Strength Of Test Specimens Research Articles

Compressive Strength Study on Reactive Powder Concrete with 30% Quartz Sand and Variations in Fly Ash Composition as Partial Substitution of Cement

The concrete industry is considered environmentally unfriendly and unsustainable due to the significant consumption of natural materials. Currently, the industry predominantly uses Portland cement as its main ingredient, leading to an increase in Portland cement production. However, the use of fly ash can help make the concrete industry more sustainable in the future. Fly ash can be used as a partial replacement for Portland cement in concrete production. This study aims to determine the effect of fly ash variations on the compressive strength of reactive powder concrete. The research method used is experimental. The concrete mix design includes 30% quartz sand and fly ash variations of 0%, 5%, 10%, 15%, 20%, and 25%. The compressive strength test specimens are cylindrical with a diameter of 7.5 cm and a height of 15 cm. The resulting test specimens have a compressive strength of more than 41.4 MPa, thus qualifying as high-strength concrete. The compressive strength test results for fly ash variations of 0%, 5%, 10%, 15%, 20%, and 25% are 62.62 MPa, 66.27 MPa, 75.59 MPa, 68.78 MPa, 66.21 MPa, and 63.70 MPa, respectively.

Advanced statistical analyses to reduce inconsistencies in bond strength data focused on donor factors: A six-factor analysis using linear mixed and nonlinear regression models.

This study aimed to investigate the effects of the age and sex of tooth donors on dentin bond strength. A total of 38 extracted teeth (12 male and 26 female donors; age range: 17-82 years) were used in this study. In addition to donor age and sex, four other microtensile bond strength (μTBS) test specimen factors were evaluated: dentin position, bonding area, presence of voids at the interface, and computed tomography (CT) values of dentin. The μTBS was measured immediately (24 h) and 6 months after storage in water. After the μTBS testing, linear mixed and nonlinear regression models were used to analyze the effects of these factors on the μTBS data. The results from the linear mixed model revealed that the bonding area (P = 0.02), presence of voids at the interface (P = 0.04), and storage time (P < 0.001) significantly affected bond strength. In contrast, no correlation was observed between the μ TBS and dentin position (P = 0.08) or sex (P = 0.07). The results of the nonlinear regression model with robust variance-covariance estimators revealed that age significantly affected bond strength (P < 0.001). In addition, a significant positive correlation was found between μTBS and age (P < 0.001), with nonlinearity (P = 0.002). However, no correlation was observed between the μTBS and CT values (P = 0.69) without nonlinearity (P = 0.39). These findings suggest that bond strength increases with age until 60 years but not afterward.

Application of the use of local natural materials as cement treated base materials

The use of local natural materials as alternative materials in road construction could save construction costs, especially for Maluku Province. One of the local natural materials in Maluku Province is Limestone in Kelan Village and Kaliobar Village. Therefore, this study aims to see how far the use of limestone to be applied as a cement treated base material. Before being applied, the limestone is tested first in the laboratory. After the limestone was applied as a cement treated base (CTB) material, compaction and compressive strength tests were carried out. The number of CTB compressive strength test specimens was 26 samples from STA 4+100 to STA 8+900. The limestone on Larat Island is unique in that it contains the composition CaCO3 (Calcium Carbonate), which is the result of shallow sea sedimentation. The potential of limestone in the work location area has not been utilized optimally to improve the economic level of the community. The test results show that the compressive strength values obtained are still within the interval range, namely between 25 - 40 gr/cm2. Therefore, it can be concluded that the CTB mixture material at this location meets the requirements to be used as a foundation layer for road pavement using local natural materials.

Pengaruh Bahan Tambah Serat Ijuk Terhadap Sifat Mekanik Beton SCC (Self Compacting Concrete)

In the current development of concrete innovation technology, there are also expensive materials that are cheap as concrete additives for the efficiency of the cost of making concrete. cheap and can be used as concrete innovation. The purpose of adding palm fiber fiber is to improve the quality of concrete, both compressive strength and split tensile strength. The method used in this study was experimentation by adding palm fiber to the SCC concrete mixture with variations of 2%, 4% and 6%. As for the addition of chemical substances, the superplasticizer admixture aims to make it easier for SCC concrete to achieve a slump flow value that meets the requirements. After testing, the highest compressive strength test specimen is BC 1 2% palm fiber worth 19.38 MPa and for the lowest compressive strength test is BC 2 6% palm fiber worth 5.46 MPa. And for the split tensile strength test the highest is BC 4 2% palm fiber worth 9.47 MPa and for the lowest split tensile strength test is BC 3 6% palm fiber worth 5.82 MPa.

ANALISIS MUTU BETON TERHADAP BETON PASCA BAKAR

A fire is an unwanted disaster, in the framework of a post-fire building structure it becomes the basis for deciding whether the building structure can still be used or not. The rise in high temperatures in concrete structures will result in changes in concrete, the problem faced is how to handle post-fire buildings. From this explanation, this research will discuss the strength of concrete structures, especially the ratio of normal concrete to concrete that has been burnt with variations in duration of burning 1 hour, 2 hours and 3 hours under normal conditions. Concrete compressive strength testing was carried out when the specimens reached the age of 3 days, 7 days, 14 days, 21 days, and 28 days with cylindrical specimens and the flexural strength of concrete was carried out when the specimens reached 28 days. The number of concrete compressive strength test specimens is 36 unit, and the flexural strength is 12 unit. The normal quality of concrete used is 30 MPa. From the results of the analysis regarding the tests carried out on compressive strength, it can be concluded that from the results of the compressive strength tests of 1 hour, 2 hours and 3 hours it decreased by 26.83%, 41.46% and 59.67% compared to concrete normal, for the flexural strength test results of 1 hour, 2 hours, and 3 hours decreased by 33.25%, 66.75%, and 66.75% compared to normal concrete.

Design and Fabrication of a Cost Effective Lab Rock Cutting and Polishing Machine

To meet some testing specifications, rock samples taken from an in-situ rock mass must be cored and polished into standard sizes. The sample length, smoothness, diameter, and thickness are examples of such specifications. All of these specifications have an impact on the test result and the achievement of the test goal. As a result, rock polishing and cutting operations are required in the laboratory to prepare and work on various types of samples. Most of the time, these machines are built differently, which is efficient but costly, rigorous, and takes volume and shape in the laboratory. A specimen-cutting and polishing machine was designed and built to help researchers obtain mineral/rock specimens for strength testing. This machine is made up of an electric motor, a diamond cutting disc, and an electric pump for water cooling. To convert electrical energy into mechanical energy, a 1.15KW electric motor was used. A central electrical distribution grid provides alternating current to an electrical motor. The designed machine used a 380V, 50Hz electric motor with a rotating speed of 1.83 m/min and a torque of 109.38 KN. The cutting machine was designed and built to cut and polish different materials in order to obtain specimens for strength tests and structure inspection.

Influence of printing procedure and printing axis of dental alloys on dimensional accuracy, surface roughness, and porosity

Objectives: This study aimed to evaluate the printing procedure and printing axis and its influence on the dimensional accuracy, surface roughness, porosity, and strength of 3D-printed dental alloys used in orthodontics prepared using binder jetting (BJ), electron beam melting (EBM), or selective laser melting (SLM). Material and Methods: Specimens with a dimension of 50 mm × 12 mm were produced using BJ, EBM, and SLM techniques of dental alloys and were printed either along the X-, Y-, or Z-axis (n = 8 per group). Specimen dimension was chosen according to the ISO standard 6892-1 for tensile strength test specimens. Surface roughness parameters Sa, Sz, Sq, and Ssk were obtained using a 3D laser microscope and porosities were visualized with scanning electron microscopy (SEM). The specimen surfaces were optically scanned and volumetric deviations from the original stereolithography files were calculated. Afterward, tensile strength was measured. Results: The printing method and printing axis significantly affected surface roughness parameters (P &lt; 0.05). Overall, the lowest surface roughness Sa values were found for BJ (9.1 ± 3.4 µm) followed by SLM (39.8 ± 24.2 µm) and EBM (50.4 ± 6.4 µm). BJ showed the smallest dimensional deviation followed by EBM and SLM. SEM analysis revealed a porous structure of BJ while fewer pores were observed on EBM and SLM samples. The ultimate tensile strength was only determined for BJ (495 ± 6 MPa) and EBM (726 ± 50 MPa) as the strength of SLM superseded the strength of the holder of the universal testing machine. Conclusion: BJ printing provides the highest dimensional accuracy with the smoothest surfaces irrespective of the printing axis. However, the remaining porosities owed to this printing procedure may have decreased the strength of the material.

THE EFFECT OF ULTRA-FINE ALLOYING ELEMENTS ON THE PHASE COMPOSITION, MICROSTRUCTURE, HIGH-TEMPERATURE STRENGTH AND FRACTURE TOUGHNESS OF Ti–Si–X AND Ti–Cr–X COMPOSITES

Advanced Ti-based composites are promising for applications in components of modern aircraft and rocket engines as well as other power equipment owing to their high strength-to-weight ratio and fracture toughness in a temperature range of 20 °C to 650 °C. However, there is a need to increase their operating temperature range up to 700−800 °C. In this work, mechanical behavior of Ti–Si–X composites (X=Al and/or Zr, Sn, C) has been studied. For comparison, mechanical behavior of Ti–Cr–X composite (X=Al and/or C) has been studied. As-cast and thermo-mechanically deformed series of beam specimens were examined. Strength tests of specimens were performed under three-point bending in a temperature range of 20 °C to 1000 °C. Single-edge notch beam (SENB) tests under three-point bending of specimen series were carried out in a temperature range of 20 °C to 900 °C for estimating fracture toughness of materials. Based on the constructed dependences of fracture toughness and strength on testing temperature for the specimen series as well as the microstructure and failure micromechanism analyses, the role of ultra-fine alloying elements in achieving good high-temperature strength and fracture toughness of the studied composites was substantiated.

Quasi-Static and Dynamic Mechanical Properties of a Ti-6Al-4V Titanium Alloy Produced Using Unconventional Manufacturing Methods

The purpose of this paper was to determine the mechanical properties of a Ti-6Al-4V titanium alloy produced by traditional CIP (Cold Isostatic Pressing) and by LENS (Laser Engineered Net Shaping), an additive manufacturing process. A reference material, being a commercial Ti-6Al-4V alloy, was also tested. The strength test specimens were produced from a high-quality, Grade 5 titanium powder. Each specimen had its density, porosity, and hardness determined. Compression curves were plotted for the tested materials from the strength test results with static and dynamic loads. These tests were performed on an UTS (Universal Testing Machine) and an SHPB (Split Hopkinson Pressure Bar) stand. The test results obtained led to the conclusion that the titanium alloy produced by CIP had lower strength performance parameters than its commercially-sourced counterpart. The LENS-produced specimens outperformed the commercially-sourced alloy both in static and dynamic load conditions.

Anisotropic properties of 3-D printed Poly Lactic Acid (PLA) and Acrylonitrile Butadiene Styrene (ABS) plastics

Research was conducted on the mechanical and anisotropic properties of 3-D printed plastics (PLA and ABS), and the prevailing orientation and deposition of additive layers. Samples were tested in accordance with ASTM D638 - Standard Test Method for Tensile Properties of Plastics. Five print orientations were tested, including 0°, 30°, 45°, 60°, and 90°. Six samples were tested in each orientation, with a total of 30 samples being tested in each iteration of the experiment. An initial, “proof of concept” iteration was conducted with PLA plastic, followed by a second iteration which tested both PLA and ABS.Testing was conducted and based on the hypothesis that the material printed in the 0° orientation (parallel to the direction of applied tension) would be stronger, and that the strength of test specimens would be largely dependent on orientation of the material. In contrast, it was believed that the strength of 90° samples (perpendicular to the direction of applied tension) would be largely dependent on the strength of the bonds formed during the layer by layer deposition of heated material, and comparatively weaker. This was largely proven during testing. Samples printed in the 0° orientation exhibited statistically higher properties of both stress and strain. Conversely, plastics printed in the 90° orientation exhibited statistically weaker properties. It was noted that samples printed in the 30°, 45°, and 60° orientations exhibited some measure of improved ductility, although this was not the focus of the study.

Mechanical degradation of contemporary CAD/CAM resin composite materials after water ageing

ObjectiveThe aim of the present study was to assess the effect of water storage on the quasi-static properties and cyclic fatigue behavior of four contemporary CAD/CAM resin composite materials. MethodsThe CAD/CAM resin composites Grandio Blocs, LavaTM Ultimate, CerasmartTM and Brilliant Crios, as well as the direct resin composite Grandio SO, were evaluated. Rectangular plates were cut from the blocks or fabricated using a silicon mold to obtain specimens for fracture toughness (KIc, n = 10), biaxial strength (σ0, n = 30) and cyclic fatigue testing (n = 30). Half of the specimens was stored for 24 h in dry conditions and the other half was aged for 60 days in distilled water at 37 °C. KIc was determined using the Compact-Tension (C(T)) method and σ0 and cyclic fatigue were tested using the Ball-on-Three-Balls assembly. Additional disc-shaped specimens (n = 5) were produced to obtain water sorption curves of the materials. Weibull statistics and two-way ANOVA with Tukey’s post-hoc test were used for data assessment. ResultsThe highest water sorption was observed for LavaTM Ultimate (42.6 μg/mm3), whereas Grandio SO displayed the lowest uptake (14 μg/mm3). A statistically significant drop in KIc and σ0 was measured for all materials after water storage, except for the σ0 of CerasmartTM. Water ageing had a dissimilar effect on the cyclic fatigue behavior, increasing the slow crack growth susceptibility of LavaTM Ultimate, but decreasing it for CerasmartTM and Brilliant Crios. SignificanceContemporary CAD/CAM resin composites are susceptible to water driven degradative processes, although differences in filler content and resin matrix constitution play an important role in how it impacts their mechanical properties.

Durability of bond strength to dentin using two universal adhesives in different etching modes

Aim. To evaluate the bond durability of two universal adhesives; mild and ultra-mild in both etch-and-rinse and self-etch modes after simulated in-vitro degradation by long-term water storage or thermocycling. Methods. A total of 144 specimens were used in this study; 120 specimens (prepared from 30 teeth) for microshear bond strength testing and fracture mode assessment, and 24 specimens for scanning electron microscopic evaluation (prepared from 24 teeth). Specimens were prepared from 54 recently extracted caries free third molars and randomly divided into 12 groups, according to the adhesive treatment (All Bond or Scotchbond Universal), etching mode (etch-andrinse or self-etch) and aging method (thermocycling or water storage). Each tooth was sectioned mesio-distally into two halves exposing free dentin surface for bonding where dentin substrate 1 mm below the dentino-enamel junction was used. After adhesive application and composite build up, specimens were tested in shear mode after storing in distilled water at 37˚C for 24 hours or 1 year, or after being thermocycled between 5 and 55 °C for 10,000 cycles (n=10). Microshear bond strength (μSBS) was tested using a universal testing machine. Adhesive-dentin interface was examined using scanning electron microscope (SEM) (n=2). Data were analyzed using 3 way AN0VA and pairwise comparisons was performed using Bonferroni correction at significance level of α ≤0.05. Results. Statistical analysis revealed non-significant difference for etching mode in both adhesives (p=0.596). After aging, the bond strength was only reduced in Scotchbond Universal after one year of water storage in both modes (p&lt;0.001). SEM evaluation revealed intact hybrid layer and longer resin tags for etch-and-rinse mode than selfetch mode of both adhesives. Conclusion. The bond strength of universal adhesives is not affected by the etching mode, however its durability was shown to be material dependent.

Does Al2O3 airborne particle abrasion improve repair bond strength of universal adhesives to aged and non-aged nanocomposites?

This study investigated the effect of universal adhesives on the resin composite–composite adhesion for immediate and aged repair with and without air-borne particle abrasion. Composite resin specimens were fabricated by placing multiple increments of resin composite (Clearfil Majesty Posterior) into cylindrical cavities (diameter: 4 mm, height: 2 mm) and photo-polymerized. Specimens (N = 720) were randomly assigned to 4 groups (fresh dry specimens, 24 h and 6 months water storage and thermocycled). These four main groups (n = 180) were further assigned to 2 groups (n = 90) according to the surface conditioning procedures; (a) Al2O3 air-abrasion and (b) No air-abrasion. Then, all subgroups were divided into six subgroups due to the adhesive procedures (a) All Bond Universal: AB (Bisco Inc.), (b) Monobond Plus: MP (Ivoclar Vivadent), (c) G-Premio Bond: GP (GC), Gluma Bond Universal: GB (Heraus Kulzer), Clearfil Universal Bond: CU (Kuraray), Clearfil Universal Bond Quick: SK (Kuraray). All bonding systems were applied according to the manufacturer’s instructions and new composite blocks were bonded to the specimens for shear bond strength testing at the Universal Testing Machine (0.5 mm/min). Al2O3 air-abraded groups showed significantly higher bond strength values compared to non-treated groups (p < 0.0001). CU and SK groups showed higher bond strength values and the worst values were observed for the groups of MP. Conditioning with Al2O3 air-abrasion and silane in universal adhesives improves the bond strength of universal adhesives in composite repair.

Potential of Portland pozzolana cement in the stabilization of an expansive soil subjected to alternate cycles of wetting and drying

Cement/lime stabilization of soils is one of the common techniques adopted for improving its geotechnical properties. Lately, the focus of investigation has shifted to blended stabilization with industrial wastes as auxiliary additives. However, the role of blended cement in stabilization of soil has been studied insufficiently despite the fact that it is manufactured under controlled conditions. This investigation deals with the use of Portland pozzolana cement (PPC) instead of ordinary Portland cement (OPC) in the stabilization of an expansive soil subjected to alternate cycles of wetting and drying. Unconfined compression strength (UCS) test specimens of dimensions 38mm x 76mm were cast and cured for periods of 7, 14 and 21 days. Then, the specimens were subjected to 1, 2 and 3 cycles of wetting and drying and the UCS of the specimens were determined. Based on the results of the investigation, it was found that OPC performed significantly better than PPC under normal conditions. However, under conditions of wetting and drying, PPC stabilized soil performed much better than OPC stabilized soil when sufficient binder content was available.

Enhanced bonding behavior of multi-walled carbon nanotube cement composites and reinforcing bars

Bonding between reinforcing bars and cement was enhanced using multi-walled carbon nanotubes (MWCNTs). To investigate the bonding behavior between the composites and a reinforcing bar, 20 bond strength test specimens were fabricated and a pullout test was performed. Additionally, the compressive strengths of MWCNT-cementitious composites were evaluated with different MWCNT concentrations. To analyze the internal structural mechanisms of MWCNT cementitious composites, mercury intrusion porosimetry (MIP) and field emission scanning electron microscopy (FE-SEM) were conducted. The results demonstrated that 0.5 wt% MWCNTs increased the compressive strength of the cementitious composites and enhanced the bonding between the cement composite and the reinforcing bar.

Feasibility of Manufacturing Strand-Based Wood Composite Treated with β-Cyclodextrin-Boric Acid for Fungal Decay Resistance.

The feasibility of using β-cyclodextrin (βCD) as an eco-friendly carrier of boric acid for the protection of strand-based wood composites against decay fungi was evaluated. The formation of a βCD–boric acid (βCD–B) complex was confirmed by the appearance of the boron–oxygen bond by using attenuated total reflection–Fourier transform infrared spectroscopy. Chemical shifts of around 6.25 and 1.41 ppm were also observed in 1H Nuclear Magnetic Resonance (NMR) and 11B NMR spectra, respectively. The βCD–B preservatives at two levels (5 and 10 wt.%) were uniformly blended with southern pine strands that were subsequently sprayed with polymeric methylene diphenyl diisocyanate (pMDI) resin. The blended strands were formed into a loose mat by hand and consolidated into 25 × 254 × 12 mm oriented strand boards (OSB) using a hot-press. The OSB panels were cut to end-matched internal bonding (IB) strength and fungal decay resistance test specimens. The vertical density profiles (VDPs) of the IB specimens were measured using an X-ray based density profiler and the specimens with statistically similar VDPs were selected for the IB and decay tests. The IB strength of the treated specimens was lower than the control specimens but they were above the required IB strength of heavy-duty load-bearing boards for use in humid conditions, specified in the BS EN 300:2006 standard. The reduced IB of preservative-treated OSB boards could be explained by the destabilized resin upon the addition of the βCD–B complex, as indicated by the differential scanning calorimetry (DSC) results. The resistance of the OSB panels against two brown-rot fungi (i.e., G. trabeum or P. placenta) was evaluated before and after accelerated leaching cycles. The treated OSBs exposed to the fungi showed an average mass loss of lower than 3% before leaching, while the untreated OSBs had 49 and 35% mass losses due to decay by G. trabeum or P. placenta, respectively. However, upon the leaching, the treatment provided protection only against G. trabeum to a certain degree (average mass loss of 15%). The experimental results suggest that protection efficacy against decay fungi after leaching, as well as the adhesion of the OSB strands, can be improved by increasing the amount of pMDI resin.

Study of bond strength of one-piece glass fiber posts-and-cores with flared root canals in vitro

To compare the effects of three kinds of fiber posts (CAD/CAM one-piece glass fiber posts-and-cores, prefabricated glass fiber post and light curing plastic fiber post) on the bond strength of flared root canals and the effect of thermal cycling on their bond strength. Extracted human single teeth (n=90) were endodontically treated and randomly divided into three groups (n = 30 each). The teeth were restored by three kinds of fiber post: CAD/CAM one-piece glass fiber posts-and-cores, prefabricated posts and light curing plastic fiber post. Following post cementation, the specimens were stored in distilled water at 37 °C for 7 days. Half bonded specimens of each group were submitted to thermal cycling (6 000 times, 5 to 55 °C) prior to micro-push-out bond strength test. Fabrication of micro-push-out bond strength test specimens was conducted by precision slicing machine. The micro-push-out bond strength was tested using a universal testing machine, and the failure modes were examined with a stereomicroscope. In CAD/CAM one-piece glass fiber posts-and-cores group, the bond strength of cervical, middle and apical was (9.58±2.67) MPa,(8.62±2.62) MPa,(8.21±2.48) MPa respectively before thermal cycling, and after thermal cycling the bond strength of cervical, middle and apical was (8.14±3.19) MPa,(6.43±2.47) MPa,(6.45±3.20) MPa respectively. In prefabricated posts group, the bonding strength of cervical, middle and apical was (3.89±2.04) MPa,(4.83±1.23) MPa,(4.67±1.86) MPa respectively before thermal cycling, and after thermal cycling the bond strength of cervical, middle and apical was (6.18±1.61) MPa,(5.15±1.94) MPa,(6.39±2.87) MPa respectively. In light curing plastic fiber post group, the bond strength of cervical, middle and apical before thermal cycling was (4.05±2.41) MPa,(1.75±1.70) MPa,(2.60±2.34) MPa respectively, and after thermal cycling the bond strength of cervical, middle and apical was (5.04±2.72) MPa,(1.96±1.70) MPa,(1.34±0.92) MPa respectively. Postal types and root canal regions were found to significantly affect the push-out bond strength. Compared with the other two groups, the one-piece glass fiber posts-and-cores had the highest bonding strength in the cervical, middle and apical. Temperature cycling has no significant effect on the micro push-out bond strength of three kinds of fiber posts. One-piece glass fiber posts-and-cores has better bonding strength and excellent bonding performance.

The Influence of Silica Dioxide and Aluminum Oxide Nano Fillers Reinforced Heat Cured Acrylic Denture Base Material and Thermocycling on Tensile and Shear Bond to Denture Soft Lining Material

Background: Soft lining materials play an important role in modern prosthodonticstreatment because of their capability to restore the inflamed and distorted mucosa.The purpose of the research was to estimate the influence of acrylic denture basereinforcement with silanted nano fillers (Al2O3 and Sio2) separately on tensile andshear bond strength of soft lining material and studying effect of thermo cyclingon bonding strength.Materials and methods: Total 120 specimens were prepared; it divided into 60Specimens for shear bond strength test and 6o specimens for tensile bond strengthtest. Specimens were sub grouped into 30 Specimens without thermo cycling and30 specimens with thermo cycling. Each sub group is consisted from: 10Specimens control, 10 specimens were reinforced with 2 wt% of Al2O3 nano fillersand 10 specimens were reinforced with 5 wt% of SiO2 nano fillers. Samples wereprocessed depending on test applied. Soft lining material was applied for eachtesting group. Samples were immersed in distal water for 24 hours at 37°C beforetesting. For thermo cycling test, specimen were thermo cycled in thermo cyclingdevice. Bonding strength test was done using INSTRON universal testingmachine.Results: reinforcement of acrylic denture base with nano-fillers was significantlyincrease both tensile and shear bonding of lining material and thermo cyclingdecreases both bonding strength.Conclusion: reinforcement of acrylic denture base with nano fillers could improvebonding strength of lining material, while thermo cycling had a deleterious effecton bonding strength.

Effect of Aluminium Powder on Light-weight Aerated Concrete Properties

Light-weight aerated concrete (LAC) is produced by making LAC involves the addition of a gas-forming admixture like aluminium powder (AP) to a wet mortar mixture. In concrete during curing, AP will react with the calcium hydroxide in the mixture to form hydrogen. The amount of gas-forming is dependent on the mechanical properties requirements. The aim of the current work was to investigate the properties of aerated concrete (AC) containing 30% fly ash and various AP content, including dry density, porosity and modulus of elasticity, as well as strengths of test specimens. The results of this study showed that when AP content increased, the density of AC decreased, but its porosity increased. Whereas an increase in the amount of AP caused a decrease in both the compressive strength, tensile strength and the modulus of elasticity of ACspecimens. The investigation of newly modified AC through combination of local by-product in Vietnam would decrease the content of Portland cement was used and as well as reduce the amounts of ash and slag TPP as well as industrial waste thrown at a landfill. Therefore, assisting the thermoelectric power plants to be more environmentally friendly in the future.

Effect of hygrothermal aging on the interlaminar shear strength of a carbon fibre composite

Carbon Fibre Reinforced Plastic (CFRP) composites are used many applications in aerospace structures due to their high specific strength and stiffness. Composite aircraft structures are usually exposed to a range of environmental conditions such as hygrothermal, UV radiation, chemical environments, biological condition etc., in their service life and may degrade. Moisture absorption at different hygrothermal conditions and its effects on properties of CFRP composites is a useful parameter to designers and application engineers. In this study, UD carbon fiber/epoxy composite laminates were fabricated (HexPly® M21E/34%/UD/194/IMA) from prepreg using standard autoclave process. Inter Laminar Shear Strength (ILSS) test specimens were cut and prepared from theses laminates. Hot-wet specimens were aged at two different conditions; 75 0C/ 85% RH, 55 0C/ 100% RH until attaining moisture absorption saturation. Three-point bend tests were conducted as per ASTM test standard specifications using a 25 KN servo-hydraulic test machine to determine ILSS properties for aged and unaged material. Respective hot-wet conditions were maintained even during the mechanical tests. Tests results show that moisture absorption rate increases gradually and attains saturation at about 1 wt. % under both conditions. Inter laminar shear strength reduced significantly by about 33% due to presence of moisture. Microscopic observation of failed samples also investigated to study the fracture behavior and reported in this paper.