concrete is the most widely used construction material in the world

Environmental impact of cement production
Concrete is the most common construction material used in the world. Cement is the principal ingredient in concrete. Producing one tonne of cement results in the emission of approximately one tonne of CO2, created by fuel combustion and the calcination of raw materials. Cement manufacturing is a source of greenhouse gas emissions, accounting for approximately 7% to 8% of CO2 globally (1), and approximately 1.8% of CO2 emissions in Canada (2). The cement industry has made significant progress in reducing CO2 emissions through improvements in process and efficiency, but further improvements are limited because CO2 production is inherent to the basic process of calcinating limestone.

Cement and CO2 in the Vancouver region
The cement manufacturing industry in the Greater Vancouver Regional District (GVRD) in British Columbia Canada, currently produces approximately 50% of industrial CO2 emissions, or 13% of the total CO2 emissions in the GVRD. The EcoSmart Concrete Project was initiated to address the issue of greenhouse gas emissions in the Lower Mainland.

EcoSmart™ concrete reduces CO2 & benefits the environment
There is an increasing demand for concrete worldwide, estimated to double within the next 30 years. How can that demand be met without a corresponding increase in greenhouse gases? By using Supplementary Cementing Materials (SCMs) to replace a maximum amount of the cement in concrete, we can reduce energy and resource consumption, reduce CO2 emissions, and lessen the negative environmental impact. There is a further environmental benefit in that most commonly used SCMs (such as fly ash) are waste products and would otherwise end up in landfills.

Global trends in CO2 emissions and potential impact of EcoSmart concrete
Projected increase in cement production over the next decade may produce a significant increase of greenhouse gas emissions. The scenario below shows that if just 30% of cement used globally were replaced with Supplementary Cementing Materials (SCMs), the rise in CO2 emissions from cement production could be reversed.
Cement Required Graph
This scenario shows the percent of Supplementary Cementing Material replacement required to achieve zero percent increase in CO2 production from cement manufacture from 1995 to 2010.
SCM Graph

(1) Mehta, P.K“Role of Pozzolanic & Cementitious By-Products in Sustainable Development of the Concrete Industry”, in Sixth CANMET/ACI/JCI Conference: Fly Ash, Silica Fume, Slag & Natural Pozzolans in Concrete, 1998.

(2) GHG emissions from Portland cement (PC) production as a % of Canada’s total GHG emissions = [ 13.2 Mt PC produced in 2002 ] x [ 1 tonne CO2e / 1 tonne PC ] / [ 731 Mt CO2e produced in Canada in 2002 ] = 1.8%

Calculation based on data from the following sources:
Greenhouse Gas Division, Environment Canada. Canada’s Greenhouse Gas Inventory: 1990-2002. August 2004.
Venta, G.J., Bouzoubaâ, N. and Fournier, B. “Production and Use of Supplementary Cementing Materials in Canada and the Resulting Impact on Greenhouse Gas Emissions Reductions”, Eighth CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete, Supplementary Papers, Las Vegas, U.S.A., pp. 73-87, May 23-29, 2004.
Vagt, Oliver“Cement.” Canadian Minerals Yearbook, 2002.Minerals Sector, Natural Resources Canada. 2002.