- Review examined thirty experimental studies published between 2007 and 2023, evenly divided among cement, sand, and gravel replacement.
- Analysis revealed that replacing Portland cement with waste materials reduces carbon dioxide emissions, embedded energy, and direct material costs by two to forty percent, while substituting fine aggregate sand or coarse gravel achieves reductions ranging from five to one hundred percent per cubic meter.
- Key threshold formulations improved structural performance: substituting five percent of cement with paper slag ash increased compressive strength by 15.22 percent, while replacing fifty percent of sand and eighty percent of gravel with marble waste elevated compressive strength by twenty-eight percent and 39.24 percent, respectively.
- Concrete ranks as the most consumed substance on Earth after water, and the construction sector accounts for approximately thirty-five percent of all carbon dioxide emissions.
- Cement production expands at an annual rate of 2.5 percent, represents the third largest industrial energy consumer, and releases approximately 1,350 million tons of greenhouse gases annually.
Replacing cement with industrial byproducts in concrete can significantly reduce carbon emissions and costs. A review in Discover Civil Engineering found that substituting Portland cement with waste materials can lower emissions by 2% to 40% and cut costs by $0.967 to $19.817 per cubic meter.
The analysis also showed that using waste materials instead of fine aggregate sand or coarse gravel can achieve emissions reductions ranging from 5% to 100% per cubic meter. For instance, replacing 5% of cement with paper slag ash increased compressive strength by 15.22%, while substituting 50% of sand and 80% of gravel with marble waste boosted compressive strength by 28% and 39.24%, respectively.
Concrete is the most consumed substance on Earth after water, and the construction sector is responsible for 35% of global carbon dioxide emissions. Cement production alone releases approximately 1,350 million tons of greenhouse gases annually and consumes more energy than any other material, making this shift crucial for sustainability.78
The review evaluated data from 30 experimental studies conducted between 2007 and 2023, modeling reductions in carbon emissions and embedded energy using established methodologies. The findings underscore the potential for waste materials to mitigate the environmental impact of concrete production while enhancing its performance.
“The review of 30 studies found that substituting 5% of cement with paper slag ash raised compressive strength by 15.22%, while replacing 50% of sand and 80% of gravel with marble waste boosted it by 28% and 39.24%, respectively. Cement production alone releases about 1,350 million tons of greenhouse gases annually.”
Bioengineer.org
