Researchers measure high-SCM grouts’ compliance

To boost market prospects for masonry walls exhibiting high recycled materials content, Concrete Masonry Association of California and Nevada (CMACN) is supporting an investigation through Brigham Young University to a) confirm that California Building Code-required strength is maintained with grouts where portland cement is substituted with fly ash at 45–65 percent and fly ash + GGBF slag at 65–85 percent; and, b) observe how prism units containing such grouts behave with Type M, S and N mortars.

Under the direction of Professor Dr. Fernando Fonseca, BYU Department of Civil and Environmental Engineering staff is preparing to test 180-day grout strengths, following measurement at one, seven, 28 and 56 days. Utah Masonry Council masons and BYU students assembled 600 prisms earlier this year, using 8 x 8 half blocks supplied by Oldcastle Architectural; fly ash from Headwaters Construction Materials; and, NewCem GGBF slag from Lafarge Cement.

Mix designs for the high supplementary cementitious material grouts mirror those of 2010 CMACN research to validate code-compliant alternatives to portland cement-only formulations. Findings from it have supported widespread specification in California of high fly ash or fly ash/slag grouts, which have been found to consistently develop code-required 2,000-psi strength at 28 days.