1 International Journal of Research in Science & Technology Volume : 1 | Issue : 9 | October 2014 | ISSN: 2349-0845 IJRST D. Aditya Sai Ram Ch. Surendra Reddy PG Scholar, Department of Civil Engineering, Jogaiah Institute of Technology and Sciences, Palakollu. dasairam102@gmail.com Associate Professor, Department of Civil Engineering, Jogaiah Institute of Technology and Sciences, Palakollu. surendrachirla@gmail.com Experimental Investigations on Influence of Carbon Composite Fibres in Concrete KEYWORDS Carbon fibres, Compressive Strength, Tensile Sterngth ABSTRACT: The use of short pitch-based carbon fibres (0.05% of weight of cement, 0.189 vol. % Concrete), together with a dispersant, chemical agents and silica fume, in concrete with fine and coarse aggregates resulted in a flexural strength increase of 85%, and a flexural toughness increase of 205%, a compressive strength increase of 22%, and a material price increase of 39%. The slump was 4 in at a water/cement ratio of 0.50. The air content was 6%, so the freeze-thaw durability was increased, even in the absence of an air entertainer. The aggregate size had little effect on the above properties. The minimum carbon fiber content was 0.1 vol. %. The optimum fiber length was such that the mean fiber length decreased from 12 mm before mixing to 7 mm after mixing, which used a Hobart mixer. The drying shrinkage was decreased by up to 90%. The electrical resistivity was decreased by up to 83%.To investigate the effect of carbon fibres on M20 concrete. The parameters considered percentage of carbon fibres (0.1,0.5&0.1%) and three aspect ratios (50,75,100).Compressive strength, tensile strength are the two major properties are to be investigated. To investigate influence of carbon fibres on the properties of concrete. To obtain stress-strain characteristics of carbon fibre reinforced concrete. To establish the failure criteria of carbon fibre reinforced concrete under uniaxial and biaxial stress conditions.