The Performance and Reaction Mechanism of Untreated Steel Slag Used as a Microexpanding Agent in Fly Ash-Based Geopolymers

Steel slag is an industrial by-product of the steelmaking process, which is under-utilized and of low value due to its characteristics. Alkali-activated technology offers the possibility of high utilization and increased value of steel slag. A geopolymer composition was composed of steel slag, fly ash, and calcium hydroxide. Four experimental groups utilizing steel slag to substitute fly ash are established based on varying replacement levels: 35%, 40%, 45%, and 50% by mass. The final samples were characterized by compressive strength tests, and Fourier-transform infrared spectroscopy measurements, thermogravimetric measurements, scanning electron microscopy with energy dispersive spectroscopy, X-ray diffraction, and mercury intrusion porosimetry were used to investigate the chemical composition and microstructure of the final products. Higher steel slag/fly ash ratios lead to a lower bulk density and lower compressive strength. The compressive strength ranges from 3.7 MPa to 5.6 MPa, and the bulk density ranges from 0.85 g/cm3 to 1.13 g/cm3. Microstructural and energy-dispersive X-ray spectroscopy analyses show that the final geopolymer products were a type of composite consisting of both calcium aluminate silicate hydrate and sodium aluminate silicate hydrate, with the unreacted crystalline phases acting as fillers.

[1]  A. Rashad,et al.  Thermal insulation and durability of alkali-activated lightweight slag mortar modified with silica fume and fly ash , 2024, Construction and Building Materials.

[2]  Yiyan Lu,et al.  Effects and mechanisms of component ratio and cross-scale fibers on drying shrinkage of geopolymer mortar , 2024, Construction and Building Materials.

[3]  Fusong Wang,et al.  Effects of GBFS content and curing methods on the working performance and microstructure of ternary geopolymers based on high-content steel slag , 2024, Construction and Building Materials.

[4]  B. Ghiassi,et al.  A comparative study of calcium hydroxide, calcium oxide, calcined dolomite, and metasilicate as activators for slag-based HPC , 2023, Structures.

[5]  Chengqing Wu,et al.  A novel development of HPC without cement: Mechanical properties and sustainability evaluation , 2023, Journal of Building Engineering.

[6]  Tengyu Ma,et al.  Understanding the changes in engineering behaviors and microstructure of FA-GBFS based geopolymer paste with addition of silica fume , 2023, Journal of Building Engineering.

[7]  Changqing Wang,et al.  Effect of ground concrete waste as green binder on the micro-macro properties of eco-friendly metakaolin-based geopolymer mortar , 2023, Journal of Building Engineering.

[8]  Zhengguang Sun,et al.  Properties and microstructure of self-waterproof metakaolin geopolymer with silane coupling agents , 2022, Construction and Building Materials.

[9]  Yang Luo,et al.  The mechanism of pristine steel slag for boosted performance of fly ash-based geopolymers , 2022, Journal of the Indian Chemical Society.

[10]  Luming Wang,et al.  The performance of micropore-foamed geopolymers produced from industrial wastes , 2021 .

[11]  L. Pérez-Villarejo,et al.  Effect of steel slag and curing temperature on the improvement in technological properties of biomass bottom ash based alkali-activated materials , 2021 .

[12]  Shupin Wang,et al.  Utilization of BOF steel slag aggregate in metakaolin-based geopolymer , 2021 .

[13]  C. White,et al.  The effects of calcium hydroxide and activator chemistry on alkali-activated metakaolin pastes , 2021, Cement and Concrete Research.

[14]  B. Ghiassi,et al.  Fracture properties and microstructure formation of hardened alkali-activated slag/fly ash pastes , 2021, Cement and Concrete Research.

[15]  Yujing Zhao,et al.  Influence of steel slag on the properties of alkali-activated fly ash and blast-furnace slag based fiber reinforced composites , 2020 .

[16]  Shucai Li,et al.  Investigation the synergistic effects in quaternary binder containing red mud, blast furnace slag, steel slag and flue gas desulfurization gypsum based on artificial neural networks , 2020 .

[17]  Shaoyun Pu,et al.  Efficient use of steel slag in alkali-activated fly ash-steel slag-ground granulated blast furnace slag ternary blends , 2020 .

[18]  Faiz Shaikh,et al.  Characterization and properties of geopolymer nanocomposites with different contents of nano-CaCO3 , 2020 .

[19]  L. Tang,et al.  Shrinkage behaviour, early hydration and hardened properties of sodium silicate activated slag incorporated with gypsum and cement , 2020 .

[20]  Luming Wang,et al.  The reaction between Ca2+ from steel slag and granulated blast-furnace slag system: a unique perspective , 2020, Chemical Papers.

[21]  J. Labrincha,et al.  Geopolymer foams: An overview of recent advancements , 2020 .

[22]  A. Akbarnezhad,et al.  Recycled geopolymer aggregates as coarse aggregates for Portland cement concrete and geopolymer concrete: Effects on mechanical properties , 2020 .

[23]  Ji-xiang Wang,et al.  Synthesis of fly ash-based self-supported zeolites foam geopolymer via saturated steam treatment. , 2020, Journal of hazardous materials.

[24]  Zhiduo Zhu,et al.  Effect of steel slag on fresh, hardened and microstructural properties of high-calcium fly ash based geopolymers at standard curing condition , 2019 .

[25]  Xianhui Zhao,et al.  Investigation into the effect of calcium on the existence form of geopolymerized gel product of fly ash based geopolymers , 2019, Cement and Concrete Composites.

[26]  G. Ye,et al.  Mitigating the autogenous shrinkage of alkali-activated slag by metakaolin , 2019, Cement and Concrete Research.

[27]  Xiao-dong Shen,et al.  Reaction of Portland cement clinker with gaseous SO2 to form alite-ye'elimite clinker , 2019, Cement and Concrete Research.

[28]  Hamza Güllü,et al.  On the rheology of using geopolymer for grouting: A comparative study with cement-based grout included fly ash and cold bonded fly ash , 2019, Construction and Building Materials.

[29]  V. Mechtcherine,et al.  Correlation of microstructural and mechanical properties of geopolymers produced from fly ash and slag at room temperature , 2018, Construction and Building Materials.

[30]  John L. Provis,et al.  Alkali-activated materials , 2018, Cement and Concrete Research.

[31]  B. Tao,et al.  Influence of steel slag on the mechanical properties and curing time of metakaolin geopolymer , 2018, Ceramics International.

[32]  Xiaolu Guo,et al.  Mechanical properties and mechanisms of fiber reinforced fly ash–steel slag based geopolymer mortar , 2018, Construction and Building Materials.

[33]  Guillermo Soriano,et al.  Preparation, characterization, and determination of mechanical and thermal stability of natural zeolite-based foamed geopolymers , 2018 .

[34]  Mohammad Ismail,et al.  Geopolymer mortars as sustainable repair material: A comprehensive review , 2017 .

[35]  Prabir Sarker,et al.  Flexural strength and elastic modulus of ambient-cured blended low-calcium fly ash geopolymer concrete , 2017 .

[36]  Xu Wu,et al.  Co-disposal of MSWI fly ash and Bayer red mud using an one-part geopolymeric system. , 2016, Journal of hazardous materials.

[37]  Stephen J. Foster,et al.  Utilisation of steel furnace slag coarse aggregate in a low calcium fly ash geopolymer concrete , 2016 .

[38]  Liang Chen,et al.  Preparation and Properties of Alkali Activated Metakaolin-Based Geopolymer , 2016, Materials.

[39]  Hjh Jos Brouwers,et al.  Properties of alkali activated slag-fly ash blends with limestone addition , 2015 .

[40]  Hao Wang,et al.  Geopolymer foam concrete: An emerging material for sustainable construction , 2014 .

[41]  A. Al-Tabbaa,et al.  Strength and drying shrinkage of reactive MgO modified alkali-activated slag paste , 2014 .

[42]  Adam R. Kilcullen,et al.  Gel nanostructure in alkali-activated binders based on slag and fly ash, and effects of accelerated , 2013 .

[43]  Jian He,et al.  Synthesis and characterization of red mud and rice husk ash-based geopolymer composites , 2013 .

[44]  Yu-zhen Yu,et al.  The strength and microstructure of two geopolymers derived from metakaolin and red mud-fly ash admixture: A comparative study , 2012 .

[45]  J. Temuujin,et al.  Influence of calcium compounds on the mechanical properties of fly ash geopolymer pastes. , 2009, Journal of hazardous materials.

[46]  Jinqiang Hu,et al.  Investigation on the application of steel slag-fly ash-phosphogypsum solidified material as road base material. , 2009, Journal of hazardous materials.

[47]  Wellington Longuini Repette,et al.  Drying and autogenous shrinkage of pastes and mortars with activated slag cement , 2008 .

[48]  J. Deventer,et al.  The coexistence of geopolymeric gel and calcium silicate hydrate at the early stage of alkaline activation , 2005 .

[49]  I. Odler,et al.  Investigations on the relationship between porosity, structure and strength of hydrated Portland cement pastes. II. Effect of pore structure and of degree of hydration , 1985 .

[50]  S. Alonso,et al.  Calorimetric study of alkaline activation of calcium hydroxide–metakaolin solid mixtures , 2001 .