بررسي آزمايشگاهي ديوار خشتي با ملات مسلح‌شده با كاه تحت كشش قطري

Experimental Investigation on Mud Brick Walsl with Mortar Containing Straw Fibers under Diagonal Tension

در اين نوشتار عملكرد آزمايشگاهي ديوار خشتي با درصد‌هاي مختلف الياف كاه در ملات تحت بار استاتيكي قطري مورد بررسي قرار گرفته است. تعداد 12 عدد ديوار با انواع مختلف ملات (ملات معمولي، ملات مسلح‌شده با درصدهاي وزني: 4/0، 6/0، 8/0، 1، و 2/1 الياف كاه) با خشت غيرمسلح در ابعاد 22×120×120 سانتي‌متر ساخته شده‌اند. ديوارها تحت بار فشاري قطري بارگذاري ‌شده‌اند تا نوع ترك‌ها، نيروي نهايي، تغييرشكل نهايي، و جذب انرژي آن‌ها به‌دست آيد. در ديوارهاي با ملات مسلح‌شده با 8/0% كاه، مقدار نيرو به اندازه‌ي 78/26? و جذب انرژي ديوارهاي مذكور به اندازه‌ي 22/94? بيشتر از ديوارهاي با ملات ساده و غيرمسلح بوده است. نتايج نشان داده‌اند كه مي‌توان از افزودني كاه به‌عنوان تسليح‌كننده در ملات ديوارهاي خشتي استفاده كرد، تا رفتار سازه بهبود بخشيده شود.

This study presents an experimental investigation on mud brick walls with mortar containing straw fibers under diagonal axial compression. The brick size was: 22 × 22 × 7 cm (face × bed × end). The average compressive strength of the bricks was 4.73 MPa. To determine the performance of straw fibers in the mortar of mud brick wall, 12 walls, with size 120 × 120 × 22cm, with various percentages of straw fibers (0/4, 0/6, 0/8, 1 and 1/2), were investigated. For evaluation of failure modes in ultimate diagonal compressive load, types of crack, load capacity and ductility, and energy absorption characteristics, were studied. Cracks in specimens with mortar reinforced by straw fibers have less width than unreinforced mortar. The ultimate load capacities of walls reinforced with various percentages of straw fibers (0/4, 0/6, 0/8, 1 and 1/2), were obtained as 20.3, 21.05, 20.7 and 18.5 kN, respectively. The average load capacitiy was increased about 26.78% compared to the unreinforced mortar wall in the ultimate load. The result shows that energy absorption in reinforced mortar specimens increased about 94.22 percent. Ultimate displacement for the unreinforced walls was 23.1 and for reinforced walls with 0/8% straw fiber in mortar was 34.8mm. It shows that ultimate displacement increased about 51 percent. Test results show that straw fibers can be used for reinforcing the mortar of mud brick walls, which is an advantage both economically and in enhancing structural behavior. In this study, when the straw fibers were increased to 0.8 percent in the mortar, the load carrying capacity was increased more than any other percentage of fiber in the mortar.