This paper presents a study on the mechanical properties and durability of concrete made with a high-volume fly ash blended cement using a coarse fly ash that does not meet the fineness requirement of ASTM C 618. The results were compared with those of the HVFA concrete in which unground fly ash had been added at the concrete mixer. The properties of the fresh concrete determined included the slump air content slump loss stability of air content bleeding and setting time; those of the hardened concrete investigated included the compressive strength flexural- and splitting-tensile strengths Youngâ€™s modulus of elasticity drying shrinkage resistance to abrasion chloride-ion penetration freezing and thawing cycling and to de-icing salt scaling. The results show that except for the resistance of the concrete to the de-icing salt scaling the mechanical properties and the durability of concrete made with this blended cement were superior to the concrete in which the unground fly ash and the cement had been added separately at the mixer. The production of HVFA blended cements therefore offers an effective way for the utilization of coarse fly ashes that do not otherwise meet the fineness requirements of ASTM C 618.
This paper was originally published in Cement and Concrete Research Vol. 31 No. 3 Oct. 2001. It includes a list of tables and figures detailing the results of the studies.
Technical Report Author: M.H. Zhang, Nabil Bouzoubaa, V.M. Malhotra, CANMET Energy Technology Centre, Natural Resources Canada,
This paper presents data from durability studies of concretes containing up to 60% fly ash; studies include carbonation chloride resistance permeability and strength. Data are also presented from a recent construction project in Toronto where high-volume fly ash concrete was used as part of a â€œGreen Building Strategyâ€. Finally the paper presents recent data from studies using ternary blends of cement with high levels of fly ash -e.g. 56%- and small levels of silica fume -3 to 4%- . It is shown that the poor early-age performance that may be associated with high-volume fly ash can be offset by the inclusion of silica fume.
Technical Report Author: M.D.A. Thomas, D.S. Hopkins, Gurinder Girn, Robert Munro, Ernese Muhl
Global urbanization has placed huge demands on the construction industry in terms of the world s material and energy resources. Infrastructure regeneration and rehabilitation and cement and concrete materials have an undeniable part to play in enhancing the quality of human life. If we are to avoid global environmental degradation sustainable development of the cement and concrete industry has to be the foundation for all construction activity in the next millennium.
This approach demands that cementitious materials are manufactured for durability rather than for strength and that pozzolanic and other industrial cementitious byproducts are seen as vital and essential constituents of concrete. However sustainability in the construction industry will remain a pipedream unless design for specified durable service life is the basis for all future construction.
Technical Report Author: R.N. Swamy
This paper presents the results of a study on the mechanical properties and durability of concrete made with high volume fly ash -HVFA- blended cement produced in a cement plant. The test results obtained were compared with those of a control concrete made with a commercially available ASTM Type I cement; the control concrete had a 28-day compressive strength comparable to that of the concrete made with the HVFA blended cement.
The results showed that in order to obtain similar slump and air content to those of the control concrete the use of HVFA blended cement required increased dosages of the superplasticizer and the air-entraining admixture. This resulted in some delay in the initial and final setting times of concrete.
The use of HVFA blended cement resulted in lower compressive and flexural strengths at early ages -before 28 days- and higher mechanical properties after 28 days as compared with those of the control concrete made with ASTM Type I cement. The concrete made with the HVFA blended cement developed a 1-day compressive strength of 13 MPa -compared to 19 MPa for the control concrete- which is considered more than satisfactory for formwork removal.
The use of the HVFA blended cement improved significantly the durability characteristics of the concrete; the only exception was the resistance to the de-icing salt scaling as determined in ASTM C 672 test.
Technical Report Author: Nabil Bouzoubaa, Benoit Fournier, V.M. Malhotra, D.M. Golden
The report explains how high-volume fly ash concrete overcomes the durability and environmental shortfalls of conventional Portland cement concrete. However the decision to use high volume fly ash for the Live/Work Studios -Waterfall Building- was based on aesthetics not on EcoSmart concrete s durability or environmental benefits. The mix design used in this case study is provided in the report. Several conclusions are presented in the report including that fly ash concrete exceeded compressive strength requirements; that costs for fly ash concrete were comparable with those of conventional concrete; and that the structure s service life was increased by increasing concrete durability. The report also contains personal feedback from case study participants.
Case Study Report Author: Michael Neundorf, Roland Haebler, Haebler Construction,