Welcome to Silpozz

Micro Silica manufacturer in India

N K Enterprises is a manufacturer and exporter of Silpozz, an excellent super-pozzolan. Our product – Silpozz micro-silica is used as a admixture in a big way to make special concrete mixes and refractory. There is a growing demand for fine amorphous silica in the production of special cement and concrete mixes. This market is currently filled by silica fume or micro silica , being imported from Norway, China and also from Bhutan . Due to limited supply of silica fumes in India and the demand being high the price of silica fume has risen to as much as US$ 550 / ton in India.

How Silpozz Works :

Silpozz is a super pozzolan having reactive silica content of over 85%. A simple everyday definition of ‘pozzolan’ could be ‘a finely powdered material which can be added to lime mortar (or to Portland cement mortar) to increase durability and, in the case of lime mortars, to provide a positive set’. A more formal definition is given by ASTM C618 as ‘a siliceous or siliceous and aluminous material which, in itself, possesses little or no cementitious value but which will, in finely divided form in the presence of moisture, react chemically with calcium hydroxide at ordinary temperature to form compounds possessing cementitious properties’.

Silpozz enhances the rheological properties and controlling bleeding of fresh concrete, these materials greatly improve the durability of concrete through control of high thermal gradients, pore refinement, depletion of cement alkalis, resistance to chloride and sulphate penetration and continued microstructural development through long-term hydration and pozzolanic reactions. Silpozz also reduces the severity of concrete deterioration problems arising from chemical phenomena such as alkali silica reaction, delayed ettringite formation and thaumasite formation.

The materials have an average particles size on the order of 25 micron meter, and surface areas in the range of 15-20 m2/g. Our product Silpozz is in powder form with a density of about 600 kgs/m3. The compacted or granulated form (bulk density 600kg/m3) the material is easier to handle and is economical for transportation.

Silpozz performs in two ways :

  1. Pozzolonic effect

When water is added to OPC, hydration occurs forming two products, as shown below:

OPC + H2O →CSH (Calcium silicate hydrate) + Ca(OH)2

In the presence of Silpozz, the silicon dioxide from Silpozz will react with the calcium hydroxide to produce more aggregate binding CSH as follows:

Ca(OH)2 + SiO2 → H20 + CSH

The reaction reduces the amount of calcium hydroxide in the concrete. The weaker calcium hydroxide does not contribute to strength. When combined with carbon dioxide, it forms a soluble salt, which will leach through the concrete causing efflorescence, a familiar architectural problem. Concrete is also more vulnerable to sulphate attack, chemical attack and adverse alkali-aggregate reactions when high amounts of calcium hydroxide is present in concrete.

  1. Micro filler effect

Silpozz is an extremely fine material, with an average diameter much finer than cement. The particles of Silpozz are well distributed in the paste which segment the bleed-water channels and consequently are able to prevent bleeding and segration. Also, Silpozz fills up the empty spaces and cause densification (pore refinement) and strengthening of the microstructure, particularly in high porous and least cracking-resistant interfacial zone which exit in the vicinity of coarse aggregate particles. This eliminates bleed and the weak transition zone between aggregate and paste found in normal concrete. This micro filler effect also greatly reduces permeability and improves paste-to aggregate bond in Silpozz concrete compared to conventional concrete. The transformation of an open-pore system into a closed-pore system, through the process of pore refinement has a much greater effect on the permeability than on the strength of the materials.

Silpozz for strength: Adding Silpozz micro silica to the concrete mix even in low replacement will dramatically enhance strength of concrete mixes, increasing the compressive strength by 10% – 20 %.

Silpozz for water proofing: Silpozz has excellent water resistance (impermeability) properties and is used in waterproofing compounds to give amazing results. It reduces the water penetration by as much as 60 %.

Silpozz  for better concrete in marine environment: Adding Silpozz to concrete helps to reduce the chloride ion penetration by as much as 50 % into the structure, thus improving life of the  building.

Silpozz for lower heat of hydration: Adding Silpozz to concrete lowers the heat of hydration by as much as 30 %  and prevents formation of cracks during casting.

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