Mechanical and microstructural properties of mortars: Obsidian powder effect

Abstract

Concrete has been the world's most produced and utilized building material for years due to its economic and easy accessibility. However, it attracts attention due to the CO2 emitted from cement, the raw material of concrete, during the production and consumption stages. Although there are different research studies to reduce this emission, one of the most logical solutions is to use pozzolanic materials with cement and reduce the need for cement. This paper investigated the general material characteristics of mortar samples generated by substituting obsidian powder with pozzolanic properties into cement at different ratios by weight. Mortar specimens with varying proportions of obsidian, such as 0%, 10%, 20%, and 30% by weight, were subjected to mechanical tests at 3, 7, 14, and 28 days. Material tests like X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize the material. As a result of the mechanical tests, 42.52 MPa compressive strength was obtained from the 28-day reference sample, while 44.331 MPa compressive strength was obtained from the mortar sample with 30% obsidian substitution. The outcomes of this paper noted that obsidian powder, which has pozzolan-ic properties, increased the mechanical strength of cementitious mortar specimens. This work indicates the suitability of using obsidian as pozzolan material with cement was determined.