Test Method for Determining the Mechanical Properties of Hardened Concrete Under Triaxial Loads

10.1520/c0801 ◽  
2004 ◽  
Author(s):  
Keyword(s):  
Mechanical Properties ◽  
Test Method ◽  
Hardened Concrete ◽  
Triaxial Loads

Methodology of studying the mechanical properties of composite materials (reinforced concrete)

2018 ◽  
Vol 84 (12) ◽  
pp. 61-67
Author(s):  
V. A. Eryshev
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Experimental Studies ◽  
Analytical Relationship ◽  
Hardened Concrete ◽  
Deformation Model ◽  
Joint Work ◽  
Concrete Shrinkage ◽  
Axial Tension ◽  
Tension And Compression

The mechanical properties of a complex composite material formed by steel and hardened concrete, are studied. A technique of operative quality control of new credible concrete and reinforcement, both in laboratory and field conditions is developed for determination of the strength and strain characteristics of materials, as well as cohesion forces determining their joint operation under load. The design of the mobile unit is presented. The unit provides a possibility of changing the direction of loading and testing the reinforced element of the given shape both for tension and compression. Moreover, the nomenclature of testing equipment and the number of molds for manufacturing concrete samples substantially decrease. Using the values of forcing resulting in concrete cracking when the joint work of concrete and reinforcement is disrupted the values of the inherent stresses and strains attributed to the concrete shrinkage are determined. An analytical relationship between the forces and deformations of the reinforced concrete sample with central reinforcement is derived for axial tension and compression, with allowance for strains and stresses in the reinforcement and concrete resulted from concrete shrinkage. The results of experimental studies are presented, including tension diagrams and diagrams of developing axial deformations with an increase in the load under the central loading of the reinforced elements. A methodology of accounting for stresses and deformations resulted from concrete shrinkage is developed. The applicability of the derived analytical relationships between stresses and deformations on the material diagrams to calculations of the reinforced concrete structures in the framework of the deformation model is estimated.

scholarly journals Application of the plasticity characteristic determined by the indentation technique for evaluation of mechanical properties of coatings: I. specific features of the test method procedure

2004 ◽  
Vol 36 (1) ◽  
pp. 27-41 ◽  
Author(s):  
A.V. Byakova ◽  
Yu.V. Milman ◽  
A.A. Vlasov
Keyword(s):  
Mechanical Properties ◽  
Indentation Load ◽  
Test Method ◽  
Simplified Model ◽  
Micro Hardness ◽  
Properties Of Coatings ◽  
Modified Model ◽  
Plasticity Characteristic ◽  
Measurement Results ◽  
Hardness Values

Specific features of the test method procedure capable for determining the plasticity characteristic dH by indentation of inhomogeneous coatings affected by residual stress was clarified. When the value of the plasticity characteristic for coating was found to be as great as dH > 0.5 a simplified model was found to be reasonably adequate, while a modified model assumed compressibility of the deformation core beneath indentation. The advantage of the modified approach compared to the simplified one was grounded experimentally only if the elastic deformation for coating becomes greater than ?e ? 3.5%, resulting in the decrease of plasticity characteristic dH < 0.5. To overcome non accuracy caused by the effect of the scale factor on measurement results a comparison of different coatings was suggested using stabilized values of the plasticity characteristic dH determined under loads higher than critical, P ? Pc, ensuring week dependence of micro hardness values on the indentation load.

A novel test method for mechanical properties of characteristic zones of girth welds

2021 ◽  
pp. 104533
Author(s):  
Hailiang Nie ◽  
Weifeng Ma ◽  
Kai Xue ◽  
Junjie Ren ◽  
Wei Dang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Test Method ◽  
Girth Welds

scholarly journals Global analysis of DEF damage to concretes with and without fly-ash

2022 ◽  
Vol 15 (3) ◽  
Author(s):  
Nicole Pagan Hasparyk ◽  
Dioice Schovanz ◽  
Francieli Tiecher ◽  
Selmo Chapira Kuperman
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Global Analysis ◽  
Physical And Mechanical Properties ◽  
Test Method ◽  
Cement Matrix ◽  
Negative Effects ◽  
Ettringite Formation ◽  
Pozzolanic Cement ◽  
Over Time

Abstract Delayed Ettringite formation (DEF) is an internal expansive reaction that can damage concrete. DEF is strongly influenced by the temperature, above about 60-65°C, and other factors involving cement chemistry especially, but also its physical characteristics. The exposure environment over time also promotes a condition to increase deterioration from DEF. Expansions results from secondary ettringite formation are progressive and can lead concrete to microcracking impacting its performance and durability over time. Several concrete structures are pointed to be severely attacked by DEF, and test method as well a better comprehension on this pathology is necessary to promote specific and proper preventive measures to avoid future damages. Furthermore, compared to alkali-silica reaction, DEF occurs more readily and aggressively, and sometimes prematurely, depending on several factors, such as type of cement, concrete mix design, exposure conditions, among others. This paper involves an overall analysis of the behavior of concretes with two types of Portland cements (High early-strength cement and a Portland pozzolanic cement, with fly-ash) in relation to DEF process. Several data from a laboratory study where DEF was induced through a specific thermal curing procedure are presented and discussed. The analyses involved the assessment of physical, mechanical, and expansive properties besides microstructural monitoring of samples from concretes over time. These experiments allowed detecting high values of expansions from DEF (up to 1.2%) in the concrete without fly ash. The mechanical properties were severely impacted from this deleterious process; as expansions increased, losses in the mechanic and elastic properties were verified. Expansion levels in the order of 0.5% prompted remarkably high reductions and, at about 1% the losses were relevant for both strengths (tensile and compressive) and modulus of elasticity, of 60% and 80%, respectively, in the presence of cement without fly-ash. Concrete microstructure has indicated massive formations of ettringite as well as micro-cracking and the fragility of the cement matrix because of DEF. On the other hand, expansion up to 0.2% did not promote important negative effects on the properties of concrete, especially with the pozzolanic cement tested. Furthermore, an overall approach with several correlations between physical and mechanical properties was taken to obtain different levels of deterioration for a concrete presenting DEF.

scholarly journals Mechanical Properties of Compression Moulded Aggregate-Reinforced Thermoplastic Composite Scrap

2021 ◽  
Vol 5 (11) ◽  
pp. 299
Author(s):  
Julien Moothoo ◽  
Mahadev Bar ◽  
Pierre Ouagne
Keyword(s):  
Mechanical Properties ◽  
Tensile Properties ◽  
Test Method ◽  
Thermoplastic Composite ◽  
Recycled Aggregate ◽  
Thermoplastic Composites ◽  
Mechanical Recycling ◽  
Compression Moulding ◽  
Grain Sizes ◽  
Recycled Composites

Recycling of thermoplastic composites has drawn a considerable attention in the recent years. However, the main issue with recycled composites is their inferior mechanical properties compared to the virgin ones. In this present study, an alternative route to the traditional mechanical recycling technique of thermoplastic composites has been investigated with the view to increase mechanical properties of the recycled parts. In this regard, the glass/polypropylene laminate offcuts are cut in different grain sizes and processed in bulk form, using compression moulding. Further, the effect of different grain sizes (i.e., different lengths, widths and thicknesses) and other process-related parameters (such as mould coverage) on the tensile properties of recycled aggregate-reinforced composites have been investigated. The tensile properties of all composite samples are tested according to ISO 527-4 test method and the significance of test results is evaluated according to Student’s t-test and Fisher’s F-test respectively. It is observed that the tensile moduli of the recycled panels are close to the equivalent quasi-isotropic continuous fibre-reinforced reference laminate while there is a noteworthy difference in the strengths of the recycled composites. At this stage, the manufactured recycled composites show potential for stiffness-driven application.

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.

Properties of Spanish Broom Fiber Reinforced Concrete

2021 ◽  
Vol 322 ◽  
pp. 72-77
Author(s):  
Sandra Juradin ◽  
Ivica Boko ◽  
Ivanka Netinger Grubeša ◽  
Dražan Jozić ◽  
Silvija Mrakovčić ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Building Materials ◽  
Tap Water ◽  
Reinforce Concrete ◽  
Climatic Conditions ◽  
Fiber Reinforced Concrete ◽  
Hardened Concrete ◽  
Fiber Reinforced ◽  
Plant Fibers

Building materials based on renewable resources such as plant fibers are increasingly needed, especially if the plant is local and easily accessible. One such plant is the Spanish broom, a typical shrub of the Mediterranean region. In this work, Spanish broom fibers were used for the first time to reinforce concrete. Four mixtures were made: a reference mixture and three mixtures reinforced with 3 cm long fibers, in the amount of 0.5% of the total volume. Cement CEM I 42.5R, crushed limestone aggregate (D = 16 mm), and tap water were used for all the mixtures and in equal quantities. Four mortar mixtures were also made: standard mortar and 3 fiber-reinforced mortars. The mortar is reinforced with fibers of the same length and quantity as the concrete. The fibers were obtained by maceration of Spanish broom in solutions of 8%, 10%, and 15% NaOH. The quality and mechanical properties of the cellulose fibers depend on the geographical and climatic conditions and the fiber extraction procedures so the aim of this study was to evaluate the influence of different chemical pre-treatments of the fibers on the mechanical properties of the concrete. The properties of the fresh mix were determined using the flow method. Hardened concrete was tested for compressive and flexural strength and dynamic modulus of elasticity. Compressive and flexural strengths were determined on cement mortars. The results obtained on concrete were compared with those obtained on the mortar. It was concluded that the quality of composite materials is more influenced by the quality of the placement than by fiber treatment.

scholarly journals The influence of an applied standard test method on a measurement of concrete stabilized secant modulus of elasticity

2018 ◽  
Vol 163 ◽  
pp. 07001
Author(s):  
Lucyna Domagała ◽  
Justyna Dobrowolska
Keyword(s):  
Modulus Of Elasticity ◽  
Lightweight Aggregate ◽  
Standard Test ◽  
Normal Weight ◽  
Test Method ◽  
Hardened Concrete ◽  
Secant Modulus ◽  
Testing Procedures ◽  
Standard Test Method ◽  
The Difference

The paper focuses on the influence of the standard test method applied to determine the concrete stabilized secant modulus on a specified value. The new European Standard EN 12390-13 for testing hardened concrete accepts two methods (A and B) for the determination of the secant modulus of elasticity in compression. The aim of the research was to establish how different testing procedures affect a measured value of modulus of elasticity. Four structural concrete series: two lightweight aggregate concretes and two normal-weight ones were subject to tests of moduli of elasticity determined by both standard methods, as well as compressive strength and density. The carried out tests revealed that the procedure of testing modulus of elasticity influenced a measured value. Method A led to higher values of modulus in relation to Method B, irrespective of concrete density and strength. Nevertheless, a certain relationship between the concrete structure homogeneity and the difference in results of moduli determined by both methods may be observed.

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