Nowadays, fibers are being used vastly due to their positive effect on concrete properties. Fibers versatility in materials, shapes and their production technique made the concrete having various properties regarding material, geometrical shape and production method. Sine their use in concrete is inevitable, so more and detailed studies are required in this field. Man-made fibers such as Polypropylene (PP) and Glass (Gl) were used in this study. They were mixed with water, cement, perlite, waste stone. In this study waste stone was used as the main constituent of cementitious composite which are the waste of stone cutting industries. Waste stones are environment threatening materials because they contaminate underground and ground water, alkalize the soil and deteriorate the plant coverage. Thus, using these waste materials in constructional structures could have beneficiate economically and environmentally. In order to investigate stone waste effect on concrete performance, following tests were carried out: pull out, compression, bending, thermal and SEM. In addition, two types of concrete, lightweight and heavy weight, were used. The presence of Gl fibers in lightweight concrete results in reduction of compression and bending strength while adding PP (0.8 wt%) increased the compression and bending strength about 35%. In contrast, adding Gl fibers (0.8 wt%) to heavy-weight concrete results in flexural strength increase while decreases compression strength about 4%. The presence of PP fibers improved the flexural strength approximately 85%. In overall, fibers had a negative impact on compression properties. Result showed that the presence of fibers had a positive effect on concrete performance under thermal conditions (200, 400 and 800 ?C). Since Gl fibers have high melting point, they made the concrete retain its integrity in severe thermal conditions (as high as 800 ?C). SEM images confirmed that Gl fibers did not melt in the concrete, so they could play their role as reinforcing part. Consequently, concrete reinforced with Gl fibers had superior mechanical properties in 400 ?C than unreinforced concrete sample.
