The hardest thing about concrete just might be the problem of how to make the ubiquitous building material in an environmentally friendly manner. Recent laboratory results at Princeton University indicate that the challenge of making greener concrete may eventually be cracked.
Concrete raises climate-change concerns because manufacturing its primary component, Portland cement, is responsible for as much as 8 percent of human carbon dioxide emissions. Even worse from an environmental standpoint, forecasters predict Portland cement production will double over the next 30 years.
There are possible replacements for Portland cement. One option, called alkali-activated materials, promises to perform the same function and cut cement-related carbon emissions by up to 90 percent. Studies have shown that alkali-activated materials are as strong as Portland cement. But there is relatively little long-term data about the greener cement’s durability-a key question for someone building a structure to last decades or more.
Researchers at Princeton and other institutions have been working to address the lack of information about the new cement replacements. Claire White, an assistant professor of civil and environmental engineering and the Andlinger Centre for Energy and the Environment, said it can be challenging in the lab to simulate accurately the long-term durability of concrete. But the information is critical if industry is to adopt the material.
“One of the reasons that alkali-activated materials are not widely used is a lack of testing standards at a national level,” White said.
“Alkali-activated materials are a new beast, and we need to put a lot of effort into studying their durability,” said Maria Juenger, a professor in the department of civil, architectural and environmental engineering at the University of Texas-Austin.
In an article, in the Journal of the American Ceramic Society, White’s research team describes a novel approach to evaluate the alkali-activated material’s permeability. Permeability is a critical weakness for any cement because chemicals such as carbon dioxide, sulphates or chloride that intrude into a concrete structure can weaken the concrete as well as corrode the steel used as a reinforcement for most modern buildings.
Permeability is an important measure of a cement’s durability, but it is very hard to measure accurately in a lab, White explained. To solve this problem, White’s research team used a method called a beam-bending test, which is not typically used to measure permeability.
The hardest thing about concrete just might be the problem of how to make the ubiquitous building material in an environmentally friendly manner. Recent laboratory results at Princeton University indicate that the challenge of making greener concrete may eventually be cracked.
Concrete raises climate-change concerns because manufacturing its primary component, Portland cement, is responsible for as much as 8 percent of human carbon dioxide emissions. Even worse from an environmental standpoint, forecasters predict Portland cement production will double over the next 30 years.
There are possible replacements for Portland cement. One option, called alkali-activated materials, promises to perform the same function and cut cement-related carbon emissions by up to 90 percent. Studies have shown that alkali-activated materials are as strong as Portland cement. But there is relatively little long-term data about the greener cement’s durability-a key question for someone building a structure to last decades or more.
Researchers at Princeton and other institutions have been working to address the lack of information about the new cement replacements. Claire White, an assistant professor of civil and environmental engineering and the Andlinger Centre for Energy and the Environment, said it can be challenging in the lab to simulate accurately the long-term durability of concrete. But the information is critical if industry is to adopt the material.
“One of the reasons that alkali-activated materials are not widely used is a lack of testing standards at a national level,” White said.
“Alkali-activated materials are a new beast, and we need to put a lot of effort into studying their durability,” said Maria Juenger, a professor in the department of civil, architectural and environmental engineering at the University of Texas-Austin.
In an article, in the Journal of the American Ceramic Society, White’s research team describes a novel approach to evaluate the alkali-activated material’s permeability. Permeability is a critical weakness for any cement because chemicals such as carbon dioxide, sulphates or chloride that intrude into a concrete structure can weaken the concrete as well as corrode the steel used as a reinforcement for most modern buildings.
Permeability is an important measure of a cement’s durability, but it is very hard to measure accurately in a lab, White explained. To solve this problem, White’s research team used a method called a beam-bending test, which is not typically used to measure permeability.
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