Construction methodology across India has changed with adoptability to new technologies such as shear wall construction technique and precast technique. In order to meet these construction techniques, the rheodology of the concrete shall meet the requirements.

Types of concrete are classified based on its usage
.• Flow Concrete – Shear Wall Construction method in high rise Building
• Low slum concrete with early concrete setting – Slip form construction
• High early strength concrete  – Precast construction
• Self-Compacting Concrete – Congested reinforcement
• Spray concrete – High early setting concrete
• Roller compacted concrete – Concrete dams.

Concrete admixture will have major role in obtaining required concrete rheology without compromising wet and hardened properties of the concrete.

High Early Strength Concrete – Major breakthrough
Precast Construction system is an upcoming construction technique in India to speed up the process of construction to reduce construction days and early hand over. Precast product resulted from concrete in a reusable moulds and cured in control environment. These precast products are then transported to construction site and lifted into place.

Governing factors in precast concrete
• Low water-cement ratio.
• Medium workability.
• Very high water reducing admixture.
• Need for high early strength for early de-moulding to increase productivity.
• Compatibility with cement replacements.
• Compatibility with 100 per cent crushed sand or manufactured sand.

High Early Strength Concrete (HES):
Strength of concrete required to increase the productivity to accommodate faster construction and thereby reduction in construction cost.

Cementitious content and its type
Type of cement and cement replacement material in high early strength concrete  play very important role in obtaining desired strength.

Fosroc offer Auracast product range to suit current requirements.
Auracast 100 is a low-viscosity, single component PCE-based admixture for low slump concrete that enables obtaining of 50 per cent of the characteristic strength in 24 hours. This makes it an ideal admixture for precast segments such as underground metro rings and precast walls and slabs for buildings.

Auracast 270M is a low-viscosity,, single component PCE-based admixture for normal slump concrete with slump retention and enables obtaining of 50 per cent of the characteristic strength in 24 hours, This makes it ideal for large volume of concreting in precast industries.

Auracast 405 is a low-viscosity, single component PCE-based admixture for flow concrete with slump retention. It enables obtaining 50 per cent of the characteristic strength in 24 hours. This makes it an ideal choice for concrete poured in structures having congested reinforcement and tunnel forming etc.
Applications• Pre-fabricated high rise buildings.• Metro rail construction.• Road and railway bridges.• Precast elements such as barricades for roads and water splash area.• Railway sleepers.

Authored by-
G. Shivaprakash,
Product Segment Managers – Admixture and Surface Treatment
Fosroc Chemicals (India) Limited Bangalore, India
Mob: +91 9611155794,Fax: +91 80 23551510