CEMCOTEC is the UK distributor for Forton water based specialty polymer compound. It is a copolymer emulsion specifically developed for use with AR glassfibres. It is the only polymer with a >25-year pedigree with GRC. It has been extensively and independently evaluated in both natural [19 years real time data available] and accelerated ageing tests. In America it is sold as V774 but in Europe, it is sold as LP9908 and manufactured to the highest standards by a subsidiary of Engineered Polymer Solutions Inc. who are part of The Valspar Corporation.
"Due to the plasticising effect of the LP9908 polymer, the water/cement ratio will be lowered. It also gives good processing and compaction, particularly in Premix GRC, which makes for a stronger composite and improved productivity"
When mixed with Portland cement and silica sand, the polymer particles disperse throughout the slurry, coating sand and cement particles. When combined with the AR glass fibres in the mould, the polymer particles also migrate into the inter-filament spaces of the fibre bundle, thereby reducing the growth of the harsh products of hydration within the fibre bundles. GRC modified with LP9908 eliminates the 7 day wet cure normally associated with good concrete practice. Once placed and compacted in the mould, the polymer film-forms helping to keep the water of hydration in the product thus ensuring a well cured GRC composite.
The improvements and advantages of GRC with polymer can be summarized as follows:
*Due to the plasticising effect of the LP9908 polymer, the water/cement ratio will be lowered. It also gives good processing and compaction, particularly in Premix GRC, which makes for a stronger composite and improved productivity
*The coating of the cement and sand particles with polymer helps to reduce drying shrinkage cracks and crazing on the surface of the GRC product.
*The wet curing regime can be eliminated by using LP9908 polymer. This guarantees an LOP strength at least equal to that obtained with a 7 day wet cure.
*The moisture absorption in absolute terms, and the rate of moisture absorption, will be significantly reduced.
*The amount of polymer added influences the initial drying shrinkage of GRC and also reduces moisture induced movements.
*By protecting the glass fibre bundles, the performance of the GRC in natural weathering is greatly improved.
*Long term strain to failure of the composite in natural weathering is higher.
*LP9908 polymer is alkali resistant and ultra-violet light stable.
*New cement matrix systems, such as Cem-FIL Star GRC which uses pozzolanic metakaolin, is greatly aided by the addition of LP9908 polymer. This system greatly improves long term strength retention and reduced efflorescence