To address the issues of high porosity and low strength in calcium sand of artificial islands, this study focuses on improving the calcium sand's mechanical properties. The effects of WER curing methods and coconut fiber modification on the UCS and microscopic mechanisms of calcium sand are investigated. The results indicate that both fiber incorporation and the increase in WER ratio can enhance the unconfined compressive strength of calcareous sand, with the addition of a certain amount of coconut coir fiber showing a more significant strength increase. The optimal recommended dosage of WER is 15%, which results in an UCS of 1218 kPa, an increase of nearly 4.27 times compared to 9% WER dosage. Coconut coir fiber has good tensile strength that can improve the compressive strength of calcareous sand after curing. The UCS of calcareous sand cured with a fiber content of 0.3% to 0.5% is increased by 1247 kPa to 1792 kPa compared to cured soil with no fiber. The strong binding nature of WER addresses the issue of large porosity in calcareous sand. Together with the penetrating coconut coir fibers, it forms a three-dimensional reticular framework structure, thereby enhancing the compressive performance of the calcareous sand-cured soil mass.
Naphthalene is a fungicide that can also be a phase-change agent owing to its high crystallization enthalpy at about 80 degrees C. The relatively rapid evaporation of naphthalene as a fungicide and its shape instability after melting are problems solved in this work by its placement into a cured epoxy matrix. The work's research materials included diglycidyl ether of bisphenol A as an epoxy resin, 4,4 '-diaminodiphenyl sulfone as its hardener, and naphthalene as a phase-change agent or a fungicide. Their miscibility was investigated by laser interferometry, the rheological properties of their blends before and during the curing by rotational rheometry, the thermophysical features of the curing process and the resulting phase-change materials by differential scanning calorimetry, and the blends' morphologies by transmission optical and scanning electron microscopies. Naphthalene and epoxy resin were miscible when heated above 80 degrees C. This fact allowed obtaining highly concentrated mixtures containing up to 60% naphthalene by high-temperature homogeneous curing with 4,4 '-diaminodiphenyl sulfone. The initial solubility of naphthalene was only 19% in uncured epoxy resin but increased strongly upon heating, reducing the viscosity of the reaction mixture, delaying its gelation, and slowing cross-linking. At 20-40% mass fraction of naphthalene, it almost entirely retained its dissolved state after cross-linking as a metastable solution, causing plasticization of the cured epoxy polymer and lowering its glass transition temperature. At 60% naphthalene, about half dissolved within the cured polymer, while the other half formed coarse particles capable of crystallization and thermal energy storage. In summary, the resulting phase-change material stored 42.6 J/g of thermal energy within 62-90 degrees C and had a glass transition temperature of 46.4 degrees C at a maximum naphthalene mass fraction of 60% within the epoxy matrix.
There are significantly toxic Cu contaminants in seasonal frozen soil areas under industrial production and mineral exploitation. However, the hydration reactions of mainstream alkaline curing agents such as cement are disturbed by the solidification and thawing of moisture, and their solidification/stabilization is ineffective to heavy metals. Therefore, there is an urgent requirement to optimize the use of current curing agents to improve the solidification/stabilization (S/S) effect of Cu contaminants in seasonal frozen soil areas. In this study, the Epoxy resin (EP) with excellent waterproofing and frost resistance was incorporated into artificially prepared Cucontaminated soil to maintain a steady engineering application strength and inhibit the outward diffusion of toxic Cu contaminants under freeze-thaw cycles. The freeze-thaw resistance of EP-cured Cu-contaminated soil and the feasibility of EP remediation technology have been investigated, including mechanical properties, environmental effects and microstructure. The decline in mechanical strength and the increment in Cu leaching during freeze-thaw cycles are effectively suppressed by the remediation of EP. Even after 8 freeze-thaw cycles, there is merely a mechanical strength decline of 5 %, solely a secondary Cu leaching of 4.74 mg/L, and astonishingly a leachable index of 11.70 in the specimens with 12 % EP dosage. The expansion phenomenon of pores and clay fractures under freeze-thaw cycles were gradually alleviated after incorporation of EP. The above results demonstrate the Cu-contaminated seasonal frozen soil remedied by EP are high-strength, basically non-toxic, and environmentally friendly material which are suitable for in-situ stabilization/solidification in seasonal frozen soil areas.
Epoxy resins exhibit outstanding curability, durability, and environmental compatibility, rendering them extensively utilized in the realm of engineering curing. Nevertheless, the current curing mechanism of epoxy-based resins in cohesion with sand remains inadequately elucidated, significantly impeding their applicability within the domain of soil curing. This study employed molecular dynamics simulations to investigate the adsorption behavior of three distinct types of epoxy resins on the sand surface: diglycidyl ether of bisphenol-A epoxy resin (DGEBA), diglycidyl ether 4,4 '-dihydroxy diphenyl sulfone (DGEDDS), and aliphatic epoxidation of olefin resin (AEOR). The objective was to gain insights into the interactions between the sand surface and the epoxy resin polymers. The results demonstrated that DGEDDS formed a higher number of hydrogen bonds on the sand surface, leading to stronger intermolecular interactions compared to the other two resins. Furthermore, the mechanical properties of the adsorbed models of the three epoxy resins with sand were found to be relatively similar. This similarity can be attributed to their comparable chemical structures. Finally, analysis of the radius of gyration for the adsorbed epoxy resins revealed that AEOR exhibited a rigid structure due to strong molecular interactions, while DGEDDS displayed a flexible structure owing to weaker interactions.
In this paper glass/chicken feathers reinforced epoxy composite and glass/chicken feathers reinforced polyester composite was prepared in the laboratory at different percentage of the glass and chicken feathers. Tensile properties, flexural properties, shore hardness and impact strength of the glass/chicken feathers reinforced epoxy composite and glass/chicken feathers reinforced polyester composite was studied experimentally and compared at different percentage of the glass and chicken feathers. The composite will be used in humid and corrosive environment; therefore, water absorption and acid corrosion test were performed. To understand the degradation behaviour of the composite, soil test was performed. Scanning electron microscopy analysis was carried out to find the fracture and interfacial characteristics of the composites after tensile test. This hybrid composite can be used in automobile, structural and defense sector. Glass/chicken feathers reinforced epoxy composite and glass/chicken feathers reinforced polyester composite plate was prepared in the laboratory at different percentage of the glass and chicken feathers. Tensile properties and shore hardness of each composite was studied experimentally and compared at different percentage of the glass and chicken feathers. image
The aim of this research was to undertake laboratory testing to investigate the beneficial effects of epoxy resin grouts on the physical and mechanical properties of sands with a wide range of granulometric characteristics. Six sands of different particle size and uniformity coefficients were grouted using epoxy resin solutions with three ratios of epoxy resin to water (3.0, 2.0 and 1.5). A set of unconfined compressive strength tests were conducted on the grouted samples at different curing periods and a set of long-term unconfined compressive creep tests in dry and wet conditions after 180 days of curing were also carried out in order to evaluate the development of the mechanical properties of the sands, as well as the impact of water on them. The findings of the investigation showed that epoxy resin resulted in appreciable strength values in the specimens, especially those of fine sands or well graded sands, grouted with the different epoxy resin grouts. Whilst the higher compressive strength and elastic modulus values at the age of 180 days were obtained for the finer sand, which ranged from 2.6 to 5.6 MPa and 216 to 430 MPa, respectively, the lower compressive strength and elastic modulus values were attained for the coarser sand with low values of the coefficient of uniformity, which varied from 0.68 to 2.2 MPa and 75 to 185 MPa, respectively. Moreover, all grouted sands showed stable long-term creep behaviour, with high values of the creep limit ranging from 67.5 to 80% of compressive strength. The presence of water had a negative marginal effect in the majority of the grouted specimens. In terms of physical properties, the permeability and porosity were estimated. The permeability of fine sands or well graded sands was decreased by two to four orders of magnitude. Using laboratory results and regression analysis, three mathematical equations were developed that relate each of the dependent variables of compressive strength, elastic modulus and coefficient of permeability to particular explanatory variables.
Grouting is a method or technique that is carried out to improve underground conditions by injecting material that is still in a liquid state, through pressure (it can inject semi -viscous materials) so that the material will fill in all the existing cracks and holes. The main purpose of grouting in this study is to strengthen the soil and increase soil strength. The injection material will enter the soil pores, react with the soil, and harden to form a strong and sturdy bond. The grouting material in this study was applied to filling boreholes in pile foundations when a load is applied, will be held by the frictional resistance between the piles, cement, epoxy paste, and soil. The filling materials for this grouting are soil paste, cement, and epoxy resin which were observed in a laboratory with a tensile test system to see the behavior of increasing soil strength at 7 days, 14 days, and 28 days. Based on the results of laboratory tests carried out, the use of epoxy resin, cement, soil, and water as grouting materials for foundations increases the soil stiffness value expressed in the modulus of elasticity value and increases the soil shear parameter values, namely the values c and phi. The increase in value occurs at the ratio ER/W = 80/180 where with a longer curing time, namely 28 days, the value of shear stress, c and phi and the modulus of elasticity are each 2.3kg/cm2; 39,520; 12.08 MPa
In order to enhance the application of epoxy mortar in pavement repair engineering, an epoxy -based repair material with short molding time, easy fabrication, high early strength and good durability was developed. In the past, the fillers of epoxy mortar were mainly fly ash and silica fume. In this paper used loess (LS) and river sand (RS) which were lower cost and more readily available, mixed with epoxy resin to make a new epoxy mortar system. The influence of epoxy resin mass fraction (20%,25%,30%), filler type (LS, RS), and LS -to -RS ratio (2:1,1:1,1:2) on the mechanical properties and durability of the epoxy mortar were investigated. It was observed that the early compressive strength of the specimens increased significantly with the increase of the proportion of epoxy resin in the mixture, reaching 49.2 MPa after 2 h of curing. Moreover, when the mass fraction of epoxy resin increased from 20% to 30%, the flexural strength increased by more than 20% after curing for 2 h. Additionally, compared to single filler, mortar containing both LS and RS exhibited superior durability. Unlike the specimens of the all -river sand group L0, which showed a 40% to 60% decrease in mechanical properties in sulfate and chloride saline solutions, almost no loss of strength occurred in the L1R1 group. This phenomenon can be explained by the findings from SEM and MIP tests that the L1R1 group has a more compact pore structure compared to the L0 group.
Among different types of heavy metal-contaminated soil, copper (Cu)-contaminated soil is very serious, and the Cu concentration in it is usually very high. It is common to solidify/stabilize Cu-contaminated soil using alkaline cementitious material. However, the remediated Cu-contaminated soil fails to meet the requirements of environmental safety and load-bearing capacity. This dilemma in the remediation of Cu-contaminated soil hinders the effective utilization of land resources. In this study, epoxy resin (EP) was utilized to solidify/stabilize Cu contaminated soil due to its stable and rapid curing performance and excellent resistance to acid, alkali, and salt erosion. The mechanical properties, environmental effects, and curing mechanism of EP-cured Cu -contaminated soil were investigated. The results showed that the application of EP significantly enhanced the unconfined compressive strength (UCS), cohesion and internal friction angle of Cu-contaminated soil. All specimens met the UCS criterion specified by the United States Environmental Protection Agency (USPEA), namely no less than 0.35 MPa, which indicated that those EP-cured Cu-contaminated soil were qualified for practical engineering applications. According to the toxicity characteristic leaching procedure (TCLP), the application of EP enhanced the stability of Cu in Cu-contaminated soil. The leaching index of Cu ranged from 11 to 14. A high leaching index showed that the S/S treatment was safe and effective and the remediated Cu-contaminated soil satisfied the environmental requirement for heavy metals. This study confirmed the feasibility of utilizing EP in the solidification/stabilization (S/S) technology to convert high-concentration Cu-contaminated soil into secure and stable engineering materials. The remediation of Cu-contaminated soil by EP lays a solid foundation for the safe treatment and reuse of heavy metal-contaminated land resources.