Measuring Compressive Strength Characteristics of Soil-Dobak-Glue Mixtures over Curing Time

The building materials used by mankind in the past, such as stone, soil, and wood, have been environment-friendly. However, the various building materials invented over time with the development of the industrial age pose problems such as environmental hormone generation and waste generation/disposal. To overcome these problems, building materials based on soil, a traditional building material, are being developed by researchers. However, the improvement in soil’s structural characteristics is insufficient as it excessively emphasizes efficacy and function only. In this study, lime and Dobak-glue were mixed with soil to solve the structural problems and improve the strength of soil, and water content and change in strength in accordance with curing time were tested. In order to understand the change in strength, a compaction test was performed by preparing a standard specimen based on the optimum water content and maximum dry density. The lime mix required optimum water content and quantity of lime equal to 3% of soil weight, while the Dobak-glue mix was prepared by soil mixing in the same weight ratio as optimum water content. Changes in water content and compressive strength were measured over curing time of 3, 7, and 28 days. Three specimens, lime mixed specimen, Dobak-glue mixed specimen, and standard specimen, were prepared, and their water content and compressive strength values were averaged. Although the change in water content according to the curing period differed depending on the material mixed with soil, there was no significant difference between 7.12% and 2.82% after 7 days. As for the change in compressive strength, the initial compressive strength in lime mixed specimen was excellent, but the Dobak-glue mixed specimen displayed the greatest strength after 7 days. To conclude, Dobak-glue is an eco-friendly material, and it can be very useful in compensating for the structural shortcomings of soil.

Comparison of Digital Image Correlation (DIC) Technique with Nanomaterial-Based Sensor for the Analysis of Strain Measurements

Digital Image Correlation (DIC) techniques can be used to visually map and measure strain in materials such as metals and metallic alloys. The strain induced in an American Society for Testing and Materials (ASTMs) standard specimen can be measured using a DIC technique. Image patterns indicating the localized strain variations as a function of time for the constant load applied were also obtained. Results obtained using the DIC technique were more accurate compared to conventional strain sensors. DIC results were also compared with nanomaterial-based strain sensor output. Localized strain induced in the material can be visualized and quantified analytically using DIC.

Mechanical Modification of Resin Capsules by Adding Steel Particles

Five kinds of steel particles with sizes ranging from 0.6 mm to 2.2 mm with increments of 0.4 mm were mixed with mining resin materials, and the mixing ratio of the particles was also varied. By using this approach, the film gloving problem of coal mine bolting should be effectively solved due to the shredding effects of the particles during bolt rotation. The premise is that the mechanical behavior should not be weakened under such conditions. A total of 47 standard cylindrical specimens were manually prepared, which included pure resin specimens and specimens containing particles with different sizes and weights. First, the homogeneity of a prepared standard specimen was verified by computed tomography (CT) scanning technology. Second, the mechanical improvements provided by each type of particle were evaluated. Thirdly, the effectiveness of both the particle weight and particle size was comprehensively discussed, and the eventual recommendation was to set for the particle size and weight as 1.4 mm and 40 g, respectively, and the particles weight percentage was 7.27%. Finally, the failure patterns for all specimens were collected and comprehensively compared. Additionally, pullout tests were carried out to vindicate the recommended particle size and weight.

Small specimen techniques for estimation of tensile, fatigue, fracture and crack propagation material model parameters

Small specimen mechanical testing is an exciting and rapidly developing field in which fundamental deformation behaviours can be observed from experiments performed on comparatively small amounts of material. These methods are particularly useful when there is limited source material to facilitate a sufficient number of standard specimen tests, if any at all. Such situations include the development of new materials or when performing routine maintenance/inspection studies of in-service components, requiring that material conditions are updated with service exposure. The potentially more challenging loading conditions and complex stress states experienced by small specimens, in comparison with standard specimen geometries, has led to a tendency for these methods to be used in ranking studies rather than for fundamental material parameter determination. Classifying a specimen as ‘small’ can be subjective, and in the present work the focus is to review testing methods that utilise specimens with characteristic dimensions of less than 50 mm. By doing this, observations made here will be relevant to industrial service monitoring problems, wherein small samples of material are extracted and tested from operational components in such a way that structural integrity is not compromised. Whilst recently the majority of small specimen test techniques development have focused on the determination of creep behaviour/properties as well as sub-size tensile testing, attention is given here to small specimen testing methods for determining specific tensile, fatigue, fracture and crack growth properties. These areas are currently underrepresented in published reviews. The suitability of specimens and methods is discussed here, along with associated advantages and disadvantages.

Failure Analysis of Glulam Lumber Beam Made from Meranti Lumber Pieces (Shorea SP)

The development of glue-laminated (glulam) lumber beam gives many good results. Meranti (Shorea SP) is one of the construction lumber that can be used as glulam to optimize its use. The limitation of the glulam lumber beam is the limited length of the lumber, so it must be joined to get a certain length. The lumber available in the market on average has a limited size and cross-sectional length. The larger the cross-sectional size and length of the lumber make the higher the price. Used lumber and residual lumber also have many weaknesses, such as the length of suitable lumber is too short, lumber defects, and lumber damages. Further research needs to be done to optimize the use of new, used, and residual meranti lumber through the use of lumber pieces as a glulam lumber beam maker. Standard specimen and test based on ASTM D-198. Glulam lumber beam is made from pieces of meranti lumber planks of certain length which are arranged into lamina beam with the size of 5.5x9.5x150 cm3. Variations in the length of the pieces of meranti lumber planks for making glulam lumber beam, among others, 40 cm, 50 cm, 60 cm, 50 cm with full length lowest layer and 150 cm (full length). The adhesive used is polyurethane glue. The span between supports is 130 cm. The beam is tested for center point loading. The analysis results show that the joints on the outermost layer that receive tensile stress of the glulam lumber beam can cause weakening in the beam because the tensile strength of the adhesive is weaker than the tensile strength of lumber. Failure at the tensile joint of the outer layer of the beam can trigger a shear failure mode. Design of joints should not be placed on layers that are subject to tensile stresses so as not to trigger shear failure modes so that the strength of the glulam lumber beam can be optimal.

Effect of Specimen Geometry on Selected Physical and Mechanical Properties of Epoxy-Based Building Materials

The paper deals with problematics of the influence of size and shape of test specimens prepared according to the valid standard procedures in comparison to specimens prepared according to the standards used for different types of materials (grouts, coatings). The aim of this paper is to verify the possibility of using non-standard specimen sizes to reduce the economic demands of the development of building materials. The issue is tested on the polymer composites prepared in three different amounts of the filler. The polymer composite based on epoxy resin serves as a representative and homogenous material which achieves the same results under various curing temperatures and humidity. The porous structure of prepared samples was also studied and its effect on the selected mechanical properties was observed. It was shown that the specimen shape and size had impact on the mechanical properties of epoxy-based composites.

The Aetiology of pneumonia from analysis of Lung aspirate and Pleural fluid samples: Findings from the PERCH study

Background An improved understanding of childhood pneumonia aetiology is required to inform prevention and treatment strategies. Lung aspiration is the gold standard specimen for pneumonia diagnostics. We report findings from analyses of lung and pleural aspirates collected in the Pneumonia Etiology Research for Child Health (PERCH) study. Methods The PERCH study enrolled children aged 1–59 months hospitalized with World Health Organization defined severe or very severe pneumonia in 7 countries in Africa and Asia. Percutaneous trans-thoracic lung (LA) and pleural fluid (PF) aspiration was performed on a sample of pneumonia cases with radiological consolidation and/or pleural fluid in 4 countries. Venous blood and nasopharyngeal/oropharyngeal swabs were collected from all cases. Multiplex quantitative PCR and routine microbiologic culture were applied to clinical specimens. Results Of 44 LAs performed within 3 days of admission on 622 eligible cases, 13 (30%) had a pathogen identified by either culture (5/44) or by PCR (11/29). A pathogen was identified in 12/14 (86%) PF specimens tested by either culture (9/14) or PCR (9/11). Bacterial pathogens were identified more frequently than viruses. All but one of the cases with a virus identified were co-infected with bacterial pathogens. Streptococcus pneumoniae (9/44 [20%]) and Staphylococcus aureus (7/14 [50%]) were the predominant pathogen identified in LA and PF, respectively. Conclusions Bacterial pathogens predominated in this selected subgroup of PERCH participants drawn from those with radiological consolidation or pleural fluid, with S. pneumoniae and S. aureus the leading pathogens identified.

Intraoperative breast specimen assessment in breast conserving surgery: comparison between standard mammography imaging and a remote radiological system

Objective: To compare standard specimen mammography (SSM) with remote intraoperative specimen mammography (ISM) assessment in breast conserving-surgery (BCS) based on operative times, intraoperative additional excision (IAE) and re-intervention rates. Methods and materials: We retrospectively compared 129 consecutive patients (136 lesions) who had BCS with SSM at our centre between 11/2011 and 02/2013 with 138 consecutive patients (144 lesions) who underwent BCS with ISM between 08/2014 and 02/2015. SSM or ISM were performed to confirm the target lesions within the excised specimen and margin adequacy. The utility of SMM and ISM was evaluated considering pathology as gold-standard, using χ2 or Fisher’s exact tests for comparison of categorical variables, and non-parametric Mann–Whitney test for continuous variables. Results: The two groups did not statistically differ for age (p = 0.20), lesion size (p = 0.29) and morphology (p = 0.82) or tumor histology type (p = 0.65). Intraoperative time was significantly longer (p < 0.00001) for SSM (132 ± 43 min) than for ISM (90 ± 42 min). The proportions requiring IAE did not significantly differ between SSM group (39/136 lesions (40%)) and ISM group (52/144 lesions (57%)) (p = 0.19), overall and in stratified analysis by mammographic features. Re-intervention rates were not statistically different between the two groups [SSM:19/136 (14%), ISM:13/144 (9%); p = 0.27]. Conclusion: The introduction of ISM in BCS significantly reduced surgical time but did not change IAE and re-intervention rates, highlighting facilitated communication between surgeons and radiologists. Advances in knowledge: Compared to standard mammography imaging, the use of ISM significantly reduced surgical time.

Compressive Behaviour of Laminated Neoprene Bridge Bearing Pads under Thermal Aging Condition

The present study was conducted to obtain a better understanding of the variation rule of mechanical properties of laminated neoprene bridge bearing pads under thermal aging condition using compression tests. A total of 5 specimens were processed in a high-temperature chamber. After that, the specimens were tested subjected to axial load. The parameter mainly considered time of thermal aging processing for specimens. The results of compression tests show that the specimens after thermal aging processing are more probably brittle failure than the standard specimen. Moreover, the exposure of steel plate, cracks and other failure phenomena are more serious than the standard specimen. The compressive capacity, ultimate compressive strength, compressive elastic modulus of the laminated neoprene bridge bearing pads decreased dramatically with the increasing in the aging time of thermal aging processing. The attenuation trends of ultimate compressive strength, compressive elastic modulus of laminated neoprene bridge bearing pads under thermal aging condition accord with power function. The attenuation models are acquired by regressing data of experiment with the least square method. The attenuation models conform to reality well which shows that this model is applicable and has vast prospect in assessing the performance of laminated neoprene bridge bearing pads under thermal aging condition.