Disadvantages Of Self Compacting Concrete

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Abstract – Concrete occupies unique position among the modern construction materials, Concrete is a material used in building construction, consisting of a hard, chemically inert particulate substance, known as a aggregate (usually made for different types of sand and gravel), that is bond by cement and water.Self – compacting concrete (SCC) is a high – performance concrete that can flow under its own weight to completely fill the form work and self consolidates without any mechanical vibration. Such concrete an accelerate the placement, reduce the labor requirements needed for consolidation, finishing and eliminate environmental pollution. The so called first generation SCC is used mainly for repair application and for casting concrete in …show more content…

The proto type performed satisfactorily with regard to drying and hardening shrinkage, heat of hydration, denseness after hardening, and other properties. This concrete was named “High Performance Concrete” and was defined as follows at the three stages of concrete:
1. Fresh : Self – Compactable.
2. Early age : Avoidance of initial defects
3. After hardening: Protection against external factors.
“High Performance Concrete” was defined as a concrete with high durability due to a low water-cement ratio by professor Aitcin et al (Gangneetal 1989). Since then, the term high performance concrete has been used around world to refer to high durability concrete. Therefore, H.Okamura and M.Ouchi, the authors, of an invited paper on SCC for JACT 2003 have changed the term for the proposed concrete, for their work, to “Self – compacting High performance Concrete”.

1.4 MECHANICAL CHARACTERSTICS:
Characteristic compressive strength at 28 days shall be 25 – 60 Mpa.
Early age compressive strength shall be 5 – 20 Mpa at 12 – 15 hours (Equivalent age at200 C)
“Normal” creep and shrinkage
1.5 …show more content…

The job of SP is to impart a high degree of flow ability and deformability, however the high dosages generally associate with SCC can lead to a high degree of segregation. Conplast SP 430 is utilized in this project, which is a product of FOSROC Company having a specific gravity of 1.222. Super plasticizer is a chemical compound used to increase the workability without adding more water i.e. spreads the given water in the concrete throughout the concrete mix resulting to form a uniform mix. SP improves better surface expose of aggregates to the cement gel. Super plasticizer acts as a lubricant among the materials. Generally in order to increase the workability the water content is to be increased provided a corresponding quantity of cement is

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