Abrasion and erosion resistant concrete

Concrete is among the principal dam construction material and with changing times there has been huge demands for the enhanced properties of concrete especially in high strength and high performance, low heat of hydration, cracking resistance, and abrasion and cavitation resistance etc. The hydraulic structures like spillway, stilling basin, tunnels etc are subjected to high velocities leading to heavy abrasion and cavitation erosion due to silt laden water. Damages have been found to occur in spill ways, invert of diversion tunnel, flushing tunnel and outlet structures etc. ranging from few centimeters to meters. Such damage has been observed in most of the dams in India and even in advanced countries and has been an area of concern for engineering fraternity. In order to improve the performance of concrete to resist abrasion and erosion, a high strength and high abrasion and erosion resistant concrete containing super plasticizer and silica fume are developed and are in use in most of Dam projects.

Teesta III hydroelectric project (6×200 MW) is a run of the river scheme and is located on Teesta River just 400 m downstream of confluence of Lachen chu and Lachung chu, the two limbs of Teesta. The chute spillway glacis, diversion tunnel and flushing tunnel shall be negotiating very high velocity and therefore high performance concrete (HPC) has been used in these works. The high performance concrete was designed at the project and the laboratory program was undertaken for mix design trials and evaluation of the abrasion resistance of concrete mixes. Since the aggregates were potentially alkali reactive, PPC cement (fly ash based) was used for the job. This paper summarizes the details of trial concrete mixes and evaluation of their erosion resistant characteristics.