Москва, 2013 в Calcium nitrate as Antifreeze Admixture in Concrete

Calcium Nitrate Premium grade Appearance Granules without mechanical impurities, white to greyish-yellow Calcium nitrate, % min 9696 Moisture content, % max 3 Insolubles, % max 0,1 Ammoniacal nitrogen, % max 0,3 Granulometric composition: Under 1 mm, % max mm, % min under 6 mm, % Static strength of granules, MPa (kgf/cm 2 ), min 2,0 (20) Friability, % 100 Packaging: PE bags 25kg, palletized 1000 kg big-bags Shelf life: 6 months from date of manufacture Formula: Ca(NO 3)2 Specification:

Longterm hardening acceleration Datesσ с 0.0% Calcium nitrate (MPa) σ с 3.5% Calcium nitrate (MPa) 8 h3.23± ±0.3 1 d44.9± ±0.9 3 d63.9± ±0.4 7 d76.8± ± d90.8± ±1.0 The compressive strength of concrete with WPP HSC, 4% silica fume, w/c = 0.35 and a mixture of plasticizer / superplasticizer Increase in strength at early stage due to the deceleration caused by the action of the plasticizer (lignosulfonate) and superplasticizer (based on naphthalene). Also, there is a prolonged strength development. As a consequence, it is possible to use a smaller count of cement for the same strength.

4 Calcium Nitrate as Concrete Set Accelerator Reduced setting time during work completion, floor slab jacking or operations with pre-fabricated (factory-made) elements Lower pressure on forms when consecutive concrete batches are prepared Higher setting rate for concretes with low water-cement ratio or large concentrations of plasticizers/superplasticizers which cause longer setting time When transporting concrete over long distances or casting in hot weather, concrete with lignosulfonate admixture can be made workable on the site by adding calcium nitrate into the truck mixer drum. When casting in cold weather, accelerated strength gain will prevent an excessively fast concrete setting after heat release as a result of hydration. Production of high-strength concrete and flat elements with high-quality surfaces.

Concrete with calcium nitrate after 5 years at 38 º C 5 Corrosion Inhibition Reinforcements removed from concrete cylinders with NaCl concentration equal to 3.2% of cement mass (looking like dirty sand). The cylinders were stored during 3 years under the temperature of 38  C and relative humidity of 90%. Where calcium nitrate was added, steel parts were not affected by corrosion and only small surface areas were covered with rust. A new series of concrete specimens with 3% calcium nitrate in cement as an inhibitor To initiate corrosion added 3.2% sodium chloride (NaCl) by weight of cement The ribbed rebar only small traces of rust Calcium nitrate - better inhibitor than sodium nitrite, which confirms the theory

6 Calcium Nitrate as Antifreeze Admixture Calcium nitrate is used as antifreeze admixture in the negative temperature range from 0°C to -20°C Calculated hardening temperature Calcium nitrate amountSodium formate amountSodium nitrite amount о С1 – 2 %2 – 3 %4 – 8 % - 15 о С3 %4 %8 – 10 % Temperature10°С20°С30°С40°С Solubility, g/l Sodium formate Solubility, g/l Calcium nitrate Solubility of calcium nitrate and sodium formate

7 Reducing the risk of cracking Calcium nitrate 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 the accelerated strength development. When testing the concrete mixtures with w/c = 0.45, with 2% of calcium nitrate by weight of cement without additives. Concrete rings were subjected to drying hood with the wind speed of 4.5 m/s, at 20 º C and a relative humidity of 43%. Concrete without additives had shrinkage cracks, while not observed any crack in concrete 2% calcium nitrate.

8 In the process of the production of horizontal building blocks can form small "trickling" pits that necessary to eliminate after hardening The use of calcium nitrate, provided the surface of higher quality and prevent appearance of these cavities due to an earlier setting and good cohesiveness The recommended dosage is % by weight of cement Flat surface by use of calcium nitrate Manufacture of building blocks

9 Indicative dosage of calcium nitrate depending on improved property of concrete: Improved property of concreteDosage, % Antifreeze admixture1-3,5 Reinforcement corrosion inhibitor2-4 Reduction of cracking1-2 Hardening accelerator0,5-1,2 Prolonged strength development2-2,5

10 Преимущества нитрата кальция Increase in concrete waterproofness by 2-4 grades Increase in concrete impact strength and fracture strength Corrosion protection for reinforcement Considerable increase in concrete resistance to frost and salt Achievement of concrete strength above 70% of grade strength after the first day of setting Concrete casting in cold weather (at temperatures as low as minus 15°С) Reduction in crack formation Reduction in efflorescence Increase in concrete wear resistance Higher rate of concrete strength development over the following years No application restrictions, as opposed to sodium formate Lower dosage as compared with sodium formate

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