New Concrete Production Craft - Slag Instead of Cement

Slag is also called granulated blast furnace slag which is glassy substance before crystallization when slag in blast furnace cools down and mainly contains calcium oxide, silicon oxide and alumina. Slag has high potential activity and can generate a hydraulic cementitious materials combining with water by the force of intensification agent.

Slag can add up into concrete instead of equal cement to improve new mixed concrete working feature. According to different using requirements, slag powder can replace cement by 30/70%, and thus it can reduce cost by 15-30 RMB per cubic meter of concrete which other external mixture cannot reach. Additionally, due to lower moisture requirement f slag powder than cement, added slag powder can reduce concrete water-binder ratio and concrete secretion water, increase flexibility, raise workability and pumpability so as to keep excellent working performance.

Due to equal replacement of 30-70% cement, exothermic cement hydration can be reduced and the total hydration heat will be reduced so as to lower rising concrete temperature. It can avoid concrete crack because of rapidly rising concrete temperature.

With the fixed cement water ratio, this replacement can lower the early concrete strength. The water requirement of slag powder is lower than that of cement, so in fact the cement water ratio can be decreased and under the same slump early concrete strength will not decrease. In actual structure, due to rising inner temperature cement strength will decrease, but after slag powder added, the rising temperature will be beneficial for concrete strength: higher temperature, higher concrete strength. Therefore, the early strength in actual structure can be raised, and later strength will increase faster than that of pure cement concrete, especially concrete strength in 60 days, 90 days or one year will have greater growth.

Added slag powder can reduce cement using amount and decrease inner factors that lead corrosion. On the other hand, slag powder has finer granularity than cement and it can spread evenly into cement paste, after hydration particles are filled in cement paste gap to improve concrete pore structure and gradually decrease concrete permeability to efficiently inhibit alkali-aggregate reaction, raise sulfate resistance feature and enhance anti-seawater corrosion. To sum up, added slag powder improves ability of anti-chemical corrosion and enhances concrete durability.