High Strength Concrete Materials & Economical Benefits of Using

Abstract

The advancement of materials technology has led to production of higher grades of concrete strength. The application of High strength concrete “HSC” in civil engineering structures has increased significantly, with economy, superior strength, increased stiffness and greater durability being the principal reasons for its popularity. Beside the better quality for the basic material, production of HSC requires additional special materials to be used such as: silica fume and superplasticizer and extra quality control procedures. For many applications, the benefits gained by using HSC concrete are more than the additional cost of the special materials and extra quality control needed to produce them. The biggest advantages of HSC that makes its use attractive in high rise construction are the larger strength / unit cost, strength / unit volume, strength /unit weight and stiffness/unit cost ratios compared to normal strength concrete.

In this research, HSC special materials and their mechanism of work, HSC special production techniques, properties of HSC and the related mix design procedures and proportions have been discussed. Also, the direct technical and economical benefits of using HSC in the structural members of buildings have been evaluated. Structural analysis and design has been performed to determine the required sizes of sections and /or the required reinforcement, for the members of structural building. The Percentage reduction in section- sizes of members and the gain in floors lettable space attained by using higher grades of concrete alternatives are estimated. Comparative cost assessment was made using different concrete strength alternatives 20, 60 and 100MPa. This includes; cost analysis, price estimates and quantity calculation for both concrete materials and workmanship.

According to the results of the evaluation made, The maximum reduction in section- size attained by the use of higher strength concrete, occurs in the “Axial Short” columns (reaches to [62%] for f´c 60 and [76%] for f´c 100). In columns of a framed building, the reduction in section- size will be greater in “Internal” columns and the maximum reduction in section- size will occurs at lower storeys. Also, the use of higher strength concrete has increase the floors lettable space especially at the lower storeys of the frame building (It reaches at ground floor to [3.6%] for f´c 60 and [4.5%] for f´c 100). Comparative cost assessments made for the use of HSC in the different structural members showed that, a greater saving in direct cost can be attained by the use of higher strength concretes in “Axial Short” columns, lesser savings were detected in the columns of a frame building and almost negligible saving and sometimes increased cost in beams.