Tenth International Conference on The Constructed Environment

Abstract

Concrete is the second most used material in the world after water which will continue to increase as the world’s population continues to grow. One of concrete’s most important constituent’s, portland cement (PC), accounts for 5% of the total global CO2 emissions caused by humans. The use of supplementary cementitious materials such as blast furnace slag (BFS), and other sustainable and recycled materials can help diminish this high amount of CO2 emissions. Additionally, the use of variable aggregate sizes can assist with the particle packing, therefore in theory, reducing the amount of cement paste required. This study evaluates and provides the optimal aggregate distribution to reduce cement content needed. In order to test this particle packing theory, five different concrete mixtures were created for comparison. A control mixture was produced to compare against the other four mixtures. The second mixture investigated particle packing of only the cementitious by utilizing 70% BFS and 8% ground calcium carbonate (GCC) as cementitious replacement. A third mixture used a distribution of 50% ASTM C33 grade 57 aggregate and 50% ASTM C33 grade 4 aggregate to create a more densely graded aggregate blend mixture. The fourth mixture used the same aggregate proportions as the third mixture with a reduced cement content. The last mixture combined the second and third mixtures. Compressive strength and permeability were tested to identify the design mixture that yielded the most optimal aggregate distribution. The results are forthcoming and will be included in the paper.