Emulsifier Concentration Research Articles

N-Nitrosamine Impurities in Ethalfluralin: Determination of an Overlooked Deleterious Source in Pesticides

N-nitrosamines are a class of carcinogenic chemical compound. Considering the large-scale application of agrochemicals globally, the elimination of N-nitrosamines from pesticides should be a priority for manufacturers and regulators. A set of methods was developed and validated for the determination of the toxicologically relevant N-nitrosamine impurity of ethalfluralin (ethyl-N-(2-methylallyl) N-nitroso amine—EMANA) in 33% w v−1 emulsifiable concentrate (EC) formulations. Solid Phase Extraction (SPE) was compared with the “dilute and shoot” approach. Gas chromatography (GC) was combined with Flame Ionization Detection (FID) and mass spectrometry (MS). For MS, two mass filtering modes (Selective Ion Monitoring—SIM, tandem mass spectrometry—MS/MS) and two ionization modes (Electron Ionization—EI, Positive chemical ionization—PCI) were applied. It was concluded that, in the case of samples with high nitrosamine concentration (>90 μg g−1), the “dilute and shoot” approach can be applied without compromising the quality of the results. SPE, however, is required to attain the LOQ (0.33 μg g−1) with good recovery (97.4–110.67%), linearity (R > 0.99) and precision (%RSD 0.68–1.74). The LOQ supersedes the limit set by EFSA (1 μg g−1) in the Technical Active Substance—TAS. The concentration range of the methods is 0.05–110 μg g−1. The methods were applied for the official surveillance program of the Greek agrochemicals market.

Facilitated encapsulation of a nonionic contrast agent for X-ray computed tomography into lipid vesicles by the multiple emulsification-solvent evaporation method

We studied the encapsulation of iohexol (Ihex), a nonionic contrast agent used for X-ray computational tomography, into lipid vesicles using the multiple emulsification-solvent evaporation method to formulate a nanosized contrast agent. This lipid vesicle preparation method consists of three steps: (1) primary emulsification for producing water-in-oil (W/O) emulsions containing fine water droplets that will be converted to the internal water phase of the lipid vesicles, (2) secondary emulsification for formulating multiple water-in-oil-in-water (W/O/W) emulsions encapsulating the fine water droplets containing Ihex, and (3) solvent evaporation to remove the oil phase solvent (n-hexane) and to form lipid bilayers surrounding the fine inner droplets, resulting in the formation of lipid vesicles encapsulating Ihex. As the diameter and Ihex concentration of the primary W/O emulsion droplets decreased, a higher Ihex encapsulation yield was obtained for the final lipid vesicles. The entrapment yield of Ihex in the final lipid vesicles varied significantly with the emulsifier (Pluronic® F-68) concentration in the external water phase of W/O/W emulsion, and the highest yield (65%) was obtained when the emulsifier concentration was 0.1 wt%. We also investigated the powderization of lipid vesicles encapsulating Ihex via lyophilization. The powderized vesicles were dispersed in water after rehydration and maintained their controlled diameters. The entrapment yield of Ihex in powderized lipid vesicles was maintained for over 1 month at 25 ˚C, while significant leakage of Ihex was observed in the lipid vesicles suspended in the aqueous phase.

Formation and characterisation of concentrated emulsion gels stabilised by faba bean protein isolate and its applications for 3D food printing

Concentrated emulsions were prepared at a fixed oil concentration (50 wt%) using faba bean protein isolates (FPI) as an emulsifier and texturizer. Effects of FPI concentration (1, 3 and 5 wt%; at pH7), pH (pH 3, 5, 7, and 9; 3 wt%) and addition of salts (200 mM NaCl and 40 mM CaCl2; at 3 wt% FPI and pH 7) on the emulsion formation were studied. The oil droplet size and microstructural characteristics were examined by static light scattering and confocal laser scanning microscopy (CLSM), and the viscoelastic behaviours of emulsions were characterised by oscillatory rheology. At all different FPI concentrations, the emulsions formed viscoelastic gels with different gel strengths and stability due to network formation and interactions between jammed oil droplets and protein aggregates. The oil droplet size, rheological properties, and 3D printability of emulsions were not significantly changed by the presence of salts. The storage modulus G′ (1 Hz) values were higher at higher FPI concentrations, and higher pH values (i.e., pH 7 and 9) as the droplet size was smaller and the droplet packing was more compact, resulting in a better 3D printing performance. Furthermore, the heat treatment (90 °C for 30 min) remarkedly improved gel strength and the 3D printability because of protein denaturation and oil droplet aggregation. This finding demonstrated that the emulsion gel formed with FPI was tuneable for food 3D printing. Most of samples displayed high printing precision with great self-supporting capability, which may find potential applications in creating specialised diet.

Preparation of high complex concentration emulsion stabilized by soy protein/dextran sulfate composite particles.

Soy protein isolate (SPI) could be used as an emulsifier to stabilize emulsions, while SPI is unstable under low acidic conditions. The stable composite particles of SPI and dextran sulfate (DS) could be formed by the electrostatic interaction at the pH was 3.5. And the SPI/DS composite particles were used to prepare the high complex concentration emulsion. The stabilization properties of high complex concentration emulsion were investigated. Compared to uncompounded SPI, the particle size of SPI/DS composite particles was smaller at 1.52 μm, and the absolute value of the potential increased to 19.9 mV when the mass ratio of SPI to DS was 1:1 and the pH was 3.5. With the DS ratio increased, the solubility of the composite particles increased to 14.44 times of the untreated protein at pH 3.5, while the surface hydrophobicity decreased. Electrostatic interactions and hydrogen bonds were the main forces between SPI and DS, and DS was electrostatically adsorbed on the surface of SPI. The emulsion stability significantly enhanced with the increase of complex concentration (38.88 times higher than at 1% concentration), the emulsion average droplet size was the lowest (9.64 μm), and the absolute value of potential was the highest (46.67 mV) when the mass ratio of SPI to DS was 1:1 and the complex concentration of 8%. The stability of the emulsion against freezing was improved. The SPI/DS complex has high solubility and stability under low acidic conditions, and the SPI/DS complex' emulsion has a well stability. This article is protected by copyright. All rights reserved.

Novel iron-modified chitosan for effective demulsification and oil recovery of emulsified oily wastewater

Flocculation is considered an alternative, eco-friendly demulsification technology for treating emulsified oily wastewater. However, conventional flocculants produce a large amount of oily sludge, causing environmental risk as well as oil loss. To address this, we fabricated a demulsifying agent made of iron-modified chitosan (FeOX-CS) for demulsification and reducing the production of oily sludge. The hydrophilicity of the chitosan was enhanced after FeOX modification, which enhanced the hydrogen bond between the flocculant and the oil droplet, and improved the demulsification efficiency. The demulsification efficiency of the FeOX-CS for the oil-in-water (O/W) model emulsions is over 60% after 3 recycles. The demulsification efficiency of FeOX-CS excessed 97% within 60 min at the dosages of FeOX-CS 20 mg/L, initial model emulsion concentration of 200 mg/L, and pH of 7. The demulsified oil mainly exists in water surface and FeOX-CS surface. Thus, the synthesized FeOX-CS is a potential for treating emulsified oily wastewater.

Assessment of the Rheological and Mechanical Properties of Emulsion–Cement Paste

The main objective of this study was to evaluate the rheological and mechanical properties of emulsion–cement paste (ECP), which is generally formed during the mixing process of cold recycled mixtures. Forty-five combinations of ECP specimens were prepared at varying amounts of emulsion, cement, and water. Specimens were mixed using a low-shear mixer, then allowed to cure in an oven at 60°C for 72 h. The testing program for ECPs included multiple stress creep recovery, bending beam rheometer, linear amplitude sweep, penetration, and isothermal calorimetry tests. Statistical analyses were then conducted to assess the significance of the impact of ECP constituents on the low-, intermediate-, and high-temperature properties. Results showed that varying the proportions of emulsion, cement, and water significantly influenced the properties of ECPs. Higher cement and water contents improved the properties of ECP at high temperatures, but reduced their resistance to intermediate- and low-temperature cracking. Conversely, increasing the emulsion content improved the resistance of ECPs to fatigue and low-temperature cracking, while increasing their rutting susceptibility at high temperatures. The outcomes of this study provide more knowledge about the interactions among emulsion, cement, and water, which can be beneficial to the designers of asphalt mixtures that involve the use of emulsion, cement, and water, such as cold recycled mixtures.

One-pot construction of epoxy resin nanocarrier delivering abamectin and its efficacy on plant root-knot nematodes.

The complex preparation process and storage instability of nanoformulations hinders their development and commercialization. In this study, nanocapsules loaded with abamectin were prepared by interfacial polymerization at room temperature and ordinary pressure using the monomers of epoxy resin (ER) and diamine. The potential mechanisms of primary amine and tertiary amine in influencing the shell strength of the nanocapsules and the dynamic stability of abamectin nanocapsules (Aba@ER) in the suspension system were systematically researched. The tertiary amine catalyzed the self-polymerization of epoxy resin into linear macromolecules with unstable structures. The structural stability of the diamine curing agent with a primary amine group played a key role in enhancing the structural stability of the polymers. The intramolecular structure of the nanocapsule shell formed by isophorondiamine (IPDA) crosslinked epoxy resin has multiple spatial conformations and a rigid saturated six-membered ring. Its structure was stable, and the shell strength was strong. The formulation had stable dynamic changes during storage and maintained excellent biological activity. Compared with emulsifiable concentrate (EC), Aba@ER/IPDA had superior biological activity, and the field efficacy on tomato root-knot nematode was enhanced by approximately 31.28% at 150 days after transplanting. Aba@ER/IPDA, which has excellent storage stability and simple preparation technology, can provide a nanoplatform with industrial prospects for efficient pesticide delivery. © 2023 Society of Chemical Industry.

Preparation of enzyme-responsive composite nanocapsules with sodium carboxymethyl cellulose to improve the control effect of root-knot nematode disease

Developing an efficient drug delivery system to mitigate the harm caused by root-knot nematodes is crucial. In this study, enzyme-responsive release abamectin nanocapsules (AVB1a NCs) were prepared using 4, 4-diphenylmethane diisocyanate (MDI) and sodium carboxymethyl cellulose as response release factors. The results showed that the average size (D50) of the AVB1a NCs was 352 nm, and the encapsulation efficiency was 92 %. The median lethal concentration (LC50) of AVB1a NCs for Meloidogyne incognita activity was 0.82 mg L−1. Moreover, AVB1a NCs improved the permeability of AVB1a to root-knot nematodes and plant roots and the horizontal and vertical soil mobility. Furthermore, AVB1a NCs greatly reduced the adsorption of AVB1a by the soil compared to AVB1a emulsifiable concentrate (EC), and the effect of the AVB1a NCs on controlling root-knot nematode disease was increased by 36 %. Compared to the AVB1a EC, the pesticide delivery system significantly reduced the acute toxicity to the soil biological earthworms by approximately 16 times that of the AVB1a and had a lower overall impact on the soil microbial communities. This enzyme-responsive pesticide delivery system had a simple preparation method, excellent performance, and high level of safety, and thus has great application potential for plant diseases and insect pests control.

PH-Shifting combined with ultrasound treatment of emulsion-filled β-conglycinin gels as β-carotene carriers: Effect of emulsion concentration on gel properties

In this work, emulsion-filled gels were prepared from natural and pH-shifting combined with ultrasound β-conglycinin (7S) as emulsifiers. The emulsifier modification and emulsion concentrations (5, 10, 15, 20 wt%) were evaluated on the structural and β-carotene release properties of the gels. Compared to the 7S hydrogel, the emulsion-filled gels exhibited better water-holding and textural properties. The 7S modification and the increase in emulsion concentration resulted in altered water distribution and improved microstructure and rheological properties of the emulsion-filled gels. The dense and homogeneous gel network was formed at an emulsion content of 15 wt%. The gels were regulated by different release kinetics in a simulated gastrointestinal environment. M−15 showed the highest bioaccessibility and chemical stability (72.25% and 89.87%) with good slow-release properties of β-carotene. These results will guide the development of encapsulated delivery systems for gel food products.

LC-MS/MS Method Minimizing Matrix Effect for the Analysis of Bifenthrin and Butachlor in Chinese Chives and Its Application for Residual Study.

The matrix effect refers to the change in the analytical signal caused by the matrix in which the sample is contained, as well as the impurities that are co-eluted with the target analyte. In crop sample analysis using LC-MS/MS, the matrix effect can affect the quantification results. Chinese chives are likely to exhibit a strong matrix effect when co-extracted with bifenthrin and butachlor due to the presence of phytochemicals and chlorophyll. A novel analytical method was developed to reduce the matrix effects of bifenthrin and butachlor to a negligible level in Chinese chives. The established method had a limit of quantitation of 0.005 mg/kg and correlation coefficients greater than 0.999 within the range of 0.005-0.5 mg/kg. Matrix effects were found to be negligible, with values ranging from -18.8% to 7.2% in four different sources of chives and two leafy vegetables. Compared to conventional analytical methods for the LOQ and matrix effect, the established method demonstrated improved performances. The analytical method was further applied in a residual study in chive fields. The active ingredient of butachlor 5 granule (GR) was not detected after soil admixture application, while that of bifenthrin 1 emulsifiable concentrate (EC) showed a range from 1.002 to 0.087 mg/kg after foliar spraying. The dissipation rate constant (k) of bifenthrin was determined to be 0.115, thus its half-life was calculated to be 6.0 days. From the results, PHI and safety use standards of both pesticides were suggested. The developed analytical method can be applied to accurately determine bifenthrin and butachlor residues in Chinese chives and provides a foundation for further research on the fate and behavior of these pesticides in the environment.

Rheology and stability of drilling fluids formulated with saturated NaCl and CaCl2 solutions

Drilling fluids continue under development, being a challenge for the oil industry, which attempts to optimize technical performance, to comply with environmental laws, and to reduce fluid costs. A non-aqueous based drilling fluid widely used by Petrobras has been reformulated due to changes in Brazilian environmental legislation. The paraffinic base of the drilling fluid was replaced by an olefinic base, which is more biodegradable. Hence, to improve drilling fluid performance, the characteristics of olefin emulsions formulated with saturated NaCl and CaCl2 solutions were investigated. Therefore, for different emulsifier concentrations and stirring speeds, the droplet size distribution, the stability, and the rheological parameters of three emulsions were evaluated. All these emulsions had distinct dispersed phases, being these saturated solutions of NaCl, CaCl2, and 75% NaCl and 25% CaCl2. The increase of the stirring speed was followed by the emulsified systems apparent viscosities increase, but their polydispersity index and D50 values were reduced. The NaCl/Olefin emulsion exhibited lower stability, apparent viscosity, and emulsifier saturation concentration when compared to the CaCl2/Olefin emulsion. Besides, the CaCl2/Olefin emulsion showed more pronounced thixotropic behaviour.

Mosquito repellent microcapsules of nepeta essential oil were prepared by electro‐atomization complex coacervation

AbstractMicrocapsules containing nepeta essential oil (NEO) are prepared by electro‐atomization complex coacervation with sodium alginate and gelatin as wall materials. The effects of conditions such as sodium alginate solution concentration, core‐to‐wall ratio and emulsifier content on the release of essential oil and mosquito repellent properties of the microcapsules are studied. The microcapsules prepared under optimal preparation conditions have good performance and morphology, the encapsulation efficiency and loading capacity being 86.65% and 13.93%, respectively. The prepared microcapsules have adequate morphological characteristics observed using scanning electron microscopy. Fourier transform infrared spectra and thermogravimetric analysis show that NEO is successfully loaded in the microcapsules, and the thermal stability of NEO is improved. In addition, the results of release and repellent tests show that the NEO in the microcapsules could achieve stable release within 15 days and maintain an avoidance rate above 80% within 48 h, indicating the potential application of the microcapsules in the field of mosquito repellents. © 2023 Society of Industrial Chemistry.

Development of Photoprotective Formulations: Influence of Formulation Composition on the SPF and Mechanical Properties.

The evaluation of the vehicle formulation is important during the development of sunscreens, as it influences their efficacy. In this context, the aim of the present study was to develop photoprotective formulations and evaluate the influence of the formulation components in the sun protection factor (SPF) and physical-mechanical and sensory properties of the formulations. We evaluated four sunscreens through a 22 full factorial design in terms of concentration and emulsifier type. The design of experiments (DOE) parameters were SPF, thixotropy, and work of shear. After the screening of the formulations by DOE, the SPF values, mechanical and sensory properties, and stability were evaluated. All study formulations showed non-Newtonian pseudoplastic behavior, compatible with sunscreens, and presented SPF values above 30. The factors evaluated in DOE had significant interactions for all the analyzed parameters. The concentration of the phosphate-based emulsifier influenced the SPF parameter. The work of shear was influenced by the concentration of polyglyceryl-based emulsifier. The concentration and the type of emulsifier influenced the thixotropy. Finally, effective sunscreens were developed, and the type and concentration of emulsifiers had an influence on the SPF of the formulations. In addition, the formulations chosen by DOE were stable and showed good sensory properties.

The Effects of Surfactant and Metal Ions on the Stability and Rheological Properties of Nanoemulsions Loaded with Gardenia Yellow Pigment

The present work reports the preparation of gardenia yellow pigment containing paraffin oil nanoemulsions stabilized by Span80 and Tween80. The preparation of the required nanoemulsions was optimized by testing different conditions, such as varying the hydrophilic–lipophilic balance (HLB), the emulsifier concentration (EC), the oil–water ratio (OWR), and the temperature (T), as determined by the average droplet diameter (ADD) and polydispersity index (PDI). Our results indicated that a minimum ADD of 65.9 nm and PDI of 0.116 were obtained at an optimum HLB value of 6.0, EC of 10% (w/w), OWR of 2:1, and T of 40 °C. Both the steady-state and dynamic rheological parameters were further investigated, revealing that the emulsions exhibited pseudoplastic behaviors. The long-term stabilities of the nanoemulsions after the addition of inorganic salts were monitored by observing their visual appearances. It was found that the emulsions containing pure water or 0.1 M CaCl2 and AlCl3 became slightly separated, while the emulsions containing 0.1 M KCl and NaCl showed no separation after 30 days of storage at room T. This difference among different salts could be related to the number of valence electrons of their cations. The spatial electrostatic effects of the monovalent cationic (KCl and NaCl) and the nonionic surfactants were greater than the delamination/sedimentation forces of the system, which was better than the salt based on the cations with valences greater than one (CaCl2 and AlCl3). In conclusion, the present work illustrated the formation, rheological properties, and stability of water containing gardenia yellow pigment in paraffin oil nanoemulsions, which can be of great significance for the application of gardenia-yellow-pigment-based formulations.

A microfluidic method to systematically study droplet stability in highly concentrated emulsions

Preparation of high internal phase emulsions comes with many challenges. Droplet stability is hardly explored in these systems because they are not transparent, and highly dynamic. There is a clear need for advanced methods that allow elucidation of the mechanism of droplet coalescence in high internal phase emulsions. For this reason, we developed microfluidic chip that allow ultimate control over droplet size and high volume fraction. The chip concentrates emulsions in a concentration section, and subsequently allows coalescence investigation at volume fractions larger than 0.74. To illustrate the effect of surface active components, a systematic study was successfully carried out with β-lactoglobulin and sodium dodecyl sulfate, thus highlighting the versatility of the approach.

Effect of emulsifiers addition in sponge cake premix on the physical and sensory of sponge cake

Baked products such as bread, biscuits, and cakes are among the most popular food categories because of their convenience. Sponge cake has a porous structure like a sponge and is lightweight and soft. The single-stage mixing method has been developed and widely applied in the large-scale production of sponge cakes. The sponge cake formulations generally use an additional emulsifying agent to form better aeration. The effect of adding emulsifiers in the formulation of sponge cake premix on the cake expansion and stability, appearance, softness, and moistness of the sponge cake was investigated. The emulsifiers contain several functional molecules, including acid esters of vegetable oils, naturally occurring partial glycerides, and proteins. Different concentrations of emulsifiers significantly affect the physical of sponge cake. The addition of 3% emulsifiers resulted in the highest cake expansion and the highest score of the overall sensory attribute. According to De Garmo’s effectiveness index analysis, an addition of 3% resulted in the most optimum physical and sensorial attributes.

Investigating the impact of processing conditions on the emulsion stability, viscosity, and foaming capacity of concentrated infant formula emulsions

Factors (degree of protein denaturation, order of lactose addition, pH, and lecithin concentration) affecting emulsion stability, viscosity and foaming capacity of concentrated infant formula systems were investigated through the application of Design of Experiments (DOE) methodology. Fat globule size (D50) varied from 0.63 μm to 4.92 μm depending on the processing conditions. The degree of fat droplets flocculation, ranging from 1.2 to 9.1, was observed to be driven mainly by the interaction term of pH and lecithin concentration. The viscosity of the concentrated infant formula emulsions varied widely from 28 mPa·s to 191 mPa·s, and was found to be not only a function the flocculation state of the emulsion systems, but also was likely impacted by other contributing factors. The interaction term of pH and lecithin concentration modified also significantly the foaming capacity of the studied samples (p = 0.019). Data suggested that the foaming capacity of the concentrated infant formula emulsions was affected by the presence of flocculated oil drops (p = 0.032). The findings of the present study may be considered in the formulation design of concentrated dairy-based emulsions to mitigate the adverse effects of viscosity development and foam generation during processing of such complex systems.

Solid-like elastic behavior of nanosized concentrated emulsions: Size-dependent Young’s and bulk moduli

Concentrated emulsions with volume fractions exceeding the critical value have diverse applications in foods, cosmetics, coatings, and pharmaceuticals. They have a jammed structure and tend to exhibit a solid-like behavior. Unfortunately, the mechanical properties of monodisperse concentrated emulsions are challenging to study by experiments or simulations because of thermodynamic instability and droplet coalescence. A mesoscopic simulation method is employed to study the mechanical properties of the concentrated emulsion. Knowledge of the microstructure and interdroplet interaction among monodisperse droplets is not a prerequisite. Effects of the volume fraction (ϕ), droplet diameter (D), and interfacial tension (σ) on Young’s modulus (E) and bulk modulus (K) are investigated systematically. For ϕ < ϕc, Young’s modulus is absent and the bulk modulus rises with increase ϕ. For ϕ > ϕc, both Young’s and bulk moduli are found to grow with increasing ϕ and σ. However, these solid-like properties become more prominent as D is decreased. On the basis of the interfacial energy per unit volume, our simulation results can be well represented by the relations E ∼ ϕ0.13(ϕ-ϕc)1.55(σ/D) and K ∼ ϕ1.06(ϕ-ϕc)0.15(σ/D). Moreover, the relationship for soft materials E = 3 K(1 − 2ν) is satisfied. The Poisson’s ratio (ν) is very close to 0.5 but still decreases slightly with increasing ϕ.

Preparation and properties of nano-SiO2 modified microcapsules for asphalt pavement

This paper presents nano-SiO2 modified microcapsules prepared by in-situ polymerization to improve their performance. Low-quality vegetable oil was selected as the main material and Melamine Urea Formaldehyde (MUF) modified by nano-SiO2 was selected as the shell material. Firstly, the optimal preparation parameters of the nano-SiO2 modified microcapsules were determined, including the emulsifier type, emulsifier concentration, emulsifier shearing speed, the core-shell ratio, reaction pH, reaction temperature, and nano-SiO2 content, respectively, by using the Scanning Electronic Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Thermo-Gravimetric analysis (TGA) and nanoindentation test, etc. Secondly, the properties of the prepared microcapsules were evaluated. The particle size of the prepared nano-SiO2 modified microcapsules was ∼ 78–96 μm, and the average size was 88.16 μm. The average core content was 85.39 %, which exceeds the upper limit of 80 % of existing microcapsules. The nano-hardness and Young’s modulus were 0.33 and 2.63 GPa, respectively, improved by at least 1.4 times compared to existing microcapsules. The mass loss of microcapsules was 0.95 % at 182.73 °C, which is at least 2.9 times higher than the thermal stability of existing microcapsules. The results showed that the addition of nano-SiO2 can obviously improve the performance of microcapsules.

Field investigation of material layer properties for emulsion-treated base layer application in low-volume roads

ABSTRACT The study presents the determination of pavement design input parameters-structural layer coefficients and back-calculated layer moduli for Emulsion-Treated Base (ETB) layer materials in a Low-Volume Road (LVR) application. Seven test sections were constructed on a stretch of LVR with varying emulsion contents and 50% Recycled Asphalt Pavement (RAP) aggregate incorporation in ETB mixes. Structural performance of the test sections was periodically observed using a Benkelman Beam Deflectometer (BBD) and the data was used for the estimation of the structural layer coefficient of ETB, based on the effective structural number of the pavement. The deflection bowl data of the test sections were also captured using a Falling Weight Deflectometer (FWD) and the modulus of ETB layer was back-calculated using a back-calculation software. The study proposes a structural layer coefficient of 0.23–0.29 and back-calculated moduli of 578–919 MPa for ETB mixes characterised by Indirect Tensile Strength (ITS) values ranging between 140 kPa and 245 kPa. Traffic level-based ETB mix specifications are also proposed in the study, which enables a mix designer to proportion the mix for a selected design traffic level. For a design traffic level of 1 million standard axles, the target dry ITS specification was found to be 188 MPa.