Process Development of Fly Ash-Based Geopolymer Mortars in View of the Mechanical Characteristics.

Hatice Öznur Öz,Aykut Tamer,Neslihan Doğan-Sağlamtimur,Ahmet Bilgil,Kadir Günaydin

doi:10.3390/ma14112935

Hatice Öznur Öz, Aykut Tamer + Show 3 more

Open Access

https://doi.org/10.3390/ma14112935

Copy DOI

Abstract

This study aimed to determine the effects of design parameters, including the liquid/solid ratio (L/S), Na2SiO3/NaOH weight ratio, and curing temperature, on class F fly ash-based geopolymer composites. For this purpose, two disparate sources of fly ash were supplied from Çatalağzı (FA) and İsken Sugözü (FB) Thermal Power Plants in Turkey. Two different L/S ratios of 0.2 and 0.4 were used. The Na2SiO3/NaOH ratios in the alkaline solutions were 1, 1.5, 2, 2.5, and 3 by weight for each type of geopolymer mixture. Then, 40 different mixes were cured at two specific temperatures (70 °C and 100 °C) for 24 h and then preserved at room temperature until testing. Thereafter, the physical water absorption properties, apparent porosity, and bulk density were examined at 28 days on the hardened mortars. Additionally, compressive and flexural tests were applied to the geopolymers at 7, 28, and 90 days. It was found that the highest compressive strength was 60.1 MPa for the geopolymer manufactured with an L/S of 0.2 and Na2SiO3/NaOH ratio of 2. Moreover, the best thermal curing temperature for obtaining optimal strength characteristics was 100 °C for the FB.

Highlights

The flowability of fresh geopolymer mortars is controlled by the amount of water in the mix, without compromising the strength [44]
In line withwith the literature, this this study showed thatgeopolymer the geopolymer mortar, is produced a higher alkali study showed that the mortar, whichwhich is produced with a with higher alkali content content and at cured at a higher temperature, a lower water absorption cured a higher temperature, had ahad lower water absorption rate rate and and apparent porosity values
This study showed that geopolymer mortars can be manufactured through activation of locally available class F fly ashes (FA and FB) with different alkaline solution types and contents

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Ordinary Portland cement (OPC) is the essential material and compound in the construction industry due to the strength requirements for structural concrete. The increased production of OPC to fulfill the extensive demand for concrete has resulted in high energy consumption and depletion of natural sources, deteriorating the ecological balance. Cement production has become a leading cause of greenhouse gas emissions [1]

Objectives

Methods

Results

Conclusion