Scientists are working on new concrete formulations featuring waste materials. 

Researchers from Flinders University, in collaboration with international colleagues, have introduced a sustainable concrete formula capable of mitigating the detrimental alkali-silica reaction (ASR). 

This reaction adversely affects the mechanical properties and durability of concrete, particularly when using recycled aggregates rich in silica content, such as crushed glass sand and coarse recycled concrete aggregate (RCA).

The recent study primarily investigated the efficacy of ground granulated blast furnace slag (GGBS) and fly ash, a by-product of coal combustion, as binder materials. 

These components play a critical role in counteracting the negative impacts of ASR on the concrete's structural integrity. 

While both materials showed promise, fly ash emerged as the more effective agent in reducing ASR expansion, a significant factor in ensuring the longevity and reliability of concrete structures.

A key finding of the research is the formulation's performance when integrating 20 per cent GGBS with 30 per cent fly ash in recycled aggregate concrete containing glass sand. 

This blend exhibited similar compressive and flexural strengths, alongside comparable water absorption rates, to conventional concrete made with natural sand. 

However, it was observed that an increase in GGBS content could lead to diminished strengths and elevated water absorption in the concrete.

“The results of this study point to the significant potential of combining fly ash and GGBS at an optimum ratio to mitigate the ASR effect on recycled aggregate concrete containing crushed glass sand,” says Dr Aliakbar Gholampour, a leading expert in sustainable construction materials at Flinders University.

He says the advancement not only promises to enhance the durability of concrete structures but also aligns with broader environmental sustainability goals.

The technology - potentially useful in applications including road construction, landscaping, and infrastructure projects - could allow industries to significantly reduce greenhouse gas emissions and other pollutants associated with traditional cement production. 

The full study is accessible here.