اثر دوده سيليس در ارتقاي خواص بتن غلتكي مورد استفاده در روسازي راه

The Effect of "Silica Fume" on Improvement of Roller Compacted Concrete Pavement Mechanical Properties

Roller Compacted Concrete (R.C.C.) is a relatively new material in dams and pavement construction that has attracted considerable interest because of its economical and technical benefits. R.C.C is used in construction darns in many countries. So, for construction of pavement there are many reports for application R.C.C. specially in north America. In this thesis the effect of "silica fume" on improvement of R.C.C pavement mechanical properties is investigated. This research is according to (ACI 325.10 R-99) standard. Mixture proportioning is done by evaluation of consistency tests. Fabricating of test specimens was according to (ASTM C 1170-91) and (ASTM C 1176-92) standards and for simulate rollers a modified vibrating table is used . Compression strength, tensile strength and flexural strength that are the main parameters in concrete pavement is measured. In this thesis, experiments were designed for two amount of cements (250 and 300 kg/m3 concrete) and with different amount of silica fume (0, 5, 10 and 15 percent) as alternative for cement. The specimens for flexural strength were 75 * 15* 15 cm3 and another were cylindrical (30* 15)cm2 in all experiments. For curing, the specimens were held in water at 20 OC for 28 days. Test results show that incorporation of silica fume causes significant improvements in the mechanical properties of R.C.C pavement. The magnitude of strength increase is varied from 15 to 40 percent for a 10 percent cement replacement by silica fume. So, with regarding to kind of the aggregate and the cement material the results satisfy the ACI standard.