Characterization and compressive strength of fly ash based-geopolymer paste

Ari Widayanti,Hitapriya Suprayitno,Ria Asih Aryani Soemitro,Januarti Jaya Ekaputri,P Hajek,W.T Chan,R Sriravindrarajah,S Kristiawan,B.S Gan,B.A Hidayat,M.B Ismail,A.L Han

doi:10.1051/matecconf/201819501023

Abstract

Fly ash is a by-product obtained from coal combustion process. Some of the utilization of fly ash is to produce geopolymer products which have high compressive strength, fire, chemical resistance. This paper proposes fly ash from unit 1-7 Suralaya Power Plant Indonesia. The aims of this study are to obtain characterization of fly ash and mechanical properties of geopolymer paste based on variations of the alkali activator ratio. The method was based on previous research and laboratory investigation. XRF and compressive strength were analysed in this study. Alkali activator was obtained from NaOH and Na2SiO3 mixture. The ratio of Na2SiO3 to NaOH was in the range of 0.5-2.5. Geopolymer paste was casted in acrylic cylinders with a diameter of 2 cm and a height of 4 cm. The curing was conducted at room temperature until the day for the compressive strength test at 28 days. The result showed that the fly ash is classified as F class. Increasing the alkali activator ratio influenced the strength. The best composition of geopolymer paste is made with NaOH 8M, and the mass ratio of Na2SiO3 to NaOH is 2.5. This composition produced compressive strength of 98.6 MPa.

Highlights

The issue of environmental sustainability is one aspect that is currently being addressed by the United Nations
The aims of this study were to obtain material characteristics and compressive strength of geopolymer paste based on fly ash
The addition of calcium carbonate content up to 15% improved the workability of fresh mortar and compressive strength of mortar, mainly at early ages

Summary

Introduction

The issue of environmental sustainability is one aspect that is currently being addressed by the United Nations. This is stated in the Sustainable Development Goals, such as the issue of the innovation of infrastructure. In this case research related to innovation in materials is one part of innovation infrastructures. The Indonesian Government in the RPJMN (Rencana Pembangunan Jangka Menengah Nasional) emphasizes the importance of infrastructure development in order to improve the distribution of people and goods that will have implications on the economic, political, social, cultural and security aspect. The process of generating electricity generates environmental waste from the coal combustion process

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