Extending the Season for Concrete Construction and Repair. Phase 1 - Establishing the Technology
COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH
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The benefit of combining several commercial admixtures into a formulation to protect fresh concrete against freezing and promote significant strength development while the internal temperature of the concrete is below freezing was investigated. Laboratory studies developed eight potential admixture combinations for use at low temperatures. Each combination was shown in the laboratory to produce concrete that had reasonable workability that could be entrained with air, that did not freeze until its internal temperature dropped to -5 degrees C, that developed strength while held at -5 degrees C as rapidly as did normal concrete held at -5 degrees C, that could be entrained with air and that could be finished at --5 degrees C almost as rapidly as normal concrete held at -5 degrees C. Five field trials were conducted to demonstrate that it is possible to mix, transport, place, finish, and cure concrete made with these admixture combinations at air temperatures as low as -20 degrees C, with little or no thermal protection. Several batching sequences were demonstrated in the field trials to accommodate various haul distances and working times. The sequence where all admixtures were dosed into the truck at the jobsite created the most time for the concrete workers to place the concrete. Cost-wise, the admixture combinations tested in the field were shown to be less expensive than the conventional approach to winter concreting, which relies on heated shelters to keep the concrete warm while it cures. No special tools, techniques, or precautions were required to work with the concretes made with these admixtures.
- Refractory Fibers
- Construction Equipment, Materials and Supplies
- Structural Engineering and Building Technology