Patent ID: 7736431

Claim:
A lightweight concrete having compression strength greater than 2500 psi, the lightweight concrete comprising: (a) 1.05 to 1.75 parts by volume of Portland cement; (b) 0.75 to 1.25 parts by volume of Class F or Class C fly ash; (c) 1.15 to 1.85 parts by volume of masonry sand as defined in ASTM C144 or a fine structural filler of size no larger than masonry sand; (d) an amount of expanded perlite effective to achieve between 17% to 25% volume of the concrete, the expanded perlite having a size distribution mean between 1 mm to 2.5 mm and with at least 75% of the amount of particles falling within +/−0.6 mm from the center of the size distribution mean; (e) 0.65 to 1.20 parts by volume of water effective to achieve a water to cement (W/C) ratio in the range of 0.4 to 0.67; (f) an amount of super-plasticizer effective to produce a target slump; and (g) an amount of air entrainment admixture effective to produce 3% to 20% entrained air with a size distribution mean no larger than 70% of the size distribution mean of the expanded perlite in the concrete.