Impact of Sulfate Ion on Dolomite Concrete Performance | ||
| The International Conference on Civil and Architecture Engineering | ||
| Article 9, Volume 6, 6th International Conference on Civil and Architecture Engineering, May 2006, Pages 201-208 PDF (45.69 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/iccae.2006.45734 | ||
| Authors | ||
| W. M. Zadeldin1; S. A. Mazek2 | ||
| 1Ph.D. Civil Engineering Branch. | ||
| 2Lecturer, Ph.D., Civil Engineering Department, Military Technical College. Cairo. Egypt. | ||
| Abstract | ||
| Concrete deterioration is an important cause of sudden collapse of buildings. Sulfate ion attack is a prominent cause of concrete deterioration. The main cause of sulfate attackinduced damage is ettringite formation in voids, cracks, and contact zones between aggregates and hardened cement paste. Scanning electron microscopy (SEM) images are taken to detect delayed ettringite crystal development in voids. General diffusion equations are utilized to investigate the sulfate ion ingress and the distribution of sulfate ion concentration in concrete related to time. A numerical model demonstrates the relation between the diffusion coefficient and concentration. A computer program is developed to model the problem of ion diffusion in concrete. The sulfate attack on concrete by one-dimensional diffusion process is simulated. The numerical model demonstrates the relation between the diffusion coefficient and concentration. The computer program is developed to calculate the SO4 ion diffusion. Compared with the SO4 ion diffusion coefficient in free water, the high diffusion value and the low compressive strength of concrete specimen are the values of concrete deterioration. The experimental program included mix design of 6 concrete mixes. The parameters of the experimental program were: cement type and content, presence of silica fume, sulfates concentration, and exposure period. The results show that, the concrete deterioration by sulfate attack is strongly influenced by the sulfates concentration in the aggressive medium and the exposure time. There is a linear relation between strength loss and concentration for mixes containing silica fume. Ordinary Portland cement (OPC) concrete limits the strength reduction about 10% after one year exposure to 5,000 ppm sulfate solution. In case of 100,000 ppm sulfate solution, the reduction is (13.1%). Increasing the cement content increases the strength loss by sulfates attack even in the presence of silica fume. | ||
| Keywords | ||
| Dolomite concrete; sulfate ion; Compressive strength; Computer program; sulfate ion diffusion; Ettringite and Gypsum formation | ||
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