The development of environmentally accepted methods of used tire disposal is one of the greatest
challenges that waste management exped face today. When building materials are subjected to
fire and exposed to cooling, some changes may occur in their characteristics; such as phase
transformation, weight loss, aggregate-cement bond, etc., which directly affects on its chemical
stability and mechanical properties. In the present investigation, the effect of high temperature of
the compressive and tensile strengths af concrete mortar fabricated fiom ground waste tire nibber
(GWTR) as a paaial replacement of total fine aggregate ('FA), sand, was experimentally
investigated. The percentages by volume of GWTRITFA were, 0%, 5%, lo%, 15% and 20%. All
mortar samples were prepared and cured using tap water for 28 days, then kept in 1ab;oratory
atmosphere until the beginning of the test. The specimens were subjected to different.target
temperatures of 100, 200, 300,400 and 500°C. After reaching to the desired target temperature,
the specimens were sustained at hesired temperature for 2 hours. After heating the specimens wae
allowed to cool at room temperature until the date of the test. The test results showed that all
mortar specimens exposed to high temperature suffered a significant decrease in both compressive
and tensile strengths. Replacing sand by 5-10% GWTR recorded the highest relative compressive
strength, while replacing sand by 10-15% GWTR recorded the highest relative tensile strength'
compared with other replacement ratios. The mass loss increased with increasing of temperature
up to 500°C and GWTR %. In addition, at high temperature 500°C it was noticed that no cracks
appeared on the surface of specimens.