Preventing concrete bridges from falling apart

December 19, 2018, Springer

Extremes of temperature, rain, exposure to corrosive substances—all of these environmental factors contribute to the degradation of concrete. Specifically, a gas present in our environment, called hydrogen sulphide, turns into sulphuric acid, a corrosive substance, when combined with rainwater.

In a new study published in EPJ B, Matthew Lasich from Mangosuthu University of Technology, Durban, South Africa, examines the adverse consequences of the adsorption of natural gas constituents found in our environment—and mixtures of several such gases -into one of the materials that make up concrete: hydrate. Lasich found that the preservation of concrete infrastructure from the corrosive effects would require a pre-treatment targeting the adsorption sites in cement hydrate, where the majority of hydrogen sulphide molecules become attached. However, this approach could prove difficult because of their wide distribution.

What makes concrete vulnerable to natural gas adsorption is its porous nature. Its structure is made up of a cement matrix binding together aggregates of particles of sand. In this study, the authors perform a nanoscale analysis based on Monte Carlo simulation to mimic the migration of gas molecules into the cement hydrate structure.

They first recorded the adsorption level across various temperatures for methane, ethane, ethene, and ethyne to determine the uptake of each gas species in cement hydrate. This allowed them to study the effect of molecular size and molecular shape on the sorption of gases in cement hydrate. They then performed a similar analysis for natural gas constituents including nitrogen, , and, most importantly, hydrogen sulphide.

Their simulations suggest that a specific combination of molecular size and surface area is required for good uptake into cement hydrate. While adsorbed most favourably of all gases considered in this study, ethyne adsorbed more favourably than methane, despite being a 'heavier' molecule, because its molecular shape lent itself better to the task.

Explore further: Ahard look at polymers in cement mix

More information: Matthew Lasich, Sorption of natural gas in cement hydrate by Monte Carlo simulation, The European Physical Journal B (2018). DOI: 10.1140/epjb/e2018-90339-6

Related Stories

Ahard look at polymers in cement mix

June 25, 2018

Modelling how superplasticizers can reduce water proportions in cement mixtures may help develop more efficient superplasticizers, as well as enhance concrete performance, shows the first comprehensive study conducted by ...

Making cement sustainable

October 17, 2018

Cement production accounts for up to nine percent of global anthropogenic carbon dioxide emissions, according to the World Business Council for Sustainable Development. Sabbie Miller, assistant professor in the Department ...

Recommended for you

Technology near for real-time TV political fact checks

January 18, 2019

A Duke University team expects to have a product available for election year that will allow television networks to offer real-time fact checks onscreen when a politician makes a questionable claim during a speech or debate.

Privacy becomes a selling point at tech show

January 7, 2019

Apple is not among the exhibitors at the 2019 Consumer Electronics Show, but that didn't prevent the iPhone maker from sending a message to attendees on a large billboard.

China's Huawei unveils chip for global big data market

January 7, 2019

Huawei Technologies Ltd. showed off a new processor chip for data centers and cloud computing Monday, expanding into new and growing markets despite Western warnings the company might be a security risk.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.