Concentration boundary layer model of mortar corrosion by sulfuric acid

Abstract

A long time immersion experiment of mortar specimens is carried out to investigate their degradation mechanism by sulfuric acid. Water-cement ratios of mortar are ranging from 0.5 to 0.7 and the pH value of sulfuric acid is 3.5 and 4.0 respectively. The pH meter is used to monitor the soak solution and the titration sulfuric acid with given concentration is added to maintain original pH value, through which the acid consumption of mortar is recorded. A theoretical reaction rate model is also proposed based on concentration boundary layer model. The results show that theoretical model fits the experimental results well and the corrosion mechanism can be modeled by a diffusion process accompanied with an irreversible chemical reaction when pH value of soak solution is no less than 3.5.

Keywords

mortar / sulfuric acid / corrosion / durability

References

[1] E W Martin. Acid Rain and Air Pollution vs the Building and Outdoor Sculptures of Montreal [J]. ART XXIII-4., 1991: 13–19

[2] J X Chen, J C Wu, H B Chen. Survey of the Durability of Building in Severe Acid Rain Circumstance [J]. Concrete., 2001 (11): 44–47(in Chinese)

[3] Z G Song, S Y Yang. Material Degradation of RC Structures Attacked by Acid Rain—a Field Investigation in Kunming [J]. Concrete, 2007(11): 23–27 (in Chinese)

[4] Y G Zhu. Analysis and Reinforcement Design of RC of Individual Footing of Column Based Corroded by Acid in a Factory Building [J]. Anhui Architecture, 2002(z1): 85–86(in Chinese)

[5] V Pavlik. Degradation of Concrete by Flue Gases from Coal Combustion [J]. Cement and Concrete Research, 1997(11): 1 731–1 745

[6] H Lee. The Formation and Role of Ettringite in Iowa Highway Concrete Deterioration [J]. Cement and Concrete Research, 2005(35): 332–343

[7] S Ehrich, L Helard. Biogenic and Chemical Sulfuric Acid Corrosion of Mortars [J]. ASCE: Journal of Materials in Civil Engineering, 1999(4): 340–344

[8] N D Belie, J Monteny, A Beeldens. Experimental Research and Prediction of the Effect of Chemical and Biogenic Sulfuric Acid on Different Types of Commercially Produced Concrete Sewer Pipes [J]. Cement and Concrete Research, 2004 (34): 2 223–2 236

[9] Jofriet J. C., Abdelmseeh V. A., Negi S. C. Deterioration of Reinforced Concrete in Farm Buildings Due to Sulfate and Sulfide Attack [C], 2004 Canada Ottawa ASAE / CSAE Annual International Meeting 1-11.

[10] D Israel, D E Macphee, E E Lachowski. Acid Attack on Pore-Reduced Cements [J]. Journal of Materials Science, 1997(32): 4 109–4 116

[11] Q Zhou, J Hill. The Role of pH in Thaumasite Sulfate Attack [J]. Cement and Concrete Research, 2006(36): 160–170

[12] E Hewayde, M Nehdi, E N Allouche. Experimental Investigations of the Effect of Selected Admixture on the Resistance of Concrete to Sulfuric Acid Attack [J]. ASCE: Pipelines, 2003: 504–513

[13] E Hewayde, M Nehdi. Effect of Mixture Design Parameters and Wetting-Drying Cycles on Resistance of Concrete to Sulfuric Acid Attack [J]. ASCE: Journal of Materials in Civil Engineering, 2007(2): 155–163

[14] S D Xie, Q Li. Investigation of the Effects of Acid Rain on the Deterioration of Cement Concrete Using Accelerated Tests Established in Laboratory [J]. Atmospheric Environment, 2004(38): 4 457–4 466

[15] M Bohm, J S Devinny. On a Moving-Boundary System Modeling Corrosion in Sewer Pipes [J]. Appl. Math. Comp., 1998(92): 247–269

[16] Jahani F., Devinny J. Investigation of Sulfuric Acid Corrosion of Concrete: Part I. Modeling and Chemical Observations[J]. J. Envir. Engrg., 2005, 127(7): 572-579.

[17] M Bohm, J S Devinny. A Moving Boundary Diffusion Model for the Corrosion of Concrete Wastewater Systems: Simulation and Experimental Validation [C]. Proc., Am. Control Conf., 1999: 1 739–1 743

[18] E B Robin, W D Horst. Modeling Acid Attack on Concrete: Part I. The Essential Mechanisms [J]. Cement and Concrete Research, 2005(35): 2 333–2 339

[19] Quality Supervision Bureau of the People’s Republic of China. Method of Testing Cement-Determination of Strength (GBT 17671-1999) [S]. Beijing: Standards Press of China, 1999