Increasing the durability and lifespan of commonplace building materials could dramatically reduce the environmental impact of the construction sector.
Researchers have used computer simulations of molecular structures to identify the optimum conditions for manufacturing more resilient and long-lasting forms of glass and cement.
While glass and cement would appear to be amongst the most firm and tangible of building materials, they are both susceptible to gradual structural changes as time passes that can severely affect their performance.
In the case of glass, a material which is essentially in a “frozen liquid” state, the passage of time in tandem with temperature variation can cause it to undergo gradual “relaxation” that changes its state.
Over the long term, these imperceptible changes can eventually deform glass components such as windows and digital screens to the point where they are rendered unfit for their original purposes.
While cement differs radically from glass in terms of ostensible physical properties, it possesses a similar molecular structure that makes it susceptible to the same type of structural “relaxation” with the passage of time.
In the case of cement, this change in its physical resilience can result in cracking that undermines the structural integrity of important large-scale structures such as bridges and multi-storey buildings.
A team of researchers from the UCLA Henry Samueli School of Engineering and Applied Science and Universite Pierre et Marie Curie in Paris have used computers to analyze the molecular structures of these materials in order to devise the best manufacturing conditions for increasing their resilience.
Computer simulations of the molecular dynamics of glass enabled scientists to identify the optimum levels of pressure and mix of ingredients for inducing “thermal reversibility” – which refers to the ability of a material to retain its original physical properties even following exposure to changes in temperature over a long period of time.
According to Mathieu Bauchy, assistant professor of civil and environmental engineering, these optimum manufacturing conditions can result in the creation of glass that is almost impervious to aging.
“The key finding is that if you use specific conditions to form glass – the right pressure and the right composition of the material – you can design reversible glasses that show little or no aging over time,” said Bauchy.
Bauchy compares the molecular structure of glass to the framework components comprising the Eiffel Tower, with resilience and rigidity determined to a significant extent by the angles at which beams and crossbeams meet.
Producing more resilient forms of glass and cement entails creating the optimum angles between molecular bonds for achieving structural strength.
Increasing the durability and thus the lifespan of glass and cement could dramatically raise the sustainability of the construction sector, as the production of both these materials consumes copious amounts of energy.
It could also significantly reduce humanity’s overall environmental impact, given the sheer amount of glass and cement that modern societies consume.
According to Columbia University’s Earth Institute, concrete, which has cement as a key ingredient, is society’s second-most consumed substance after water, with three tons of the material consumed on a per capita basis globally each year. The cement and concrete industry alone is responsible for approximately five per cent of the world’s carbon dioxide emissions.
“The smaller the quantity of material we used to rebuild deteriorating structures, the better it is for the environment, said Bauchy.