scholarly journals Performance Evaluation of Concrete Structures Using Crack Repair Methods

2021 ◽  
Vol 13 (6) ◽  
pp. 3217
Author(s):  
Tae-Kyun Kim ◽  
Jong-Sup Park
Keyword(s):  
Environmental Factors ◽  
Flexural Strength ◽  
Concrete Structures ◽  
Freezing And Thawing ◽  
Concrete Core ◽  
Surface Protection ◽  
Repair Method ◽  
Physical Chemical ◽  
Strength Tests ◽  
Crack Repair

Concrete structures deteriorate over time due to cracks induced by various physical, chemical, and environmental factors. This performance degradation not only reduces their service life but may lead to human casualties and other property damage as well. While concrete crack repair can help address this problem, the implementation of the optimal repair method is important according to the environmental conditions. In this study, epoxy, impregnating, and epoxy/impregnating methods were used to repair concrete cracks. Epoxy was used for crack injection, and a supernatant was used for surface protection. The epoxy/impregnating method was used to protect both cracked areas and surfaces. Activated cracks were induced using flexural strength tests, and the stiffness of the specimens according to the repair method was compared to examine the structural performance. In addition, after the flexural strength tests, the strength, carbonation, chloride, and freeze–thaw durability were evaluated for the concrete core specimens. The impregnating method yielded the best repair performance for strength, epoxy/impregnating method for carbonation, epoxy and epoxy/impregnating methods for chloride, and epoxy/impregnating method for freezing and thawing. The results of our study enable selection of the optimal repair method to be used in practical applications based on physical, chemical, and environmental factors.

scholarly journals Use of Ecofriendly Glass Powder Concrete in Construction of Wind Farms

2021 ◽  
Vol 11 (7) ◽  
pp. 3050
Author(s):  
Eva M. García del Toro ◽  
Daniel Alcala-Gonzalez ◽  
María Isabel Más-López ◽  
Sara García-Salgado ◽  
Santiago Pindado
Keyword(s):  
Wind Farm ◽  
Glass Powder ◽  
Wind Farms ◽  
Main Element ◽  
Partial Replacement ◽  
Surface Protection ◽  
Air Content ◽  
Concrete Mixtures ◽  
Strength Tests ◽  
Rate Of Substitution

Silicon is the main element in the composition of glass and it has been seen that it can be used as a partial replacement for cement in the manufacture of concrete. Different dosages of glass powder and cement were applied to manufacture the concrete mixes. Initially, the characteristics of fresh concrete were studied, such as consistency, air content, apparent density and workability. Secondly, compressive strength tests were performed on the different concrete mixtures produced. The consistency tests allowed us to classify these concretes within the group of fluids. The air content of these concretes increased with the rate of substitution of cement by glass powder, resulting in lighter concretes. Density tests showed that this parameter decreased as the rate of substitution of cement increased. A coefficient k has been calculated for the substitution of glass powder by cement in the binder, using the Bolomey formula. Also, a mathematical model has been proposed to further analyze the experimental data. Major contributions of this work were to study the possible application of this concrete in different dispersions as a surface protection layer against the action of corrosion, in wind turbine foundations as well as the stabilization of the wind farm roads.

scholarly journals Outline of Recommendation for Concrete Repair and Surface Protection of Concrete Structures by JSCE

2005 ◽  
Vol 43 (11) ◽  
pp. 3-11 ◽  
Author(s):  
I. Funakawa ◽  
S. Ushijima ◽  
T. Miyagawa ◽  
Y. Yamamoto
Keyword(s):  
Concrete Structures ◽  
Concrete Repair ◽  
Surface Protection

Mechanisms of Congenital Malformations. Proceedings of the Second Scientific Conference of the Association for the Aid of Crippled Children (1954)

PEDIATRICS ◽  
1957 ◽  
Vol 19 (3) ◽  
pp. 536-536
Author(s):  
JOSEF WARKANY
Keyword(s):  
Environmental Factors ◽  
Congenital Malformations ◽  
Scientific Conference ◽  
Neonatal Deaths ◽  
Present Volume ◽  
Physical Chemical

For many years the Association for the Aid of Crippled Children has supported teratologic research in many ways. Among the activities of the Association scientific conferences and publication of their proceedings play an important role. In the present volume one will find brief summaries of papers presented at a conference in 1954 and abstracts of the discussions contributed by the participants. Part I dealing with physical, chemical and sociological aspects of the fetal environment contains an interesting report by J. Walker of Aberdeen, Scotland, on the effects of obstetrical, physical and environmental factors on the incidence of stillbirths, neonatal deaths and prematurity.

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

Assessment of post-heat behavior of cement mortar incorporating silica fume and granulated blast-furnace slag

2020 ◽  
Vol 11 (2) ◽  
pp. 221-246
Author(s):  
Ghasem Pachideh ◽  
Majid Gholhaki
Keyword(s):  
Tensile Strength ◽  
Flexural Strength ◽  
Blast Furnace Slag ◽  
Strength Test ◽  
Content Type ◽  
Granulated Blast Furnace Slag ◽  
Cement Mortars ◽  
Strength Tests ◽  
Pozzolanic Materials ◽  
Furnace Slag

Purpose With respect to the studies conducted so far and lack of researches on the post-heat behavior of cement mortars containing pozzolanic materials, the purpose of this paper is to investigate the post-heat mechanical characteristics (i.e. compressive, tensile and flexural strength) of cement mortars containing granulated blast-furnace slag (GBFS) and silica fume (SF). In doing so, selected temperatures include 25, 100, 250, 500, 700 and 9000c. Last, the X-ray diffraction test was conducted to study the microstructure of mixtures and subsequently, the results were presented as power-one mathematical relations. Design/methodology/approach Totally, 378 specimens were built to conduct flexural, compressive and tensile strength tests. Accordingly, these specimens include cubic and prismatic specimens with dimensions of 5 × 5 × 5 cm and 16 × 4 × 4 cm, respectively, to conduct compressive and flexural strength tests together with briquette specimen used for tensile strength test in which cement was replaced by 7, 14 and 21 per cent of SF and GBFS. To study the effect of temperature, the specimens were heated. In this respect, they were heated with a rate of 5°C/min and exposed to temperatures of 25 (ordinary temperature), 100, 250, 500, 700 and 900°C. Findings On the basis of the results, the most profound effect of using GBFS and SF, respectively, takes place in low (up to 250°C) and high (500°C and greater degrees) temperatures. Quantitatively, the compressive, tensile and flexural strengths were enhanced by 73 and 180 per cent, 45 and 100 per cent, 106 and 112 per cent, respectively, in low and high temperatures. In addition, as the temperature elevates, the particles of specimens containing SF and GBFS shrink less in size compared to the reference specimen. Originality/value The specimens were cured according to ASTMC192 after 28 days placement in the water basin. First, in compliance with what has been specified by the mix design, the mortar, including pozzolanic materials and superplasticizer, was prepared and then, the sampling procedure was conducted on cubic specimens with dimension of 5 × 5 × 5 mm for compressive strength test, prismatic specimens with dimensions of 16 × 4 × 4 mm for flexural strength test and last, briquette specimens were provided to conduct tensile strength tests (for each temperature and every test, three specimens were built).

Sign in / Sign up

Export Citation Format

Share Document