Investigation on the physical and chemical properties of mortar using Metakaolin and Bagasse ash as a Partial Replacement of Ordinary Portland Cement

Abstract

In recent years, the transformation of industrial waste into products of commercial interest and utilization of these products plays a crucial role to ensure the circular economy and thereby safeguard the environmental impacts. Filter cakes are the by-product materials of the Aluminate Sulphate chemical factory, Ethiopia. These materials have a similar chemical composition as that of kaolinite and they are simply dumped in a landfill in a factory. Similarly, sugarcane bagasse ash is an abundant by-product of sugar industries, here in Ethiopia, which is disposed of in a landfill. If these by-product materials are collected and pre-treated, they can be used as a partial replacement for cement materials. In this work, the filter cake and the bagasse ash (BA) byproducts were collected from Awash Melkassa and Wonji Sugar factories, respectively. The collected samples were subjected to pretreatments such as size reduction, washing, oven drying, and calcination at a temperature of 600 ??C. The pre-treated samples were subjected to characterizations such as chemical composition analysis using XRF, phase purity investigation using XRD, thermal analysis using TGA-DTA, morphological studies using SEM, and functional group determination using FTIR. From the XRF result, the treated filter cake exhibited similar composition as that of metakaolin (MK). Then, the blended mortar/paste was prepared by partial replacement of OPC by MK (0-20 wt%). The result of the XRD of the pre-treated BA showed an amorphous structure. Therefore, a blended mortar/paste was synthesized from partially replaced OPC by amorphous structured BA (0-20 wt%). The mortar/paste samples were subjected to characterizations and mechanical (flexural and compressive) as well as physical property investigations. We obtained better mortar sample properties using 10 %MK partial replacement of OPC cement. While the 15 % BA blended OPC-mortar sample showed a better property compared to neat mortar samples. However, these percentage composite blended mortar do not show better properties. Therefore, experimentally investigating 5% MK and 10% BA results in better performance. The ternary mortar/pastewas subjected to characterizations and mechanical, physical, and chemical property investigations. The compressive strength of the neat OPC mortar sample was 44 MPa,10%MK, and 15% BA, was about 52 MPa, and ternary composite (5%MK-10% BA) about 57 MPa after 28 days of curing time. after 28 days of curing time. The le-Chatelier expansion of the neat paste sample was 0.85, with the addition of MK decreased to 0.4, showing an increment with the addition of BA results of 2.4 mm, while the composite paste resulted in0.95 mm expansion. The addition of treated waste materials improves the mechanical, physical, and chemical properties of the OPC blended mortar/paste sample.