Special-Uses-Alkali - Expanded Shale & Clay

5.3. Metakaolin ProductsAll of the following products exhibited a much higher water demand than did the fly ash mixes.With the same amount of batch water for the fly ash mixes, these batches did not have the sameplastic concrete properties. The aggregate would roll around in the mixer with the cement andpozzolan sticking to the pieces, and would not “flow” until the w/c ratio was brought up toaround 0.47 or higher.5.3.1. Burgess Pigment CompanyAdditional water required to achieve a w/c ratio of 0.47 yielded a slump of one inch. The mixwas very stiff, sticky and hard to finish. The air content was 1.9% and the unit weight was 145.8pcf. The compressive strength was 5,860 psi at 7 days, 6,720 psi at 28 days, and 7,020 psi at 56days, exceeding the baseline numbers for all the same respective strength data. The rapidchloride permeability of the specimens averaged 853 coulombs, this value being significantlylower than the baseline, indicating a lower permeability.5.3.2. GCC of AmericaThe Microsilex had good workability with the 2.25 inch slump and a w/c ratio of 0.54. Thisslump and water to cement ratio was achieved with the addition of 81 pounds of water per cubicyard over the anticipated batch water. The air content was 2.1% and the unit weight was 143.7pcf. The compressive strength of the mix was 3,550 psi at 7 days, 5,270 psi at 28 days, and 6,740psi at 56 days. The average 28-day rapid chloride permeability level was 1,809 coulombs whichwas significantly lower than the baseline mix permeability.The second mix for the Microsilex had the addition of Boral’s Monticello Class F fly ash, for aternary concrete mix. This mix had the cement replaced by 10% of both the Microsilex and theClass F fly ash. This mix had a slump of 3.5 inches with a w/c ratio of 0.44, air content of 2.3%and a unit weight of 146.3 pcf. This mix only had a slightly higher affinity for moisture by theaddition of the Microsilex, with the fly ash keeping the mix very workable. The compressivestrength of the mix was 3,457 psi, 5,880 psi and 7,070 psi for 7, 28, and 56 days respectively.The average rapid chloride permeability of the 28-day specimens was 2,359 coulombs.24