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Alternative SCM, industrial mineral blend catapults C-S-H formation

California-based construction materials specialist Surface Tech is commercializing an alternative supplementary cementitious material (ASCM) whose requisite chemical profile (silicon dioxide + aluminum oxide + iron oxide content > 75 percent) belies binder-optimizing performance potential exceeding that of leading SCM. While fly ash, GGBF slag and silica fume tend toward dosages starting at 10 percent by weight of portland cement, Juno XP has exhibited marked strength development characteristics at 2.5 percent and 5 percent when measured against portland cement controls—particularly at seven- and 28-day cylinder breaks.

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Scanning electron microscopy reveals the fibril-like quality of minerals prevalent in Juno XP. Surface Tech researchers stress the material’s capacity to consume free lime within a portland cement concrete matrix, augmenting formation of calcium-silicate-hydrate, the backbone of strength in concrete.
BINDER EFFICIENCY
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Surface Tech researchers have proved the ability of concrete specimens with small Juno XP quantities to attain compressive strengths 10-20 percent above those of portland cement controls at standard cylinder break intervals.

Surface Tech’s market ramp up has entailed short- and long-term observation of Juno XP specimen performance as prescribed in ASTM C1709 Standard Guide for Evaluation of Alternative Supplementary Cementitious Materials for Use in Concrete. “Contractors have utilized common types of SCM for years to partially replace traditional portland cement in concrete mixes. The use of these materials has been supported by significant research and testing, as well as long-term performance monitoring,” says Surface Tech Chief Technical Officer – Concrete Jon Belkowitz, PhD. “The same rigorous testing procedures for common SCM are being applied to Juno XP, and results from C1709 Stage 4 testing are fantastic.”

“Throughout the initial 90-day set of results, the strength and durability of Juno XP-enhanced concrete specimens has proved out above C1709 references,” he adds. “The innovative technology behind Juno XP generates a hardened concrete matrix with greater cementitious efficiency and resistance to abrasion and physical impacts than conventional portland cement mixes. Proprietary pozzolanic and mineral components densify the hydrated matrix, leading to concrete that has a higher strength per pound of cementitious material.”

MATERIAL PROPERTIES

Juno XP particle sizes range from 20 µm to 700 µm. Surface Tech will recommend dosages in the a) 2 percent to 6 percent range when used in tertiary blends; or, b) 4 percent to 10 percent as a standalone ASCM.

Rich in minerals with fibril-like morphology, Juno XP is processed from natural pozzolan and industrial material raw feeds sourced in North and Central America. Surface Tech’s commercialization efforts for the agent are well timed: Concrete and cement interests are increasingly open to natural pozzolans or related ASCM blends for imparting higher performance in slabs and structures, or offering alternatives to Class F fly ash, supplies of which have tightened in key regions or markets.

“Juno XP extends concrete service life by effectively manipulating the molecular kinetics of cementitious hydration. Its mineral and pozzolanic components consume calcium hydroxide to increase development of calcium-silicate-hydrate, the backbone of concrete strength,” Belkowitz affirms. “The fibril-like morphology of minerals within Juno XP increases the toughness of the interfacial zone between the coarse and fine aggregate, and the hydrated cementitious matrix.”

Product testing per C1709 phases spans one year. Surface Tech anticipates completion of laboratory work to conclude this month, followed by a field-testing phase the remainder of the 2019 and plant production trials commencing early next year. The company plans to package Juno XP in 25- to 3,000-lb. containers, or ship in bulk. It will promote the material for concrete producers and practitioners seeking to increase binder efficiency; compressive and flexural strength; plus, resistance to abrasion, cracking forces and chemical exposure. — Surface Tech, La Jolla, Calif., 619/880-0265; www.surface-tech.com