Optimization of Cement Paste By Polycarboxylic Ether Based Superplasticizer to Achieve ultra High Performance Concrete

Abstract

Reactive powder concrete is an emerging technology that gives a new dimension to the term “High performance concrete”. It has a lot of potential in construction due to its excellent mechanical and durability properties as compared to the conventional high performance concrete, and it can also substitute steel in some applications. Reactive powder concrete is based on the implementation of some basic principles to achieve increased uniformity, high workability, high packing density, improved microstructure and high ductility. Reactive powder concrete has a very packed microstructure, which provides an additional benefit of water resistance and durability features. It can be a good substitute for industrial and nuclear waste storage facilities. A comparison of the various mechanical and durability properties of Reactive powder concrete and high performance concrete indicates that Reactive powder concrete have good compressive and flexural strength and a decreased permeability. In High performance concrete the maximum compressive strength range is 120-150 MPa or so. However, at such a level of strength, the coarse aggregate becomes the weakest link in concrete. If we want to achieve a compressive strength more than high performance concrete the way is to eliminate the coarse aggregates and achieve uniformity in the mix. This theory has been in use in modern technology which is called as reactive powder concrete. It is a special concrete in which microstructure is optimized by precise gradation of all particles in the mix to get maximum packing density. It uses the pozzolanic properties of highly refined silica fume to obtain highest strength hydrates. Reactive powder concrete includes cement, sand, quartz powder, steel aggregates and silica fume, steel fibres and a superplasticizer. The superplasticizers, used at its optimal dosage, decrease the water to cement ratio and improves the workability of the concrete. A packed matrix is achieved by modifying the granular packing of the dry fine powders. This compactness gives reactive powder concrete, ultra-high strength and durability. Reactive powder concretes have compressive strengths from 200 MPa to 810 Mpa. Reactive powder concrete with trade name ‘DUCTAL’ was first developed in France by researchers in the early 1990s at Bouygues, laboratory in France. The world’s first Reactive powder concrete structure, the Sherbrooke Bridge in Canada, was constructed in July 1997.