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392 results on '"Beushausen, H."'

278. Determination of the chloride diffusion coefficient in mortars with supplementary cementitious materials

Author

Elfmarkova, V., Spiesz, P.R., Brouwers, H.J.H., Bjegovic, D., Beushausen, H., Serdar, M., and Building Materials

Abstract

The Rapid Chloride Migration (RCM) test, described in the guideline NT Build 492, is one of the most commonly applied accelerated test methods in which chlorides penetrate the concrete at high rates due to the applied electrical field. The output result of the test is the chloride diffusion coefficient DRCM. Literature shows that the RCM test development and experience concerns only ordinary Portland cement. Therefore, a validation of this test method is needed also for other types of binders. This study analyzes the application of the RCM test on mortars prepared with different binder blends: ordinary Portland cement (OPC), ground granulated blast – furnace slag (GGBS), fly ash (FA) and silica fume (SF). The diffusion coefficients are obtained by two approaches: the basic RCM test model and the extended model which considers non-linear chloride binding in non-equilibrium. The analyses presented in this study show that the RCM test can be used for the determination of chloride diffusion coefficient in mortars with supplementary cementitious materials, and the accuracy of AgNO3 colourimetric method is sufficient for the determination of the chloride penetration front in these mortars.

Published
2014

281. The South African durability index tests in an international comparison

Author

Beushausen, H and Alexander, M G

Abstract

Over the last decade, an approach to improving the durability of reinforced concrete construction has been developed in South Africa. The durability index test methods applied in this approach are unique to the country. Internationally, similar trends can be observed and a number of test methods for the quality assessment of hardened concrete, particular the cover zone have been developed world-wide. A group of researchers from different parts of the world carried out comparative tests on the quality of concrete cover, applying the most commonly accepted international test methods. The results indicate that the South African oxygen permeability and chloride conductivity test methods are successful in characterising the concrete cover in respect of important deterioration mechanisms. A good correlation exists between results obtained from these index test methods and those obtained from related test procedures applied overseas.

Published
2008

282. Comparative test - Part II - Comparative test of 'Covermeters'

Author

Luco, L. F., Torremt, R., Alexander, M. G., Andrade Perdrix, Carmen, Basheer, M. P. A., Beushausen, H., Fischli, M., Gonçalves, A., Jacobs, F., Kropp, J., Duarte Neves, R., Podvoiskis, J., Polder, Rob, Romer, M., Balayssac, J.-P., Ballim, Y., Baumann, K., Bickley, J., Breysse, D., Brühwiler, E., Geiker, M., Hooton, D., Moro, F., Morotti, A., Nilsson, L., and Wasserman, I.

Abstract

The comparative test that deals with the NDT assessment of the actual cover depth to reinforcement in new structures, using commercially available covermeters was discussed. The capability of different covermeters to assess the cover to reinforcement was checked by using them in different environmental conditions. The comparative test proved that all instruments are capable to measure with 100% success the depth of the concrete cover within an accuracy of ±10%. The assessment of the cover depth was not significantly affected by the temperature and moisture conditions.

Published
2005

287. Effect Of Chemical Admixtures On Water Penetration Of Concrete

Author

Bjegović, D, Beushausen, H, Serdar, M, Hassani Esgandani, M, Vessalas, K, Baweja, D, Schmidt, Z, Bjegović, D, Beushausen, H, Serdar, M, Hassani Esgandani, M, Vessalas, K, Baweja, D, and Schmidt, Z

Abstract

Durability of concrete is in part determined by its resistance to the penetration of deleterious substances entering as a liquid or gas that is considered to be a function of its permeation capacity. Permeation capacity is controlled by the connectivity of pores that exist in the cementitious matrix and paste-aggregate boundaries. The presence of chemical admixtures in a mixture can greatly reduce the permeation capacity of hardened concrete by several orders of magnitude. Permeability-reducing admixtures are effective in blocking capillary pores by making them hydrophobic as well as depositing pore-blocking products into the pores. This paper presents an experimental study into the effectiveness of using permeabilityreducing admixtures including hydrophobic pore blockers and crystalline self-sealers. Concretes with increasing w/c ratios of 0.4, 0.5 and 0.6 have been investigated. The effect of admixtures on water penetration has been assessed through monitoring the changes in mass transport mechanisms. In addition to the available standard test methods, the coefficient of permeability of water has been directly determined using a specially developed test method described in this paper. Results indicate that permeability-reducing admixtures can reduce the water penetration of concrete significantly if used correctly and if the design intent is defined.

Published
2014

289. Bond

Author

Silfwerbrand, Johan, Beushausen, H, Courard, Luc, Silfwerbrand, Johan, Beushausen, H, and Courard, Luc

Abstract

Chapter 4. QC 20120130

Published
2011

299. Editorial

Author

Alexander, M., primary, Beushausen, H., additional, Dehn, F., additional, and Moyo, P., additional

Published
2009
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