Specimen Preparation Procedures Research Articles

Optimized procedure for conventional TEM sample preparation using birefringence

Specimens for quality transmission electron microscopy (TEM) analyses must fulfil a range of requirements, which demand high precision during the prior preparation process. In this work, an optimized procedure for conventional TEM specimen preparation is presented that exploits the thickness-dependence of interference colors occurring in birefringent materials. It facilitates the correct estimation of specimen thickness to avoid damage or breaking during mechanical thinning and reduces ion-milling times below 30minutes. The benefits of the approach are shown on sapphire and silicon carbide cross-section samples. The presented method is equally suitable for assessing specimen thickness during dimpling and wedge-polishing, and is particularly useful at thicknesses below 20 μm, where the accuracy of mechanical techniques is insufficient. It is precise enough to be employed for a visual thickness estimation during the thinning process, but can be additionally optimized by analyzing the RGB spectrum of the occurring interference colors.

Detection of Cell Wall-Anchoring Machinery by Immunogold-Labeling Thin-Section Electron Microscopy.

Cell wall anchoring of surface proteins and pili in Gram-positive bacteria is mediated by sortase - a highly conserved transpeptidase enzyme. Early studies have demonstrated the membrane-associated nature of this enzyme in close proximity with its cognate substrates, using immunogold-labeling thin-section electron microscopy. Here, we provide a detail protocol of this methodology, including specimen preparation, ultrathin sectioning, and immunogold-labeling electron microscopic procedures, with an experimental model of sortase enzymes from Actinomyces oris. In principle, this protocol can be employed for any bacterial ultrathin-section samples to detect subcellular localization of proteins and organelles by immuno-electron microscopy.

B-310 High Through-put Online Solid Phase Extraction of Immunosuppressive Drugs From Whole Blood on Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) in a Tertiary Hospital Laboratory

Abstract Background Cyclosporine A and Tacrolimus are immunosuppressive drugs that are commonly used in solid organ transplant and are characterized by a relatively narrow therapeutic index, potential drug interactions and significant intra- and inter-individual variability. Therapeutic drug monitoring is therefore beneficial for optimizing dosage regimens, preventing rejection of the graft and reducing toxicities in transplant recipients receiving immunosuppressive drug therapy. A commercial assay (RECIPE ClinMass LC-MS/MS Advanced kit) for simultaneous measurement of immunosuppressants in whole blood using LC-MS/MS methodology has been adapted for assay performance evaluation in our laboratory on the Agilent 1290 Infinity II liquid chromatograph coupled to an Agilent 6470 triple quadrupole mass spectrometer. Our study evaluated the analytical performance of Cyclosporine A and Tacrolimus on the RECIPE assay and compared it against our existing in-house LC-MS/MS assay. Methods The RECIPE ClinMass® LC-MS/MS Advanced Immunosuppressants assay kit consist of mobile phase solvents, precipitation reagents, stable isotopic labeled internal standards, solid phase extraction and analytical columns, lyohilized whole blood calibrators and quality controls. Drug analytes were extracted from whole blood using single-step protein precipitation followed by on-line solid phase extraction on the LC, eluted on isocratic chromatography and detected on positive ESI MS ionisation mode. The RECIPE assay run time is under 3 min. Performance validation parameters included within/total assay imprecision, linearity, recovery, limits of detection (LOD)/quantification (LOQ) and carry-over. Method correlation studies using fresh patient whole blood specimens (n = 212 Cyclosporine A; n = 120 Tacrolimus) were performed on existing in-house assay on Agilent 6460 LC-MS/MS and the RECIPE assay on Agilent 6470 LC-MS/MS systems. Results Within run and total imprecision for Cyclosporine A and Tacrolimus on the RECIPE assay were determined to be ≤4.4% and ≤7.5% on the Agilent 6470 LC-MS/MS. The assay demonstrated linearity across the analytical measurement range up to 1500 ug/L for Cyclosporine A and up to 55 ug/L for Tacrolimus. Analytical recoveries obtained for both drugs ranged between 93%–100%. The LODs were assessed to be 13.0 ug/L and 0.70 ug/L for Cyclosporine A and Tacrolimus respectively. LOQs were assessed to be 22.7 ug/L and 1.30 ug/L for Cyclosporine A and Tacrolimus respectively. Results of carry-over studies were insignificant. Participation in the CAP Immunosuppressive Drugs External Quality Assessment Survey showed good agreement with LC-MS/MS peers. Method correlation with in-house assay demonstrated good agreement: (1) Cyclosporine A: Passing Bablok regression RECIPE = 0.94 (In-house) + 17.2, Bland Altman mean bias of +2.0%, Spearman correlation coefficient of 0.985; (2) Tacrolimus: Passing Bablok regression of RECIPE = 1.03 (In-house) - 0.2, Bland Altman mean bias of -0.2%, Spearman correlation coefficient of 0.988 Conclusion The RECIPE ClinMass® LC-MS/MS Immunosuppressants assay performed within manufacturer’s specifications except for LOD/LOQs which were determined at higher concentrations. The assay is adaptable to contemporary LC-MS/MS systems and confer benefits from rapid turnaround time (<3 min), simplified specimen preparation procedures and ready prepared reagents. The advantages allow enhancements in workflow efficiency and ease of staff training in our laboratory and the assay is suitable for routine clinical use in high workload clinical laboratories.

Density-Dependent Pore Water Pressure Evolution in a Simplified Cyclic Shear Test

When specimens of different sands are produced using the same preparation method and sheared under the same conditions (consolidation stress, loading, etc.), while simultaneously keeping the drainage closed, the resulting tendencies of these sands regarding the PWP build-up will be different. This research paper presents a simplified cyclic shear test, which is used to evaluate the accumulation of PWP in sands under defined specimen preparation procedure and testing conditions. In the proposed experiment, a comparison of different sands with this respect is easily achieved. The principle of this experimental method is based on the evolution of the PWP during cyclic shearing of a water-saturated sand sample. Undrained conditions during the experiment allow for the evolution of the PWP, which is quantified by the rate of the PWP build-up. The duration of a single cyclic shear test, including specimen preparation, is approximately 30 min. The evaluation of the rate of the PWP build-up for different densities resulted in an exponential dependence of the PWP build-up on the variation of the relative density. The results confirmed a higher generation of PWP in a fine sand compared to a coarse sand. A comparison with the results of undrained cyclic triaxial tests in the case of eight different sands demonstrated a good agreement between both experimental methods. The basis for the comparison was the density-dependent evolution of PWP in these methods. The presented method delivers a value (index) that quantifies the PWP build-up in sands under the defined testing conditions.

Effect of Specimen Fabrication Variables on the Measured Mechanical Properties of Asphalt Mixtures Tested in the Asphalt Mixture Performance Tester (AMPT)

Abstract The scope of this research involves the evaluation of the effects of specimen preparation variables—mixing temperature, binder time at mixing temperature, mixer type, mixing time, loose mix conditioning temperature, loose mix conditioning depth, loose mix stirring, mold loading, placement in mold, additional time at compaction temperature before loading in mold, gyratory specimen height, and test specimen air voids—on tests such as the Dynamic Modulus and Flow Number conducted using the Asphalt Mixture Performance Tester (AMPT). The initial testing program to evaluate the precision of the Dynamic Modulus and Flow Number tests (described in National Cooperative Highway Research Program Report 702) indicated that “specimen fabrication is a major component of the between-laboratory variability” for both tests. The expected outcome of this study was that AMPT users—Federal Highway Administration (FHWA), state user agencies, and industry—understand the importance of proper specimen preparation and the effect of specimen preparation variables on the results obtained from the AMPT Dynamic Modulus and Flow Number tests. The use of AMPT Dynamic Modulus at 20°C is the most sensitive portion of the modulus-time curve and can provide a general idea of sample preparation impact on other mixture tests. This information comes at critical timing as the United States begins to implement performance-engineered mixture designs, balanced mixture designs, and performance-based pay factors. Based on the findings of the study, recommendations may be made regarding changes to specimen preparation procedures, which are expected to produce more reproducible test results.

Rebound Calculation for Deep Excavation in Soft Soil Based on Rebound-Recompression Method

The excavation-induced stress relief and inward movement of the retaining wall will result in soil rebound deformation at the bottom of the excavation, adversely affecting nearby existing tunnels and foundation piles. Various existing methods for calculating the excavation rebound rely on rebound parameters and void ratio obtained from laboratory tests, with considering the effects of sampling, specimen preparation and laboratory procedures on the rebound parameters. As a result, a novel method is proposed in this article for calculating excavation rebound based on rebound-recompression method (RRM). This method first modifies initial void ratio (e0) and laboratory recompression index (CLR) used in traditional methods (TM) for calculation, based on field rebound and recompression curve proposed by the RRM, to in situ void ratio (ev0) and field recompression index (CFR). Then, the final rebound at the bottom of the excavation is calculated using a layered summation method. In addition, through two engineering examples, the proposed method is compared with existing calculation methods and measurements, demonstrating that this method is easy of calculate, yields reliable results, and can accurately predict the final soil rebound at the bottom of the excavation.

Predicting the microstructure of compacted graphite iron using a fuzzy knowledge-based system

One of the important engineering materials is compacted graphite iron (CGI). Obtaining an expected microstructure leading to desired material properties is relatively difficult. In this paper, we present an approach to predicting the microstructure with a fuzzy knowledge-based system. On the basis of the results of statistical analysis and expert knowledge, an original taxonomy of CGI casts was formulated. The procedure of data acquisition, specimen preparation, analysis procedure and microstructures obtained are presented. Methods for expert experience-supported knowledge extraction from experimental data, as well as methods for formalizing knowledge as fuzzy rules, are introduced. The proposed rulesets, the reasoning process, and exemplary results are provided. The verification results showed that, using our approach, it is possible to effectively predict the microstructure and properties of CGI casts even in the absence of sufficient data to use data-driven knowledge acquisition. On the basis of the results obtained, examples of possible applications of the developed approach are presented.

Shear Modulus of a Carbonate Sand–Silt Mixture with THF Hydrate

The maximum shear modulus (Gmax) is an important factor determining soil deformation, and it is closely related to engineering safety and seafloor stability. In this study, a series of bender element tests was carried out to investigate the Gmax of a hydrate-bearing carbonate sand (CS)–silt mixture. The soil mixture adopted a CS:silt ratio of 1:4 by weight to mimic the fine-grained deposit of the South China Sea (SCS). Tetrahydrofuran (THF) was used to form the hydrate. Special specimen preparation procedures were adopted to form THF hydrate inside the intraparticle voids of the CS. The test results indicate that hydrate contributed to a significant part of the skeletal stiffness of the hydrate-bearing CS–silt mixture, and its Gmax at 5% hydrate saturation (Sh) was 4–6 times that of the host soil mixture. Such stiffness enhancement at a low Sh may be related to the cementation hydrate morphology. However, the Gmax of the hydrate-bearing CS–silt mixture was also sensitive to the effective stress for an Sh ranging between 5% and 31%, implying that the frame-supporting hydrate morphology also plays a key role in the skeletal stiffness of the soil mixture. Neither the existing cementation models nor the theoretical frame-supporting (i.e., Biot–Gassmann theory by Lee (BGTL)), could alone provide a satisfactory prediction of the test results. Thus, further theoretical study involving a combination of cementation and frame-supporting models is essential to understand the effects of complicated hydrate morphologies on the stiffness of soil with a substantial amount of intraparticle voids.

Towards standardizing the preparation of test specimens made with material extrusion: Review of current techniques for tensile testing

Researchers and industries rely heavily on standardized testing methods to ensure products are designed and manufactured with high quality. With increasing use of additive manufacturing processes, such as material extrusion (MEX), there is a significant gap in material testing standards tailored for such components, and a lack of guidance on preparing appropriate test specimens with mesostructures that best represent the final part being analyzed. This paper aims to support the standardization of MEX material testing by reviewing the current methods used for preparing test specimens for tensile testing and proposing guidelines for implementation in a new standard. The need for standardization of MEX specimen preparation is addressed by analyzing the effects of slicing parameters on resulting tensile properties of the specimen. It is suggested that a standard should acknowledge these parameters, in addition to specimen geometry, toolpath optimization, printer and material specifications, so that they are appropriately selected for the test specimen by regarding the final part structure. Consideration of the proposed guidelines in a standardized method may enable comparisons between published results and support the development of MEX technology for use in advanced applications. • Material testing standards are incomplete for specimens made by material extrusion. • Test specimen preparation procedures found in literature are inconsistent. • Process parameters greatly influence tensile strength and stiffness. • Guidelines for a standard test specimen preparation procedure are proposed.

A method to evaluate the tensile strength and ductility of asphalt binders using a thin confined film

ABSTRACT It has become clear over the last few years with an increasing use of asphalt binder modifiers, additives and recycled materials that there is a need to develop methods and concomitant parameters that can evaluate the full tensile behaviour including nonlinearity and damage resistance of asphalt binders. This study presents a simple, repeatable test method to examine the tensile strength and ductility of asphalt binders using a poker-chip geometry. The poker-chip geometry has previously been used to induce a realistic stress state in asphalt binder similar to that exerted on asphalt binder confined between two aggregates. This study develops and presents a new simplified procedure for specimen fabrication and preparation using the poker-chip geometry. A set of nearly 100 asphalt binders including different aging conditions, different levels and types of modification, and recycled asphalt binders and contents were examined using the proposed approach. The results indicate that a ductility parameter obtained using the test is highly repeatable with an average coefficient of variation of 9%. In addition, the test was able to distinguish between different levels of modification and was sensitive to aging, recycled binder ratio and modifier type.v

Elementary behavior of dual-particle composites cemented by self-compacting mortar: Experimental and constitutive modelling

Artificial cementation can effectively increase the modulus and strength properties of granular materials. To characterize and simulate the cementation effect between granules is of great significance for the analysis of cemented granular materials (CGM). The aim of this study is to investigate the elementary behavior of dual-particle composites cemented by self-compacting mortar (SCM) and provide a unit model for the numerical representation of CGM. A specimen preparation procedure of dual-particle composites was proposed to simulate the filling process of SCM through rockfills in practice. A series of uniaxial compression and tension tests were carried out and the effects of influential factors, including the particle size, particle distance and SCM fluidity, were considered. Based on analyses of the test results, a uniaxial constitutive model was proposed for the targeted dual-particle composites. Finally, through finite element implementation of the model and simulation studies of uniaxial compression tests on CGM, the established constitutive model has been effectively verified to be reliable in predicting the deformation and failure properties of CGM.

An improved specimen preparation method for marine shallow gas-bearing sand sediments and its validations

Instabilities of shallow gas-charged seabed are potential geological hazards in ocean engineering. In practice, the conventional field sampling techniques failed to obtain undisturbed gas-bearing sediments from the seabed for laboratory mechanical testing because of sensitive gas exsolution and escape from sediments. However, preparation of representative remoulded gas-charged specimens is a challenging issue, because it is rather difficult to quantitatively control the gas content and obtain uniform distribution of gas bubbles within the specimen. Given the above problems, this work proposes a reliable approach to reconstitute the high-saturation specimen of gas-charged sediments in the laboratory by an improved multifunction integrated triaxial apparatus (MITA). This apparatus is developed based on an advanced stress path triaxial system by introducing a temperature-controlled system and a wave-monitoring system. The temperature-controlled system is used to accurately mimic the in situ environments of sediments in the seabed. The wave-monitoring system is utilized to identify exsolution point of free gas and examine the disturbance of gas to specimens during gas exsolution. The detailed procedure of gassy specimen preparation is introduced. Then, the quality of prepared specimens using our improved apparatus is validated by the high-resolution micro-X-ray computed tomography (μCT) scanning test, from which bubble occurrence and size distribution within the gassy sand specimen can be obtained; and preliminary mechanical tests on gassy sand specimens with various initial saturation degrees are performed. The proposed specimen preparation procedure succeeds in proving the postulated occurrence state of gas bubbles in coarse-grained sediments and accurately controlling the gas content.

Определение хлорорганических соединений в химических реагентах, применяемых при добыче, транспортировке и переработке нефти, рентгенофлуоресцентным методом

The organic chloride content in crude oil being among the most crucial quality characteristics of the crude is strictly controlled. The presence of organic chlorides in crude oil greatly endangers the oil refineries since it causes a severe equipment corrosion. Specialty oilfield chemicals, which are widely used in the crude oil extraction, transportation, refining and storage, could be a source of the crude oil contamination with organic chlorides. As a consequence, the organic chloride content determination in the chemicals is required. It was demonstrated that the organic chloride content in the specialty oilfield chemicals can be determined by X-ray fluorescence spectrometry (XRF) using an appropriate specimen preparation procedure. Two specimen preparation procedures, i.e. the solvent extraction and the distillation of a specimen mixed with the crude oil or its model, were tested. It was established that an organic chloride content can be successfully determined in a broad range of the specialty oilfield chemicals by the XRF technique when applying these specimen preparation procedures. The investigation of four types of the specialty oilfield chemicals confirmed that the specimen preparation procedure, involving a solvent extraction of organic chlorides from the chemicals into isooctane, is more comprehensive than the distillation procedure since it is free from the limitations associated with the use of high temperatures.

Humidity and specimen preparation procedure: influence on compressive strength of concrete blocks

abstract: It is extremely important that the quality control of the concrete block used in structural masonry is conducted based on standard procedures that allow reliable estimation of the properties of these components. This work aims to analyze and evaluate the influence of the concrete block moisture on the result of the compression test. Hollow concrete blocks were prepared and subsequently maintained in different environments for various periods of time and under different conditions of temperature and humidity to determine the influence of the type of drying on the relative humidity of the block at the time of testing and consequently on its compressive strength. As a conclusion, it can be stated that, because it is necessary to use water in the process, the grinding rectification of the faces of the blocks led them to have high humidity, above 70%. If tested in this condition, the results of the compressive strength tests will be lower than that of blocks under usual environmental conditions. No differences were found in the average block strength when they were kept dry in the controlled environment of the laboratory during periods of 24 or 48 h. After grinding, it is not necessary to dry the blocks inside an oven at 40ºC before the tests; simply leaving them at a usual room temperature of 23ºC and humidity of 40 ± 5% for 24h is sufficient. The attempt to accelerate drying in an oven at 100ºC is not adequate because this leads to an increase in the compressive strength. From the results, it was possible to determine expressions to correlate the compressive strength as a function of the moisture of the block at the time of the test. The best-fit expressions are distinct for each block type, but the formulations are consistent in indicating a considerable difference in resistance as a function of moisture.

Assessment for Thermal Conductivity of Frozen Soil Based on Nonlinear Regression and Support Vector Regression Methods

The comprehensive understanding of the variation law of soil thermal conductivity is the prerequisite of design and construction of engineering applications in permafrost regions. Compared with the unfrozen soil, the specimen preparation and experimental procedures of frozen soil thermal conductivity testing are more complex and challengeable. In this work, considering for essentially multiphase and porous structural characteristic information reflection of unfrozen soil thermal conductivity, prediction models of frozen soil thermal conductivity using nonlinear regression and Support Vector Regression (SVR) methods have been developed. Thermal conductivity of multiple types of soil samples which are sampled from the Qinghai-Tibet Engineering Corridor (QTEC) are tested by the transient plane source (TPS) method. Correlations of thermal conductivity between unfrozen and frozen soil has been analyzed and recognized. Based on the measurement data of unfrozen soil thermal conductivity, the prediction models of frozen soil thermal conductivity for 7 typical soils in the QTEC are proposed. To further facilitate engineering applications, the prediction models of two soil categories (coarse and fine-grained soil) have also been proposed. The results demonstrate that, compared with nonideal prediction accuracy of using water content and dry density as the fitting parameter, the ternary fitting model has a higher thermal conductivity prediction accuracy for 7 types of frozen soils (more than 98% of the soil specimens’ relative error are within 20%). The SVR model can further improve the frozen soil thermal conductivity prediction accuracy and more than 98% of the soil specimens’ relative error are within 15%. For coarse and fine-grained soil categories, the above two models still have reliable prediction accuracy and determine coefficient (R2) ranges from 0.8 to 0.91, which validates the applicability for small sample soils. This study provides feasible prediction models for frozen soil thermal conductivity and guidelines of the thermal design and freeze-thaw damage prevention for engineering structures in cold regions.

Unravelling new principles of site-selective doping contrast in the dual-beam focused ion beam/scanning electron microscope

Doping contrast using the secondary electron (SE) signal in the scanning electron microscope (SEM) can satisfy the International Roadmap for Semiconductors (ITRS) requisites for quantitative dopant profiling of next-generation integrated circuits and devices, but only if adopting a site-selective specimen preparation procedure. In this study, site-specific dopant profiling was performed on the trench side-wall cut by a 30-kV Ga+ focused ion beam (FIB) into silicon p–n junction specimens and milled using successively lower voltages in the dual-beam FIB/SEM. Although depositing the protective platinum strap on the surface effectively controls ‘curtaining’ effects at low final milling voltages, significantly reduced doping contrast from the side-wall compared to that from a cleaved surface subjected to the same ion-beam energy is ascribed to the material affected by a previous milling step, as well as the dissimilar geometries of milling and imaging. New principles underpinning the doping contrast mechanism were surveyed taking into account the depth and concentration of ion implantation and amorphization damage as a linear function of the final milling voltage. Patch fields are suppressed, but the bulk doping-dependent surface band-bending fields at the amorphous-crystalline interface is crucial for doping contrast. In general, as the milling voltage decreases the doping contrast increases, which although reaches up to only half that attainable from a freshly-cleaved specimen, is usable, and demonstrates the feasibility of site-specific dopant profiling in situ in the SEM.

Effect of freeze-thaw cycles on mechanical strength of lime-treated fine-grained soils

Abstract Lime treatment is a widely-used technique for the stabilization and improvement of fine-grained soils in earthworks for transportation. In cold regions, lime treatment can be considered as an appropriate method to improve freeze-thaw resistance of fine-grained soils. The effectiveness of treatment can depend on soil nature, lime dosage and curing time. In the present work, three soils (silt of low plasticity, clay of low plasticity, and silt of high plasticity) were treated at three lime contents (lower, equal and higher than the lime fixation point) at four curing periods (7, 28, 90 and 365 days). The mechanical strength was determined from unconfined compression test performed on specimens having a diameter of 100 mm and a height of 100 mm. Freeze-thaw cycles were applied by varying the specimen temperature between −20 °C and 20 °C, the specimens being beforehand saturated. The mechanical strength of specimen subjected to ten freeze-thaw cycles was compared to those maintained in laboratory temperature (20 °C). Results showed that freeze-thaw cycles significantly decrease the mechanical strength of sample. This decrease can be explained by damage induced by ice lenses formation/thawing during freeze-thaw cycles, as illustrated by the observation at X-ray computed tomography. Interestingly, lime treatment mitigates this damage and increase the soil freeze-thaw resistance. The treatment appears more efficient for lower plasticity soil, a higher lime content, and a longer curing time. This conclusion seems depend on the specimen preparation procedure.

Automatic Registration of Correlative Microscopies with Error Assessment and Applications for the Optimization of Multimodal Acquisitions.

Correlative microscopy allows combining different scales of observations and different contents, functional and morphological, based on the large panel of microscopy technologies available for life or material sciences. The purpose is to accurately follow a region of interest across modalities and scales of imaging, for guiding and targeting the specimen preparation procedure needed for another modality, to guide the acquisition at the second microscope and to adjust the field of view of the microscope to this feature. In a last, and most accurate registration step, the acquired data from both modalities are mapped.

Evaluation of a TEM based Approach for Size Measurement of Particulate (Nano)materials.

An approach for the size measurement of particulate (nano)materials by transmission electron microscopy was evaluated. The approach combines standard operating procedures for specimen preparation, imaging, and image analysis, and it was evaluated on a series of certified reference materials and representative test materials with varying physical properties, including particle size, shape, and agglomeration state. The measurement of the median value of the minimal external particle diameter distribution was intra-laboratory validated. The validation study included an assessment of the limit of detection, working range, selectivity, precision, trueness, robustness, and ruggedness. An uncertainty that was associated to intermediate precision in the range of 1–7% and an expanded measurement uncertainty in the range of 7–20% were obtained, depending on the material and image analysis mode. No bias was observed when assessing the trueness of the approach on the certified reference materials ERM-FD100 and ERM-FD304. The image analysis method was validated in an inter-laboratory study by 19 laboratories, which resulted in a within-laboratory precision in the range of 2–8% and a between-laboratory precision of between 2% and 14%. The automation and standardization of the proposed approach significantly improves labour and cost efficiency for the accurate and precise size measurement of the particulate materials. The approach is shown to be implementable in many other electron microscopy laboratories.

A ‘Sandwich’ Specimen Preparation and Testing Procedure for the Evaluation of Non-Structural Injection Grouts for the Re-Adhesion of Historic Plasters

ABSTRACT Non-structural injection grouting aims to stabilise delaminated plaster by introducing in the void, typically between delaminated plaster layers, a compatible adhesive material with bulking properties (the injection grout). Injection grout formulations are firstly tested in the laboratory to determine their performance characteristics including their physical-mechanical compatibility with the original materials (plaster or other building materials). However, laboratory tests on grouts are often not sufficiently representative of actual cases in which the grout sets between two plaster layers. This problem is particularly significant when water vapour permeability, capillary water absorption and adhesion need to be assessed. A study was conducted on the development of a ‘sandwich’ system (plaster-grout-plaster) to better simulate the real situation. This paper describes a new methodology for such specimen preparation and the adapted procedures for laboratory testing. The results are discussed comparing them with those obtained from standard specimen preparation and testing procedure.