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<p>The resurgence of earthen materials in construction is a response to the desire to make the sector more environmentally friendly by promoting the use of alternative binders to cement in the stabilization of earthen building materials. The current climate, characterized by an increase in arid events, particularly in the Sahelian zones, accompanied by multiple droughts and fires, raises questions about the suitability of Compressed Earth Blocks (CEBs) despite their low intrinsic energy. This study examined the thermal stability of CEBs stabilized with a geopolymer binder. Lateritic soil from the Kamboinsin quarry (Ouagadougou) was stabilized with a geopolymer binder synthesized with metakaolin (MK) in mass proportions of 10–20%. A 12&#xa0;M sodium hydroxide solution was used to activate MK. The wet mixtures were placed in a <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(295\times140\times95{\text{m}\text{m}}^{3}\)</EquationSource> </InlineEquation>prismatic mold in a Terstaram press, where a pressure of 3.5&#xa0;MPa was applied to produce the CEBs. The CEBs samples were exposed to high temperatures at a rate of 10&#xa0;°C/min up to 300&#xa0;°C, 600&#xa0;°C, 900&#xa0;°C, and 1200&#xa0;°C for a 2&#xa0;h plateau. X-ray diffraction (XRD) and thermal gravimetric analysis (TGA), coupled with Fourier transform infrared analysis (FTIR), revealed mineralogical changes, particularly dehydration and dehydroxylation of some mineral phases (kaolinite, halloysite, and goethite) and hydration products (zeolites A and U, calcium silicate hydrates, and portlandite) in the CEBs. Mass losses increased with increasing temperature, peaking at 19.63% at 1200&#xa0;°C for CEB stabilized at 8% cement (CEB_8C). This resulted in a very low wet-to-dry compressive strength ratio of less than 0.2 for all CEBs at 300&#xa0;°C. Above 300&#xa0;°C, only CEB_10G at 600&#xa0;°C and 1200&#xa0;°C and CEB_8C at 600&#xa0;°C had ratios below 0.5, which reduced their durability as a result of exposure to high temperature, although geopolymer-stabilized CEBs (CEB_G) performed better than CEB_8C. Thus, based on the results, CEB_G can be used in dwellings or even in incinerators in arid areas prone to fire.</p>

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High-temperature exposure of metakaolin-geopolymer stabilized compressed earth blocks: mineralogical and physico-mechanical evolution

  • 期刊论文

  • 发表日期：

    2026年4月9日

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  • Kader Banaou Djibo,
  • Seick Omar Sore,
  • Philbert Nshimiyimana,
  • David Yao Akodenyon,
  • Adamah Messan

摘要

The resurgence of earthen materials in construction is a response to the desire to make the sector more environmentally friendly by promoting the use of alternative binders to cement in the stabilization of earthen building materials. The current climate, characterized by an increase in arid events, particularly in the Sahelian zones, accompanied by multiple droughts and fires, raises questions about the suitability of Compressed Earth Blocks (CEBs) despite their low intrinsic energy. This study examined the thermal stability of CEBs stabilized with a geopolymer binder. Lateritic soil from the Kamboinsin quarry (Ouagadougou) was stabilized with a geopolymer binder synthesized with metakaolin (MK) in mass proportions of 10–20%. A 12 M sodium hydroxide solution was used to activate MK. The wet mixtures were placed in a \(295\times140\times95{\text{m}\text{m}}^{3}\) prismatic mold in a Terstaram press, where a pressure of 3.5 MPa was applied to produce the CEBs. The CEBs samples were exposed to high temperatures at a rate of 10 °C/min up to 300 °C, 600 °C, 900 °C, and 1200 °C for a 2 h plateau. X-ray diffraction (XRD) and thermal gravimetric analysis (TGA), coupled with Fourier transform infrared analysis (FTIR), revealed mineralogical changes, particularly dehydration and dehydroxylation of some mineral phases (kaolinite, halloysite, and goethite) and hydration products (zeolites A and U, calcium silicate hydrates, and portlandite) in the CEBs. Mass losses increased with increasing temperature, peaking at 19.63% at 1200 °C for CEB stabilized at 8% cement (CEB_8C). This resulted in a very low wet-to-dry compressive strength ratio of less than 0.2 for all CEBs at 300 °C. Above 300 °C, only CEB_10G at 600 °C and 1200 °C and CEB_8C at 600 °C had ratios below 0.5, which reduced their durability as a result of exposure to high temperature, although geopolymer-stabilized CEBs (CEB_G) performed better than CEB_8C. Thus, based on the results, CEB_G can be used in dwellings or even in incinerators in arid areas prone to fire.