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Nitkal – Additives For Concrete

Thursday, December 1st, 2011

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In the winter concreting, the accelerated increase in strength will prevent too-rapid hardening after heat due to hydration. Getting concrete with high strength. DEPENDENCE ON THE TYPE OF PERFORMANCE CT examination of the effectiveness of NITCAL with 10 different brands of Portland cement showed that there was no correlation between the accelerated strength development and content of C3A (calcium aluminate three-celite). However, the correlation was found with S2S (two calcium silicate blanches) content. NITCAL efficiency as an accelerator of curing decreases with increasing Na2O content of alkali in the concrete mix, while the hydroxides and sulfates accelerate the activity calcium. NITCAL used for cements with low alkali cement is used for both low and high Belita (C2S). NITCAL – is most effective as an accelerator for the curing of Portland Belita high and low content of alkali.

Reduced induction period and time of curing can be used in several ways: In the winter period to avoid hypothermia fresh concrete prior to hardening. Production of ready-made elements (faster reuse of forms). Reduced risk of cracking due to shrinkage of concrete. Reduced time to finishing (smoothing) of concrete floors. Increased early strength concrete. To activate the concrete after a long transport or transportation in hot climates. RISK REDUCTION NITCAL cracking can be used as an additive that reduces the risk cracking due to rapid loss of moisture in fresh concrete. The most likely effect of accelerated curing.

When tested concrete mixes with w / c = 0.45, with 2% NITCAL from cement and no additives. Concrete rings were subjected to drying in the installation, with a wind speed of 4.5 m / s at 20 C, relative humidity 43%. Concrete without additives had shrinkage cracks, while not seen any cracks in concrete with 2% NITCAL. CORROSION INHIBITOR NITCAL Prevents corrosion of the reinforcement, caused by high chloride content. Dosage 2 – 4%. During the lengthy trial proved that calcium nitrate slows down the corrosion of reinforcing steel caused by chloride as added directly into the water for mixing, and added later, as well as greater calcium nitrite tests for corrosion. The mechanism of action of nitrate and nitrite as corrosion inhibitors are similar in alkaline environments, such as concrete. Kinetics of nitrate more slowly than nitrite, but it is only important in short-term trials, since in practice the process of corrosion – a rather lengthy process. As follows from the theory, calcium nitrate provides more cushion than calcium nitrite. The addition of antifreeze additive NITCAL as the accelerator timing of cement used for production of concrete mixtures, in particular, recommended at low temperatures. The introduction of additives in the concrete mixture NITCAL at low ambient temperature causes a lowering of the freezing point of water, thereby kneading the concrete at Air – 10 C, without slowing down the cement hydration process. Effective influence NITCAL the concrete mix is achieved at a temperature of – 15 C ambient, if you add more than 1-2% additive by weight of cement. The application has a stable NITCAL growth on a global scale, is used in many major construction projects. The concrete mixture used in the construction NITCAL mines in the North Sea (altitude 369 m), under oil and gas platforms. Expediency NITCAL use was the fact that he opposed the slowing effect of hardening the mixture by pouring high and massive structures. Sales volume in the world is more than 1 million tons per year. The material is based on the YARA INDUSTRIAL manufacturer and testing of Professor Harold Dzhastnesa, SINTEF Civil engineering, simulation environments, cement and concrete, Trondheim, Norway.