An accelerated-curing concrete masonry unit (CMU) mixture includes
aggregate material, hydraulic cement and spent blasting abrasive
particles, and may also include paint residue particles. The abrasive
particles or abrasive and paint particles combined preferably make up at
least 5.0% of the mixture by volume. Preferably, the hydraulic cement is
Portland cement and the abrasive or combined particles make up about
10.0% to 17.0% of the mixture by volume. The abrasive particles typically
have a fineness modulus ranging from 0.6 to 1.5 and more preferably from
0.75 to 1.2. Plastic particles may make up some or all of the abrasive
particles. CMUs formed with this mixture are substantially more water
repellent than standard CMUs and have a water absorption often no greater
than 9.0 pounds per cubic foot. Preferred CMUs have an average net
compressive strength of over 2,500 psi while levels of 3,000 psi or 3,500
psi are not uncommon.