Fly Ash Ratio Research Articles

Evaluating the Strength and Durability Properties of Geopolymer-Stabilized Soft Soil for Deep Mixing Applications

Soft soil poses serious challenges and is unsuitable for engineering projects because of its insufficient bearing capacity, low shear strength, and high compressibility. Deep soil mixing (DSM) is one of the most popular methods of enhancing soft soil qualities, such as increased bearing capacity and reduced settling, which are critical for building any structure. The environmental effects of creating binders such as cement and lime make it crucial to identify alternative materials for geotechnical applications. This study employed fly ash (class C) --based geopolymer to investigate its effectiveness as an environmentally friendly substitute for cement for DSM applications. The experimental program included unconfined compressive strength, flexure strength, and durability tests. The parameters in the study are binder content (10, 15, and 20%) and activator/binder ratio (0.4, 0.6). Results revealed that UCS and flexural strength, GP-treated soil were in the range of 0.9–5.3 and 0.8–1.5 MPa, respectively (depending on the ratio of fly ash and activator). These strengths were even higher than those of cement-stabilized soil. The geopolymer-treated specimens exhibited excellent endurance over the wetting-drying cycle, with a modest weight loss of less than 4.5%. A binder dosage of more than 10% and an AC ratio of 0.6 were recommended to meet DSM application guidelines. The current study concludes that employing a fly ash-geopolymer binder to stabilize soft soil is an effective alternative to cement in DSM applications.

Evaluation of Concrete Compressive Strength Prediction Using the Maturity Method Incorporating Various Curing Temperatures and Binder Compositions

This study aims to systematically analyze the effects of different curing temperatures, unit binder content, and the mixture ratios of ground granulated blast-furnace slag and fly ash based on ordinary Portland cement in binders on the development of concrete compressive strength. Particularly, the study evaluates strength characteristics by calculating the maturity equivalent to 28 days of curing at 20 °C. A model based on the relationship between maturity and strength was applied to predict the compressive strength, and the experimental data were analyzed to derive strength coefficients for each variable. The results showed that at a low temperature of 5 °C, the actual strength was lower than the predicted strength, leading to higher error rates. In contrast, at temperatures of 20 °C and 40 °C, the coefficient of determination (R2 > 0.90) for the predictive equation was high, and the error rates were reduced to within 10%. The study demonstrates that by combining the maturity method with the strength–maturity relationship, the concrete compressive strength can be effectively predicted under specific curing and binder design conditions.

Research on the optimization of proportions for synchronous grouting material in composite muck during shield tunneling

To tackle the challenge of onsite resource reuse of composite muck, which relies on a shield tunneling section in the case of Nanjing Metro Line 7, this paper examines the effects of component substitution and varying proportions of factors on slurry properties through laboratory tests and multiobjective modeling. From a practical application perspective, the potential of using composite muck as a synchronous grouting material for shield tunneling was explored. In reference to the common mixed strata encountered in shield tunneling construction in the Nanjing area, a general slurry mixing ratio suitable for various mixed strata conditions was derived. The research results indicate the following optimized mixing ratios for the composite muck slurry: a water-to-binder (cement + fly ash) ratio of 0.76, a cement-to-fly ash ratio of 0.53, a binder-to-soil (silty clay + silty fine sand + river sand) ratio of 0.67, a clay (i.e., silty clay)-to-sand (i.e., silty fine sand + river sand) ratio of 0.4, and a substitution ratio (i.e., silty fine sand/silty fine sand + river sand) of 0.2. This slurry is feasible for practical applications and can reduce construction costs by 38.13%. The obtained general mixing ratio for the composite muck slurry, suitable for various mixed stratigraphic conditions, essentially meets onsite construction requirements (the bleeding rate is controlled within a low range of 1.1–3.1%, and the maximum compressive strength reaches up to 6.76 MPa at 28 days), with reasonable costs. It streamlines construction by eliminating the need for onsite screening of muck, allowing for the direct onsite reuse of composite muck in shield tunneling.

Mechanical properties and micro-mechanisms of geopolymer solidified salinized loess

Salinized loess exhibits poor engineering properties, including low strength, salt migration, and instability, due to the combined characteristics of loess and saline soil. This poses serious threats to the safety and stability of buildings, roads, and other infrastructure. To address this issue, this study aims to solidify salinized loess using geopolymer produced through alkali activation of industrial waste, including slag powder and fly ash. An orthogonal experimental design was used to systematically investigate the mechanical properties, microstructural characteristics, and solidification mechanism of geopolymer solidified salinized loess. The tests included unconfined compressive strength (UCS), direct shear, pH, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) to evaluate the influences of different factors on the solidification effect. The results showed that the sodium silicate solution modulus was the primary factor affecting the strength of solidified salinized loess, followed by the amounts of fly ash and slag powder. The Baumé degree (°Bé) had the least impact. Under the optimal conditions (1 modulus, 35 °Bé, slag powder and fly ash ratio of 1:0), the UCS of the sample at 28 days reached 3204.06 kPa, which increased by 16.32 times compared with the unsolidified sample. Lowering the modulus and increasing the proportion of slag powder and the Baumé degree increased the sample pH. Micro-analysis revealed that the strength increase was mainly due to the bonding of soil particles by gel substances (C-S-H, N-A-S-H, and C-A-S-H) formed during alkali activation, as well as the filling effect of unreacted slag powder and fly ash. The findings of this study provide valuable theoretical and practical insights for treating salinized loess in engineering, offering essential references for optimizing geopolymer solidifier ratios.

Assessment of the self-healing capacity of PVA fiber-reinforced composites by chloride permeability and stiffness recovery

This paper investigates the intrinsic ability of PVA fiber-reinforced cementitious composites to re-establish the durability properties of the uncracked state. Comparative chloride penetration tests are used as a direct measure to quantify the effect of self-healing on the chloride penetration resistance after cracking. Two different composites with cement to fly ash ratios of 1:1.5 and 1:2.0 were studied under the influence of healing periods of up to 28 days. After inducing cracks between 100 and 120 μm, samples were exposed to chlorides for 72 h and the resulting chloride penetration depth was compared to the unhealed state. Based on this procedure, a durability recovery index was proposed to quantify the material’s ability to re-establish its function as a protective layer after cracking. Results show that after 14 days of self-healing, chloride penetration through cracks was reduced between 81% and 99%. An extended healing period of 28 days leads to further reduction of the penetration depth to 84%–100%, indicating that most of the reaction takes place within the first 14 days of healing. While the stiffness recovery analysis showed that increasing cement content by 20% correlated with the formation of stronger healing products, no significant difference was found regarding crack closure.

Utilization of waste phosphogypsum in high-strength geopolymer concrete: Performance optimization and mechanistic exploration

Phosphogypsum (PG) is an industrial waste produced during the manufacture of phosphoric acid. In this study, dihydrate phosphogypsum (DPG), ground granulated blast furnace slag (GGBFS), fly ash (FA), Portland cement clinker (PCC), sulfate alumina cement clinker (SACC), water reducer, sand, and stone were combined to create a phosphogypsum-based geopolymer (PBG) concrete. Concrete mix design was carried out based on the principle of maximum packing density, and the effects of water reducer type, sand ratio, water-to-binder ratio, and DPG content on PBG concrete properties were investigated. Results indicated that compared to SiKa ViscoCrete 540P (SVC 540P) water reducer, Melflux PLUS 1087L (MP1087L) significantly enhanced the performance of PBG concrete. With a water-to-binder ratio of 0.34, a sand ratio of 32.2 %, and a PG:GGBFS:FA ratio of 5:4:1, the 28-day unconfined compressive strength (UCS) of the concrete exceeded 60 MPa. The concrete primarily consisted of phases such as dihydrate gypsum (CaSO4·2H2O), ettringite (Ca6(Al(OH)6)2(SO4)3(H2O)26), polymer (-Si-O-Al-), quartz (SiO2), albite (Na(AlSi3O8)) and Muscovite ((K,Na)Al2(Si,Al)4O10(OH)2). Using two mild alkalis as activators, PBG concrete can avoid the efflorescence often associated with geopolymer preparation and can cure at 20 °C. PBG concrete offers high strength, ease of preparation, and environmental benefits, providing a new avenue for the reuse of PG.

Mechanical performance and co2 footprint analysis: recycled aggregate polypropylene geopolymer concrete compared with conventional concrete

Abstract Geopolymer concrete (GPC) has gained significant awareness in recent years as an eco-friendly alternative to conventional concrete due to its lower CO2 emissions and utilization of industrial waste materials. The cementitious material fly ash (FA), GGBS, silica fume (SF) with incorporation of polypropylene fiber (PF), recycled aggregates (RA) further promote the strength properties of geopolymer concrete, particularly in terms of ductility and crack resistance. Exploratory tests been conducted to assess the effects of various parameters including activator type, curing conditions, fiber content, and aggregate characteristics on the mechanical behaviour and CO2 emissions of geopolymer concrete (GPC). The mechanical performance aspects like as compressive strength(45.7Mpa), flexural strength(4.78Mpa), and split tensile strength(4.12Mpa) were attain by optimum mix design GPC-FG where cement substituted with ratio of FA:GGBS:SF - 40:50:10 and compressive strength(50.4Mpa), flexural strength(5.51Mpa) and split tensile strength(4.99Mpa) were attain by optimum mix design of Polypropylene based GPC-FGP where cement substituted with ratio of FA:GGBS:SF:PF - 40:49:10:1. The optimal mix design GPC-FG and GPC-FGP are compared there is raise in compressive strength of 9.325%, flexural strength of 13.241%,split tensile strength 17.434% of GPC-FGP, along with CO2 of polypropylene fiber-based geopolymer concrete with recycled aggregates as shown 60.01% reduction of CO2 when compared with traditional concrete. The results demonstrate the potential of geopolymer concrete to achieve comparable or superior mechanical performance while significantly reducing CO2 emissions compared to conventional concrete. This research adds to sustainable construction knowledge by showcasing geopolymer concrete’s environmental benefits, mechanical strength, and potential applications in the industry and infrastructure development.

Design and microstructural analysis of the mixture proportion of alkali-activated fly ash-slag composite cementitious material

Abstract To explore the resource utilization of fly ash, slag, and coal gangue, the composition of hydration products and strength characteristics of fly ash-slag composite cementitious material (FSGF) were studied with NaOH as an alkali activator. First, response surface analysis was used to determine factors influencing the optimal NaOH content, basalt fiber dosage, and length to obtain the complete mix ratio of the composite cementitious material. Microscopic techniques such as XRD, FTIR, TG-DSC, and SEM were employed to analyze the crystal structure, thermal properties, and micro-morphology of the composite cementitious material, and to investigate the mechanism of NaOH-activated fly ash-slag cementitious material. The results indicated that the sensitivity of each factor affecting the mechanical properties of the composite cementitious material followed this sequence: NaOH content > basalt fiber length > basalt fiber dosage, with varying degrees of interaction among them. When the mass ratio of fly ash, slag, and coal gangue was 5:1:4, with 3% NaOH by weight, 2% basalt fiber dosage, and a fiber length of 3 mm, the optimal mix was achieved. The composite material achieved a compressive strength of 8.97 MPa after 28 days of standard curing at room temperature. NaOH, as an alkali activator, provided the strong alkaline environment required for the initial hydration of fly ash-slag composite cementitious materials, promoting the hydration of slag and fly ash. The hydration products in the fly ash-slag composite system were unevenly distributed, primarily consisting of gels like C-S-H, C-A-H, and C-A-S-H. NaOH was highly effective as an alkali activator in the fly ash-slag system.

The Effect of the Ratio of Fly Ash to Alkaline Activator and the Molarity of NaOH on the Mechanical Properties of Fly Ash-Based Aggregates

The global demand for aggregates has escalated, leading to a decline in the availability of quality natural aggregates. In response, the cold bond pelletization (CBP) process emerged in the early 2000s as a novel approach to artificial aggregate production, utilizing dry powdered fly ash. This method involves agglomerating fly ash particles at room temperature in an inclined rotating pan to form pellets. However, the abstract lacks clarity in elucidating the significance of this approach. Our study investigates the mechanical properties of aggregates produced through the CBP method via experimental laboratory methods, focusing on variations in the ratio of fly ash to alkaline activator (FA/AA) and the molarity of Sodium Hydroxide (NaOH). Notably, we found that an effective molarity of 15 resulted in the lowest Aggregate Impact Value (AIV) percentage, indicating improved mechanical properties. Furthermore, we observed fluctuations in AIV values across different FA/AA ratios and NaOH molarities, suggesting nuanced effects on aggregate quality. Our findings underscore the importance of optimizing parameters in the CBP process for enhanced aggregate performance.

Study on optimization of mixing ratio and shrinkage property of alkali-activated ultrafine fly ash-slag mortar

Alkali-activated cementitious materials have received widespread attention due to their favorable mechanical properties and environmental benefits. However, there are fewer studies on the optimal mixing ratio of alkali-activated ultrafine fly ash-slag (AAUS) mortar, and shrinkage cracking is a critical issue that hinders its further application. Based on this, the study used the response surface method (RSM) to optimize the mixing ratio of AAUS mortar, explored the effect of basalt fibers (BF) on the compressive strength and drying shrinkage of AAUS mortar, and finally analyzed the energy consumption and carbon emission of fiber-reinforced AAUS mortar. The experiment used X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques for microstructural characterization to research the microstructure and mineral phase changes of AAUS mortar. The results demonstrated that the 28d compressive strength of AAUS mortar reached its maximum when the substitution ratio of ultrafine fly ash (UFA) was 14.5 %, the alkali equivalent was 10.34 %, and the modulus of the activator was 1.6, based on the RSM; BF of appropriate length and volume fraction can productively improve the compressive strength of AAUS mortar and limit drying shrinkage; AAUS mortar with optimal mixing ratio can be sufficiently activated by alkali activator to construct a considerable number of C-(A)-S-H gels to establish a high-density microstructure; the carbon emission of the B124 test group was reduced by 61.1 % compared with ordinary Portland cement (OPC) mortar.

Design of a novel ternary blended Self-Compacting Ultra-high-performance Geopolymer Concrete

In this research study, the Taguchi orthogonal array (TOA) optimisation method was used to design the optimum mixture proportions of ternary blended Self-Compacting Ultra-High-Performance Geopolymer Concrete (SCUHPGC). The SCUHPGC mixtures, cured at ambient conditions, included Ground Granulated Blast Furnace Slag (GGBFS), Fly Ash (FA), and Silica Fume (SF) as aluminosilicate sources and sodium hydroxide solution and sodium silicate solution as alkaline activators. The effects of six factors at three levels on the compressive strength of SCUHPGC were investigated. The considered factors were the binder content, the ratio of fly ash to ground granulated blast furnace slag (FA/GGBFS), the ratio of silica fume to binder content (SF/Binder content), the ratio of alkaline activator to binder content (AAL/Binder content), the ratio of sodium silicate to sodium hydroxide (SS/SH), and the concentration of sodium hydroxide solution. Twenty-seven SCUHPGC mixtures were evaluated. The slump flow diameter of the optimum SCHUPGC was 740 mm, which satisfies the requirements of self-compacting concrete. The maximum 28-day compressive strength of 132.7 MPa was achieved by the optimum SCUHPGC mixture, which contained a binder content of 1050 kg/m3, a FA/GGBFS ratio of 0.3, an SF/Binder content ratio of 0.05, an AAL/Binder content ratio of 0.4, a SS/SH ratio of 4.0, and an SH concentration of 12 M. The 28-day flexural strength and tensile strength of the optimum SCUHPGC mixture were 9.6 MPa and 4.9 MPa, respectively.

Effect of glass powder on alkali-silica reaction mitigation for tunnel waste rock slag in concrete

Alkali-silica reaction (ASR) poses a critical damage to concrete structures, which will lead to a serious reduction for the service life of concrete. This study investigated the mitigation of ASR using glass powder (GP) through accelerated mortar bar tests (AMBT), with fly ash (FA) and ground granulated blast-furnace slag (GGBS) setting as control groups, and the replacement ratio of GP, FA and GGBS is 0, 5 %, 10 %, 20 %, 30 % and 40 % respectively. The results reveal that both FA and GGBS can mitigate the possibility of ASR: GGBS can significantly mitigate ASR only when its content reaches up to 40 % and FA effectively suppressed ASR with a dosage of 20 %. For the GP, particles larger than 75 μm will increase the risk of ASR, and as evidenced by the clear presence of ASR-gel and cracks in the mortar bars observed. Conversely, GP with particle sizes smaller than 75 μm effectively mitigated ASR, achieving significant suppression at a content of 20 %. The possible mitigation mechanism of GP could be attributed to the pozzolanic reaction between the GP and the alkali in the concrete, which reduces the alkali in the cement. This work might offer some reference to ASR risk control in concrete.

Feasibility study of utilizing Autoclaved Aerated Concrete (AAC) waste for the production of cold bonded lightweight artificial aggregate using high volume fly ash (HVFA) binders

Autoclaved Aerated Concrete (AAC) is a popular construction material used for partitions and insulation in buildings. At the end of its service life, AAC (Autoclaved Aerated Concrete) will be demolished and subsequently disposed of in landfills, thereby creating depository problem. Therefore, the study of reutilization and recycling of AAC waste is imperative. Artificial aggregate production can be an alternative to the reutilization of AAC waste. This paper assesses the feasibility of using Autoclaved Aerated Concrete Powder (AACP) waste as a raw material for the production of artificial aggregate and investigate its physico-mechanical properties. The investigation incorporates the comparison of cement-based binder with high-volume fly ash (HVFA) binder with different replacement levels of cement. The study uses image analysis based on photographic, optical microscopic, and scanning electron microscopy (SEM) images, to describe the porosity of the aggregate. The results show that the AACP aggregates with both cement and HVFA binders meets the current industry requirement for density and cylinder crushing strength as lightweight artificial aggregate. The appropriate binder content lies between 30 % and 40 %. The best cement to fly ash ratio in HVFA binder is determined to be of 1:1 with 50 % replacement of cement with fly ash. Image analysis showed that the porosity largely affected the properties of the AACP aggregate such as density and water absorption. However, further investigation into the reducing high-water absorption of AACP aggregates is necessary to improve their overall quality.

Experimental study on the stabilization of marine soft clay as subgrade filler using binary blending of calcium carbide residue and fly ash

This study endeavors to realize the concurrent utilization of marine soft clay (MSC) and industrial waste, specifically calcium carbide residue (CCR) and fly ash (FA), through a series of experimental investigations. The optimal ratio between CCR and FA, as well as the efficacy of the composite agent (CF–1), were examined, and an empirical equation associating the unconfined compressive strength (qu) of stabilized MSC was developed through unconfined compressive strength (UCS) tests. Microscopic analyses, including X–ray diffraction (XRD), scanning electron microscopy (SEM), and energy–dispersive spectroscopy (EDS), were employed to unveil the intrinsic mechanisms underlying CF–1 stabilized MSC. Subsequently, the suitability of CF–1 solidified MSC as a roadbed filler was ascertained through laboratory tests. Results revealed the optimum CCR:FA ratio for CF–1 to be 4:1, demonstrating superior curing effects compared to individual components such as Portland cement (PC), CCR, and FA, with commendable environmental and economic benefits. The developed empirical equation exhibited effectiveness in predicting the qu of CF–1 solidified MSC under varying curing dates (T) and dosages (Wg) conditions. Characterization through XRD, SEM, and EDS identified the primary products formed within the stabilized MSC matrix with CF–1 as comprising calcium–silicate–hydrate (C–S–H) gel, calcium–aluminate–hydrate (C–A–H) gel, and a minor amount of calcite. As T and Wg increased, the reduction in pores between soil particles enhanced the structural integrity and macro–strength of the cured MSC. The failure pattern of CF–1–solidified MSC elementary samples depended on the CF–1 dosage and curing duration. The solidification mechanism of CF–1 on MSC involved pozzolanic, ion exchange, and carbonation reactions. CF–1 solidified MSC satisfied all the specified requirements for roadbed filler in the relevant code, demonstrating substantial potential for in–situ solidification projects involving MSC.

Pengaruh Air Laut terhadap Kuat Tekan, Permeabilitas, dan Mikrostruktur Beton Geopolimer dengan Flyash dan Tanah Putih sebagai Pengganti Semen

The increasing infrastructure development of an area is sometimes located in an aggressive environment, one of which is in coastal areas so that direct contact with sea air cannot be avoided. This research aims to determine the effect of sea water on geopolymer concrete using fly ash and white soil as cement substitutes with testing parameters for compressive strength, permeability and microstructure. The test objects used were cylindrical in shape measuring 150x300 mm and 100x200 mm. The ratio of fly ash and white soil used was 85%:15% and the activator used was NaOH 8M and Na2SiO3 with a ratio of 1:2,5. The mixture proportion using a ratio of 1 fly ash: 1,497 sand: 2 split: 0,451 alkali activator with a mutual plan is 35 MPa. Tests were carried out after the concrete had gone through a curing process for 56 days, then the concrete was conditioned without soaking and with soaking for 28 days. Tests were carried out at concrete ages of 56 and 87 days. The test results show that geopolymer concrete with the influence of sea water has a higher compressive strength value and a smaller permeability coefficient compared to concrete without the influence of sea water. Microstructural testing of geopolymer concrete under the influence of sea air produces a matrix-shaped structure morphology that is denser with fewer pores compared to concrete without the influence of sea air.

Investigating key factors for superior CRMC-based mortars cured under CO2 pressurized environment

An exploratory programme was undertaken to individually test the influence of reactive magnesia to waste-based material (biomass fly ash) ratio, water to solids in binder ratio, static compaction pressure, accelerated carbonation curing period, and curing temperature, on the compressive strength results of Carbonated Reactive Magnesia Cement (CRMC)-based mortars. Subsequently, the observed optimal conditions of each parameter were combined to assess their influence when applied together. A total of twenty-four mixture labels were designed, with specimens moulded under static compaction pressure and subjected to a pressurized accelerated carbonation curing under controlled conditions. The devised mortars were evaluated through compressive strength tests, and the microstructure was carried out through TG-DTG, ATR-FTIR, XRD, SEM-EDX, and MIP analyses. The results demonstrated that none of the tested influencing factors can be exclusively considered as the sole determinant for the compressive strength outcomes. Thus, this study highlights the importance of thoroughly considering any modifications in both mixture design and accelerated carbonation curing conditions to achieve the optimal properties of CRMC-based mortars. Additionally, the devised CRMC-based mortars exhibited favourable binding properties with biomass fly ashes, allowing for its secondary use and contributing to waste circularity by avoiding landfill disposal, supporting the development of the waste circularity and CO2 sequestration through mineralization in carbonated materials.

Optimization and Evaluation of Alkali Activated Fly Ash for Lightweight Aggregate Production

This study investigates the utilization of solid waste, specifically fly ash, and other materials to produce aggregates through geopolymerisation. The research aims to explore the properties of fly ash aggregates and assess their viability in concrete production. The objectives of the study encompass the preparation of aggregates using different proportions of fly ash and alkali activator such as sodium hydroxide and sodium silicate, alongside the casting of concrete cubes utilizing the artificial aggregate. The methodology employed involves the preparation of alkali activator, mix proportioning, and the subsequent processes of mixing, casting, crushing, and curing. Various ratios of fly ash to activator (2.5:1, 3:1, and 3.5:1) were investigated, with corresponding results obtained for properties such as abrasion value, impact value, bulk specific gravity, and water absorption. The findings reveal that the properties of the fly ash aggregates vary with different ratios, with notable differences observed in abrasion value, impact value, bulk specific gravity, and water absorption. For 2.5:1 abrasion value is 26.02%, impact value is 19.32%, bulk specific gravity 1.821 and water absorption 9.61%.For 3:1 abrasion value is 37.14%, impact value is 25.15%, bulk specific gravity 1.78 and water absorption 10.58%.For 3.5:1 abrasion value is 46.5%, imapct value is 32.87%, bulk specific gravity 1.648 and water absorption 12.83%. Casting cude using ratio 2.5:1, 28 day strength is 20.46 N/mm2.. This research project offers an eco-friendly solution for utilizing fly ash in the production of high-performance aggregates, contributing to sustainable construction practices. The implications of the findings include reduced environmental impact, enhanced resource efficiency, and the potential for resilient and environmentally conscious built environments. Further research and development in this area could lead to broader adoption of geopolymerized fly ash aggregates in the construction industry, paving the way for a more sustainable and Greener future.

Mineralized carbon sequestration evaluation of coal-based solid waste consolidated backfill: A novel data-driven approach

The coal mining industry and its byproduct utilization are confronted with challenges such as the accumulation of coal-based solid waste and the emission of CO2, which seriously jeopardize environmental protection. A lucrative way of mitigating these problems is CO2 mineralization storage technology of coal-based solid waste consolidated backfill. Its successful realization stringy depends on the CO2 mineralization sealing stock and requires accurate account of the carbon sequestration rate of cemented backfill. Therefore, this study proposes a novel hybrid intelligent model combining the adaptive enhanced whale optimization algorithm and the support vector regression (A-E-WOA-SVR) to forecast the carbon sequestration performance of cemented backfill. The respective data set of cemented backfill was obtained through laboratory tests under different values of seven factors influencing the carbon sequestration rate, including water–solid ratio, cement ratio, fly ash ratio, slag ratio, curing pressure, curing temperature, and curing time. The results exhibit that the adaptive enhanced whale optimization algorithm can effectively optimize the hyperparameters of the support vector regression. The A-E-WOA-SVR hybrid intelligent model proposed in this paper accurately predicted the carbon sequestration rate of cemented backfill. Coefficient of determination, mean absolute error, root mean square error, and other indices were used to evaluate the performance of the intelligent prediction model. The obtained values of these indices implied small errors. The mean impact value sensitivity analysis revealed that water–solid ratio, cement content, curing pressure, and curing time were the key sensitive factors controlling the carbon sequestration performance of cemented backfill, which should mainly considered in the control of cemented backfill mineralization carbon sequestration performance. The research results provide a theoretical reference which enhance the CO2 mineralization storage performance of coal-based solid waste consolidated backfill.

Determining the appropriate ratio of fly ash as cement replacement in concrete and evaluating the radiation dose of the fly ash concrete

Determining the appropriate ratio of fly ash as cement replacement in concrete and evaluating the radiation dose of the fly ash concrete

New geopolymer preparation methods and its application by recycle of double-waste: ground granulated blast furnace slag and fly ash

ABSTRACT This article mainly studies new geopolymer preparation methods by recycle of double waste:ground granulated blast furnace slag (GGBFS) and fly ash as geopolymer precursor, through different mass ratio of GGBFS and fly ash, to prepare geopolymers by alkali activation, the samples is cured at ambient temperature and the mechanical test is carried out together with the analysis of XRD, SEM and EDS to research the mechanism of strengthening and geopolymerisation. After analysis we find that the sample prepared by 30% mass ratio of GGBFS have good initial strength and short setting time, as well as best mechanical performance, which is attributed to moderate Ca2+ introduction accelerates the speed of geopolymerisation and the reactants of N-A-S-H gel, C-A-S-H gel and hydrated C-S-H help to bridge the gaps between the different hydrated phases, unreacted particles and matrix, result in a homogeneous and compacted geopolymeric sample. When GGBFS mass ratio above 50%, the mechanical of samples is deteriorated due to too much hydrated calcium containing compounds are formed and covered on the unreacted GGBFS particles surface to block further geopolymerisation. The acid attack test and water resistance test are carried out to analysis the durability between 30% GGBFS introduced geopolymer and ordinary Portland cement (OPC). In additional, a field application in case of 30% GGBFS introduced geopolymer grouting repair material indicated desirable construction based on visual observation and ground-penetration radar scanning.