Cleaner production of the lightweight insulating composites: Microstructure, pore network and thermal conductivity

This paper investigates the effect of incorporation of lightweight aggregate and foam in the preparation of lightweight aggregate geopolymer concrete (LWAGC) and lightweight aggregate foamed geopolymer concrete (LWAFGC). The geopolymer paste was formed by alkali activation of Class F fly ash in mixture of sodium silicate and sodium hydroxide solution. LWAGC was incorporated with expanded clay lightweight aggregate and river sand while hydrogen peroxide was added as foaming agent for LWAFGC. Results showed that LWAGC and LWAFGC achieved an excellent 28-day compressive strength of 60 MPa and 20 MPa, respectively. The bulk densities were 1815 kg/m3 for LWAGC and 1593 kg/m3 for LWAFGC. Even so, low thermal conductivity of 0.12 W/mK and 0.09 W/mK were reported. It was concluded that the joint effect of lightweight aggregate and foam produced geopolymer concrete with good mechanical strength while having excellent thermal insulating properties. The geopolymer concretes possessed high strength-to-density ratio to be regarded as lightweight high-performance structures.

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“…has been obtained by Subaer & van Riessen [64]. Generally, geopolymer has 50% [34,65,66] lower TC than PC concretes with 1.5 W/mK [66].…”

Section: Thermal Conductivity (Tc)mentioning

confidence: 87%

Compressive Strength and Thermal Conductivity of Fly Ash Geopolymer Concrete Incorporated with Lightweight Aggregate, Expanded Clay Aggregate and Foaming Agent

Yun-Ming¹,

Sandu²,

Cheng-Yong³

et al. 2019

Rev. Chim.

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“…Fongang et al [4] used sawdust as a foaming agent to produce lightweight insulating composites. Yahya et al [5] used rice husk as an additive in fly ash-based geopolymer mortars.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and mechanical, physical and structural properties of sustainable lightweight metakaolin-based geopolymer cements and mortars employing rice husk

Riyap

Bewa

Banenzoué

et al. 2019

Journal of Asian Ceramic Societies

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This work focuses on an in-depth investigation of the formation of pores in the structure of lightweight geopolymer cements and mortars using rice husk as a foaming agent. The hardener used in this study was sodium waterglass. Metakaolin was replaced by 0, 10, 20, 30 and 40 % by mass of husk and the obtained powders were used to produce lightweight geopolymer cements and mortars. The formation of pores in the lightweight geopolymer cements was monitored using X-ray diffractometry and infrared spectroscopy while those in the mortars were assessed using apparent density and compressive strength measurements, mercury intrusion porosimetry and optical and scanning electron microscopy. The values for the compressive strength and apparent density were in the ranges of 28.92-0.75 MPa and 1.88-1.70 g/cm 3 , respectively. The results indicated that the values for the compressive strength and apparent density of geopolymer mortars decreased while those of the cumulative pore volume increased with increases in the metakaolin replacement level. Stereomicroscopic and scanning electron microscopic images showed the presence of rice husk and fibres of rice husk, respectively, in the networks. It was found that rice husk can be used as a foaming agent for producing sustainable lightweight geopolymer mortars.

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“…Insulating and flame-resistant materials have been recently developed as greener alternatives to the more traditional petrochemical-derived solutions [6]: an increasing use of renewable resources and new manufacturing processes integrating wastes are being largely adopted in the production of insulating products [1,4,[7][8][9]. Nevertheless, fully meeting the technical and safety requirements and at the same time reducing the environmental impact of the manufacturing process still represents an issue to address.…”

Section: Introductionmentioning

confidence: 99%

“…As well as being excellent candidates for the development of thermal insulating and flame-resistant products, geopolymers have the advantage that they can be obtained from a wide range of by-products and waste materials, including coal combustion ashes, biomass ashes, metallurgical slags, construction and demolition wastes and the like, having therefore a negligible impact on the environment [7,9,22]. Among them, ashes derived from the combustion of vegetal and animal residues still represent an understudied source material for the production of alkali activated materials, given their peculiar chemical nature largely based on calcium phosphates, alkali sulphates and chlorides and only secondarily on reactive aluminosilicates [23,24].…”

Section: Introductionmentioning

confidence: 99%

Porous Geopolymer Insulating Core from a Metakaolin/Biomass Ash Composite

et al. 2017

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Ashes derived from the combustion of vegetal and animal biomass still represent a mostly unexplored secondary raw material for the production of alkali-activated materials, given their peculiar chemical nature. In this work, calcium phosphate biomass ashes were successfully used as partially reactive fillers in a metakaolin-based geopolymer composite to produce, by direct foaming, sustainable and lightweight boards with thermal insulating properties. The investigated materials were obtained by activating a blend of metakaolin and biomass ash in a weight ratio of 1: 1 and foamed with the addition of H 2 O 2 in measure of 5 wt. %, to maximize the volume of disposed ash and ensure adequate properties to the material at the same time. The obtained geopolymer composite was characterized by microstructural, chemical-physical, mechanical and thermal analysis: the obtained results showed that biomass ash and metakaolin well integrated in the microstructure of the final porous material, which was characterized by a density of about 310 kg/m 3 and a thermal conductivity of 0.073 W/mK at a mean test temperature of 30 • C, coupled with an acceptable compressive strength of about 0.6 MPa. Dilatometric and thermogravimetric analysis, performed up to 1000 • C, highlighted the thermal stability of the composite, which could be regarded as a promising material for low-cost, self-bearing thermal insulating partitions or lightweight cores for thermostructural sandwich panels.

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Cleaner production of the lightweight insulating composites: Microstructure, pore network and thermal conductivity

Cited by 45 publications

References 26 publications

Compressive Strength and Thermal Conductivity of Fly Ash Geopolymer Concrete Incorporated with Lightweight Aggregate, Expanded Clay Aggregate and Foaming Agent

Compressive Strength and Thermal Conductivity of Fly Ash Geopolymer Concrete Incorporated with Lightweight Aggregate, Expanded Clay Aggregate and Foaming Agent

Microstructure and mechanical, physical and structural properties of sustainable lightweight metakaolin-based geopolymer cements and mortars employing rice husk

Porous Geopolymer Insulating Core from a Metakaolin/Biomass Ash Composite

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