Optimization of the Mix Formulation of Geopolymer Using Nickel-Laterite Mine Waste and Coal Fly Ash

Alberto Longos,Michael Angelo Promentilla,Hirofumi Hinode,April Anne Tigue,Ithan Jessemar Dollente,Ivyleen Bernardo-Arugay,Winarto Kurniawan,Roy Alvin Malenab

doi:10.3390/min10121144

Abstract

Geopolymer cement has been popularly studied nowadays compared to ordinary Portland cement because it demonstrated superior environmental advantages due to its lower carbon emissions and waste material utilization. This paper focuses on the formulation of geopolymer cement from nickel–laterite mine waste (NMW) and coal fly ash (CFA) as geopolymer precursors, and sodium hydroxide (SH), and sodium silicate (SS) as alkali activators. Different mix formulations of raw materials are prepared to produce a geopolymer based on an I-optimal design and obtained different compressive strengths. A mixed formulation of 50% NMW and 50% CFA, SH-to-SS ratio of 0.5, and an activator-to-precursor ratio of 0.429 yielded the highest 28 d unconfined compressive strength (UCS) of 22.10 ± 5.40 MPa. Furthermore, using an optimized formulation of 50.12% NMW, SH-to-SS ratio of 0.516, and an activator-to-precursor ratio of 0.428, a UCS value of 36.30 ± 3.60 MPa was obtained. The result implies that the synthesized geopolymer material can be potentially used for concrete structures and pavers, pedestrian pavers, light traffic pavers, and plain concrete.

Highlights

The rapid increase in construction activity has been observed to meet the ever-increasing infrastructure demands [1]
This paper presents an experimental study to produce an optimized geopolymer material that yields the highest value of unconfined compressive strength from the mixture of nickel–laterite mine waste (NMW), coal fly ash (CFA), and an alkali activator with components of sodium hydroxide (SH)
The optimum formulation mix was found to have an activator-to-precursor ratio of 0.428% NMW of 50.1%, and SH-to-sodium silicate (SS) ratio of 0.520, which produces a geopolymer with an average 28-day compressive strength of 36.3 MPa

Summary

Introduction

The rapid increase in construction activity has been observed to meet the ever-increasing infrastructure demands [1]. Cement-based concrete is an essential and widely used material. The use of cement-based concrete, like ordinary Portland cement (OPC), is globally accepted due to ease of operation, excellent mechanical properties, and low-cost production compared to other construction materials [2]. OPC has drawbacks as it releases approximately one ton of CO2 , a greenhouse gas, to produce one ton of OPC [3]. It has high energy consumption during production, and it consumes a significant amount of natural resources [2,3].

Methods

Results

Conclusion