Durability Study Partially Saturated Fly Ash Blended Cement Concrete

Authors: N. Shafiq, M. F. Nuruddin, S. C. Chin

Abstract:

This paper presents the experimental results of the investigation of various properties related to the durability and longterm performance of mortars made of Fly Ash blended cement, FA and Ordinary Portland cement, OPC. The properties that were investigated in an experimental program include; equilibration of specimen in different relative humidity, determination of total porosity, compressive strength, chloride permeability index, and electrical resistivity. Fly Ash blended cement mortar specimens exhibited 10% to 15% lower porosity when measured at equilibrium conditions in different relative humidities as compared to the specimens made of OPC mortar, which resulted in 6% to 8% higher compressive strength of FA blended cement mortar specimens. The effects of ambient relative humidity during sample equilibration on porosity and strength development were also studied. For specimens equilibrated in higher relative humidity conditions, such as 75%, the total porosity of different mortar specimens was between 35% to 50% less than the porosity of samples equilibrated in 12% relative humidity, consequently leading to higher compressive strengths of these specimens.A valid statistical correlation between values of compressive strength, porosity and the degree of saturation was obtained. Measured values of chloride permeability index of fly ash blended cement mortar were obtained as one fourth to one sixth of those measured for OPC mortar specimens, which indicates high resistance against chloride ion penetration in FA blended cement specimens, hence resulting in a highly durable mortar.

Keywords: chloride permeability index, equilibrium condition, electrical resistivity, fly ash

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1080716

References:

[1] R. A. Cook and K. C. Hover, "Mercury porosimetry of cement based materials and associated corrosion factors", ACI Materials Journal, Vol. 90, No. 2, 1993, pp. 152-158.
[2] P. W. Brown and D. Shi, "Porosity-Permeability Relationships", Materials Science of Concrete, Vol. 2, Skalny, J and Mindess, S, (eds.), 1993, pp. 83-109.
[3] J. G. Cabrera and P. Ghoddoussi, "The Influence of Fly Ash on the Resistivity and Rate of Corrosion of Reinforced Concrete", ACI SP 145, Durability of Concrete, Nice (France), 1994, pp. 229-244.
[4] British Standards Instituition, BS 12; (1996), "Specifications for Portland Cement", BSI, London.
[5] British Standards Institution, BS 882; (1992), "Specifications for Aggregates from Natural Sources for Concrete", BSI, London.
[6] British Standards Institution, BS 1881, PART 116; (1983), "Method of Determination of Compressive Strength of Cubes", BSI, London.
[7] RILEM, CP 113; (1984), "Absorption of Water by Immersion under Vacuum", Materials and Structures, Research and Testing, No. 101, pp. 393-394.
[8] J. G. Cabrera and C. J. Lynsdale,, "Measurement of Chloride Permeability in Superplasticised Ordinary Portland Cement and Pozzolanic Cement Mortars", Int. Conference, "Measurements and Testing in Civil Engineering", Lyon-Villeurbranne, 1988 pp. 279-290.
[9] K. Tutti, "Corrosion of Steel in Concrete", Swedish Cement and Concrete Research Institute (CBI), Stockholm, 1982, No. 4.82.
[10] V. M. Malhotra and N. J. Carino "Non-destructive Testing of Concrete", CRC Press, 1991, pp. 217-225.
[11] P.R.W. Vassie, "Evaluation of Techniques for Investigating the Corrosion of Steel in Concrete", TRL: Supplementary Report 397, 1978
[12] N. S. Berke and M. C. Hicks, "Predicting Chloride Profiles in Concrete", Corrosion Engineering, Vol. 50, No. 3, 1993, pp. 234-239.
[13] P. B. Bamforth, and D. C. Pocock, "Minimising the Risk of Chloride Induced Corrosion by Selection of Concreting Materials", Proceedings of the Conference on, "Corrosion of Reinforcement in Concrete", Society of Chemical Industry, Elsevier Applied Science, 1990, pp.119- 131.
[14] N. Shafiq, M. F. Nuruddin and I. Kamaruddin, "Comparison of engineering and durability properties of fly ash blended cement concrete made in UK and Malaysia"; Journal of Advances in Applied Ceramics Institute of Materials, Minerals and Mining, Maney publishers, volume 106, No: 6, 2007, pp:314-318.