In this study, a clayey soil classified as A-7-5 according ASTM D3282, was stabilized using alkali-activated cementitious materials (AAC) added to the soil dry in percentages of 20 and 30%. Fly ash (F1, F2) with high unburned carbon content (up to 38.76%), hydrated lime (L) and granulated blast furnace slag were used. Unconfined compressive strength and flexural strength at 28 days of curing and the durability after 12 wetting-drying cycles were evaluated. The results were compared with a soil-cement reference mixture. The soil treated with AAC-F1L showed a volume expansion of 0.51% and volume contraction of -0.57% compared with the 0.59% expansion and -0.68% contraction of the soil-cement reference mixture. Additionally, the mass loss after the wetting and drying cycles is only 3.74% which is slightly lower than the mass loss of the soil stabilized with ordinary Portland cement (OPC) (3.86%) and well below the value specified in Colombian regulations (7%).
The interest of the construction industry in alkali-activated materials has increased to the extent that these materials are recognized as alternatives to ordinary Portland cement-based materials in the quest for sustainable construction. This article presents the design and construction of a prototype of an eco-friendly house built from concrete blocks produced using alkali activation technology or geopolymerization. The prototype meets the requirements of the current Colombian Regulations for Earthquake Resistant Buildings (NSR-10) and includes standards related to the performance of the materials, design, and construction method for earthquake-resistant confined masonry of one- or two-story buildings. The alkali-activated blocks were obtained from different precursors (aluminosilicates), including a natural volcanic pozzolan, ground granulated blast furnace slag, fly ash, construction and demolition waste (concrete, ceramic, brick, and mortar), and red clay brick waste. The physical-mechanical characterization of the alkali-activated blocks allowed their classification according to the structural specifications of the Colombian Technical Standard NTC 4026 (equivalent to ASTM C90). The global warming potential (GWP) or “carbon footprint” attributed to the raw materials of alkali-activated blocks was lower (25.4–54.7%) than that of the reference blocks (ordinary Portland cement concrete blocks). These results demonstrate the potential of alkali-activated materials for application in the construction of eco-friendly houses.
El creciente interés por el desarrollo de alternativas frente al uso masivo de cementantes tradicionales en aplicaciones geotécnicas, tales como cemento y cal, se debe en gran medida a los retos ambientales y costos asociados en este tipo de aplicaciones. Los cementantes activados alcalinamente surgen como una de las alternativas de mayor sostenibilidad, particularmente por su bajo consumo energético y en teoría la baja huella de carbono en su fabricación; además, tienen la posibilidad de utilizar residuos y subproductos industriales como materiales precursores en su fabricación. Este artículo presenta un estado del arte de los diversos materiales empleados convencionalmente en la estabilización química de suelos y realiza una revisión de los artículos publicados en relación con la implementación de cementantes activados alcalinamente, su viabilidad técnica, los impactos ambientales asociados y los retos que se deben superar para lograr posicionarlos como una alternativa sostenible para procesos geotécnicos.
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