FLEXURE AND SHEAR BOND STRENGTH OF RED MUD – FLY ASH BASED GEOPOLYMER MORTARS

Smita Singh, H. P.Mahesh, M. U. Aswath, R. V. Ranganath

Abstract: Flexure and shear bond strength for masonry structures are important when they are subjected to in plane or out of plane loads. The paper focuses on the study of flexure and shear bond strength of masonry using red mud – fly ash based geopolymer mortar. Experiments have been carried out to determine the compressive strength of the geopolymer mortar. A total of 108 numbers, 70 mm size mortar cubes were casted by varying different percentages of red-mud (RM) along with fly-ash (FA) and silica fume (SF) of different molarities starting from 6M to 12M with an increment of 2M by keeping sodium hydroxide to sodium silicate solution ratio as 2.5. Mortar cubes of binder to fine aggregate ratio of 1:3, 1:4 and 1:6 have been casted and tested for compressive strength. For all the variationsin the composition of binder material, cubes casted with 10M alkali solution have themaximum strength. Hence mortar of molarity 10M was used in making triplets and prisms for shear and flexure bond test. By using 10% red mud, maximum shear and flexure bond strength obtained are 0.318 and 0.277 Mpa and for 30% red mud, 0.25 Mpa and 0.215 Mpa. The compressive strength of the red mud – fly ash geopolymer mortar was found to be lesser than that of the cement mortar of same binder:aggregate ratio but it exhibited excellent bond strength.

Keywords: redmud, fly ash, silica fume, alkaline liquids, compressive strength, masonry, shear, flexure

DOI: https://doi.org/10.15623/ijret.2016.0532036