Study and Development of Self compacting concrete using particle packing approach

Abstract

The major concern with Self-compacting concrete (SCC) is the higher usage of binders even for low and medium resistance concrete (20-35 Mpa) to maintain rheological properties, which results in higher impact on environment and economy. The present research puts forward a simple statistical mix design method for SCC based on particle packing approach and targeted flow properties. To save binders in concrete production aggregates needs to be optimally packed. Therefore, an attempt is made to develop a new particle packing model for multi component angular aggregates which is unique and simple to use and saves extensive laboratory testing and trials. Using proposed particle packing model analytical packing density of blended coarse aggregate (20 mm and 10 mm) and fine aggregate is found, and the results are validated experimentally. Also, guideline for required particle size distribution for blended coarse and fine aggregate is given for optimum packing. The accuracy of the model is at par with the present efficient packing models. To validate the model, SCC mixes are casted by varying size and volume of aggregate, cement content, w/c ratio and paste volume. It is found that slump flow has correlation with other fresh properties of SCC and it depends on excess paste volume available after filling the voids. Therefore, slump flow test alone can be performed at site for speedy determination of suitability of SCC mix for casting concrete. Based on various experimental results and statistical regression model, guideline is prepared for SCC mixes for targeted slump flow and compressive strength. Using particle packing approach about 15% binders can be saved without compromising SCC properties. It was found that for SCC mixes with less paste volume, about 4% fines in total aggregate volume are necessary to make SCC mix cohesive. This Ph.D. thesis will help to design economical SCC mixes for low to medium resistance concrete (20-35 Mpa) with least laboratory trials, so that advantage of SCC over conventional concrete can b