Reaction Of Fly Ash Research Articles

Enhancing physiochemical properties and reactivity of landfilled fly ash through thermo-mechanical beneficiation

This study investigates the impact of thermo-mechanical beneficiation techniques on the physiochemical characteristics and reactivity of landfilled fly ashes (LFAs) obtained from power plants in Wyoming and Colorado, USA. Thermo-mechanical beneficiation significantly improved the physiochemical properties of LFAs, leading to a decrease in loss in ignition (LOI) and an increase in fineness. The results revealed improvements in the strength activity index of all LFAs after beneficiation, surpassing the minimum requirement of 75% at 28 days. Beneficiation also enhanced heat release and calcium hydroxide consumption, indicating improved pozzolanic reactivity. The findings demonstrated that as beneficiation temperatures increased, there was a significant reduction in LOI, with levels falling below 3% at temperatures above 450 °C. The relationship between LOI and heat release indicated that reducing LOI could enhance the reactivity of fly ash. However, there was an inflection point at certain LOI thresholds, suggesting that further reductions in LOI may not significantly impact hydration kinetics. The results also showed that the specific surface area of LFA was correlated with heat release and calcium hydroxide consumption, emphasizing the importance of increased fineness for enhanced reactivity. The study also found associations between calcium hydroxide consumption, heat release, and early- and later-age strength activity indices. Higher calcium hydroxide consumption corresponded to increased heat release and reactivity, which in turn contributed to greater strength development over time, particularly at later.stages.

Novel porous ambient temperature cured fly ash geopolymer for lead adsorption from wastewaters

ABSTRACT This paper discusses the ability of the fly ash (FA) and abmbient cured Alkali activated Fly ash geopolymer (FAAG) for sequestering Pb (II) ions from aqueous solution. Various physiochemical properties such as the influence of pH and contact time were investigated for achieving the conditions for maximum removal via batch mode using powdered samples. The adsorbents were characterized by employing powder X-Ray diffraction, Attenuated Total Reflection Fourier Transform Infra-Red spectroscopy, and Scanning Electron Microscopy/EDAX before and after the treatment. The adsorption capacity of Pb2+ ions by raw FA and FAAG were examined by the Inductively coupled plasma mass spectrometry (ICP-MS). The results represented that the maximum adsorption capacity of Pb2+ ions by FAAG is 75 mg/g with attained equilibrium time of 120 min whereas raw fly ash at 150 min at 21.5 mg/g capacity. The pozzolanic reactivity of fly ash in water glass hardening resulted mainly N-A-S-H gel and traces of lead silicate due to the immobilization of lead in the network. This was conformed from the binding energy lines at 139.7 eV in XPS survey lines and lead silicate at 25 and 34° 2θ as identified in XRD phase assemblages. ICP-MS test results of leachate of lead immobilized geopolymer sample are devoid of lead ions and thus sorption sites of fly ash geopolymer lead to potential safety disposal of lead. Thus, recycling of fly ash into geopolymer by less energy intensive process and subsequent use in heavy metal disposal could achieve the concept of disposal waste and recycling, which could contribute to achieve the sustainable goals.

Fluorine soil stabilization using hydroxyapatite synthesized from minerals wastes

The objective of this study was to present a new approach to mineral waste valorization, based on the synthesis of hydroxyapatite (HAP) as an efficient and cost-effective adsorbent for the stabilization of fluorides (F-) in soil. Hydroxyapatites were synthesized from the reaction of potassium dihydrogen phosphate (KH2PO4) and waste paper fly ash (WPFA), fine limestone clay (FLC) and limestone filler (LF) rich in calcite. X-ray diffraction characterization results showed that for HAPFLC and HAPFL the main resulting phases were brushite (CaHPO5·2H2O) and for HAPWPFA was hydroxyapatite (Ca5(PO4)3OH). The FTIR spectra showed similar patterns to natural HAP containing orthophosphate groups (PO43-), hydroxylated groups (OH–) and both types A/B of carbonate apatite. SEM-EDS analysis of the individual HAP revealed a morphology consistent with phosphocalcic hydroxyapatite crystals. EDS analysis revealed a Ca/P atomic ratio equal to 1.92, 1.85 and 1.7 for HAPFLC, HAPLF and HAPWPFA respectively, which is similar to the stoichiometry of hydroxyapatites (Ca/P = 1.67). The use of HAP as an amendment to stabilize fluorides (F-) in the soil was demonstrated to be effective, the addition of 1% of the different HAP allowed the decrease of the concentration of F in the raw soil (73.8 mg/kg) to concentrations below the IWSI threshold (10 mg/kg), to 4.68 mg/kg, 5.63 mg/kg, and 0.8 mg/kg for HAPFLC, HAPFL and HAPWPFA respectively. Fluoride (F) sequential extraction results showed that it was extracted from the residual fraction (Fraction 4) after soil treatment, and was generally trapped on the hydroxyapatites (Ca5(PO4)3(OH)) by anion exchange with the hydroxides (OH–) to form the stable and insoluble fluorapatite ((Ca5(PO4)3F).

Time Dependence of Viscosity of Alkali-Activated Fly Ash Based Geopolymer Mortar

FA was used as the raw material, and the net slurry of FA base Geopolymer was set as the control group to study the influence of sand content, gradation, reaction temperature and time on the time dependence of the viscosity of alkali-activated fly ash based geopolymer mortar. The experimental results show that the curing reaction of alkali-activated fly ash based geopolymer mortar was affected by the temperature dependence of fluid viscosity and the activation energy of the chemical reaction, which is relatively complex. This paper will divide the whole polymerization process into three stages to elaborate. The increase of sand cement ratio will increase the viscosity of FA base polymer mortar. If the sand is too coarse or too fine, the viscosity of FA base polymer mortar will increase significantly, and the fine sand has a greater impact on the viscosity of FA base polymer mortar than the coarse sand. Increasing temperature will significantly accelerate the reaction speed and increase the influence of chemical reaction activation energy on the viscosity of the system while the too high temperature will make the viscosity of the system decrease more significantly in the reaction. This study will reveal the intrinsic relationship between the viscosity of geopolymer and the reaction process, the reaction mechanism of the curing process so that the reaction stage can be represented by the viscosity state of the slurry.

Empirical Compression Model of Ultra-High-Performance Concrete Considering the Effect of Cement Hydration on Particle Packing Characteristics.

The mix design of UHPC has always been based on a large number of experiments; in order to reduce the number of repeated experiments, in this study, silica fume (SF), fly ash (FA), and limestone powder (LP) were used as the raw materials to conduct 15 groups of experiments to determine the particle size distribution (PSD) properties of UHPC. A model of multi-component hydration based on the SF, FA, and LP pozzolanic reactions was devised to quantify the rate and total heat release during the hydration process. Additionally, a microscopic pore development model, which was based on the accumulation of hydration products, was established to measure the effect of these products on the particle-packing properties. Utilizing this model, a UHPC strength prediction technique was formulated to precisely forecast the compressive strength based on a restricted experimental data set. The applicability of this prediction method was verified using 15 sets of existing experimental data along with the data collected from 4 research articles. The results show that the prediction method can predict the strength values of different mix proportions with an accuracy rate of over 80%.

Deep insight into reactive chemical structures of Class F fly ash

Reactive amorphous aluminum silicates dominate the reactivity of fly ash in alkali cement; however, the quantitative characterization of valid chemical compositions and structures information is highly challenging due to the heterogeneity and complexity of these phases. To acquire this information, in this work, Class F fly ash was treated with 1% hydrofluoric acid, followed by step-by-step analysis using a scanning electron microscope with an energy dispersive spectrometer (SEM-EDS), solid-state magic angle spinning nuclear magnetic resonance (MAS-NMR), and Fourier transform infrared (FT-IR) spectroscopy. Based on the acidolysis method, along with SEM-EDS statistical analysis, four amorphous aluminum silicate phases with relatively higher reactivity were successfully separated and quantitatively showcased, along with their respective average atomic percentage compositions (i.e., Si, Al, Ca, Fe, Na, K, and Mg%). In addition, the use of MAS-NMR and FT-IR analyses allowed for further quantitative insight into the reactive chemical structures and their associations with reactivity. The proposed characterization techniques have unique advantages for acquiring detailed reactive amorphous chemistries, which are difficult to obtain using conventional analysis procedures in alkali systems.

Correlation between dissolubilities of Si, Al, and Fe from aluminosilicate precursor and strength of fly ash-based geopolymer

Fly ash (FA) is the most used aluminosilicate precursor to synthesize geopolymer. However, as a coal-combustion by-product, the inherent characteristics of FA can be significantly altered by multiple factors such as coal sources, combustion temperatures, particle size, and impurity level. Thus, unstable performances of FA-based geopolymer due to extremely varied reactivity of FA have been widely reported in the literature and are limiting the further valorization of FA. To offset the inconsistent characteristics of FA, this study provides a universal index to quantify and evaluate its reactivity to be used as aluminosilicate precursor feedstock. Alkali leaching tests were conducted on seven types of FA sourced from six different coal power plants in the Southeast Queensland region to determine the dissolubilities and dissolution efficiencies of reactive Si and Al within 2 h. The dissolubility and dissolution efficiency demonstrated decent correlations with the mechanical properties of the resultant FA-based geopolymer, especially 7-day strength. Moreover, bulk and reactive Si/Al molar ratios were derived to distinguish each type of FA further and verified by scanning electron microscopy / energy-dispersive X-ray spectroscopy. Lastly, a reactivity index considering the dissolution efficiency of Si, Al, and Fe and reactive Si/Al molar ratios was developed and correlated to the mechanical properties of FA-based geopolymer. Dissolubility at a leaching time of 30 min best reflected the reactivity of FA, having the highest correlation coefficient of 0.82.

Uncovering the Mechanism of the Role of Fly Ash in the Self-Healing Ability of Mortar with Different Curing Ages.

As an admixture of cement-based materials, the reaction of fly ash (FA) usually takes place in the late age of curing, so FA will affect the self-healing ability of long-age cement-based materials. The self-healing potential and the characteristics of self-healing products of cementitious materials before and after crack healing were analyzed by microscopic tests, and the mechanism of the effect of fly ash on the self-healing performance of cementitious materials was revealed. The results showed that the increase in fly ash content promoted the improvement of the self-repair performance of cracked specimens at 28 d, especially when the fly ash dosage was 40%, the crack opened after 30 d of healing in water was completely closed, the UPV value after recovery was close to 3000 m/s, the self-repair efficiency of maximum amplitude and main frequency amplitude was up to more than 60%, and the recovery rate of compressive strength was increased to more than 30%. However, the increase in fly ash content was not conducive to the self-repair of cracked samples at 210 d, and with the increase in fly ash content, the crack closure effect weakened, the UPV value after recovery decreased, the crack repair rate based on ultrasonic transmission decreased to about 20%, and the compressive strength recovery rate increased slightly. In addition, calcium carbonate precipitation was the main repair product of crack filling and healing, including calcite and spherulite. With the increase in fly ash content, the content of element C in the self-repair products of 28-day-old specimens gradually increased, and the size of calcium carbonate crystals gradually decreased, but the filling was denser, whereas the calcium carbonate crystals in the self-repair products of 210 d specimens gradually became fine and loose.

Long-term Pull-out behavior of coir fiber from cementitious material with statistical and microstructural analysis

In this study, the long-term pullout behavior and microstructure of the embedded coir fibers (a bundle of multi-monofilament fibers) from cementitious matrix were investigated. The experimental results were analyzed through statistical tests (i.e., Shapiro-Wilk test, Kolmogorov-Smirnov test, and Analysis of variance with Tukey’s honestly significant difference test) to address the reliability of the analyses and conclusions. The duration of fiber embedment in the matrix (i.e., 1, 2, 4, 8, 12, and 24 weeks), and the addition of fly ash (i.e., weight replacement ratio to cement for 0%, 10%, and 20%) were considered as the test parameters. The results show that the fibers with larger diameters tended to have tensile failure rather than pullout failure during the test. When the fibers had larger embedment length in the cementitious material, the pullout load–displacement curve changed from slip-hardening to slip-softening pattern. The highest fiber pullout strength was recorded when tested at 24-week. However, the highest fiber pullout energy was not recorded at 24-week but at 2-week. It can be concluded that with a longer embedment duration, the interfacial bond between fiber and matrix will increase but the coir fiber itself will be embrittled. This is due to the penetration of mortar into fiber surface along with a longer embedded duration, which was observed under scanning electron microscope. The pozzolanic reaction of fly ash did not improve the fiber–matrix interfacial bond strength. To the contrary, the pullout energy of the samples with 20% fly ash at week 1 was significantly lower than that with 10% fly ash or without fly ash. This was due to the unreacted spherical fly ash particles on the fibers surface that acted as lubricant during pullout.

Role carbon nanomaterials in reinforcement of concrete and cement; A new perspective in civil engineering

Nanotechnology has resulted in many advantages in different majors of science and created new approaches to them. nanotechnology has more effect on civil engineering such as utilizing nanomaterials as cement reinforcement. The improvement in quality of materials used in civil engineering such as self-cleaning, self-structural health monitoring, self-sensing, self-vibration damping, self- rehabilitation, cement reinforcement, and self-healing created a new revolutionary civil engineering. Concrete is one of the important parts of civil engineering and especially in the discussion of building and bridge retrofitting. Nanotechnology plays an important role in the concrete process such as alkali silicate reactions (ASR), hydration reactions, and fly ash reactivity. Much of the research showed that nanomaterials improved compressive and flexural strength in concrete and created the best situation for building resistant structures such as bridges, towers, and tall buildings. Due to the mechanical behavior and tensile strength of carbon nanotubes (CNTs), these compounds play a special role in improving concrete properties. Prevention of cracking is one of the positive effects of using carbon nanotubes in improving concrete properties, which has increased significant growth in the application of it in the industry. The present review paper focused on the role of nanomaterials in improving and reinforcement of concrete and the advantages of them in civil engineering.

Effects of fly ash and silica fume on alkalinity, strength and planting characteristics of vegetation porous concrete

Supplementary Cementitious Materials (SCMs) have been utilised for decades to lower the OPC concrete's alkalinity. However, the usage of SCMs to lower the alkalinity of Vegetation Porous Concrete (VPC) is limited. The present study examined the effects of Fly Ash (FA) and Silica Fume (SF) on the alkalinity, strength and planting properties of VPC. Since the Coarse Aggregate Size Ratio (CASR) has a substantial impact on the VPC strength, the current-study also examines the influence of CASR on the void content, strength and planting properties of VPC. The blending of cement with FA and SF reduced the alkalinity of the VPC, and that increasing the dose rate of FA and SF lowered the alkalinity of the VPC even more. The pozzolonic reaction of FA and SF in the VPC consumes CH crystals to form C–S–H gels, and the reduction in the quantity of CH crystals causes the pH of the VPC to decrease. Consequently, the plant's root length growth and LRWC improved by 7.91% and 4.95%, respectively. The inclusion of FA decreased the compressive strength due to the lower activity of the FA with the cement matrix; however, the accelerated pozzolanic reaction between Ca(OH)2 and SiO2 in the SF enhanced VPC strength. Despite an increase in CASR improves the aggregate interlocking property and the strength, it also reduces the void content of the VPC. The reduction in VPC pores hampered root mobility through the concrete, delaying root development and reducing the availability of water and nutrients.

Characterization of Alkali Activated Materials Prepared from Continuous Attrition and Ball Milled Fly Ashes

Mechanical activation is known to greatly influence the reactivity of fly ashes. In this paper, we report a comparative study of the properties of alkali-activated geopolymer materials prepared using both ball-milled and attrition-milled fly ashes. Ball milling was carried out for 30 min and 60 min while attrition milling was carried out continuously in a high-speed attritor. The surface area of the raw fly ash decreased from 4017 cm2/g to 3999 cm2/g and 3912 cm2/g after ball milling for 30 min and 60 min, respectively. By contrast, the surface area of the continuously attrition-milled fly ash increased to 5545 cm2/g. Fly ash processed by continuous attrition milling showed a 50% particle size reduction to 25–38 μm, whereas fly ash ball-milled for 30 and 60 min was reduced in size by 33.4 and 42.9%. The milled fly ash samples were activated with 8 M NaOH solution and cured at 40 °C for 68 h. After curing, the samples were maintained at room temperature, and their 7-, 14-, and 28-day compressive strengths were measured. The compressive strength of the attrition-milled 28-day geopolymer paste was 24.6 MPa; that of the geopolymers ball-milled for 30 and 60 min was 23.37 MPa and 17.58 MPa, respectively; and that of the unmilled control geopolymer fly-ash-based paste was 17 MPa. The improvement in the mechanical properties is attributed to the increased gel formation resulting from the increased surface area (decreased particle size) in the fly ash glass starting material.

Synthesis and application of calcium silicate hydrate (C-S-H) nanoparticles for early strength enhancement by eco-friendly low carbon binders

Abstract C-S-H–PCE nanocomposites are known to perform as highly effective seeding materials in Portland cement. Here the effectiveness of a C-S-H–PCE nanocomposite admixture on early strength development of eco-friendly cements (clinker blended with up to 35% fly ash or calcined clay) was investigated. First, C-S-H–PCE nano-composites were synthesized from Ca(NO3)2/Na2SiO3 via a co-precipitation method and their particle size distribution was analyzed. Differently structured PCE comb polymers based on IPEG chemistry were used in the synthesis. Nanofoils of ∼50 nm length were identified as most promising seeding material. Furthermore, addition of such C-S-H–PCE nanofoils was found to substantially increase mortar strength at early ages, particularly after 6–24 h of curing. Isothermal heat flow calorimetry and in-situ XRD measurements indicate that silicate hydration in cement is significantly accelerated. Most remarkably, C-S-H–PCE also was confirmed to speed up the pozzolanic reaction of fly ash and calcined clay and to stimulate the formation of hemicarbo aluminate (Hc), especially in calcined clay cement. Thus, C-S-H–PCE can foster the more widespread use of eco-friendly CEM II/III cements.

Synergic effect of recycled aggregate, fly ash, and hydrated lime in concrete production

The use of construction and demolition waste (CDW) as recycled aggregate (RA) and fly ash (FA) in the composition of cementitious materials can make the resulting concrete more sustainable. However, RA is more heterogeneous, porous, and less dense than the natural aggregate (NA), influencing the mechanical strength. On the other hand, the reaction of FA with hydration products of Portland cement is slow, delaying the strength development at an early age. An alternative to increase the strength of concrete with FA at an early age is using the hydrated lime (HL). This research intends to evaluate the efficiency of adding HL in concrete with RA and FA. In this way, this research intends to evaluate the efficiency of adding HL in concretes with RA and FA and comprises two stages. First, a w/c ratio of 0.55 and a replacement of 50% natural coarse aggregate by concrete recycled aggregate (CRA) and mixed concrete aggregate (MRA) was established, considering similar compressive strengths. In the second stage, the properties of concretes with 20% FA in partial replacement of Portland Cement (PC), adding HL at 5% and 10% (by mass) were evaluated. The results showed that concretes with CRA present performance better than concretes with MRA, and the effect of HL was significant for all properties investigated. Concretes with CRA, FA, and 10% HL improved the compressive strength by 12.47%, reduced water absorption and porosity by 9.87% and 23.82%, respectively, and increased apparent density by 8.77% compared to the mixture without HL. The SEM analysis showed the beneficial effect of HL in concretes with RA, due to the high availability of calcium hydroxide. For concretes with RCA, a reduction in the mean equivalent diameter of 62.29% was verified; for concretes with MRA, this reduction was 23.25%. A reduction of carbonation depth was observed when concretes with MRA, FA and 10% HL showed a carbonation coefficient 44.5% lower than concrete without HL after 35 days of exposure to CO2, while concretes with CRA presented a carbonation coefficient of 87.7% lower.

Characterization and reactivity of size-fractionated unconventional fly ashes

Characterization and reactivity of size-fractionated unconventional fly ashes

Quantification of the reaction degree of fly ash in blended cement systems

Fly ash (FA) usually has an insufficient reaction degree in cement-based materials, and the quantification of its reaction degree is essential for understanding its pozzolanic hydration behavior. This work presents a new approach to quantifying the reaction degree of FA in blended cement systems, based on the chemical composition differences revealed by image analysis. We considered some specific elements rich in the unreacted FA particles but poor in the surrounding paste as the characteristic elements, and then employed them to segment the unreacted FA particles from the blended cement paste. In light of the high heterogeneity of FA, one can conduct intensity normalization during the analysis, using grey-level images that are displayed in the intensity of each characteristic element, respectively. At last, the unreacted FA particles, including the partially reacted and irregular-shaped ones, were discriminated from the paste, enabling an accurate calculation of the FA's reaction degree.

Evaluation of Strength In Fly Ash Based Geo polymer Concrete

Construction materials that are friendly to the environment are now being researched and developed all over the globe in an effort to limit the use of natural resources that are depleting at an alarming rate and to cut down on the production of greenhouse gases. In this respect, geopolymer plays an extremely important function, and a large number of researchers have investigated the numerous dimensions of its viability as a material for binding. In order to alter the geopolymerisation reaction of fly ash, ground granulated blast furnace slag (abbreviated as GGBS) has been used into fly ash-based geopolymer concrete (abbreviated as GPC). In this paper, the influence of various proportions of GGBS (0-100%) on Fly Ash based GPC, as well as the effect of the amount of Alkaline Activated Solution (AAS) in the mixture of GPC, is studied to determine how it affects the compressive strength of the GPC under conditions of ambient temperature. It was observed from the results of the experiments that the compressive strength of the GPC increases both with an increase in the percentage of GGBS and also with an increase in the amount of the sodium silicate solution in which the concentration of sodium hydroxide in the aqueous solution is fixed at a constant value of 10M. This was the case even though the amount of sodium hydroxide that was present in the solution remained the same.

Investigating the Impact of Fly Ash on the Strength and Micro-Structure of Concrete during Steam Curing and Subsequent Stages

Steam curing, a common way of curing precast concrete, can greatly improve its 1-day strength. However, the thermal effect of prolonged high-temperature curing can negatively impact the concrete's performance, thus compromising production of precast products in cold regions. Fly ash (FA) is used as a supplementary cementitious material to improve part of the properties of concrete. In this paper, we investigated the effect of FA (10~30%) on the compressive strength and microstructure of manufactured sand concrete at the steam curing and later stages. Specifically, we analyzed the behavior of FA in the constant temperature phase under steam curing. Results indicated that the pozzolanic reaction of FA started to occur at 24 h of constant temperature curing. Early hydration under steam curing produces a large amount of Ca(OH)2, causing the pozzolanic reaction of FA to occur significantly earlier, and the high pH value of the solution and the fibrous mesh structure of the FA surface promote the pozzolanic reaction. The addition of 30% FA to manufactured sand concrete causes a significant reduction in early strength under steam curing, which is not beneficial to the formwork removal and tensioning of precast members. Notably, manufactured sand concrete with 20% FA under steam curing had the highest late strength. The filling effect of FA and the additional gel produced by the pozzolanic reaction would result in the reduction in large pore content, refinement of pore size, improvement of microstructural compactness, and increase in gel system strength. Therefore, the addition of 20% FA to the manufactured sand concrete can improve the long-term strength, which is beneficial to the production of precast beams in cold regions.

Multiscale study of the effect of fly ash geopolymer on the fatigue cracking of cement stabilized macadam

Understanding of the correlation between the micro-composition and macro-mechanics of cement stabilized macadam (CSM) is crucial to an optimized design of cement-treated base (CTB) with improved crack resistance. In this study, acoustic emission (AE) technique was used to monitor the crack propagation of plain cement stabilized macadam (P-CSM) and fly ash geopolymer cement stabilized macadam (FAG-CSM) under cyclic loading. Experimental tests and characterizations, including such as nanoindentation, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS), were further performed. The test results show that FAG-CSM has better fatigue performance than that of P-CSM; the AE counts, risetime/AE amplitude values (RA) and b-value can be used to assess the damage degree, cracking mode as well as the bulk modulus of cement composites. Interfacial transition zone (ITZ) is the weakest modulus area in CSM and the incorporation of fly FAG can effectively increase the indentation modulus of ITZ. The volcanic ash reaction of fly ash leads to the hydration of cement to produce more hydration products, which reduce the voidance within ITZ and thus improve the bonding between the aggregate and mortar, which supports the findings of the macro-mechanical analysis and AE monitoring of CSM.

Study on Mechanical Properties and Micro Characterization of Fibre Reinforced Ecological Cementitious Coal Gangue Materials.

Eco-gelled coal gangue materials (EGCGMs) are usually produced using coal gangue, slag, and fly ash in a highly alkaline environment. Herein, to improve the mechanical properties of such materials, polypropylene fibers were uniformly mixed with them. An unconfined compressive strength test and a three-point bending test of the fiber-reinforced EGCGMs under different conditions were conducted. Based on the performance degradation control technology of the fiber structure, the interface mechanism of the composite materials was analyzed from the micro level using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). In the mechanical test, the 28 d UCS and flexural properties of the fiber-reinforced EGCGMs were analyzed using the Box-Behnken design response surface design method and orthogonal design method, respectively. The order of significance was as follows: sodium hydroxide, fiber length, and fiber content. Within the scope of the experimental study, when the NaOH content is 3, the fiber content is 5 ‱, and the fiber length is 9 mm, the mechanical properties are the best. Based on the microscopic equipment, it was discovered that the amorphous ecological glue condensation product formed by the reaction of slag and fly ash in the alkaline environment was filled between the coal gangue particles and the fibers, and several polymerization products accumulated to form a honeycomb network topology. The distribution of fibers in the EGCGM matrix could be primarily divided into single embedded and network occurrences. The fiber inhibits the crack initiation and development of the matrix through the crack resistance effect, and improves the brittleness characteristics through the bridging effect during the failure process, which promotes the ductility of the ecological cementitious coal gangue matrix.The results presented herein can provide a theoretical basis for improving the mechanical properties of alkali-activated geopolymers.