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REFERENCES Thomas M D A: “Optimizing the use of fly ash in concrete”. PCA IS548, Portland Cement Association, Skokie, IL, 2007, pp. 1-24. 2. Du L, Folliard KJ: “Mechanisms of air entrainment in concrete”. Cement and Concrete Research, Vol. 35, No. 8, 2005, pp. 1463–1471. 3. Pedersen K H, Jensen A D, Skjøth-Rasmussen M S et al.: “A review of the interference of carbon containing fly ash with air entrainment in concrete”. Progress in Energy and Combustion Science , Vol. 34, No. 2, 2008, pp. 135–154. 4. Justnes H, Ng S: “Future Challenges for Concrete Admixtures

., Testing the frost resistance of concrete with different cement types - experience from laboratory and practice. Architecture Civil Engineering Environment 2 (2010) 41-51. 12. Giergiczny Z., Baran T., Dziuk D., Ostrowski M., The increase of concrete frost resistance by using cement with air-entraining agent. Cement Wapno Beton 21 (2016) 96-104. 13. Molendowska A., Wawrzeńczyk J., Freeze – thaw resistance of air-entrained high strength concrete. Structure and Environment 9(1) (2017) 25-33. 14. Information on http

Abstract

In this paper we discuss the test results for concretes containing various amounts of ggbs as compared to concretes made with Portland cement. The main objective of these tests is to evaluate the influence of varying air content in such mixtures on the structure and frost resistance of concrete. The authors suggest that the approach presented here allows for a safe design of concrete mixtures in terms of their frost resistance.

The results indicate that concrete can be resistant to surface scaling even at the W/C ratio markedly higher than 0.45. Increased addition of ggbs leads to a decrease in concrete resistance to surface scaling. Proper air entrainment is the fundamental factor for frost-resistant concrete, and the air void system has to be assessed (micropore content A300, spacing factor L¯). The addition of ggbs increases pore diameters, thus, to obtain the appropriate air pore spacing factor, micropore quantities introduced have to be increased.

Abstract

The objective of this investigation was comparing the penetration of chloride ions in ordinary and air-entrained concretes containing a waste material Fluidized Bed Combustion Fly Ash (FBCFA). All concretes were tested with 15% and 30% cement replacement by FBCFA, with the same water-binder ratio of 0.45. Two kinds of fly ash coming from fluid bed combustion in two power plants in Poland have been used.

In this study the rapid chloride permeability test - Nordtest Method BUILD 492 method - was used. The microstructure of the concrete was analyzed on thin polished sections and the measurement of air voids sizes and their distribution, using digital image analysis, was carried on according to PN-EN 480-11:2008.

Obtained results have shown a significant influence of partial cement replacement by FBCFA on the chloride ions movements in concrete. It has been found that this kind of addition reduced considerably the chloride ion penetration. The influence of air entrainment on the chloride diffusion coefficients was also measured and it was shown that application of air-entraining admixture for concretes with FBCFA reduce the chloride diffusion coefficient but it should be used with caution.

References ALBRECHT D., 1968: Belüftung des ruhrwassers am wehr spillenburg. Die Wasserwirtschaft, 11. APTED R. W., NOVAK P., 1973: Some studies of oxygen uptake at weirs. Proc. of the XV Congress, IAHR, Paper B23. AVERY S. T., NOVAK P., 1978: Oxygen transfer at hydraulic structures. J. Hydraulic Div., ASCE, 104 , 11, 1521-1540. BAYLAR A., EMIROGLU M. E., 2002: The effect of sharp-crested weir shape on air entrainment. Canadian J. of Civil Engng., 29 , 3, 375-383. CASTILLO-E. L. G., 2007: Pressures characterization of undeveloped and developed jets in shallow

.S. Department of Transportation Federal Highway Administration, USA, October 1989. 5. Lazniewska-Piekarczyk B: ”The effect of superplasticizers and anti-foaming agents on the air entrainment and properties of the mix of self-compacting concrete”. Article in Cement, Wapno, Beton. May 2009 [Online] https://www.researchgate.net/publication/287164082 [Accessed on 29.1.2019] 6. Łaźniewska-Piekarczyk B, Szwabowski J & Miera P: ”Superplasticizer compatibility problem with innovative air-entraining multicomponent Portland cement”. Proceedings , 14 th International Congress on

Abstract

This research aims to investigate the effect of introducing different mineral admixtures on the mechanical properties of concrete. The research is focused on optimizing the properties of fresh and hardened concrete, looking in particular at how factors such as slump, unit weight, air entrancement, compressive strength, tensile strength, flexural strength and modulus of elasticity are affected by different mineral admixtures in a concrete mix. Different mineral admixtures are used, namely silica fume, limestone and ultra-fine gypsum, and for the tests each mineral admixture replaced 25 % of the cement. The paper also compares the performance of the fresh and hardened properties of concrete.

REFERENCES Ansys Inc. 2014. ANSYS Fluent Version 15.0.7. B entalha C., H abi M. 2015. Numerical simulation of air entrainment for flat-sloped stepped spillway. Journal of Computational Multiphase Flows. Vol. 7. No. 1 p. 33–41. B oes R.M., H ager W.H. 2003. Two-phase flow characteristics of stepped spillways. Journal of Hydraulic Engineering. Vol. 129. No. 9 p. 661–670. B ombardelli F.A., M eireles I., M atos J. 2011. Laboratory measurements and multi-block numerical simulations of the mean flow and turbulence in the non-aerated skimming flow region of

interference of carbon containing fly ash with air entrainment in concrete, Progress in Energy and Combustion Science, 34, 135-154, 2008. 15. A. M. Brandt, Cement based composites - 2nd ed: Materialas, mechanical properties and Performance, Taylor & Francis, UK, 526, 2009. 16. P. Chindaprasirt, C. Chotithanorm, H.T. Cao, V. Sirivivatnanon, Influence of fly ash fineness on the chloride penetration of concrete, Construction and Building Materials 21, 356-361, 2007.

Abstract

The article presents the influence of the suggested operating media on the modification of parameters of cement concrete intended for airfield pavements. Cement concrete contains cement CEM I 42,5, granite grit, fine washed aggregate, water and air entraining as well as plasticizing additive. Analyses included the assessment of changes in mechanical and physical parameters (weight absorbability and water capillary action) of hardened concrete. The observed changes were associated with the internal structure of concrete composite. Based on the obtained results, different influence of the applied operating media on mechanical parameters of hardened concrete was determined.