Particle Packing Approach for Designing the Mortar Phase of Self Compacting Concrete

Abstract

Self Compacting Concrete (SCC) is a tailored concrete mix, strongly dependent on the constituent proportions and the physical characteristics of the constituents. In order to achieve the self compacting concrete, mortar phase plays a vital role as it contributes to the active suspension phase of aggregates. High powder content and optimum fine aggregate is required for the desired flowability and stability of mortar. Hence, for accomplishing a self compacting concrete, the design of paste and mortar phase needs to be carefully proportioned. A positive correlation exists between the flow properties of the concrete and the packing density of the mix. The packing density of the cementitious materials plays a key role in deciding the final strength of concrete. Improved packing offers the benefit of reduction in water demand, reduced permeability, reduction in bleeding and reduced porosity of the transition zone. The objective of this study is to design the mortar phase for a self compacting concrete reinforced with glass fibres by applying the concept of particle packing. Design of paste and mortar phase was done based on particle packing approach using Puntke test. Initially the powder content (cement and slag) was arrived based on Puntke test and the optimum addition of slag was determined with the slag activity index. The super plasticizer dosage was fixed by performing flow studies using Marsh cone test and the fine aggregate content was established by Puntke Test. The selected powder to fine aggregate content established by particle packing method was taken for mini slump studies and further the optimization of glass fibres content is determined. The outcome of the current study exposed the possibility of obtaining a self compacting mortar incorporating glass fibres which in turn useful for designing the self-compacting concrete.