Performance of Groundnut Shell Ash as a Partial Replacement of Cement in Masonry Mortar

Abstract

Mortar is an important part of masonry construction worldwide. Presently, OPC remains the binder material of choice for mortar to develop structures for our socio-economic needs. The purpose of this study was to determine the feasibility of local groundnut shell ash being used to replace the PPC-32.5N cement in type M and N masonry mortars. The characterization of the local GSA found it to be pozzolanic, belonging to class C. The properties of type M mortar (17.2N/mm2) and type N mortar (5.2N/mm2) were evaluated with partial cement replacement with GSA intervals of 0%, 7.5%, 12.5%, 17.5% and 22.5%. The compressive strength of the type M mortar cubes did not achieve the required minimum compressive strength of 17.2N/mm2 at 28 days of curing, but the mortar prism cured beyond 28 days achieved the minimum compressive strength of 17.2N/mm2 at 56 and 90 days of curing at 7.5% GSA replacement. In contrast, in type N mortar, a minimum compressive strength of 5.2N/mm2 at 28 days of curing was achieved at an optimum replacement of 17.5% GSA for cement. Similarly, mortar prism cured beyond 28 days achieved the same strength of 5.2N/mm2 at 90 days of curing with 17.5% GSA replacement. The flexural strength for both mortars exhibited high strength compared with the corresponding compressive strength in the range of 10-40%. The reactivity of the mortar was achieved at 7.5% GSA replacement in both types of mortars. Both initial and secondary sorptivity values increased with an increase in GSA content and did not conform to the specified values. In conclusion, type M mortar is to be replaced up to 7.5% while type N mortar is to be replaced up to 17.5% GSA for optimum strength.