Cement manufacturing creates a surprising amount of greenhouse gas emissions, accounting for eight per cent of global carbon dioxide.
The global cement industry produces four billion tonnes of cement annually with five billion tonnes expected in 30 years.
The industry is vital. Cement is the most used construction material on the planet with 90 per cent of construction projects using the product.
According to the Cement Association of Canada the industry plans to reduce emissions by 2030 with the target of net zero emissions by 2050.
The industry uses waste materials containing calcium, silica, aluminum and iron to replace raw materials such as limestone and can use slag, fly ash, limestone and gypsum as clinker.
The Portland cement made in Canada reduces emissions by 10 per cent and with blended PLC cement can cut emissions by 30 per cent.
Using substitutes for limestone involves obstacles.
Government buys half the cement in Canada but does not require low carbon cement in tenders.
Not having stable supplies of recycled materials to use for clinker presents a concern.
Four cement companies in Canada are experimenting with carbon capture storage tactics. One uses CO2 from cement manufacturing to create a slag that can be sold as biofuels or for animal feed.
A Halifax operation has an emissions reducing system used in 60 concrete plants. This technology injects waste carbon dioxide from industrial operations into concrete, making the cement greener and stronger.
Solidia Technologies of Texas uses Portland Cement with less limestone at lower temperatures to reduce emissions by 70 per cent and using 60 per cent less water.
Blue Planet Systems of California uses carbon dioxide and waste calcium materials to replace limestone.
Fifty to 60 per cent of emissions occur while the limestone is broken down by heat.
This process stores carbon dioxide as well as creating stronger end use products.
Carbonized concrete bridges can last 80 years compared to 40 to 50 years for regular cement.
Carbon concrete fibre replacement builds a stronger product but the cost is about 20 times that of reinforced concrete
The main issue seems the lack of waste materials to replace limestone.
Thousands of tonnes of concrete products are dumped in landfills every year. That waste could be used in cement production.
Ron Walter can be reached at ronjoy@sasktel.net
The views and opinions expressed in this article are those of the author, and do not necessarily reflect the position of this publication.
