Journal of Materials Science and Engineering A 4 (12) (2014) 372-375 doi: 10.17265/2161-6221/2014.12.006 Effects of Micro Silica on Permeability of Plastic Concrete Majid Pasbani Khiavi and Mortaza Ali Ghorbani Faculty of Engineering, University of Mohaghegh Ardabili, Ardabil 56199-11367, Iran Received: November 10, 2014 / Accepted: December 02, 2014 / Published: December 25, 2014. Abstract: Water tightness and seepage control are important considerations in the design and construction of dams. Plastic concrete cut-off walls are one of the effective means for seepage control in earth dams constructed on permeable substrate. An important requirement for the plastic concrete in such applications is adequate strength for the design loads and low enough permeability to meet the water tightness requirements of the dam. As permeability of cement-based materials, such as concrete, is mainly dependent on water to cement ratio, the permeability of plastic concretes is much higher than those of normal concretes. It is thus apparent that the achieving to low permeability is an important problem in plastic concrete. So a method, which could reduce the permeability of plastic concretes without unduly increasing their elastic modulus, would provide considerable technical advantages. In the present research, the possibility of lowering the permeability of plastic concrete thorough replacement of a portion of cement by micro silica was investigated. The aim of the experimental research was to investigate the effects of various levels of cement replacement by micro silica, including 0%, 3%, 6%, 9%, 12% and 15% on strength and permeability of plastic concrete. The results illustrate that the use of micro silica for replacement of some of the cement content in plastic concrete results in very substantial decrease in permeability. Obtained results show that through the use of micro silica in plastic concrete, it is possible to keep the strength and elastic modulus at the level of control mix and still achieve to reduction in permeability. Key words: Plastic concrete, hydraulic conductivity, cut-off walls, permeability, micro silica. 1. Introduction Water tightness and seepage control are important considerations in the design and construction of dams. Plastic concrete cut-off walls are one of the effective means for seepage control in earth dams constructed on permeable substrate [1]. The important requirements for the plastic concrete in such applications are adequate strength for the design loads and low enough permeability to meet the water tightness requirements of the dam. The usual range for w/c ratio of normal concretes is generally 0.4-0.6. As permeability of cement-based materials, such as concrete, is mainly dependent on w/c ratio, the permeability of plastic concretes is much higher than those of normal Corresponding author: Majid Pasbani Khiavi, assistance professor, research field: hydraulic structures. E-mail: [email protected]. concretes. A method, which could reduce the permeability of plastic concretes without unduly increasing their elastic modulus, would provide considerable technical advantages [2, 3]. Previous research has established that incorporation of silica fume in concrete is very effective in reducing permeability by pore size refinement and improvement of the transition zone between the pastes and aggregate. In the present research, the possibility of lowering the permeability of plastic concrete thorough replacement of a portion of cement by micro silica was investigated. Due to the importance of the compressive strength, the effect of incorporation of micro silica on this property was also determined [4, 5]. 2. Materials Materials used in plastic concrete mixes studied included cement, water, bentonite, micro silica and D DAVID PUBLISHING
Effects of Micro Silica on Permeability of Plastic Concrete
Apr 26, 2023
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