Rational Mix Design Approach for High Strength Concrete Using Sand with very High Fineness Modulus

Problem statement: Production of concrete is always deal with inconsistency. Sources of variation like materials from different geographical basis, mix design method, fineness of aggregates and so on will attribute to different level of achievement of the concrete. Even though researcher had verified that higher fineness modulus of sand would yield better performance for the concrete, but so far there have been scarce amount of paper reported on the mix design method adopting high fineness modulus of sand. Approach: This study discussed the revolution of design mix proportion towards achieving high strength with considerably cement content using local availably constituent materials. A total of 15 mixes was casted till to the high strength at more than 65 MPa was achieved. The compressive strength and workability of each mixes were presented. The method of mixture proportioning was begun with British Department Of Environment (DOE) method. Then, rational design method of achieving high strength concrete was developed. Results: At the end of experimental program, it was found that DOE method was not suitable to apply in designing high strength concrete. 12% was the optimum level of replacement of the total binder content by silica fume. Further increase of total binder content without adjustment to the amount of aggregate content has decreased the strength achievement of the concrete. Very coarse fine aggregate with fineness modulus 3.98 increased the compressive strength of the concrete in large extent. The increased of superplasticiser from 2.0% to 2.5% has decreased the compressive strength of the concrete. Conclusion: The rational mix design approach was developed. A Grade 70 concrete can be produced with moderate level of cement content by this approach.