Concrete, a durable material with high heat storage capacity, can be used to moderate building temperature swings. Because traditional concrete is one of the most inert building materials, it is generally also a good product from an indoor air quality standpoint, even for chemically sensitive people.

Up to 60% of the cement content used in traditional concrete may be replaceable with a “supplementary cementitious material” (SCM) salvaged from industrial waste (or derived from natural soil or rock), depending on the concrete application, the type and quality of the substitute, and the results of batch testing.

Industrial by-product SCMs include fly ash, a waste product from coal-fired power plants; blast furnace slag, a waste product from steel production; silica fume, a waste product from the silicon metal industry; and rice hull (or husk) ash, which is generated when agricultural rice waste is burned to produce power. Replacing a percentage of the cement in concrete with an SCM reduces energy consumption and carbon dioxide production, reduces solid waste, and can improve concrete strength, performance, and durability.

To minimize potential environmental drawbacks to concrete, the following measures should be taken.

• Reduce concrete waste by recycling crushed concrete for fill material or road base, or grinding it up for aggregate.
• Carefully estimate the amount of concrete required to avoid ordering excess amounts that become waste.
Consider less material-intensive alternatives to poured-in-place concrete, such as insulation-form walls and autoclaved cellular concrete block. Precast concrete is factory-made to order, which, due to controlled production processes, also reduces concrete waste.
• Use insulated shallow foundations in northern climates; consider pier-and-beam foundations instead of slabs on grade.
• Protect aquatic ecosystems by washing forms and equipment where runoff will not contaminate waterways.
• Use the maximum amount of fly ash or other SCM appropriate to the construction application, location and material quality.