b'THE OFFICIAL NFBA MAGAZINEcontinued from page: 15Under-Slab Insulation located directly under the final slab position.Specific details regarding insulation installationSubbase Moisture and Temperatureis beyond the scope of this article.However,Moisture and temperature conditions of the concrete placement must integrate with thesubbase during concrete placement are critical installed insulation.For example, if insulationand need to be considered.Excess moisture on is to be installed under a concrete slab floorsite can increase the water to cement ratio of with in-floor heating, the concrete placementthe placed concrete.The difference between the proceduresmustnotdamagetheunder- lower temperature of either the subbase material floor insulation and in-floor heating system.or ambient air and the expected temperature of RESEARCH & TECHNOLOGYA concrete pump is often used for placing concretethe concrete material should ideally be no more over insulation.Construction of the building shellthan 20 F but could be as much as 30 F.If this prior to slab placement will typically eliminate usedifference will be greater than 30 F, the ambient of a boom concrete pump but should still enableair temperature or base material temperature use of a truck- or trailer-mounted line pump. should be warmed so concrete setting times are Steel Reinforcement not reduced due to cold temperatures.Concrete should not be placed on frozen base material.SteelreinforcementshouldbeproperlyConcrete Procurementsecured in place prior to concrete placement. ThoughtshouldbegiventoconcreteA comprehensive 11-page discussion of concrete deliveryassomereinforcementmayneedmaterials and mixture proportioning is found to be left out temporarily to enable concretein ACI 302.1 R-15.The selection of materials truck access to some parts of the floor area. and mixture proportions are similar for normal Photo 2: Reinforcement positioned above aconcreting as well as for cold and hot weather prepared slab on grade base with a vapor barrierconcreting.The major difference between the Photo 2: Reinforcement positioned above a prepared slab on grade base with a vapor barrier located directly under the final slab position.16 / FRAME BUILDER -OCT2020'