Rocrete SP is a surfactant and is a sodium salt of polycondensate of naphthalene acids with formaldehyde. It is available in the form of a beige powder with very low water content and low bulk density. This translates into savings in product transport and storage.
The Rocrete SP production technology allows a product containing trace amounts of free formaldehyde and free naphthalene to be obtained. As a result, it does not have an environmental classification and does not affect the content of free aromatic hydrocarbons in the products for which it is used.
Rocrete SP is a dispersing compound made of a hydrophobic organic chain and a hydrophilic sulfone group. Due to its structure, it can adsorb onto solid particles, forming on them a layer of homonymous electrical charges (sulfone groups). Their mutual repulsion causes the breakdown of agglomerates of these particles. Due to its very good dispersing properties, it works as a great liquefier and reducer of batched water in concrete mixtures.
Rocrete SP’s operation is mainly based on the principle of electrostatic repulsion. After the product is adsorbed onto cement or gypsum grains, a layer of homonymous electrical charges (sulfone groups) forms on them. Their mutual repulsion causes the agglomerates of cement grains (or gypsum) to break down and release water trapped in them, resulting in an increase in liquidity of the mix. At the same time, the separation of cement grains from each other over considerable distances extends the time of formation of cement hydration products, which delays the start and end time of setting of the concrete mix.
A small addition of Rocrete SP allows you to reduce the water/cement ratio (and thus reduce the consumption of batched water) by up to 25% without compromising the consistency of the mix. As a result, the porosity of hardened concrete is reduced, which in turn translates directly into a significant increase in the late strength of concrete (up to 30% compared to a mixture without its addition). Concrete tightness is also improved, i.e. its resistance to aggressive substances and frost, as well as resistance to abrasion. Early strengths also increase, so it becomes possible to quickly demould the concrete element. If the w/c coefficient remains unchanged and the amount of batched water used is reduced, it is possible to reduce the amount of cement used. In addition to the economic benefits, this also leads to a reduction in the heat of hydration emitted and a reduction in the shrinking that occurs during the setting of the concrete.
Rocrete SP does not contribute to corrosion of steel reinforcements in concrete structures due to the very low concentration of chlorides in the product, which is its undoubted advantage. It does not introduce large amounts of air into the concrete mix, which can potentially lead to deterioration of frost resistance. In addition, it allows concrete to be made at an air temperature of up to -5 ° C without inhibiting cement hydration.
Rocrete SP is a very good superplasticizer in concrete mixes. Its big advantage is its powder form, which reduces transport costs even over considerable distances. The use of even small amounts of Rocrete SP allows you to produce cheap and environmentally friendly concrete, which is also characterized by very good strength and rheological properties. It is mainly recommended for the production of ready-mixed concrete, precast concrete and cement mortars.