Limestone processor enters concrete market with three calcium carbonate grades

Sources: Huber Carbonates LLC, Atlanta; CP staff

Huber Carbonates launched HuberCrete, a series of ground calcium carbonates for fly ash substitution and self-consolidating concrete mixes, at the 2018 Precast Show in Denver. The product is processed in Prime, Preferred and Extra Fine grades of these respective median particle size and Blaine fineness profiles: 15-24 µm, 300-500 m2/kg; 8-13 µm, 500-700 m2/kg; and 3-5 µm, 700-1,000 m2/kg.

HuberCrete gradations enable concrete practitioners to take full advantage of the particle packing effect of companion mix design materials, company engineers note. While not pozzolanic, they add, the powders promote sub-micron level reactivity by providing calcium surface area augmenting formation of hydrated cement compounds. Testing in SCC mixes with target 24-in. spread, HuberCrete Extra Fine and Prime specimens have attained compressive strengths of 100 percent at 18 hours against portland cement controls. Extra Fine and Prime concrete specimens reached respective 28-day compressive strengths of 102 percent and 90 percent compared to controls.

Additional HuberCrete benefits for concrete include improved mix workability and color consistency; neutral effect on curing time; and, contribution to a project’s LEED points through the lowering of portland cement requirements and finished structures/surfaces’ solar performance characteristics.

HuberCrete and other calcium carbonate products are milled at facilities integrated with Huber Carbonates underground limestone mines in Marble Hill, Ga., Quincy, Ill., and Marble Falls, Texas. The new powder series meets ASTM C1797 Specification for Ground Calcium Carbonate and Aggregated Mineral Fillers for Use in Hydraulic Cement Concrete. –