Electrokinetic pozzolanic nanoparticle treatments have been reported in the literature to achieve rapid porosity reductions and deeply penetrating strength enhancement of cement and concrete. The high electric fields required to achieve these results have tended to be accompanied by particle suspension instability. Coagulation is an instability that can limit the efficiency and effectiveness of a treatment by removing particles from suspension. The current study examines how electro-coagulation impacts electrokinetic treatment effectiveness. The nano-pozzolan suspension used in this study was Nalco 1056, alumina-coated silica (24-nm). A threshold electric field strength of 0.4 V/cm was identified for avoiding direct electro-coagulation. Treatments conducted at this threshold value exhibited a 50% strength increase. Treatments conducted above this threshold value exhibited significant particle electro-coagulation losses and strength increases of only 25%. This study found that electro-coagulation was influenced by the electric field strength, through a combination of particle crowding at pore entrances and pH shifts as driven by electrolysis.
Mindess, S. and Young, J.F. (1996) Concrete. Prentice-Hall, Englewood Cliffs.
Lageman, R. (1993) Electroreclamation. Applications in the Netherlands. Environmental Science & Technology, 27, 2648-2650. https://doi.org/10.1021/es00049a003
Kim, Y.Y., Lee, K.M., Bang, J.W. and Kwon, S.J. (2014) Effect of W/C Ratio on Durability and Porosity in Cement Mortar with Constant Cement Amount. Advances in Materials Science and Engineering, 2014, Article ID: 273460. https://doi.org/10.1155/2014/273460
Lian, C., Zhuge, Y. and Beecham, S. (2011) The Relationship between Porosity and Strength for Porous Concrete. Construction and Building Materials, 25, 4294-4298. https://doi.org/10.1016/j.conbuildmat.2011.05.005
Song, H.W., Pack, S.W., Nam, S.H., Jang, J.C. and Saraswathy, V. (2010) Estimation of the Permeability of Silica Fume Cement Concrete. Construction and Building Materials, 24, 315-321. https://doi.org/10.1016/j.conbuildmat.2009.08.033
Bahadori, H. and Hosseini, P. (2012) Reduction of Cement Consumption by the Aid of Silica Nano-Particles (Investigation on Concrete Properties). Journal of Civil Engineering and Management, 18, 416-425. https://doi.org/10.3846/13923730.2012.698912
Cardenas, H., Kupwade-Patil, K. and Eklund, S. (2011) Corrosion Mitigation in Mature Reinforced Concrete Using Nanoscale Pozzolan Deposition. Journal of Materials in Civil Engineering, 23, 752-760. https://doi.org/10.1061/(ASCE)MT.1943-5533.0000194
Cardenas, H., Kupwade-Patil, K. and Eklund, S. (2011) Recovery from Sulfate Attack in Concrete via Electrokinetic Nanoparticle Treatment. Journal of Materials in Civil Engineering, 23, 1103-1112. https://doi.org/10.1061/(ASCE)MT.1943-5533.0000255
Cardenas, H. E. and Struble, L. J. (2006) Electrokinetic Nanoparticle Treatment of Hardened Cement Paste for Reduction of Permeability. Journal of Materials in Civil Engineering, 18, 554-560. https://doi.org/10.1061/(ASCE)0899-1561(2006)18:4(554)
Cardenas, H., Alexander, J. and Kupwade-Patil, K. (2010) Field Testing of High Current Electrokinetic Nanoparticle Treatment for Corrosion Mitigation in Reinforced Concrete. Second International Conference on Sustainable Construction Materials and Technologies, Ancona, 28-30 June 2010.
Kanno, J., Richardson, N., Phillips, J., Kupwade-Patil, K., Mainardi, D.S. and Cardenas, H.E. (2009) Modeling and Simulation of Electromutagenic Processes for Multiscale Modification of Concrete. Journal of Systemics, Cybernetics and Informatics, 7, 69-74.
Kupwade-Patil, K., Cardenas, H.E., Gordon, K. and Lee, L.S. (2012) Corrosion Mitigation in Reinforced Concrete Beams via Nanoparticle Treatment. ACI Materials Journal, 109, 617-626. https://doi.org/10.14359/51684159
Cardenas, H.E. (2002) Investigation of Reactive Electrokinetic Processes for Permeability Reduction in Hardened Cement Paste. University of Illinois at Urbana-Champaign, Urbana and Champaign.
Hamley, I.W. (2013) Introduction to Soft Matter: Synthetic and Biological Self-Assembling Materials. John Wiley & Sons, New Jersey.
Heard, D.H. and Seaman, G.V.F. (1960) The Influence of pH and Ionic Strength on the Electrokinetic Stability of the Human Erythrocyte Membrane. The Journal of General Physiology, 43, 635-654. https://doi.org/10.1085/jgp.43.3.635
Berg, J.M., Romoser, A., Banerjee, N., Zebda, R. and Sayes, C.M. (2009) The Relationship between pH and Zeta Potential of ～30 nm Metal Oxide Nanoparticle Suspensions Relevant to In Vitro Toxicological Evaluations. Nanotoxicology, 3, 276-283. https://doi.org/10.3109/17435390903276941
Wiese, G.R. and Healy, T.W. (1970) Effect of Particle Size on Colloid Stability. Transactions of the Faraday Society, 66, 490-499. https://doi.org/10.1039/tf9706600490
Heris, S.Z., Etemad, S.G. and Esfahany, M.N. (2006) Experimental Investigation of Oxide Nanofluids Laminar Flow Convective Heat Transfer. International Communications in Heat and Mass Transfer, 33, 529-535. https://doi.org/10.1016/j.icheatmasstransfer.2006.01.005
Jiang, J.K., Oberdorster, G. and Biswas, P. (2009) Characterization of Size, Surface Charge, and Agglomeration State of Nanoparticle Dispersions for Toxicological Studies. Journal of Nanoparticle Research, 11, 77-89. https://doi.org/10.1007/s11051-008-9446-4
Wisniewska, M. (2010) Influences of Polyacrylic Acid Adsorption and Temperature on the Alumina Suspension Stability. Powder Technology, 198, 258-266. https://doi.org/10.1016/j.powtec.2009.11.016
Li, T., Zhu, Z., Wang, D., Yao, C. and Tang, H. (2006) Characterization of Floc Size, Strength and Structure under Various Coagulation Mechanisms. Powder Technology, 168, 104-110. https://doi.org/10.1016/j.powtec.2006.07.003
Rahmani, A.R. (2008) Removal of Water Turbidity by the Electrocoagulation Method. Journal of Research in Health Sciences, 8, 18-24.
Khaled, B., Wided, B., Béchir, H., Elimame, E., Mouna, L. and Zied, T. (2019) Investigation of Electrocoagulation Reactor Design Parameters Effect on the Removal of Cadmium from Synthetic and Phosphate Industrial Wastewater. Arabian Journal of Chemistry, 12, 1848-1859. https://doi.org/10.1016/j.arabjc.2014.12.012
Ahmad, Z. (2006) Chapter 3—Corrosion Kinetics. In: Ahmad, Z., Ed., Principles of Corrosion Engineering and Corrosion Control, Butterworth-Heinemann, Oxford, 57-119. https://doi.org/10.1016/B978-075065924-6/50004-0
Jones, D.A. (1992) Principles and Prevention of Corrosion. Macmillan, New York City.
Drewett, J. and Broomfield, J. (2011) An Introduction to Electrochemical Rehabilitation Techniques. Technical Notes No. 2, Corrosion Prevention Association, Hampshire, 8.
Schmick, B.L. (1997) Concrete Repair Manual. 2nd Edition, Vol. 2, The Concrete Repair Association, Farmington Hills, MI.
Phillips, J. (2011) A Modeling and Simulation Framework for Electrokinetic Nanoparticle Treatment. Louisiana Tech University, Ruston, Louisiana.
Harris, D.C. (2012) Exploring Chemical Analysis. Macmillan, New York City.