“…This behaviour may be attributed to incorporating GBFS forms many C-S-H gels while generating considerable heat, accelerating the geopolymerization process (Karamanova et al, 2011). Besides, the GBFS contains many calcium ions with enormous electrostatic attraction and charge neutralization capability compared with sodium ions, accelerating the formation of amorphous aluminosilicate gels and decreasing the setting time of geopolymers (Li et al, 2021). Figure 7.Compressive strength of all studied specimens (at the age of 28-days).…”
Geopolymer concrete has developed as a potential alternative to ordinary Portland cement-based concrete, wherein various industrial by-products have been converted as beneficial spin-offs. Apart from appropriate compressive strength in the construction sector worldwide, the durability, sound absorption, thermal conductivity, and weight of concrete are also major concerns. Lightweight geopolymer concretes have gained attention because of their superior strength, durability, lower environmental impact, and sustainable characteristics. In this view, the current study examined the feasibility of using sawdust as a natural fine and coarse aggregate substitution in fly ash (FA)-granulated blast furnace slag (GBFS) based geopolymer concrete. Four mixes with a different percentage of sawdust (25, 50, 75, and 100) substituting natural aggregate were designed to examine the effects of sawdust on fresh and hardened features of geopolymer concrete compared to those conventional FA-GBFS-based geopolymer concrete with natural aggregate. Sodium silicate (NS) and sodium hydroxide (NH) (with NS/NH ratio of 0.75) were utilized to dissolve the alumina silicate from FA and GBFS. Informational models were developed using an experimental dataset to estimate the compressive strength of geopolymer concrete mix designs. Besides, using the weight of the developed network, a global sensitivity (GS) analysis was developed to identify the sensitivity of compressive strength to the waste sawdust content. Test results confirmed that by substituting natural aggregate with 100% sawdust, there was around a 35% decrease in compressive strength. Nevertheless, the sound absorption coefficient was increased by an average of 38% in frequencies range between 1800 and 2500 HZ, and thermal conductivity decreased by around 4.5 times once the natural aggregate was substituted by 100% sawdust.
“…This behaviour may be attributed to incorporating GBFS forms many C-S-H gels while generating considerable heat, accelerating the geopolymerization process (Karamanova et al, 2011). Besides, the GBFS contains many calcium ions with enormous electrostatic attraction and charge neutralization capability compared with sodium ions, accelerating the formation of amorphous aluminosilicate gels and decreasing the setting time of geopolymers (Li et al, 2021). Figure 7.Compressive strength of all studied specimens (at the age of 28-days).…”
Geopolymer concrete has developed as a potential alternative to ordinary Portland cement-based concrete, wherein various industrial by-products have been converted as beneficial spin-offs. Apart from appropriate compressive strength in the construction sector worldwide, the durability, sound absorption, thermal conductivity, and weight of concrete are also major concerns. Lightweight geopolymer concretes have gained attention because of their superior strength, durability, lower environmental impact, and sustainable characteristics. In this view, the current study examined the feasibility of using sawdust as a natural fine and coarse aggregate substitution in fly ash (FA)-granulated blast furnace slag (GBFS) based geopolymer concrete. Four mixes with a different percentage of sawdust (25, 50, 75, and 100) substituting natural aggregate were designed to examine the effects of sawdust on fresh and hardened features of geopolymer concrete compared to those conventional FA-GBFS-based geopolymer concrete with natural aggregate. Sodium silicate (NS) and sodium hydroxide (NH) (with NS/NH ratio of 0.75) were utilized to dissolve the alumina silicate from FA and GBFS. Informational models were developed using an experimental dataset to estimate the compressive strength of geopolymer concrete mix designs. Besides, using the weight of the developed network, a global sensitivity (GS) analysis was developed to identify the sensitivity of compressive strength to the waste sawdust content. Test results confirmed that by substituting natural aggregate with 100% sawdust, there was around a 35% decrease in compressive strength. Nevertheless, the sound absorption coefficient was increased by an average of 38% in frequencies range between 1800 and 2500 HZ, and thermal conductivity decreased by around 4.5 times once the natural aggregate was substituted by 100% sawdust.
“…of engineering structures [1][2][3][4][5][6][7][8]. As a possible alternative application, it has been demonstrated that entrapment into a geopolymeric network of many hazardous compounds from inorganic waste or polluted products [9][10][11] can limit their release; in this context, they can be used to recycle fly ashes [12][13][14][15][16][17][18] or inertize some industrial by-products [19][20][21][22][23][24][25] thus showing a possible way which could permit to avoid their landfill disposal.…”
Production and characterization of geopolymers prepared by mixing metakaolin, end-of-life dolomite refractories, sodium silicate solution, and sodium hydroxide solution have been performed. The as-received refractory was crumbled in order to obtain products having, respectively, 250 μm, 1 mm, and 2.5 mm maximum particles size. Each batch of powder was added in different proportions to a blank geopolymeric matrix. It has been observed that the addition of waste refractory reduces workability of the reference refractory-free slurry. After hardening, only the set of samples prepared with powders with maximum size of 250 μm maintain integrity while the others resulted affected by the presence of fractures caused by volumetric instabilities; samples with composition R100 showed the highest compressive strength, whereas higher refractory addition lowers strength. Specific surface area appears independent by materials composition; conversely pore volume slightly increases with the addition of dolomite refractory powder. During the thermodilatometric tests all compositions display a shrinkage of about 0.1% between 170 and 400 °C; however, sintering starts at higher temperature (above 600 °C) and samples melt in the range between 650 and 750 °C as a function of their composition, thus showing that the resulting materials loose refractoriness with respect to both the reference geopolymer and the dolomite refractory.
Graphical Abstract
“…In the design of two-part AAMs, water should be largely eliminated due to its documented adverse impacts [24]; notwithstanding that fact, water is still included in the design of some two-part AAMs and geopolymers. In such cases, researchers with following cementitious approaches [25], introduced CNTs into the aqueous media but the activation initiated by liquid alkaline activators [26][27][28][29][30]. With the non-aqueous formulation, there is one case reporting CNTs' incorporation with an alkaline dispersion procedure in a two-part composite [31].…”
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