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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 12 Abstracts search results
August 1, 1988
D. Perraton, P.C. Aiticin, and D. Vezina
Water, chloride-ion, and air permeability of two series of silica fume and non-silica fume concretes having water-cementitious ratios of 0.4 and 0.5 were studied as well as that of a 0.24 water-cementitious ratio silica fume concrete. Silica fume dosage varied from 5 to 20 percent by weight of cement. The water permeability of concrete samples having water-cementitious ratios lower than 0.5 is so low that they can be considered impervious whether they contain silica fume or not. The chloride-ion impermeability provided by silica fume rivals that of latex for water-cementitious ratios of 0.4 to 0.5 and polymer-impregnated concrete with a 0.24 w/c ratio. The two drying methods used in this research yielded a positive correlation between silica fume dosage and air permeability. Equal variations were observed for values of up to 10 percent, whereas at twenty percent, the increase was markedly sharper. The characterization of concrete permeability is not as simple as it appears. Sample preparation and fluid type can significantly affect the interpretation of the effect of an admixture such as silica fume.
S. L. Marusin
This paper summarizes the results of permeability studies that have been undertaken since 1979. The research used a test procedure developed during the NCHRP Project 12-19A, "Concrete Sealers for Protection of Bridge Structures", which was reprinted in 1981 as NCHRP Report No. 244. This test method utilizes 10 cm concrete cubes, and chloride ion penetration is determined at 4 depths after 21 days exposure to 15 percent NaCl solution. The test results show that lowering of water-cement ratio in portland cement concrete or presence of superplasticizers, polymer admixtures, and silica fumes are able to significantly reduce concrete permeability.
Study of permeability was made using six concrete mixtures ranging in water-to-cementitious material (w-c) ratio from 0.26 to 0.75. Concrete specimens were tested for permeability to water and air, permeability to chloride ions (rapid and long-term), volume of permeable voids, and porosity. Results confirm that permeability is a direct function of w-c ratio. The addition of silica fume results in even greater decreases in permeability than would be anticipated based solely on w-c ratio. A period of initial moist curing of at least seven days is essential for achieving low permeability. Results also indicate that rapid test procedures offer a reasonable alternative to more lengthy and complex conventional permeability tests.
D. J. Janssen
Equipment and procedures for measuring actual permeability of portland cement concrete are presented. The equipment is built from readily available parts and materials and requires only standard laboratory air pressure and vacuum sources. The sample size used is 3 in. (7.5 cm) diameter x 3-1/8 in. (8 cm) long, but other sample sizes could be used. Typical measurements are presented to show repeatability and time required for permeability testing. The equipment has been used for permeabilities as low as 1 x 10-11 cm/sec. Concrete with lower permeability would require equipment modifications and/or longer measurement times.
C. Ozyildirim and W. Halstead
The effects of two pozzolanic admixtures, fly ash and silica fume, and a ground-granulated blast furnace slag on the chloride ion intrusion of concretes prepared with low water-to-cementitious material ratios (0.35 to 0.45) were investigated. Results of the rapid permeability test (AASHTO T 277) showed that the resistance of concrete to the penetration of chloride ions increases significantly as the water-to-cementitious material ratio is decreased for the same proportions of solid ingredients. Most concretes with pozzolans or slag exhibited higher resistance to chloride ion penetration than the control concretes containing portland cement as the cementitious material. Results of the 90-day ponding test (similar to AASHTO T 259), which was conducted with 0.40 w/c concretes only, indicated minimal chloride content at depths below 3/4 in. (19 mm) for all the test concretes. Strength values for all concretes made with the pozzolans and slag at 90 days were in excess of 5000 psi (34.5 MPa), which is satisfactory.
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