COMPRESSIVE STRENGTH AND DURABILITY OF CEMENT CONCRETE CONTAINING ALKALI WASTES OF OIL AND CELLULOSE PAPER INDUSTRIES AND EXPOSED TO AGGRESSIVE ENVIRONMENTAL CONDITIONS | ||||
| JES. Journal of Engineering Sciences | ||||
| Article 3, Volume 34, No 4, July and August 2006, Page 1061-1085 PDF (1.78 MB) | ||||
| Document Type: Research Paper | ||||
| DOI: 10.21608/jesaun.2006.110767 | ||||
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| Authors | ||||
| Rashwan M. M* ; Mahmoud H. A* ; Aly G. A.* ; Abo-Elfadel M* | ||||
| Civil Engineering Department, Faculty of Engineering, Assiut University, Assiut, Egypt | ||||
| Abstract | ||||
| Most of R.C. constructions, especially underground, are always subjected to aggressive environmental conditions during their exploatation. These conditions are represented by the aggressive sodium and magnesium sulfate attack from surrounding soil or underground water. When cement-based materials are exposed to sodium sulfate attack, gypsum and ettringite are produced by chemical reactions of sulfate and Ca (OH)2,and C3A. Formation of gypsum plays an important role in the damage of materials. According to that, the actual compressive strength of R.C. elements decreases accompanied with large deformations of concrete. Consequently, a higher reduction of the construction durability occurs. So, the need for using an effective and economic admixtures for the protection of concrete elements against sulfate attack or any other environmental conditions is required. Therefore, the main purpose of this research is to study experimentally the possibility of producing effective and economic admixtures from alkali wastes of oil and cellulose paper industries. Then study their mechanism effect on the compressive strength and durabiliyt of cement concrete specimens, subjected to external sulfate attack and different cycles of durability test. The main variables studied in this research on concrete mixes and hardened specimens were: -three different types of plasticizing organic admixtures(SM-S, CM-B &SM-O), which contain in their compositions an amount of alkali wastes from secondary products of oil and cellulose paper industries, plus a known plasticizing admixture in the Egyptian markets (Addicrete DM2),- three different concentrations of external surrounded sodium and magnesium sulfate solutions and four different numbers of cycles of durability test. The experimental results showed that, The optimum composition of all components of the suggested admixtures (SM-S, CM-B & SM-O) containing alkali wastes from oil and cellulose paper industries and production of them in a liquidity solution was successfully and experimentally achieved. Concrete specimens modified with these admixtures and hardened in 6%Na2SO4+3% MgSO4 until 7 months showed a large increase in their compressive strength by about 46, 37, & 38% and a large increase of their durability index, after 50 cycles, by about 86, 84 & 76%. respectively compared to the control tested specimens without admixtures. Microscopic analysis showed that specimens modified with the suggested organic admixtures have denser and homogeneous structure, their large pores decreased and micro pores increased compared to the control specimens. The vacuums of specimens containing these admixtures after 50 cycles of durability test were filled with prismatic new formations and showed a very small shrinkage cracks between cement paste and filling materials. | ||||
| Keywords | ||||
| organic admixture; alkali wastes; compressive strength; concrete; sulfate attack; mechanism effect; aggressive; durability; microstructure | ||||
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