چكيده به لاتين
Abstract:
Road transportation is one of the most known methods of transporting passengers, cargo and is one of the vital security requirements. Nowadays the use of concrete paving in road construction is common. Although the use of concrete in road construction has many advantages, the used concrete should be High-Performance to have satisfactory load bearing capacity in terms of vehicle loads and also, should be able to tolerate different environmental conditions. There have been many studies in the world to introduce the best economical High Performance Concrete (HPC) to be used in concrete pavements. The main goal of this research is to investigate the mechanical properties of concrete mixes containing cement replacement materials, fibers and air-entraining admixture for using in concrete pavements. For this purpose concrete samples containing air-entraining admixture, fibers and cement replacement materials were mixed, casted and cured to the age of 28 and 90 days in water with temperature of 21˚C. The obtained results from compressive, flexural and splitting tensile strengths and also, abrasive and impact resistance experiments show that the use of Macro-Synthetic Fibers will enhance mechanical properties of concrete samples. In contrast, the results show that the use of air entraining admixtures has negative effect on the mechanical properties of concrete samples. However, this drawback is improved when air entraining admixture was used with macro-synthetic fibers or cement replacement materials like silica fume and metakaolin in the concrete mixes. The obtained results from mechanical experiments of concrete mixes were compared with the minimum values introduced by DIN standard for highways concrete paving. The results show that the mixes containing air entrained admixture have not met the needed conditions. However the mixes containing air and fibers or silica fume and metakaolin, could pass the minimum values introduced by DIN standard. The results obtained from splitting tensile, abrasive and impact resistance experiments were related to compressive strengths of same samples. The gained diagrams were compared with minimum compressive strength value of DIN standard and as a result, minimum values for splitting tensile strength, abrasive and impact resistance of highway concrete pavements were proposed.
Keywords: Mechanical Strengths, Highway Concrete Pavements, Air Entraining Admixtures, Macro-Synthetic Fibers, Cement Replacement Mater
