Feature from Environmental Building News
March 1, 1993
Sidebar: Using Concrete Wisely: A Checklist for Builders and Designers
Reduce waste. Carefully estimate quantities of concrete required on the jobsite. For large jobs, hire an
expediter, who will be on site during pours to estimate exact material requirements.
Consider alternative foundation systems. Pier foundations use far less concrete than poured full-height foundation walls or slab-on-grade foundations (be sure to provide adequate insulation and air sealing details at the floor system). Building a shallow footing and frost walls with horizontal insulation, which effectively reduces the frost depth, can cut concrete use considerably in northern climates.
Consider pre-cast concrete systems. The integrated footer/foundation wall/insulation system produced by Superior Walls, Inc. uses considerably less concrete than conventional poured foundation walls.
Specify minimal admixture use. If your clients have chemical sensitivities, specify minimal use of chemical additives for controlling concrete properties and workability—at least until adequate studies are done to determine whether offgassing might be a realistic concern. Sucrose-based retarders should not pose any problems.
Specify fly ash. Fly ash can be added to most concrete mixtures, usually with an improvement in workability and strength. Proportions up to 15% can be achieved quite easily, and higher levels are possible. Fly ash from western sources is generally better than that from eastern sources.
Avoid on-site environmental damage. On the building site, use care to avoid soil compaction and resultant damage to trees. Make provisions for concrete trucks to reach the building site with a bare minimum of repositioning and turning around. Also avoid driving over tree roots. Plan ahead with these issues in mind.
Control washwater run-off. If washwater from rinsing concrete chutes and trucks is not otherwise regulated, the general contractor should plan with the concrete truck driver exactly where rinsing can be done. Avoid locations where run-off will get into topsoil or flow into surface water.
Use concrete waste as fill. Whenever possible, specify crushed concrete debris as clean fill around buildings or as aggregate under parking lots and driveways.
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