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Supplementary Cementicious Materials (SCMs). The cement industry is working to reduce the amount of CO2 emissions in cement production. It's also lowering cement's carbon footprint by using supplementary cementicious materials (SCMs), which replace a portion of cement in a concrete mix.

Contractors have been getting two popular SCMs — fly ash and blast slag — in their mixes for years. Research continues in the industry in regards to perfecting these mixes and integrating new sources of SCMs. Concrete contractors often work closely with their ready mix suppliers to test mix designs taking SCM replacement percentages higher and higher.

Other SCMs being used and tested in the industry include silica fume and fine glass powder, a by-product of the retroreflectivity glass ball industry that acts a lot like a fly ash. There's also work out there on replacing a portion of cement with ground limestone. Normal practice in the industry uses replacement up to 5 percent, but some manufacturers are looking to boost replacement levels up to 10 percent.

Recycling. There are several roads to travel in regards to recycling and concrete. Industry sources estimate that 5 percent of all ready mix is returned to the plant. This extra concrete can be used to form landscape blocks, paving at the plant or allowed to harden and then demolished into Crushed Concrete Aggregate (CCA) for use as aggregate back into a mix. This practice keeps material out of a landfill and saves suppliers money they would otherwise spend on virgin aggregate.

Another practice involves ready mix plants separating the returned concrete, basically taking apart the ingredients in a concrete mix with a reclaimer. They also have water recycling programs in use that allow them to reuse wash water.