Design and performance of sustainable/green concrete

Abstract

Concrete is the most used construction material in the world. However, the production of one ton of cement, which is the main ingredient of concrete, releases about one ton of carbon dioxide, and consumes natural resources, such as limestone and clay. Furthermore, a concrete structure made of normal concrete can be permeable which expedites the steel reinforcement corrosion process when exposed to severe weather conditions. Therefore, this reduces its durability and service life. Implementing sustainable/green technologies in concrete design and production can solve these problems and extend the structure lifespan. In this thesis, the possibilities of making sustainable/green concrete from locally available materials were investigated. Supplementary cementitious materials, such as ground granulated blast furnace slag (GGBS) and silica fume (SF), were used in order to reduce the cement content and to improve the size distribution and the grading of the particles. Their quantities were determined based on a new mix modeling platform called EMMA program. 130 concrete specimens of 10 different concrete mixes were tested and evaluated to measure the improvement levels in the new concrete. Low air content test results between 1% and 1.4% and higher concrete strength were obtained. These results reflected the improved particles packing of the concrete produced by EMMA program. Mechanical tests showed that the compressive strength of concrete incorporating SF and GGBS improved by 16%. Rapid Chloride Permeability Test (RCPT) showed results as low as 392 coulombs for mixes with supplementary cementitious materials. Microstructural analysis using a Scanning Electron Microscope (SEM) supported the RCPT findings and the mechanicals tests which showed that concrete with supplementary materials has less voids, has a more homogenous integration of ingredients and has an abundance of C-S-H product. EMMA program modeling has been useful to improve particles packing in the concrete. Last, a cost analysis showed that sustainable/green concrete in the UAE can be produced at the same price of the regular concrete.