ABSTRACT
Steel fibre reinforced concrete (SFRC) is being used as a construction material and extensive research work has been carried out in this area during the last three decades. As a result, SFRC is finding wider applications in cement concrete industry. Recently it has been used in marine structures, industrial structures, sewer pipes, highway and airfield pavements, chemical storage tanks etc. SFRC, when used in these structures, may be subjected to aggressive environment containing chloride and sulphate salts. Sulphate salts cause concrete corrosion and chloride salts are responsible for steel corrosion. Therefore, randomly distributed fibres in SFRC are more prone to corrosion by chloride salt.
This investigation has been undertaken to study the resistance of SFRC against chloride salts. For this purpose, two hundred forty cubes of M-20 grade concrete, each of 100mm size, were cast and subsequently saturated in sodium chloride solutions. The chloride concentrations used were 19,38,76 and 152 gm/litre which were varied in multiples of 19 gm/litre ie. approximately equivalent to the sea-water chloride concentration. Simultaneously, thirty reference cubes each of SFRC and conventional concrete having same size were cured in tap-water. The cubes were tested in compression at the age of 14,28,60,120,270 and 540 days. The chloride ion concentrations and pH values were obtained at three different depths of the tested cubes. The results indicate that steel fibres in SFRC are more effective when SFRC had been exposed to lower chloride ion concentration only.
