Evaluating In-situ Testing Properties of New Alternative Cementing
Use of fly ash (FA) in concrete started in United States in early 1930’s. Standardized FA (SFA) by Canadian Standard Association (CSA) is frequently used as partial replacement of cement in manufacturing binary or ternary concrete mixtures. In addition to economic and ecological benefits, use of FA in concrete (a) improves workability (due to increased paste volume and spherical form of particles), (b) reduces heat of hydration, permeability, segregation, and bleeding (by providing greater fines volume and lower water content), (c) reduces alkali-silica reaction (ASR) expansion (due to the capacity of FA to fix alkalis presented in interstitial solution), (d) enhances sulfate resistance, strength (FA exhibits very little cementing value at early age due to slow pozzolanic reaction of FA; however it contributes considerably to strength at later age), and durability.
Suitable FA is not always available near construction site, and transportation and storage costs may nullify any cost advantage (can reach 40% of total cost). The SFA is only available in provinces where electricity is primarily produced from coal-fired powers. Out of these provinces, as in Quebec where 96% of electricity generated hydraulically, the cement factories must import the SFA from other places such as Ontario, Maritimes region, or United States.
Kruger Energy has built and commissioned a 23-MW biomass cogeneration plant at Kruger paper mill in Brompton (Québec) in 2007. The combustion of the residues of biomass generates 70 tons/day of FA. This ash was initially hided in earth. The use of Kruger FA (KFA), as an alternative to SFA, represents a very promising solution for ecological concrete design. This can solve the lack of sources for the SFA.
The field validation is demanded for the acceptance of any new cementing materials to be used as a replacement of Portland cement. This is very important step towards standardization of any new product in the construction industry. The field study will make it possible to evaluate the behavior of concrete in service, to offer a technological window, and to give recommendations to the potential users of the construction industry. The ultimate objective is to ensure adequate lifespan for the infrastructures manufactured with the new materials as in our study is the Kruger Fly Ash (KFA).
