Concrete Products

APR 2018

Concrete Products covers the issues that attract producers of ready mixed and manufactured concrete focusing on equipment and material technology, market development and management topics.

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60 • April 2018 Huber Carbonates launched a series of ground calcium carbonates earlier this year at The Precast Show in Denver, underscoring the powders' capacity to replace fly ash; improve concrete mix workability; contribute to self-consoli- dating mix spread profile; and, maintain consistent white color without impacting fresh or hardened concrete properties. HuberCrete calcium carbonate is pro- cessed in Prime, Preferred and Extra Fine grades of these respective median particle size and Blaine fineness profiles: 15-24 µm, 300-500 m 2 /kg; 8-13 µm, 500-700 m 2 /kg; and 3-5 µm, 700-1,000 m 2 /kg. Prime is the most cost effective for fly ash replacement and will not cause fluctua- tions in admixture dosage requirements. HuberCrete Extra Fine helps to improve surface finish characteristics from most concrete mixtures, as the particles impart smoothness and accentuate form reliefs. Preferred calcium carbonate offers a finer particle distribution than fly ash and pro- vides a better early hydration reaction, Huber Carbonates engineers note. Each HuberCrete gradation, they add, a) enables concrete practitioners to take full advantage of the particle packing effect of companion mix design materials; b) has neutral effect on curing time; and, c) contributes to a project's LEED rating potential through the lowering of port- land cement requirements and finished structures/surfaces' solar performance characteristics. While not pozzolanic, HuberCrete powders promote sub-micron level reactivity by providing calcium surface area augmenting formation of hydrated cement compounds. Testing in self con- solidating concrete mixes with target 24-in. spread, HuberCrete Extra Fine and Prime specimens attained compressive strengths of 100 percent at 18 hours against portland cement controls. At 28 days, Extra Fine and Prime concrete spec- imens exhibited respective compressive strengths of 102 percent and 90 percent compared to controls. HuberCrete and other calcium car- bonate products are milled at facilities integrated with Huber Carbonates under- ground limestone mines in Marble Hill, Ga., Quincy, Ill., and Marble Falls, Texas. The new powder series meets ASTM C1797 Specification for Ground Calcium Carbon- ate and Aggregated Mineral Fillers for Use in Hydraulic Cement Concrete. — Huber Carbonates LLC, Atlanta, www.huberma- INNOVATIONS MATERIALS Processor grades calcium carbonate for fly ash substitution, SCC MAKING THE GRADATIONS Huber Carbonates diagrams where the HuberCrete products fall within the median particle size and specific surface area range versus other concrete mixture agents. HuberCrete gradations allow concrete practitioners to take full advantage of other mix design materials' particle packing effect. PROFILES IN CONSISTENCY Particle size distributions evidence HuberCrete gradations' consistency. Preferred calcium carbon- ate closely resembles Type I cement particle distribution, while Prime promotes packing between cement particles and sand grains. HuberCrete Extra Fine calcium carbonate particles enhance finished concrete textures. Raw feed for HuberCrete Prime, Preferred or Extra Fine gradations at Huber Carbonates' flag- ship limestone mine and processing mill, Marble Hill, Ga.

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