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BASF agent propagates CSH crystals to increase early, late-age strength

Focusing on the compound at the heart of quality concrete, BASF Construction Chemicals has developed a first-of-its-kind liquid admixture that improves early- and late-age strength development. Master X-Seed 55 is a stable suspension of synthetically produced crystalline calcium silicate hydrate (CSH) nanoparticles that facilitate growth of CSH crystals between cement grains and improve overall portland cement hydration.

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A scanning electron micrograph of a Master X-Seed 55-dosed paste sample evidences elevated calcium silicate hydrate crystal growth between portland cement grains. Added crystal formation advances strength development at all ages of the concrete.
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BASF chemists illustrate the new admixture’s effect on concrete by comparing the CSH crystal characteristics of typical hydrated cement grains and those where Master X-Seed 55 nanoparticles tighten a matrix by compounding crystal formation.

“Given the X-Seed technology’s widespread success in Europe since its 2009 launch, we worked to develop a unique formula specifically designed for North America,” said BASF Admixture Systems Product Manager Chris Eagon during a World of Concrete 2018 product unveiling. “Master X-Seed 55 admixture utilizes CSH nanoparticles, along with other technologies, to facilitate and improve strength development at all ages of the concrete.”

Dosed at up to 10 oz./100 cwt, he added, the admixture allows ready mixed and precast concrete producers to expand the performance space of a given mixture—conventional slump to self-consolidating—and optimize the cementitious material content. Master X-Seed 55 likewise provides a strength safety factor, permits earlier stripping of forms to improve production efficiency, and promotes sustainable construction by enabling higher than normal levels of portland cement replacement.

Testing concretes prepared with total cementitious material content of 611 lbs./yd. at 0.47 w/cm, BASF engineers noted respective 1-, 7- and 28-day compressive strength gains of 46 percent, 18 percent and 19 percent for X-Seed 55-dosed specimens against controls. Companion tests gauging compressive strength development at the three intervals demonstrated the admixture’s potential to offset total binder requirements by 10 percent.BASF Construction Chemicals, Admixture Systems, Cleveland, 800/628-9990; www.master-builders-solutions.basf.us