Construction poured concrete

Below-grade walls may be constructed of poured concrete, masonry blocks, or other materials such as all-weather wood or stone. This chapter discusses details for use of poured concrete and masonry foundation because these are the materials most commonly used for new construction. Recently, trade associations such as American Plywood Association (APA) and the National Forest Products Association (NFoPA) have issued publications on designing radon resistance permanent wood foundations. Information on these types of foundations can be found by contacting the appropriate trade association.21... 

The following is a list of recommendations that builders can use to utilize the foundation as a mechanical barrier to radon entry. Foundation walls and floor slabs are often constructed of poured concrete. Plastic shrinkage, and therefore cracking, is a natural function of the drying process of concrete. Many factors, such as the water/cement/aggregate ratio, humidity, and temperature, influence the amount of cracking that occurs in a poured concrete foundation. Cracking may be minimized by... 

There are geographic areas throughout the United States in which the majority of foundation walls are poured concrete and other areas where masonry walls predominate. Poured concrete walls are generally available only in areas where contractors have the in-house expertise to build them and either rent or have invested in reusable forms. In areas where both types of construction are found, the costs of each seem competitive. 

Avoid building blocks with interconnected internal cavities in basement walls. Basement walls made from in situ (poured) concrete are recommended. Concrete elements require careful and permanent sealing of all joints. Designs similar to swimming pools, manure tanks in agriculture and bomb shelters will provide a radon safe construction. 

The exterior walls, the basin divider partitions, and the heat-exchanger flume are constructed of concrete block on poured concrete footers. The basin was made watertight by placing prefabricated asphalt matting directly on the soil and on the inside surfaces of the walls of the still. Two-inch-thick Foamglass insulation was placed around the perimeter walls so that the edge heat losses would be comparable to those of much larger stills. 

Concrete workers are unskilled workers engaged at the building sites. During construction they work largely out of doors where they pour the pre-mixed concrete into moulds containing steel reinforcements. The concrete is then vibrated manually. These workers often walk on newly poured concrete foundations while wearing rubber boots (Fig. 3). They have contact with wet cement, primarily on the hands, forearms... 

There are two central paradigms in nanofabrication top-down and bottom-up assembly. The ancient city of Petra remains a sublime example of top-down fabrication, chiseled into the face of the living rock by ancient craftsmen, who imprinted upon it an architectural vision of form and function. In contrast, the Pantheon, one of the many wonders of Ancient Rome, represents a remarkable example of the opposite approach to construction—from the bottom-up. Its stunning domed roof, still the largest structure of its kind in the world today, was formed from concrete—synthetic rock. However, its splendor required more than simply the ability to pour concrete it was the construction of complex timber formwork, guided by architectural vision, which enabled the elaborate coffering of the rotunda to be shaped. 

Wood trim pieces are sometimes placed on hard wall surfaces such as poured concrete or concrete block. These wood moldings can be bonded with SBR solvent-based adhesive, extruded from cartridge onto the back of the cove base and then pressed into position. A common form of this adhesive is referred to as construction adhesive. 

Non-dispersible concrete can be poured into a water-filled form without a tremie pipe to produce dense structural repairs. This type of material has particular advantages over conventional concrete both in terms of the quality of the repair produced and the reduction in placement cost associated with plant and diver manpower requirements. Field tests carried out on a commercially available AWA[46] show that bonding capability, pumpability and flowability around reinforcement are improved over conventional tremie-placed concrete. The quality and strengths of cores show AWA concrete to be suitable material for in situ structural concrete construction at considerable water depths [46]. 

In bridge construction, the use of retarding admixtures produces uniformity in the rate of setting and lessens the risk of deflection in partially hardened concrete that may occur in continuously reinforced structures such as spandrel beams. The retarded concrete poured over the supports remains plastic until the final pours are placed at mid-span. 

If a pour is to be halted either by operational problems or by design, the last layer placed before the interruption can be further retarded by the use of larger dosages of the admixture. This can eliminate the necessity for construction joints. The heavily retarded concrete can be horizontal in the placing of layers or vertical when a sloping layer of concrete should be left. 

S.I.L. uses standard concrete transit mixer trucks modified to provide gas or propane heat to the mix drum to prepare mixes for both precast and poured-in-place work. Since 1977 several poured-in-place field trials have been completed and numerous projects in the Calgary area have now been constructed. Precast products that have been marketed include parking curbs, pipeline weights, sewer pipe, median barriers, and sidewalk slabs. 

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