03 30 00

Structural slabs on metal deck shall attain a minimum compressive strength of 5,000 psi at 28 days. Maximum water to cementitious materials ratio shall be 0.45. Slump shall be 5 inches plus or minus 1 inch measured at the point of placement, before addition of any high range water reducing admixture. Fly ash shall not exceed 25 percent of total cementitious material by weight.

Do not place concrete when the ambient temperature exceeds 95 degrees Fahrenheit, when the concrete temperature at the point of placement exceeds 90 degrees Fahrenheit, or when the evaporation rate calculated from ACI 305 exceeds 0.2 pounds per square foot per hour, unless the Contractor submits and the Engineer accepts a written hot weather placement plan for that pour. Placement between the hours of 10:00 and 16:00 during June through September shall be assumed to require such a plan.

Cure structural slabs by continuous water curing or by an approved curing compound applied at the manufacturer's rate for a minimum of seven days. Where a curing compound is used on a slab scheduled to receive an applied floor finish, the compound shall be certified by its manufacturer as compatible with the scheduled finish, and that certification shall be submitted before the compound is used.

Slabs scheduled to receive resilient flooring or thin set tile shall be finished to an overall flatness of FF 35 and an overall levelness of FL 25, with minimum local values of FF 24 and FL 17. Measure in accordance with ASTM E1155 within 72 hours of slab finishing. Areas failing the minimum local value shall be corrected by grinding or by an approved underlayment at no additional cost.