Through Plant Architects, German equipment specialist FML Concretec GmbH brings to North America water-treatment technology that potentially extends the
Through Plant Architects, German equipment specialist FML Concretec GmbH brings to North America water-treatment technology that potentially extends the concrete mix workability window by a factor of three and produces 10 to 40 percent higher eventual hydration values and compressive strengths. The system includes a pass-through electrical water-conditioning mechanism and optional high-shear colloidal mixing and/or high-shear vortex pumping equipment, adaptable to new ready mixed or precast batch plants, or packaged for retrofits.
CONCRETE WATER TREATMENT
Known quantities in concrete production include cement Û milled under controlled conditions to meet national and international standards; admixtures Û manufactured to specifications that include quality standards for base and combined chemicals, which often are subjected to microscopic analyses; fine aggregates Û precisely graded to enhance the binding matrix; and, coarse aggregate Û carefully selected for hardness and shape to provide mass, compressive strength, wear and resiliency. But, what standards apply to one of the most basic ingredients Û water?
Although indispensable to concrete setting, which is a result of hydration or chemical reactions that occur within the emulsified materials, water is the least specified of ingredients that constitute even highest-performance mix designs. Today, concrete water, i.e., any water used in concrete production, is generally stipulated as potable or clean water suitable for household purposes.
For decades, however, forward-thinking technologists have addressed the issue of how water could be treated to enhance concrete properties. During the 1970s and early 1980s, academics in various research facilities of the former Soviet Union investigated hydration control in concrete curing and the effect of different types of water on overall concrete performance. While study results chiefly were archived and not put into practice, they indicated the importance of mineral hardness, especially with regard to material set times, demonstrating that metals, e.g., iron and heavy elements like lead, mercury and arsenic, affect concrete elasticity and workability.
Long-term research involved altering the surface tension of concrete water via electrical and magnetic pulses to achieve both chemical and molecular changes. Further, destructive testing revealed that corrosion resistance varies significantly according to the water used in concrete production; and, water type also greatly influences chemical admixture performance, in addition to the amount of time a mix remains workable.
Overall, development of primary and secondary water-treatment methods proved highly productive. Among various types of water processing undertaken for concrete production are sand and carbon filtering, reverse osmosis, and distillation Û all treatments that provide better results than using water with assumed qualities that likely vary from batch to batch. Yet, for some years, following the aforementioned original studies, an electrical pass-through water-treatment method for polarization (splitting of molecules) of water has enabled capture of heavy metals or decanting of unwanted minerals. Electrodynamics and electrical impacts are applied thereby to achieve disintegration of water-molecule clusters, change the electrical load of constituents, and improve water’s ability to react.
Disregarding water type due to lack of an applicable specification, German scientists in the 1990s applied the pass-through treatment to water used in concrete production Û both in the field and in the laboratory Û to discover that polarization of water molecules resulted in workability up to three times as long, plus significantly greater eventual hydration values and compressive strengths. Thus, polarization of basic water allowed all emulsion constituents, including cements and admixtures, to perform at a higher level. Accordingly, a carefully calibrated pass-through treatment based on testing of process water produced predictable results geared to a concrete mix of defined properties.
In 2007, FML Concretec obtained marketing and technological patent protection for a refined pass-through electrical water-treatment system specifically tailored to concrete production. The proprietary technique entails both water treatment and a high-shear colloidal mixing and/or high-shear vortex pumping system to emulsify powdered mix constituents with the treated water.
Aiming to optimize the concrete water-treatment process via emulsification, FML concrete technologists and cement chemists looked to other industries and experimented with emulsification blending and high-shear molecular modification (wet grinding) of the cement and other powders. The combination of a patented water-treatment process and emulsification of powdered constituents (with the treated water) allows cement particles and other ultrafines to thoroughly react with water molecules to produce a homogeneous mixture of all ingredients, including activated polarized plasticizers, in a short time. During the mixing process, particle size and shape Û primarily of the coarsest fines Û are refined by a wet grinding process, as finer alterations occur electrically and chemically.
Results of the combined water treatment and wet grinding proved significant, as treated mix water reacted with the fine grind of cement colloidal emulsifications, including admixtures. Exponential expansion was noted in dwell or window of chemical reactivity, markedly improving plasticity and workability by two to three times. In addition to profoundly enhanced workability, a concurrent exponential early and later strength gain was achieved.
PRODUCING BETTER CONCRETE
Increasing the workability window by using admixture chemicals, such as water-reducing agents, permits a substantial reduction in water-cement ratio of pavement mix designs and facilitates placement in heavily reinforced concrete components, e.g., dividers and bridge decks. Such design modifications are especially pertinent to ultra-high- and high-performance concrete, as well as self-consolidating concrete, used in prestressed elements and high-rise construction. Thus, enhanced mix designs aided by the emulsification process to achieve extremely low water-cement ratios ensure higher strengths with maximum density. For higher slump concrete, the emulsification process has demonstrated value as a pumping/placing and finishing aid.
While investigation continues of its effects on overall concrete performance, electrically treated water emulsification of mix constituents clearly produces a more thoroughly blended material, which can be expected to yield improved life cycles. Other benefits can be realized in the areas of concrete cooling, shrinkage and cracking control, and surface finish. Studies addressing emulsifications that reach near-perfect hydration suggest that a 40 percent improvement over transit-mixed concrete is attainable with 100 percent hydration. Moreover, use of time-released cements and admixtures for self-mending of fissures and cracking can be considered seriously in light of such near-perfect hydration values.
The dramatic changes in concrete properties accompanying electrical treatment of mix water, emulsification and wet grinding, plus mix design enhancements, prompted careful consideration of possible levels of optimization, e.g., higher strengths, faster formwork or mold turnarounds, less cement and/or admixture content. The patent holders decided to adopt a consultative approach requiring analysis of each producer’s raw materials, water, and admixture types to suit individual objectives regarding savings, performance and enhancement.
In North America, the patented FML Concretec system is offered on a consultative basis through San Antonio-based Plant Architects (210/569-9262). Plant Architects and FML representatives will be on hand at the 2010 World of Concrete, Booth N659