Article: Reducing the Massive Carbon Impact of Concrete

Recently, working with ASDRP Fremont, Cemex, and Fortera USA, I've been working on replacing cement powder (which creates lots of carbon emissions in production) with other materials, called SCMs (Supplementary Cementitious Materials). These other materials can be anything from Fly Ash (from coal combustion) to Coconut Shell Ash (the one I'm using). The abstract is below:

Abstract

With Portland concrete (OPC) use as a construction material being more and more prevalent, especially in the developing world where building new infrastructure is essential for the economic and social growth of those populations, the accompanying carbon dioxide releases from concrete production are also a growing issue. Numerous industrial and agricultural waste products, called Supplementary Cementitious Materials (SCMs), have been introduced to concrete to replace it by weight and enhance its properties, thus reducing cement production. But, with the reduction of coal burning (with fly ash as byproduct), and slag production projected to stay close to even, these common SCMs won’t be enough to supply the developing world’s concrete demand. Therefore, other potential SCMs, such as Coconut Shell Ash (CSA), must be characterized to determine potential replacement SCMs.

In this paper, a series of industry standard ASTM tests were performed on samples of concrete made with powdered CSA additions ranging from 0% to 35% weight replacement. These tests were performed multiple times over a period of 56 days. The resulting flow, strength, shrinkage and compression data was analyzed to determine the effectiveness of CSA as a cement replacement compared to other industry SCMs such fly ash and slag and other agricultural SCMs such as Rice Husk Ash.