Geopolymer foam concrete: An emerging material for sustainable construction

This study reports the synthesis and characterization of geopolymer foam concrete (GFC). A Class F fly ash with partial slag substitution was used for GFC synthesis by mechanical mixing of preformed foam. The GFCs exhibited 28 d compressive strengths ranging from 3 to 48 MPa with demolded densities from 720 to 1600 kg/m3 (105 °C oven-dried densities from 585 to 1370 kg/m3), with the different densities achieved through alteration of the foam content. The thermal conductivity of GFCs was in the range 0.15–0.48 W/m K, showing better thermal insulation properties than normal Portland cement foam concrete at the same density and/or at the same strength. The GFC derived from alkali activation of fly ash as a sole precursor showed excellent strength retention after heating to temperatures from 100 to 800 °C, and the post-cooling compressive strength increased by as much as 100% after exposure at 800 °C due to densification and phase transformations. Partial substitution of slag for fly ash increased the strength of GFC at room temperature, but led to notable shrinkage and strength loss at high temperature. Thin GFC panels (20–25 mm) exhibited acoustic absorption coefficients of 0.7–1.0 at 40–150 Hz, and 0.1–0.3 at 800–1600 Hz.

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Mechanical, thermal insulation, thermal resistance and acoustic absorption properties of geopolymer foam concrete

Fly ash-based eco-friendly geopolymer concrete: A critical review of the long-term durability properties

Characterization of geopolymer fly-ash based foams obtained with the addition of Al powder or H2O2 as foaming agents

Facile fabrication of green geopolymer/alginate hybrid spheres for efficient removal of Cu(II) in water: Batch and column studies

In this paper, we report the results of our investigation on the possibility of producing foam concrete by using a geopolymer system. Class C fly ash was mixed with an alkaline activator solution (a mixture of sodium silicate and NaOH), and foam was added to the geopolymeric mixture to produce lightweight concrete. The NaOH solution was prepared by dilute NaOH pellets with distilled water. The reactives were mixed to produce a homogeneous mixture, which was placed into a 50 mm mold and cured at two different curing temperatures (60 °C and room temperature), for 24 hours. After the curing process, the strengths of the samples were tested on days 1, 7, and 28. The water absorption, porosity, chemical composition, microstructure, XRD and FTIR analyses were studied. The results showed that the sample which was cured at 60 °C (LW2) produced the maximum compressive strength for all tests, (11.03 MPa, 17.59 MPa, and 18.19 MPa) for days 1, 7, and 28, respectively. Also, the water absorption and porosity of LW2 were reduced by 6.78% and 1.22% after 28 days, respectively. The SEM showed that the LW2 sample had a denser matrix than LW1. This was because LW2 was heat cured, which caused the geopolymerization rate to increase, producing a denser matrix. However for LW1, microcracks were present on the surface, which reduced the compressive strength and increased water absorption and porosity.

https://www.mdpi.com/1422-0067/13/6/7186/pdf

Fly Ash-based Geopolymer Lightweight Concrete Using Foaming Agent

This paper presents the results of a study on the effect of temperature on geopolymers manufactured using pozzolanic materials (fly ash). In this paper, we report on our investigation of the performance of porous geopolymers made with fly ash after exposure to temperatures from 600 °C up to 1000 °C. The research methodology consisted of pozzolanic materials (fly ash) synthesized with a mixture of sodium hydroxide and sodium silicate solution as an alkaline activator. Foaming agent solution was added to geopolymer paste. The geopolymer paste samples were cured at 60 °C for one day and the geopolymers samples were sintered from 600 °C to 1000 °C to evaluate strength loss due to thermal damage. We also studied their phase formation and microstructure. The heated geopolymers samples were tested by compressive strength after three days. The results showed that the porous geopolymers exhibited strength increases after temperature exposure.

https://www.mdpi.com/1422-0067/13/4/4388/pdf

Mohamed Bnhussain

Papers

Fly Ash-based Geopolymer Lightweight Concrete Using Foaming Agent

Fly Ash Porous Material using Geopolymerization Process for High Temperature Exposure