Tobacco waste ash: a promising supplementary cementitious material

Paalo Moreno,Rafael Fragozo,Liliana Hernandez,Jose Delgado,Mauricio Gonzalez,Sergio Vesga,Ivan D Gamboa

doi:10.1007/s40095-018-0272-x

Abstract

According to the European Cement Association, CEMBUREAU, in 2015, the global cement production was 4.6 billion tons. Traditional cement production emits approximately 1 ton of CO2 per ton of cement, which represents almost 80% of the total CO2 emissions of concrete and approximately 6% of the world’s emissions. Among supplementary cementitious materials, the use of agro-waste ash emerges due to its reduced CO2 emissions, chloride diffusion, and materials cost, in addition to its greater compressive strength. In Colombia, the disposal of agro-wastes, such as tobacco waste, is an environmental and economic concern. In this study, ash obtained from tobacco waste (TWA) was studied as a sustainable partial replacement for cement in hydraulic concrete. The TWA was reduced to a particle size of less than 75 μm and was characterized by X-ray florescence. A central composite design was used to study the influence of the ash replacement percentage of cement and the water/binder (w/b) ratio on the compressive strength at 28 days. The results show that it is possible to replace 10% of the cement with TWA using a 0.5 w/b ratio and obtain a 51% higher compressive strength than the control mixture at 28 days. Moreover, the experimental results demonstrated an improvement of 86% in the 7-day compressive strength when TWA was used.

Highlights

Concrete is the most widely used material on earth, apart from water
The goal of the present work is to study the use of tobacco waste ash (TWA) as a promising supplementary cementitious material, and the influence of the ash replacement percentage of cement and the w/b ratio on the compressive strength at 28 days
The central composite design performed corroborated the negative influence of the w/b ratio on the compressive strength and the design demonstrated that it is possible to replace 10% of cement with TWA using a 0.5 w/b ratio and achieve a compressive strength 51% higher than the control mixture (100% cement) at 28 days

Summary

Introduction

Concrete is the most widely used material on earth, apart from water. The main binder of concrete is cement. Traditional cement CO2 emissions are very high and, in some cases, can be more than 1 ton per 1 ton of cement production. 0.55 tons of the carbon dioxide emissions from 1 ton of cement production originate from the chemical reaction (calcination) of calcium carbonate that converts limestone (CaCO3) to calcium oxide (CaO). This reaction occurs at 1400 °C and requires the combustion of fossil fuels, which emits an additional 0.40 tons of greenhouse gas [2]. The cement production emissions represent almost 80% of the total CO2 emissions of concrete, which in turn, are approximately 6–7% of the planet’s total CO2 emissions [3]

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