عنوان مقاله [English]
Concrete blocks has a wide range of applications in building industry in Iran and many other countries as well in both structural and non-structural members. Their use in structural members is mainly related to structural infill walls and also unreinforced and reinforced concrete block masonry. Observation from past earthquakes indicates that the main failure mode of these blocks is tensile splitting due to excessive compressive stresses. This study aims at improving the tensile behavior of concrete blocks by adding polypropylene fibers to the concrete mixture. For this purpose, 84 cylindrical and cubic specimens were constructed and tested under tensile splitting and compressive force. Three variables of Fiber dosage, Cement content, and fiber type were taken into account to study the sensitivity of splitting strength, strain capacity, compressive strength and energy absorption to these variables. The results show that the specimens without fibers experienced a sudden non-ductile failure, whereas this is not the case for the specimens with added fibers. All the considered response parameters were improved thanks to the addition of fibers. Generally, the improvement in specimens with micro fibers was better than that of the corresponding specimens with macro fibers, especially when larger cement content was included. Whereas, no significant improvements were observed in specimens with macro fibers mainly because of the non-ideal dispersion of fibers in cement base which causes voids in concrete and hence, reducing the quality of concrete. The displacement capacity of specimens was increased because of increase in the fibers content, regardless of the fibers type. This increase was also dependent on the cement content in the specimens and it significantly increased by increasing the cement content. The same trend was observed in the energy dissipation capacity. Also, the compressive strength of the studies concrete blocks falls within the allowable amount prescribed by Code 55.