Optimization of the calcination conditions of groundnut shell ash based on the compressive strength of cement mortar

Articles in Press

Document Type : Research Paper

Authors

1 Ph.D. Student in Structural Eng., Faculty of Engineering, University of Guilan, Rasht, Iran.

2 Civil ENG. department, Engineering college, University of Guilan, Rasht-Iran

3 Assistant Professore, Department of Textile Engineering, Faculty of Engineering, University of Guilan, Rasht, Iran.

10.22124/jcr.2026.33917.1746

Abstract

Due to its high energy consumption and significant carbon dioxide emissions, the cement industry requires sustainable supplementary cementitious materials. In this study, groundnut shell ash was investigated as a partial cement replacement in mortar. The aim was to determine the optimum calcination conditions for ash production based on mortar compressive strength and evaluate the effect of shell pretreatment on mechanical performance. Ash was produced at 550–700 °C for 1–3 h, and mortars containing 5% ash replacement were prepared and tested. The optimum condition was 650 °C for 2 h, resulting in a 28-day compressive strength of 42.85 MPa. Water and acid pretreatments did not significantly improve strength compared with untreated ash. Fresh mortar properties as well as the chemical and microstructural characteristics of the ash were also evaluated. The pozzolanic activity index values at 7 and 28 days were 90.39% and 93.60%, respectively. At a 5% replacement, mortar flowability was maintained without noticeable loss. XRF results showed that ash had a chemical composition similar to Class C pozzolanic materials according to ASTM C618. SEM images showed irregular, rough, and porous ash particles. This study demonstrates that groundnut shell ash produced under controlled thermal conditions can be used as a sustainable supplementary cementitious material.

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Concrete Research

Articles in Press, Accepted Manuscript
Available Online from 16 September 2026

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