Introduction Of High Early Strength Concrete
The ingredients of high-early-strength concrete alias fast track concrete contain ordinary concrete components, special admixtures, and specific concreting practices. The high-early-strength concrete. It achieves its specified strength at an early age in respect of ordinary concrete.
The required time ranges from a few hours to several days throughout which the concrete attains the specified strength. The application of high-early-strength concrete is found for fast form reuse, precast concrete for quick production of constituents, high-speed cast-in-place construction, cold-weather construction, quick repair of pavements to minimize traffic downtime, and fast-track paving.
Production Of High-Early-Strength Concrete
The following strategies are used for the production of the high early strength concrete. The choice of the high early strength production strategy is dependent on the time throughout which the concrete can obtain specified strength:
Type III Portland Cement
With reference to normal cement or Type I cement, Type III or high-early-strength cement is a sort of Portland cement that counteracts instantly. The high-early-strength cement attains around seventy percent of its 28-day strength in three days. The initial set of concrete formed with Type III cement is within 45 minutes, and the final set is nearly 6 hours.
High Cement Content
High early strength concrete can also be formed with the growth in cement content (400 to 600 kg/m3).
Low Water-cementing Materials Ratio
The cutback of water to cementing material that varies from 0.20 to 0.45 by mass can also develop high-early-strength concrete. To form high-early-strength concrete, water to cement material ratio should remain 0.32 to 0.42 while the application of w/cm of 0.20 can develop very-high-early-strength concrete.
ALSO READ :
Greater Freshly Mixed Concrete Temperature
When the temperature of freshly mixed concrete is raised, hydration of cement also enhances. Therefore, the growth of newly mixed concrete temperature would enhance the process of strength development in concrete, and consequently high early strength concrete is produced.
Accelerating admixtures are also useful for developing high-early-strength concrete. As for instance, calcium chloride standardized by (ASTM D 98), is an accelerating admixture that can form high early strength concrete. The accelerating admixture enhances the rate of hydration of concrete as well as early strength development of concrete.
Additional Cementitious Materials
The application of additional cementitious material in concrete also develops high-early-strength concrete. By integrating the ground granulated blast furnace slag and higher curing temperature, formation of high early strength development of concrete is increased.
Steam or Autoclave Curing
The steam or autoclave curing is another useful method for developing high-early-strength concrete. The concrete compressive strength is obtained under autoclave in 24 hours is equal to concrete compressive strength that is attained in 28 days under normal curing conditions.
The concrete under autoclave curing contains superior sulfate resistance strength, and lower drying shrinkage as compared to concrete under normal curing conditions, apart from the elimination of effloresce.
Insulation to Retain Heat of Hydration
The application of insulation to capture heat in fresh concrete is another useful method to develop high-early-strength concrete.