Nanospan’s Spanocrete® Reduces Cement & Curing Time in Fly Ash Bricks

Hyderabad-based Ecotec Industries is a leading manufacturer of fly ash bricks and cement concrete blocks in South India under the trademark NUBRIK. Their products are known for their consistency and quality. Ecotec was earlier owned by renowned cement manufacturer Ultratech. This is a case study of Nanospan’s Spanocrete® 8020 (hereon called Spanocrete®) deployment at Ecotech.

Fly ash bricks are eco-friendly because they are primarily made from fly ash, a coal combustion product. The fly ash content in fly ash bricks typically ranges from 50–80% and the remaining ingredients are sand or stone dust and OPC/lime+gypsum.

High compressive strength of fly ash bricks

Increasingly, the fly ash bricks are emerging as the sustainable and superior alternatives to red bricks. They are becoming the backbone of load-bearing structures that stand tall against heavy loads without undergoing structural distortions. The characteristic property of fly ash bricks is its compressive strength. In general, the compressive strength of fly ash bricks ranges from 75-100 kg/cm2.

However, using fly ash in concrete does come with potential problems. Substituting fly ash for Portland cement in a concrete mixture leads to longer drying and curing times. When used in cold climates, mixtures with high levels of fly ash can also encounter issues with slow strength development and wastage due to cracks. As a regular practice, fly ash bricks are cured for 7-14 days to attain the required strength. The delay in the initial setting and curing time affects the production capacity and requires additional capex for facility expansion to meet the target.

Spanocrete® as a solution

Spanocrete® is a graphene-based additive which mitigates the problems that arise due to fly ash. It activates the fly ash to achieve its binding property and improves the hydration property in the concrete during its initial reaction phase, with 20-30% lesser cement. The curing cycle can be reduced to 3-7 days instead of 7-14 days, since 100% compressive strength can be achieved in 7 days.

Spanocrete speeds up the production of fly ash bricks by improving the initial setting time and reducing the curing time. The early strength property helps to reduce the time and labor required for the production. The lesser cement use brings down costs and carbon footprint. Spanocrete® also brings low water permeability, low water usage, corrosion proofing and shrinkage crack proofing inbuilt into the concrete.

Benefits realized with Spanocrete®

Spanocrete® has reduced 30% of Portland Cement without any compromise in the strength. The bricks were shipped in 7 days, and the manufacturer now has the potential to increase his sales by 100%, without any capital investment or facility expansion. The overall material cost is reduced by 10%, leading to higher profit margins.

Spanocrete® Dosage: 0.2% of total cementitious materials (by weight)

Test result

The Spanocrete trial was conducted at the manufacturing facility in the batching process. The dosage of Spanocrete® was 0.2% of the total cementitious materials. 30% cement was reduced with the introduction of Spanocrete® into the mix and 5 kg gypsum was eliminated. The 7-day compressive strength with Spanocrete® was the same as the 28-day strength with the earlier regular mix design.

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