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�F <br />!R. <br /> }A <br /> Va'f <br /> project No. 90161.e <br /> 7 June 1990 <br /> 5. Where interior concrete slabs-on-grade are to be <br /> f <br /> constructed, the slabs should be underlain by a minimum of 4 <br /> y� <br /> j inches of clean crushed rock to serve as a cushion and a <br /> r,z i:apillary break. Where floor coverings are anticipated, a <br /> Visqueen-type membrane should be placed between the cushion and <br /> the slab to provide an effective vapor barrier and to minimize <br /> i - <br /> moisture condensation under the floor covering. it is suggested <br /> that a maximum of 1 inch of sand be placed on top of the membrane <br /> to assist in the curing of the concrete. Should sand be used, <br /> is the thickness of the gravel cushion may be decreased by the <br /> thickness of the sand. A surface curing agent/sealer such as <br /> t <br /> moxie 1500 or a concrete additive such as moxie 1800 may be <br /> F utilized as an alternative to the Visqueen-type barriar. A 4- <br /> inch thick slab should be reinforced with 6x6-6/6 wire mesh at <br /> the center of the structural section or the equivalent No. 4 bars <br /> at 18 inches on center and may be utilized for anticipated floor <br /> loads not exceeding 250 p.s.f. Fiber mesh is a concrete <br /> additive, that, when placed in accordance with the manufacturer's <br /> specified 1.5 pounds per cubic yard of concrete, is a preferable <br /> alternative to wire mesh. Where fiber mesh is utilized, Zip <br /> strips or other joint systems should be provided to separate the <br /> surface area of the slabs to no more than 400 square feet, with <br /> joints spaced not more than 20 feet in any direction. <br /> 12 <br />