Grantee Research Project Results

Calcined Clays as a Low Emission Cement Substitute

EPA Grant Number: FP917176
Title: Calcined Clays as a Low Emission Cement Substitute
Investigators: Lange, Sarah Taylor
Institution: The University of Texas at Austin
EPA Project Officer: Hahn, Intaek
Project Period: August 1, 2010 through July 31, 2013
Project Amount: $111,000
RFA: STAR Graduate Fellowships (2010) RFA Text | Recipients Lists
Research Category: Fellowship - Science & Technology for Sustainability: Green Engineering/Building/Chemistry/Materials , Academic Fellowships

Objective:

The cement industry is responsible for 3.4 percent of the global anthropogenic carbon dioxide emissions contributing to adverse climate changes. Moreover, the World Health Organization states that 1.5 million people die each year from causes directly attributed to indoor air pollution. My doctoral project aims to use calcined clays as a partial cement replacement in concrete, to reduce the energy demand and carbon dioxide emissions of cement manufacturing while meeting the structural functionality and indoor emissions criteria for use as a green building material.

Synopsis
This project is a comprehensive study that focuses on understanding the effects of using calcined clays as sustainable, green building materials. The developed materials will minimize energy demand and carbon dioxide emissions associated with cement manufacturing. In addition, radon emission, ozone interaction, and mold resistance of the new clay-cement blend will be investigated to assess its effects on indoor air quality.

Approach:

The first phase of my research focuses on identifying inexpensive and abundant chemicals that will reduce the activation energy and duration of clay calcination, necessary for converting clay to display cement-like behavior. Then, concrete samples prepared with calcined clays will be tested to evaluate their structural functionality against ASTM standards. The overall energy demand and carbon dioxide emissions associated with these samples will be quantified and compared with those of current concrete manufacturing. The second phase of my research focuses on the emission characteristics of calcined clay-concrete affecting indoor air quality. In particular, the radon emission, ozone interaction, and mold resistance of the new clay-cement blend will be investigated to assess its effects on indoor air quality.

Expected Results:

This study provides a better understanding of clay-cement materials including: (i) their associated energy demand and carbon dioxide emissions of their manufacturing and transport, (ii) their structural performance and properties, and (iii) their emission characteristics affecting indoor air quality. Preliminary research shows that clay requires half of the activation temperature necessary for limestone cement manufacturing. In addition, some supplementary cement materials decrease material porosity, aiding in both external durability and improved indoor air quality. Studies have demonstrated that some green materials, including clay substances, undergo significant oxidation, creating an indoor ozone sink, reducing the indoor ozone concentration levels. It is expected that the clay-cement will display similar qualities.

Potential to Further Environmental/Human Health Protection
The development of green building materials based on calcined clays will have both environmental and health benefits. First, the environmental benefits will include: (i) the energy and carbon dioxide emission reduction in cement manufacturing and transportation, and (ii) the use of local materials for sustainability. Finally, the health benefits will include: (i) minimization of worker health risks by using less toxic materials, and (ii) improved indoor air quality through use of non-emitting cement mixtures.

Supplemental Keywords:

climate change, supplementary cement materials, pollution, indoor air quality, cement manufacturing, ozone, radon, carbon dioxide, green materials, sustainable building materials, health risks,

Progress and Final Reports:

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.