Investigations on the Flexural Behavior of Reinforced Concrete Beams Containing Supplementary Cementitious Materials

Abstract

It is now established that the incorporation of industrial byproducts, such as fly ash (FA), ground granulated blast furnace slag (GGBFS) and silica fume (SF), in concrete mixtures as partial cement replacement materials (CRMs) significantly enhances the durability related properties on concrete, besides improving its mechanical properties. Such concretes are termed High Performance Concretes (HPCs). In HPC mixtures, it is possible to have low water cement ratio (W/C) with reduced cement content by judicious choice of mineral and chemical admixtures. The assessment of the flexural behavior of reinforced HPC beams is a subject of ongoing research. Standards and codes of practice differ in the definition of compressive stress block parameters of reinforced HPC beams. Hence, investigations were undertaken at the Structural Engineering Research Centre (SERC), Chennai, to investigate the behavior of reinforced HPC beams under flexural loading. The beam specimens for the test program were designed as under reinforced, balanced and over reinforced sections as per the guidelines given in the Indian code of practice for reinforced concrete, IS:456-1978. The influence of supplementary cementitious materials (SCMs) used as cement replacement materials (CRMs), viz., fly ash (25% as CRM) and GGBFS (40% as CRM), on the flexural behavior of reinforced HPC beams was studied. The paper presents the details of the investigations and discusses the results obtained.