 h, and compressive strengths of the order of 30 to 45 MPa can be achieved at these ages. Two of the most promising heat-curing cycles for the materials under investigation consist of a 12-h cycle at 90°C with a preset time of 2 h or a 24-h cycle at 55° to 70°C with a preset time of 4 h. However, it is emphasized that each precast concrete producer will have to perform investigations to optimize the heat-curing cycle that best suits his materials and production needs.