توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱AN INVESTIGATION ON EFFECT OF USING PP FIBERS AND DIFFERENT CEMENTITIOUS MATERIALS ON MECHANICAL PROPERTIES OF EPS CONCRETE
اطلاعات انتشار: سومین کنفرانس بین المللی بتن و توسعه، سال
تعداد صفحات: ۱۰
The use of lightweight concrete in many applications of modern construction is increasing, owing to the advantages that lower density results in decreasing the magnitude of dead load of the structure which lead to smaller cross sections for load bearing elements. Expanded polystyrene (EPS) beads are a type of artificial lightweight nonabsorbent aggregates which can be used to produce low density
concretes by replacing with normal aggregates, either partially or fully, depending upon the requirements of density and strength. Also plastic shrinkage is the dimensional change that occurs in all fresh cement based materials within the first few hours after it has been placed which is not unacceptable in itself, but it is some times accompanied by development of cracks that are unsightly and bjectionable.
Polypropylene and other synthetic fibers are added to concrete as secondary reinforcement in order to control this plastic shrinkage. On the other hand, the addition of fibers affects on the properties of hardened concrete like compressive and tensile strength, elastic modulus and toughness. The present study covers the use of polypropylene fibers at contents equal to 0.1%, 0.3%, 0.5% and 1% by volume of EPS concrete in order to study about the effects of its addition into the EPS concrete matrix on mechanical properties. Also the effects of using Silica fume and Rice husk as two supplementary cementitious materials were investigated.<\div>

۲EFFECT OF POLYPROPYLENE FIBERS ON MECHANICAL AND PHYSICAL PROPERTIES OF MORTARS CONTAINING NANO–SIO2
نویسنده(ها): ، ،
اطلاعات انتشار: سومین کنفرانس بین المللی بتن و توسعه، سال
تعداد صفحات: ۱۰
It has been demonstrated that the fiber–matrix bond strongly affects the ability of fibers to stabilize crack propagation in the matrix. As the bond between fiber and matrix is mainly mechanical, it seems that incorporating nano–SiO2 (NS) into fiber reinforced cement composites provides better bond with matrix through pore refinement and better distribution of the hydrated products. Hence in this paper an effort was made to study the effect of polypropylene (PP) fibers on mechanical properties and shrinkage of mortar incorporating NS. Three fiber volume fractions, 0.1%, 0.3% and 0.5% were considered. Compressive and flexural strength, water absorption and shrinkage of mortars were reported. Results showed that NS improved mechanical and water absorption characteristics of mortars significantly. It has been observed that the addition of NS fairly enhanced the fibers effectiveness in improving the mechanical strength of mortars.<\div>

۳INVESTIGATION OF MECHANICAL AND PHYSICAL PROPERTIES OF MORTARS CONTAINING SILICA FUME AND NANO–SIO2
نویسنده(ها): ، ، ،
اطلاعات انتشار: سومین کنفرانس بین المللی بتن و توسعه، سال
تعداد صفحات: ۹
It has been found that physical properties of concrete, particularly strength and permeability significantly depend on its pore structure. Ultra fine particles of nano– SiO2 fill the voids of CSH structure and provide more homogenous distribution of hydrated products. This effect of nano–SiO2 enhances the durability of cement composites as well as the strength. In this paper, influence of nano–SiO2 on
different properties of cement mortar was investigated in comparison with silica fume (SF) as a well–known active pozzolan. Different amounts of nano–SiO2 (0, 1%, 3%, 5%, 7%and 9%) were incorporated into the ordinary cement mortar. Mechanical properties, shrinkage, water absorption of the specimens were determined. Results showed that the optimal content of Nano–SiO2 in plain cement mortar was around 7%. Nano–SiO2 particles were more effective in developing higher mechanical strength and lower water absorption than that of SF. Yet the mortar containing nano–SiO2 experienced higher shrinkage than that of SF mortar.<\div>
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