Effect of municipal solid waste ash on the strength of earthen bricks and walls

Masonry units are usually joined using cement mortar. A good bond between the bricks is essential and determines how the masonry units transfer and resist stresses due to applied loads. In this study interlocking brickswere used to construct a wall without the use of cement mortar. The aim of this study was to evaluate the effect of different amounts of Municipal Solid Waste Ash (MSWA) on the strength characteristics of the walls subjected to compressive loads. The soil used for making the bricks was stabilized using MSWA applied at the rate of 0%, 2%, 5% and 10% of the weight of soil. The compressive strength of individual soil bricks moulded in a CINVA‐Ram machine was obtained during the curing period and samples were tested on days 7, 14 and 28; after the start of the curing period. Walls, 840 mm high and 1100 mm long, were constructed using the bricks after curing them for 28 days. A compressive force was applied on the masonry walls in a direction normal to joints. Addition of 2% MSWA gave the bricks the highest compressive strength on Day 28. The failure pattern of the wall constructed using bricks stabilized with 2% MSWA followed diagonal cracks and bulging of the wall from the sides. At failure the wall had a maximum crack width of 40 mm and a vertical central deflection of 20 mm at failure. The ultimate stress of the stabilized wall was 2.47N/mm2 occurring at a strain of 11. On the other hand un‐stabilized Juja soil masonry wall had a maximum compressive stress of 2.5 N/mm2 occurring at a strain of 9.5. The failure of the unstabilized Juja soilbrickwall was mainly due to vertical cracks forming below the load application point. For the un‐stabilized brick wall, the central deflection at failure was 14 mm, and was less than the deflection of the stabilized wall at failure. This indicated that the stabilized brick wall was more ductile than the un‐stabilized brick wall. Compared to the wall constructed using bricks stabilized with 2% MSWA which had diagonal cracks, the un‐stabilized walls had nearly vertical cracks. The failure of the stabilized brick wall was consistent with the provisions of the design code BS 5628 Part 1 of the year 2005.Key words: Compressive strength, failure mode, interlocking bricks, municipal solid waste ash (MSWA), stabilization