Proceedings of the 42nd International Conference on Advanced Ceramics and Composites, Volume 39, Issue 3

Jingyang Wang, Waltraud M. Kriven, Tobias Fey, Paolo Colombo, William J. Weber, Jake Amoroso, William G. Fahrenholtz, Kiyoshi Shimamura, Michael Halbig, Soshu Kirihara, Yiquan Wu, Kathleen Shurgart, Jake Amoroso

• Publisher: Wiley-American Ceramic Society
• Year: 2018
• Print ISBN: 9781119543305
• eBook ISBN: 9781119543374
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

Proceeding of the 42nd International Conference on Advanced Ceramics and Composites, Ceramic Engineering and Science Proceedings Volume 39, Issue 3, 2018

Jingyang Wang, Waltraud Kriven, Tobias Fey, Paolo Colombo, William J. Weber, Jake Amoroso, William G. Fahrenholtz, Kiyoshi Shimamura, Michael Halbig, Soshu Kirihara, Yiquan Wu, and Kathleen Shurgart, Editors

Valerie Wiesner and Manabu Fukushima, Volume Editors

This proceedings contains a collection of 22 papers from The American Ceramic Society's 42nd International Conference on Advanced Ceramics and Composites, held in Daytona Beach, Florida, January 21-26, 2018. This issue includes papers presented in the following symposia:

• Advancing Frontiers of Ceramics for Sustainable Societal Development – International Symposium in Honor of Dr. Mrityunjay Singh
• Symposium 9: Porous Ceramics: Novel Developments and Applications
• Symposium 10: Virtual Materials (Computational) Design and Ceramic Genome
• Symposium 12 Materials for Extreme Environments: Ultrahigh Temperature Ceramics (UHTCs) and Nano-laminated Ternary Carbides and Nitrides (MAX Phases)
• Symposium 13 Advanced Ceramics and Composites for Nuclear Fission and Fusion Energy
• Symposium 14 Crystalline Materials for Electrical, Optical and Medical Applications
• Symposium 15 Additive Manufacturing and 3D Printing Technologies
• Symposium 16: Geopolymers, Inorganic Polymers and Sustainable Materials
• Focused Session 1: Bio-inspired Processing of Advanced Materials
• 7th Global Young Investigator Forum

Geopolymers, Chemically Bonded Ceramics, Eco-Friendly and Sustainable Materials

MICROSTRUCTURE AND FLEXURE STRENGTHS OF DOLOMITE PARTICULATE- REINFORCED GEOPOLYMER COMPOSITES

Patrick F. Keane¹ and Waltraud M. Kriven²

¹ Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, IL, USA

² Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801 USA

ABSTRACT

Potassium-based geopolymer was fabricated at room temperature by high shear mixing of potassium metasilicate and metakaolin, forming a composition of K₂O•Al₂O₃•4SiO₂•11H₂O. Dolomite dust waste product was used as a particulate reinforcement to form composites containing 0, 20, 30 and 40 wt % dolomite (CaMg(CO₃)₂). The composites were heat treated at 400, 800 and 1,000°C for 1 hour at a slow ramp rate of 1 °C/min. While single phase geopolymer exhibited 3-pt flexural strengths of ∼7MPa, geopolymer composites containing 20 wt % dolomite and cured at room temperature achieved ∼16 ± 3.5 MPa. In general, strengths drastically decreased due to dehydration, but began to recover after 1000 °C heat treatments. Dolomite particulates helped to dissipate crack energy and enhanced flexural strengths. The geopolymer composites experienced increased porosity due to water loss at 400°C and liberation of CO₂ gas from carbonates at ≥ 800 °C.

INTRODUCTION

Geopolymers a type of chemically bonded ceramics of chemical formula M₂O•Al₂O₃•4SiO₂•11H₂O where M = Na, K, Cs or Li. They are refractory inorganic polymers formed from both aluminum and silicon sources containing AlO_4- and SiO₄ tetrahedral units, under highly alkaline conditions (NaOH, KOH, CsOH) at ambient temperatures. They are a rigid, hydrated, alumino-silicate solid containing group I, charge-balancing cations which result in an amorphous, cross-linked, impervious, acid-resistant, 3-D structure.^1-3

Dolomite is a common rock forming mineral of chemical formula CaMg(CO₃)₂. It is produced as a fine powder during cutting of dolomite grave stones. Fine dolomite is produced in abundance during crushing and grinding of aggregate material for roads and pavements, and has too small of a particle size to be used solely when pouring large scale pavements. Fine dolomite dust by-product was obtained from an Illinois asphalt company, Gallagher Asphalt Corporation.⁴ Upon heating, dolomite begins to decompose at ∼850 °C according to the equation:

Eq. [1]

The final decomposition endotherm peaking at ∼920 °C corresponds to calcite freed from the dolomite decomposition to form lime (CaO) according to the equation:

Eq. [2]

The aim of this research was to develop geopolymer composites containing dolomite waste dust and to investigate the associated 3-point flexure strengths as a function of heat treatment temperatures. The fine dolomite particulates imparted possible benefits of crack energy dissipation upon heating geopolymer-dolomite composites, by causing a crack deflection mechanism to operate in the composite. It was also anticipated that dispersing dolomite particles into the KGP matrix enhanced stability against moisture exposure which normally produces cracking due to the 6.8 nm average diameter, nano porosity of the pure potassium-based geopolymer matrix.

EXPERIMENTAL PROCEDURES

Sample Preparation

Potassium geopolymer was produced by high shear mixing amorphous fumed silica (Cab-o-Sil, Cabot Corp., Boston, MA), DI water, 97% pure KOH, (Sigma Aldrich Inc.) and metakaolin (BASF GmbH, Germany). This was a two-step process in which fumed silica, DI water, and KOH were mixed to produce potassium water glass (K-WG) of composition K₂O + 2SiO₂+ 11H₂O. The K-WG was then mixed with metakaolin of average particle size 1.2 m, using both a high shear IKA mixer (Model RW20DZM, IKA, Wilmington, NC) as well as a Thinky ARE-250 planetary conditioning mixer (Intertronics, Kidlington, Oxfordshire, UK). After mixing and de-airing the geopolymer paste, the dolomite particles were added, followed by high shearing (IKA), gyroscopical mixing (Thinky), and de-airing (Thinky).

The average particle size of the dolomite particles was measured by sieving and weighing. The sample mixtures were poured into a vi...

Table of contents

• Cover
• Title page
• Copyright
• INTRODUCTION
• Advancing Frontiers of Ceramics for Sustainable Societal Development: International Symposium in Honor of Dr. Mrityunjay Singh
• Porous Ceramics: Novel Developments and Applications
• Virtual Materials (Computational) Design and Ceramic Genome
• Materials For Extreme Environments: Ultrahigh Temperature Ceremics (UHTCS) and Nano-Laminated Ternary Carbides and Nitrides (Max Phases)
• Additive Manufactturing and 3D Printing Technologies
• Geopolymers, Chemically Bonded Ceramics, Eco-Friendly and Sustainable Materials
• Bio-Inspried Processing of Advanced Materials
• 7TH Global Young Investigators Forum (GYIF)
• EULA