18-10-2014, 04:30 PM
Abstracts: The major Infrastructure projects like expressway, power project, tall structures, marine structure etc. Needs high strength concrete. This project is about high strength concrete having addition of chemical admixture such as super plasticizer and mineral admixture as silica fume and fly ash in different proportion and number of tests are done after 7 & 28 days of casting and average strength is measured. Material properties of Fly ash, cement aggregates, sand were found out for mix design purpose. Standard testing procedures were carried out. Generally water reducing admixtures i.e. super plasticizers are used to produce high strength concrete. Pozzolonic materials i.e. fly ash and silica fumes were used in order to produce high strength concrete. We cast 10 batches with different proportion of silica fume, fly ash and cement and their compressive strength after 7 days and 28 days are measured among these highest compressive strength achieved in batch-7 having proportion of 10% silica fume and 10% fly ash which are 45.55 MPa at 7th day and 58.22 MPa at 28th day. As shown in graph with increase in proportion of silica fume till saturation point the compressive strength of concrete cubes increases simultaneously. Further increases the silica fume the compressive strength of concrete cubes are decreases simultaneously. After testing the cubes we found that with 10% replace of silica fume higher compressive strength can be achieved. So permissible replace of silica fume is about 10%, further increase in silica fume decreases in compressive strength. As total replacement of cementious materials by 25% given highest strength among these proportions. The strength of concrete decreases with increase of fly ash content at early age stage.