Production Process of an Eco-Friendly One-Part Alkali-Activated Binder

Rodrigo H Geraldo,Jardel P Gonçalves,Gladis Camarini

doi:10.1590/1980-5373-mr-2021-0433

Abstract

One-part alkali-activated binder (AAB) is a product with lower environmental impact than Portland cement, and can be a feasible commercial alternative. The main objective of this study was to propose and test a method of obtaining one-part AAB with metakaolin and an alternative powder sodium silicate from rice husk ash (RHA). To evaluate the AAB properties, mortars were produced with different SiO2/Al2O3 molar ratios (2.7, 3.1, and 3.3), and tests were conducted to characterize the binder. The results indicated that the process was efficient in generating a non-crystalline sodium silicate powdered material. With high SiO2/Al2O3 molar ratio the mortars achieved high compressive strength and it increased with age, had low permeability, and capillary water absorption. Compressive strength results varied from 6 MPa to 12 MPa at 28 days, indicating the possibility of using the proposed method for one-part AAB production. AAB produced can be applied in different building materials.

Highlights

Alkali-activated binder (AAB) can be considered one of the breakthroughs in concrete technology of the last century[1]
AAB is an alternative to Portland cement (PC), and it is formed by a chemical reaction between an alkali-activator with an aluminosilicate precursor[2]
The method to one-part AAB obtaining was divided into steps as shown in Figure 4 and described, as follows

Summary

Introduction

Alkali-activated binder (AAB) can be considered one of the breakthroughs in concrete technology of the last century[1]. AAB is an alternative to Portland cement (PC), and it is formed by a chemical reaction between an alkali-activator with an aluminosilicate precursor[2]. The environmental benefits of AAB have driven the interest in this cement. AAB production does not demand high calcination temperatures and the chemical reaction does not release CO23,4. According to Carreño-Gallardo et al.[5], the replacement of PC by AAB can provide a reduction of up to 1480 million tons of CO2 per year. The reduction of CO2 emissions when compared to PC is one of the main facts that direct the researchers to pay attention to AAB6

Objectives

Methods

Results

Conclusion