Production and characterization of alkali-activated cements (AAC) obtained from the coffee husk ash (CHA) as alkaline activator

• Grant number: 22/06570-2
• Support Opportunities: Regular Research Grants
• Start date: August 01, 2023
• End date: July 31, 2025
• Field of knowledge: Engineering - Civil Engineering - Construction Industry
• Principal Investigator: João Claudio Bassan de Moraes
• Grantee: João Claudio Bassan de Moraes
• Host Institution: Divisão de Engenharia Civil (IEI). Instituto Tecnológico de Aeronáutica (ITA). São José dos Campos , SP, Brazil
• City of the host institution: São José dos Campos
• Associated researchers: Guilherme Chagas Cordeiro ; Thiago Costa Ferreira Gomes

Abstract

Brazil is the main coffee producer in the world. However, this production generates significant amount of wastes, as coffee husks. These residues can be employed as biomass to generate energy in a burning process in boilers. After this combustion process, another residue is generated: the coffee husk ash (CHA). A suitable destination to this waste is using it in alkali-activated cements (AAC). AACs are obtained from a reaction between a precursor solid and alkaline activator (or alkali source) in water. This project proposes the use of CHA as alkaline activator in alkali-activated cements (AAC) based on metakaolin as solid precursor. Related to the methodology, coffee husks will be obtained from coffee plantations, where it will be calcined and homogenized in laboratory in order to determine the best preparation to be utilized as alkaline activator. Then, the CHA will be chemical and physical characterized in order to assess its potential in AAC (Step 1). After the characterization, the CHA will be employed in AAC mortars (Step 2) and pastes (Step 3) in order to define the most suitable alkaline source amount to produce materials with best mechanical and physical properties. In mortars, it will be evaluated mechanical and physical properties in order to assess the optimum alkaline source content; whereas, for pastes, physical properties and microstructural tests will be carried out in order to understand the reaction process and microstructure, explaining the mortars tests results. It is expected that, with the results from this work, it can be possible do valorize the CHA as inorganic binder in AAM, yielding a suitable destination to this potential sustainable material. (AU)