scholarly journals Influence of Microfibers Additive on the Self-healing Performance of Mass Concrete

2021 ◽  
Vol 39 (1A) ◽  
pp. 104-115
Author(s):  
Alaa Z. Dahesh ◽  
Farhad M. Othman ◽  
Alaa A. Abdul-hamead
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Physical And Mechanical Properties ◽  
Sem Analysis ◽  
Mass Concrete ◽  
Self Healing ◽  
Mixture Ratio ◽  
Concrete Mixtures ◽  
Strength Tests ◽  
Positive Effect

Because cracks are the main problem of mass concrete, this paper investigates an experimental study on the effect of polypropylene microfiber (PPMFs) on self -repair behavior of mass concrete, through study the microstructure, workability, physical, and mechanical properties of mass concrete. PPMFs with a diameter of 18 µm add in different percentages (0, 0.5, 1 and 1.5) % of cement weight. Where the prepared mixture ratio was (1:2:4.8) and the water-cement ratio (W/C) was 0.4. Also, 0.6% of Superplasticizer (SP) % of cement weight to all concrete mixtures was added. In this study, an SEM analysis used to observe the effect of PPMFs on the microstructure of mass concrete, and compressive and flexural strength tests for study the mechanical properties of this. And referring to the analysis and discussion of the results, PPMFs used have changed the microstructure of mass concrete, and have an effective effect on improving compressive strength and flexural strength, and mechanism of sealing the cracks of concrete autogenously. Also, 1% PPMFs (% of cement weight) recorded as the highest addition, which has a positive effect on mass concrete properties to apply it in the construction field.

Improve Mass Concrete by Controlling the Crack Sealing Mechanism Using Microcapsules of Zinc Oxide

2020 ◽  
Vol 1002 ◽  
pp. 541-550
Author(s):  
Alaa Zamel Dahesh ◽  
Farhad Mohammed Othman ◽  
Alaa Aladdin Abdullah-Hamead
Keyword(s):  
Zinc Oxide ◽  
Physical And Mechanical Properties ◽  
Sem Analysis ◽  
Mass Concrete ◽  
Positive Contribution ◽  
Cement Ratio ◽  
Concrete Mixtures ◽  
Concrete Properties ◽  
Crack Sealing ◽  
Sealing Mechanism

This paper examines the structural, workability, physical and mechanical properties of (mass concrete) with the inclusion of microcapsule of Zinc oxide (ZnOMC) with a size (0.5) µm and in different percentages (0, 0.5, 1 and 1.5) % of cement weight. The proportions of the concrete mixture were (1:2:4.8) and the water-cement ratio (W/C) was 0.4. 0.6% of Superplasticizer (SP) by weight of cement with all concrete mixtures was added. An SEM analysis employed to obtain a better view of the concrete behavior with ZnOMC. Referring to the analysis and discussion, it was found that the types of microcapsule used to have an effective effect on the compressive and flexural strength and mechanism of sealing the crack, also the highest percentage of microcapsule which there has a positive contribution towards mass concrete properties have been recorded.

scholarly journals Numerical Studies of the Effects of Water Capsules on Self-Healing Efficiency and Mechanical Properties in Cementitious Materials

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Haoliang Huang ◽  
Guang Ye
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Cementitious Materials ◽  
Self Healing ◽  
Negative Effects ◽  
Numerical Studies ◽  
Healing Efficiency ◽  
The Impact ◽  
Positive Effect

In this research, self-healing due to further hydration of unhydrated cement particles is taken as an example for investigating the effects of capsules on the self-healing efficiency and mechanical properties of cementitious materials. The efficiency of supply of water by using capsules as a function of capsule dosages and sizes was determined numerically. By knowing the amount of water supplied via capsules, the efficiency of self-healing due to further hydration of unhydrated cement was quantified. In addition, the impact of capsules on mechanical properties was investigated numerically. The amount of released water increases with the dosage of capsules at different slops as the size of capsules varies. Concerning the best efficiency of self-healing, the optimizing size of capsules is 6.5 mm for capsule dosages of 3%, 5%, and 7%, respectively. Both elastic modulus and tensile strength of cementitious materials decrease with the increase of capsule. The decreasing tendency of tensile strength is larger than that of elastic modulus. However, it was found that the increase of positive effect (the capacity of inducing self-healing) of capsules is larger than that of negative effects (decreasing mechanical properties) when the dosage of capsules increases.

scholarly journals Properties of High-Strength Flowable Mortar Reinforced with Palm Fibers

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Eethar Thanon Dawood ◽  
Mahyuddin Ramli
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Physical And Mechanical Properties ◽  
High Strength ◽  
Test Results ◽  
Palm Fiber ◽  
Toughness Index ◽  
Strength And Toughness

This study was conducted to determine some physical and mechanical properties of high-strength flowable mortar reinforced with different percentages of palm fiber (0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, and 1.6% as volumetric fractions). The density, compressive strength, flexural strength, and toughness index were tested to determine the mechanical properties of this mortar. Test results illustrate that the inclusion of this fiber reduces the density of mortar. The use of 0.6% of palm fiber increases the compressive strength and flexural strength by about 15.1%, and 16%, respectively; besides, the toughness index (I5) of the high-strength flowable mortar has been significantly enhanced by the use of 1% and more of palm fiber.

scholarly journals Effect of microwave disinfection on physical and mechanical properties of acrylic resins

2008 ◽  
Vol 19 (4) ◽  
pp. 348-353 ◽  
Author(s):  
Rafael Leonardo Xediek Consant ◽  
Erica Brenoe Vieira ◽  
Marcelo Ferraz Mesquita ◽  
Wilson Batista Mendes ◽  
João Neudenir Arioli-Filho
Keyword(s):  
Flexural Strength ◽  
Room Temperature ◽  
Physical And Mechanical Properties ◽  
Hardness Test ◽  
Knoop Hardness ◽  
Microwave Energy ◽  
Bending Test ◽  
Acrylic Resins ◽  
Strength Tests ◽  
The Impact

This study evaluated the effect of microwave energy on the hardness, impact strength and flexural strength of the Clássico, Onda-Cryl and QC-20 acrylic resins. Aluminum die were embedded in metallic or plastic flasks with type III dental stone, in accordance with the traditional packing technique. A mixing powder/liquid ratio was used according to the manufacturer's instructions. After polymerization in water batch at 74ºC for 9 h, boiling water for 20 min or microwave energy at 900 W for 10 min, the specimens were deflasked after flask cooling at room temperature, and submitted to finishing. Specimens non-disinfected and disinfected by microwave irradiation were submitted to hardness, impact and flexural strength tests. Each specimen was immersed in distilled water and disinfected in a microwave oven calibrated to 650 W for 3 min. Knoop hardness test was performed with 25 g load for 10 s, impact test was carried out using the Charpy system with 40 kpcm, and 3-point bending test with a crosshead speed of 0.5 mm/min until fracture. Data were submitted to statistical analysis by ANOVA and Tukey's test (?=0.05). Disinfection by microwave energy decreased the hardness of Clássico and Onda-Cryl acrylic resins, but no effect was observed on the impact and flexural strength of all tested resins.

scholarly journals Examining Polyethylene Terephthalate (PET) as Artificial Coarse Aggregates in Concrete

2020 ◽  
Vol 6 (12) ◽  
pp. 2416-2424
Author(s):  
Erniati Bachtiar ◽  
Mustaan Mustaan ◽  
Faris Jumawan ◽  
Meldawati Artayani ◽  
Tahang Tahang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Polyethylene Terephthalate ◽  
Coarse Aggregate ◽  
Fresh Concrete ◽  
Coarse Aggregates ◽  
Volume Weight ◽  
Concrete Mixtures ◽  
Strength Tests ◽  
Recycled Polyethylene

This study aims to examine the effect of recycled Polyethylene Terephthalate (PET) artificial aggregate as a substitute for coarse aggregate on the compressive strength and flexural strength, and the volume weight of the concrete. PET plastic waste is recycled by heating to a boiling point of approximately 300°C. There are five variations of concrete mixtures, defined the percentage of PET artificial aggregate to the total coarse aggregate, by 0, 25, 50, 75 and 100%. Tests carried out on fresh concrete mixtures are slump, bleeding, and segregation tests. Compressive and flexural strength tests proceeded based on ASTM 39/C39M-99 and ASTM C293-79 standards at the age of 28 days. The results showed that the use of PET artificial aggregate could improve the workability of the concrete mixture. The effect of PET artificial aggregate as a substitute for coarse aggregate on the compressive and flexural strength of concrete is considered very significant. The higher the percentage of PET plastic artificial aggregate, the lower the compressive and flexural strength, and the volume weight, of the concrete. Substitution of 25, 50, 75 and 100% of PET artificial aggregate gave decreases in compressive strength of 30.06, 32.39, 41.73 and 44.06% of the compressive strength of the standard concrete (18.20 MPa), respectively. The reductions in flexural strength were by respectively 19.03, 54.50, 53.95 and 61.00% of the standard concrete's flexural strength (3.59 MPa). The reductions in volume weight of concrete were by respectively 8.45, 17.71, 25.07 and 34.60% of the weight of the standard concrete volume of 2335.4 kg/m3 Doi: 10.28991/cej-2020-03091626 Full Text: PDF

The Behavior of FRA Concrete with High Replacement Ratio

2018 ◽  
Vol 760 ◽  
pp. 204-209 ◽  
Author(s):  
Magdaléna Šefflová
Keyword(s):  
Mechanical Properties ◽  
Physical And Mechanical Properties ◽  
Absorption Capacity ◽  
Recycled Aggregate ◽  
Partial Replacement ◽  
Hardened Concrete ◽  
Replacement Ratio ◽  
Natural Sand ◽  
Concrete Mixtures

This study deals with determination of the properties of the fine recycled aggregate (FRA) concrete with partial replacement of natural sand in concrete mixtures. The FRA was obtained from concrete waste and crushed on fraction 0 – 4 mm by laboratory jaw crusher. The geometrical and physical properties of natural sand and the FRA were tested. The main goal of this study is evaluation of the basic physical and mechanical properties of the concrete with partial natural sand replacement by the FRA such as workability, water absorption capacity, compressive strength and flexural strength. A total four concrete mixtures were prepared. The first concrete mixture was prepared only with natural sand, did not include the FRA. In other concrete mixtures, natural sand was replaced by the FRA in various replacement ratios (40 %, 50 %, and 60 %). All concrete mixtures were designated with the same parameters for clear comparison. The workability of fresh concrete mixtures and physical and mechanical properties of hardened concrete were tested.

scholarly journals COMPORTAMIENTO DE LA MADERA DE Pinus taeda IMPREGNADO CON ARSENIATO DE COBRE CROMATADO (CCA)

FLORESTA ◽  
2005 ◽  
Vol 35 (1) ◽  
Author(s):  
Teresa María Suirezs
Keyword(s):  
Mechanical Properties ◽  
Pinus Taeda ◽  
Physical And Mechanical Properties ◽  
Mechanical Resistance ◽  
Burnett Method ◽  
Pinus Taeda L ◽  
American Society ◽  
Positive Effect ◽  
Copper Arsenic

Este trabajo tuvo por objetivo, estudiar el comportamiento de las propiedades físicas y mecánicas de la madera de Pinus taeda L. impregnada por vacío-presión con preservador CCA (CrO3; CuO; As2O5) con tres retenciones, 5, 10 y 15 kg/m3. El proceso de impregnado se realizó, por el método Burnett, aplicándose presión y vacío de 7 kg/m2 y – 0,5 kg/m2 respectivamente. Los ensayos de las propiedades físicas y mecánicas se determinaron según lo establecen, las Normas técnicas IRAM (Instituto Argentino de Racionalización de Materiales), ASTM (American Society for Testing and Materials) y DIN (Deutsche Industrie Norm). Las propiedades físicas como ser los pesos específicos aparentes no son afectadas por las retenciones de CCA en la madera. Las contracciones tanto en el sentido tangencial como radial en las maderas impregnadas son menores. Las propiedades mecánicas de resistencia a la flexión estática, compresión paralela a las fibras, tracción perpendicular a las fibras, disminuyen levemente sus valores promedios con respecto a la madera sin impregnar, pero estas diferencias no son estadísticamente significativas, para 95 % de confianza. La impregnación ha producido un efecto positivo en la dureza Janka transversal y en el corte paralelo a las fibras tangencial siendo estas diferencias estadísticamente significativas. Behaviour of the wood of Pinus taeda impregnated with Chrome, Copper, Arsenic (CCA) Abstract The physical and mechanical properties of the wood of Pinus taeda L. without impregnating and impregnating by empty - pressure with preserving CCA (Chrome, Copper, Arsenic) with three retentions, 5, 10 and 15 kg/m3 have been determined and analysed. The impregnation was accomplished in an autoclave applying the Burnett method. The physical and mechanical properties were determined according to the following technical Procedures; IRAM (Argentine Institute for Rationalization of materials), ASTM (American Society for Testing and Material) and DIN (Deutsche Industrie Norm). The results indicate that the specific weights of samples containing different percentages of humidity was not affected by the retentions of CCA in the wood. The shrinkage both in the tangential and radial directions in the impregnated samples were smaller in the impregnated sample. The mechanical resistance to statics flexion, compression parallel to the fibers, traction perpendicular to the fibers, hardness tangential and radial Janka and paralell radial cut, do not show statistically meaningful differences between impregnated and not impregnated samples; however the treatment has produced a positive effect in the hardness transverse Janka and in the parallel cut to the tangential fibers.

scholarly journals Research on Wetting-Drying Cycles’ Effect on the Physical and Mechanical Properties of Expansive Soil Improved by OTAC-KCl

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Bao-tian Wang ◽  
Can-hong Zhang ◽  
Xue-lian Qiu ◽  
En-yue Ji ◽  
Wen-hui Zhang
Keyword(s):  
Mechanical Properties ◽  
Expansive Soil ◽  
Physical And Mechanical Properties ◽  
Cyclic Strength ◽  
Soil Samples ◽  
Engineering Properties ◽  
Swelling Potential ◽  
Wetting And Drying ◽  
Strength Tests ◽  
Free Swell

Expansive soil experiences periodic swelling and shrinkage during the alternate wet and dry environments, which will result in severe damage to the slope stability. In this study, a promising modifier OTAC-KCl is introduced, which has a good diffusivity and is soluble in water or other solvents easily. Firstly, a reasonable combination of ameliorant 0.3% STAC and 3% KCl is chosen referring to the free swell test. Then, the best curing period, 14 days, is gotten from UCS tests. The effect of wetting and drying cycles on engineering properties of expansive soil improved by OTAC-KCl admixtures after 14-day curing is also studied accordingly. Both treated and untreated expansive soil samples are prepared for the cyclic wetting-drying tests which mainly include cyclic swelling potential and cyclic strength tests. Experimental results show that the swelling potential of expansive soil samples stabilized with OTAC-KCl is suppressed efficiently, and the untreated soil specimens will collapse when immersed in water while the treated specimens keep in good conditions. Moreover, expansive soil samples modified with 0.3% OTAC + 3% KCl show enough durability on the swelling ability, shear strength, and unconfined compressive strength, which means, that both the physical and the mechanical properties of stabilized expansive soil have been improved effectively.

Physical and Mechanical Properties and Biological Resistance of the Calcareous Composites on Activated Mixing Water

2020 ◽  
Vol 1011 ◽  
pp. 151-157
Author(s):  
Sergey Khutorskoy ◽  
Denis Emelyanov ◽  
Alexander Matvievsky ◽  
Vasiliy Smirnov
Keyword(s):  
Mechanical Properties ◽  
Treatment Effectiveness ◽  
Physical And Mechanical Properties ◽  
Study Results ◽  
Slaked Lime ◽  
Water Activation ◽  
Biological Environment ◽  
Activation Conditions ◽  
Positive Effect ◽  
Mixing Water

The study results of the calcareous composites made with the use of activated mixing water are presented. Quicklime and slaked lime are used as lime binders. The mixing water was activated by the electric current and magnetic field in various modes. The effect of water activation on the physical and mechanical properties of slaked and quicklime composites and the resistance to the effects of the biological environment are studied. The water for mixing electromagnetic treatment effectiveness analysis is presented. The increase in the density of materials based on lime, trapped in activated water using ultrasound tests is proven. It was found that the mixing water activation affects the structure formation of composites and, under certain activation conditions, leads to an increase in such physical and mechanical parameters as strength and hardness. The positive effect of the mixing water activation on the lime-based materials’ resistance to microbial growth has been established, and the decrease in the growth of composites based on quicklime and slaked lime has been proved.

scholarly journals Viscosity, Miscibility Studies and Mechanical Properties of Pullulan/Poly(vinyl alcohol) Blends at 30 ºC and 40 ºC

2019 ◽  
Vol 32 (2) ◽  
pp. 260-264
Author(s):  
M.S. Jayaprakash ◽  
K Shivakumar ◽  
Shashidhar ◽  
T.K. Vishnuvardhan
Keyword(s):  
Mechanical Properties ◽  
Vinyl Alcohol ◽  
Physical And Mechanical Properties ◽  
Sem Analysis ◽  
Poly Vinyl Alcohol ◽  
Refractive Indices ◽  
Ultrasonic Velocities ◽  
Reduced Viscosity ◽  
Ubbelohde Viscometer ◽  
Miscibility Studies

The miscibility studies of pullulan and poly(vinyl alcohol) (PVA) blends by reduced viscosity measurements, refractometry, mechanical properties and SEM analysis. Viscometric measurements at 30 and 40 ºC were taken using Ubbelohde viscometer. Ultrasonic interferometric was used to measure the ultrasonic velocities of different blend compositions. Refractive indices of blend solutions with different compositions were measured directly with an Abbe′s refractometer with thermostat containing water circulated at 30 and 40 ºC. The mechanical properties, refractive index, ultrasonic velocity and density studies showed that there is an increase of all these with PVA content in the blends. But SEM studies have given an indication of immiscibility in the blend system. Overall, pullulan/PVA blends have shown good physical and mechanical properties particularly for 90/10 composition.

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