Alkali-activated aluminosilicate composite with heat-resistant lightweight aggregates exposed to high temperatures: Mechanical and water transport properties

Abstract A lightweight composite material with alkali-activated aluminosilicate binder is investigated. The intended use of this material is the high-temperature applications, such as the fire-protecting layers for Portland-cement based structures. Therefore, a heat-resistant mixture of expanded vermiculite and electrical porcelain is used as aggregates. Basic physical characteristics, mechanical properties and water- and water vapor transport properties are studied as functions of previous heat treatment up to 1200 °C. Experimental results show that the studied material has very good high-temperature properties which are quite superior to Portland-cement concrete. The open porosity increases only up to 7% between room temperature and 1000 °C. The material keeps 35% of its original compressive strength and 66% of its flexural strength even in the worst case of 800 °C pre-heating. After pre-heating to 1200 °C the compressive strength is found 30% higher and flexural strength three-and-half times higher than in the reference state. Liquid moisture diffusivity is after the heat treatment up to three orders of magnitude higher than in reference room-temperature conditions. The water vapor transport parameters allow fast removal of water vapor and other gaseous compounds over the whole studied heat-treatment range.

[1]  D. Roy.  Alkali-activated cements Opportunities and challenges , 1999 .

[2]  A. Fernández-Jiménez,et al.  New Cementitious Materials Based on Alkali-Activated Fly Ash: Performance at High Temperatures , 2008 .

[3]  J. Sanjayan,et al.  Residual compressive behavior of alkali‐activated concrete exposed to elevated temperatures , 2009 .

[4]  F. Puertas,et al.  Mineralogical and microstructural characterisation of alkali-activated fly ash/slag pastes , 2003 .

[5]  P. Rovnaník,et al.  Mechanical and hydric properties of alkali-activated aluminosilicate composite with electrical porcelain aggregates , 2008 .

[6]  Grant C. Lukey,et al.  Physical evolution of Na-geopolymer derived from metakaolin up to 1000 °C , 2007 .

[7]  Jay G. Sanjayan,et al.  Effect of admixtures on properties of alkali-activated slag concrete , 2000 .

[8]  S. Al-Otaibi,et al.  Durability of concrete incorporating GGBS activated by water-glass , 2008 .

[9]  Fernando Pacheco-Torgal,et al.  Alkali-activated binders: A review: Part 1. Historical background, terminology, reaction mechanisms and hydration products , 2008 .

[10]  Keun-Hyeok Yang,et al.  Properties of cementless mortars activated by sodium silicate , 2008 .

[11]  Ángel Palomo,et al.  Alkali-activated fly ashes: A cement for the future , 1999 .

[12]  J. Deventer,et al.  Thermal evolution of metakaolin geopolymers: Part 1 – Physical evolution , 2006 .

[13]  Keun-Hyeok Yang,et al.  Workability Loss and Compressive Strength Development of Cementless Mortars Activated by Combination of Sodium Silicate and Sodium Hydroxide , 2009 .

[14]  R. H. Atkinson.  Recent advances in the applied chemistry of the rare metals. Jubilee memorial lecture , 1940 .

[15]  W. McCarter,et al.  The early hydration of alkali-activated slag: developments in monitoring techniques , 1999 .

[16]  R. Černý,et al.  Properties of Alkali Activated Aluminosilicate Material after Thermal Load , 2006 .

[17]  R. Černý,et al.  A simple gravimetric method for determining the moisture diffusivity of building materials , 2003 .

[18]  Fernando Pacheco-Torgal,et al.  Alkali-activated binders: A review. Part 2. About materials and binders manufacture , 2008 .

[19]  Pavla Rovnaníková,et al.  Transport processes in concrete , 2002 .

[20]  M. K. Kumaran,et al.  Moisture Diffusivity of Building Materials from Water Absorption Measurements , 1999 .

[21]  Robert Černý,et al.  Measurement of linear thermal expansion coefficient of alkali-activated aluminosilicate composites up to 1000 °C , 2009 .

[22]  V. M. Malhotra,et al.  Properties and Durability of Alkali-Activated Slag Concrete , 1992 .

[23]  Jay G. Sanjayan,et al.  Unsaturated capillary flow within alkali activated slag concrete , 2008 .

[24]  J. Carmeliet,et al.  Interlaboratory Comparison of Hygric Properties of Porous Building Materials , 2004 .

[25]  J. Sanjayan,et al.  Workability and mechanical properties of alkali activated slag concrete , 1999 .