Study of peanut husk ashes properties to promote its use as supplementary material in cement mortars

J Kreiker,E Q Crespo,M Positieri,C Andrada,M Gatani

doi:10.1590/s1983-41952014000600001

Abstract

The properties of peanut husk ashes as a potential supplementary material in cement mortars were studied in the laboratory. The ashes were prepared in an electric furnace at 500, 650 and 800 ºC during 180 minutes and used without further treatment. The characterization of ashes includes X-Ray fluorescence, X-Ray diffraction, SEM, and determination of pozzolanic activity by conductivity. The ashes were tested in mortars as partial substitute of Portland cement, in a rate of 15 % of substitution. The compression strength of mortars was evaluated between 7 and 120 days, for probes prepared using a proportion of cement:sand of 1:3 on weight with water/cement ratio of 0,5 v/v. It was observed that the calcinations conditions influenced the behavior of the ashes, giving better results the ashes obtained at 500 ºC. The compression tests showed values near to 70% at 7 days but higher than 80% after 28 days for mortars prepared with ashes, respect to the cement mortar reference.

Highlights

Peanut husks (Arachis Hypogaea) are an abundant agroindustrial waste in the region of Córdoba, Argentina, concentrating the 95% of the country’s peanut production
It is well known that the pozzolanic properties of the ashes will depend on its chemical composition, parameter associated to the nature of agro industrial waste, and to its morphology and crystallographic properties, parameters associated to its burnt conditions[23]
The objective of this study was to characterize chemical and morphologically the peanut husk ashes prepared in laboratory controlled conditions and determine its pozzolanic behavior, in order to evaluate its potential use as a supplementary material for cement of mortars

Summary

Introduction

Peanut husks (Arachis Hypogaea) are an abundant agroindustrial waste in the region of Córdoba, Argentina, concentrating the 95% of the country’s peanut production. Ashes from industrial processes (fly ashes, silica fume, slag, etc.) have demonstrated very good properties as pozzolans, because they exhibit binder behavior. This sort of ashes have been studied for many years with interesting results regarding the physical and mechanical properties and the durability of mortars containing these materials as supplement [6, 7, 8, 9, 10, 11]. The objective of this study was to characterize chemical and morphologically the peanut husk ashes prepared in laboratory controlled conditions and determine its pozzolanic behavior, in order to evaluate its potential use as a supplementary material for cement of mortars. This work includes the physical, chemical and morphological characterization of ashes prepared at 500, 650 and 800 oC, the pozzolanic behavior for conductimetric method and the compression strength tests of mortars resulting of the replacement of a 15% of cement with ashes at different ages, for corroborate the results

Objectives

Results

Conclusion