Articoli di riviste: "High strength concrete Testing"

1

Price, W. F., e J. P. Hynes. "In-situ strength testing of high strength concrete". Magazine of Concrete Research 48, n. 176 (settembre 1996): 189–97. http://dx.doi.org/10.1680/macr.1996.48.176.189.

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Johnson, Claude D., e S. Ali Mirza. "Confined capping system for compressive strength testing of high performance concrete cylinders". Canadian Journal of Civil Engineering 22, n. 3 (1 giugno 1995): 617–20. http://dx.doi.org/10.1139/l95-070.

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Abstract (sommario):

This paper presents a simple, inexpensive confined cap testing method which can be employed in the compressive strength testing of high performance concrete cylinders. An inexpensive customized cylinder capping apparatus and standard concrete laboratory testing equipment are employed. The paper describes the capping apparatus, capping and testing procedures, as well as test results for concrete compressive strengths up to and exceeding 100 MPa. Key words: capping, capping confinement, compressive strength, cylinders, end condition, grinding, high-strength concrete, specimen size, testing.

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Solikin, Mochamad. "Compressive Strength Development of High Strength High Volume Fly Ash Concrete by Using Local Material". Materials Science Forum 872 (settembre 2016): 271–75. http://dx.doi.org/10.4028/www.scientific.net/msf.872.271.

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This paper presents a research to produce high strength concrete incorporated with fly ash as cement replacement up to 50% (high volume fly ash concrete) by using local material. The research is conducted by testing the strength development of high volume fly ash concrete at the age of 14 days, 28 days and 56 days. As a control mix, the compressive strength of Ordinary Portland Cement (OPC) concrete without fly ash is used. Both concrete mixtures use low w/c. consequently, they lead to the use of 1 % superplasticizer to reach sufficient workability in the process of casting. The specimens are concrete cubes with the dimension of 15 cm x15 cm x 15 cm. The totals of 24 cubes of HVFA concrete and OPC concrete are used as specimens of testing. The compressive strength design of concrete is 45 MPa and the slump design is ± 10 cm. The result shows that the compressive strengths of OPC concrete at the age of 14 days, 28 days, and 56 days are 38 MPa, 40 MPa, and 42 MPa. Whereas the compressive strength of HVFA concrete in the same age of immersing sequence are 29 MPa, 39 MPa, and 42 MPa. The result indicates that HVFA concrete can reach the similar compressive strength as that of normal concrete especially at the age of 56 days by deploying low water cement ratio.

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Hooton, RD, M. Sonebi e KH Khayat. "Testing Abrasion Resistance of High-Strength Concrete". Cement, Concrete and Aggregates 23, n. 1 (2001): 34. http://dx.doi.org/10.1520/cca10523j.

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5

Davidyuk, Artem, e Igor Rumyantsev. "Quality control of high-performance concrete in high-rise construction during operation". MATEC Web of Conferences 170 (2018): 01035. http://dx.doi.org/10.1051/matecconf/201817001035.

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With onset of the XXI century, the demand for construction of high-rise buildings with the load-bearing framework made of high-performance cast-in-situ concrete has increased many-fold in the construction sector. Specific features of the high-performance concrete of bearing structures in the situation of real operation of high-rise buildings are continuously studied by scientists and specialists all over the world, and regulatory and methodological documents are being complemented and adjusted. High-performance concretes and structures made of them possess some specific features that should be taken into account in quality control. The methods of concrete inspection and concrete strength evaluation described in GOST 18105 “Concretes. Guidelines on Testing and Evaluation of Strength” and GOST 22690 “Concretes. Evaluation of Strength by Mechanic Non-Destructive Test Methods” were written when precast reinforced concrete was predominantly used in the construction sector and were limited to the functions of intra-factory quality control of reinforced concrete products. At present, instruments for non-destructive testing using indirect methods are usually calibrated with the help of local destructions, as a rule, a pull out or rib shear test. The said methods are in fact indirect since they indicate the force of destruction of the surface layer of a structure.

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Sovová, Kateřina, Karel Mikulica, Adam Hubáček e Karel Dvořák. "Behavior of High Strength Concrete at High Temperatures". Solid State Phenomena 276 (giugno 2018): 259–64. http://dx.doi.org/10.4028/www.scientific.net/ssp.276.259.

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Concrete is considered as a non-combustible building material. However, at High-Performance Concrete (HPC) is due to its dense structure more likely to occur in explosive spalling. This results in lost of load bearing capacity function of concrete. This paper deals with design, production and testing of the cement-based concrete with the use of different fibers (polypropylene fibers and cellulose fibers). It also assesses the influence of high temperature on strength, visual changes of specimens, changes of surface and degradation of testing specimens due to heat loads according to normative heat curve and also according to hydrocarbon curve.

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Chen, Bo, Yue Bo Cai, Jian Tong Ding e Yao Jian. "Crack Resistance Evaluating of HSC Based on Thermal Stress Testing". Advanced Materials Research 168-170 (dicembre 2010): 716–20. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.716.

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In order to evaluate the crack resistance of high strength fly ash concrete, concretes with different contents of silica fume and fly ash were compared with same strength grade by adjusting water to binder ratio. Compared with the concrete with 5% silica fume plus 35% fly ash，concrete with 40% fly ash has same mechanical properties and tensile strain as well as lower drying shrinkage. Complex crack resistance of high strength fly ash concretes were evaluated by Temperature Stress Testing Machine (TSTM). The results show that fly ash concretes have outstanding crack resistance because of higher allowable temperature differential and lower cracking temperature.

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Vincent, Thomas, e Togay Ozbakkloglu. "An Experimental Study on the Compressive Behavior of CFRP-Confined High- and Ultra High-Strength Concrete". Advanced Materials Research 671-674 (marzo 2013): 1860–64. http://dx.doi.org/10.4028/www.scientific.net/amr.671-674.1860.

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It is well established that external confinement of concrete with fiber reinforced polymer (FRP) sheets results in significant improvements on the axial compressive behavior of concrete. This understanding has led to a large number of experimental studies being conducted over the last two decades. However, the majority of these studies have focused on normal strength concretes (NSC) with compressive strengths lower than 55 MPa, and studies on higher strength concretes have been very limited. This paper presents the results of an experimental study on the compressive behavior of FRP confined high- and ultra high-strength concrete (HSC and UHSC) with average compressive strengths of 65 and 100 MPa. A total of 29 specimens were tested under axial compression to investigate the influence of key parameters such as concrete strength and method of confinement. All specimens were cylindrical, confined with carbon FRP and were 305 mm in height and 152 mm in diameter. Results obtained from the laboratory testing were graphically presented in the form of axial stress-strain relationships and key experimental outcomes are discussed. The results of this experimental study indicate that above a certain confinement threshold, FRP-confined HSC and UHSC exhibit highly ductile behavior. The results also indicate that FRP-wrapped specimens perform similar to concrete-filled FRP tube (CFFT) specimens at ultimate condition, however notable differences are evident at the transition region when comparing stress-strain curves.

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Wedatalla, Afaf M. O., Yanmin Jia e Abubaker A. M. Ahmed. "Curing Effects on High-Strength Concrete Properties". Advances in Civil Engineering 2019 (6 marzo 2019): 1–14. http://dx.doi.org/10.1155/2019/1683292.

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This study was conducted to investigate the impact of hot and dry environments under different curing conditions on the properties of high-strength concrete. The concrete samples were prepared at a room temperature of 20°C and cured under different curing conditions. Some specimens underwent standard curing from 24 h after casting until the day of testing. Some specimens underwent steam curing in a dry oven at 30°C and 50°C after casting until the day of testing. Other specimens were cured for 3, 7, 21, and 28 days in water and then placed in a dry oven at 30°C and 50°C and tested at the age of 28 days, except for the specimens that were cured for 28 days, which were tested at the age of 31 days, to study the effect of curing period on the strength of concrete exposed to dry and hot environments after moist curing. The effects of hot and dry environments on high-strength concrete with different water/binder ratios (0.30, 0.35, and 0.40), using (30%) fly ash for all mixes, and (0%, 5%, and 10%) silica fume with the binder (450, 480, and 520 kg), respectively, were separately investigated, and the effects of curing under different conditions were evaluated by measuring the compressive strength, flexural strength, microhardness, and chloride diffusion and by assessing the concretes’ microstructure. The relationships between these properties were presented. A good agreement was noted between the concrete compressive strength and concrete properties at different temperatures, curing periods, and curing methods.

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10

Bickley, J. A., J. Ryell, C. Rogers e R. D. Hooton. "Some characteristics of high-strength structural concrete". Canadian Journal of Civil Engineering 18, n. 5 (1 ottobre 1991): 885–89. http://dx.doi.org/10.1139/l91-107.

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The 68-storey Scotia Plaza tower in Toronto is an outstanding example of the use of concrete technology to achieve high-performance high-strength concrete. Cementitious hydraulic slag, silica fume, and a superplasticizer were combined with CSA type-10 Portland cement and high-quality aggregates to produce very workable high-strength concrete. During the course of construction, data were published suggesting the possibility of the strength regression of some silica fume concretes after long exposure to low humidity, the determinations being made on standard test cylinders. Tests were, therefore, made at ages of 1 year and 2 years on specimens drilled from columns in the structure. This technical note gives details of the laboratory examination and testing of these specimens. Key words: high strength, slag, silica fume, permeability, rapid chloride permeability, petrographic examination, superplasticizers.

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11

Sucharda, O., V. Bilek e P. Mateckova. "Testing and mechanical properties of high strength concrete". IOP Conference Series: Materials Science and Engineering 549 (18 giugno 2019): 012012. http://dx.doi.org/10.1088/1757-899x/549/1/012012.

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12

Jacobsen, Stefan, Hans Christian Gran, Erik J. Sellevold e Jon Arne Bakke. "High strength concrete — Freeze/thaw testing and cracking". Cement and Concrete Research 25, n. 8 (dicembre 1995): 1775–80. http://dx.doi.org/10.1016/0008-8846(95)00173-5.

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13

Wang, Zheng Jun, Mei Han e Felix Zhao. "Applying Research on Testing Technique of High Performance Concrete". Advanced Materials Research 378-379 (ottobre 2011): 226–29. http://dx.doi.org/10.4028/www.scientific.net/amr.378-379.226.

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Abstract (sommario):

In order to master timely and accurately construction quality of high performance concrete, detection of compressive strength of high performance concrete can be tested non-destructively, rapidly and accurately. The paper did preliminary research on high performance concrete with redound method, furthermore, it established estimation model between rebound value and compressive strength. Experiment shows that rebound method can effetely test compressive strength of high performance concrete. Construction quality of Cement concrete structure or component can timely grasped in period of construction with the method.

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14

Marzouk, H., e Z. W. Chen. "Nonlinear analysis of normal- and high-strength concrete slabs". Canadian Journal of Civil Engineering 20, n. 4 (1 agosto 1993): 696–707. http://dx.doi.org/10.1139/l93-086.

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Concrete slabs supported on four edges and loaded axially and transversely are used in many civil engineering applications. High-strength concrete slabs are commonly used for marine structures and offshore platforms. The catastrophic nature of the failure exhibited by reinforced concrete slabs when subjected to concentrated loads has been a major concern for engineers over many years. Therefore, there is a great need to develop accurate numerical models suitable for normal-strength or high-strength concrete in order to reflect properly its structural behaviour.Proper simulation of the post-cracking behaviour of concrete has a significant effect on the nonlinear finite element response of such slabs. Cracking and post-cracking behaviour of concrete which includes aggregate interlock, dowel action, and tension-stiffening effects is especially crucial for any nonlinear concrete analysis. The post-cracking behaviour and the fracture energy properties of high-strength concrete are different from those of normal-strength concrete. This can be realized by comparing the experimental testing results of plain normal- and high-strength concrete. The experimental results of testing plain high-strength concrete in direct tension indicated that the total area under the stress - crack width curve in tension is different from that of normal-strength concrete.A suitable softening and tension-stiffening model is recommended for high-strength concrete; other existing models suitable for normal-strength concrete are discussed. The proposed post-cracking behaviour models are implemented in a nonlinear finite element program in order to check the validity of such models by comparing the actual experimental data with the finite element results. Finally, a parametric study was conducted to provide more insight into the behaviour of high-strength concrete slabs subjected to combined uniaxial in-plane loads and lateral loads. The effects of the magnitude of in-plane load and the sequence of loading on the structural behaviour of such slabs are examined. Key words: high-strength concrete, slabs, punching shear, fracture energy, tension-softening, tension-stiffening, parametric study.

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Stehlík, Michal. "TESTING THE STRENGTH OF CONCRETE MADE FROM RAW AND DISPERSION-TREATED CONCRETE RECYCLATE BY ADDITION OF ADDITIVES AND ADMIXTURES". Journal of Civil Engineering and Management 19, n. 1 (16 gennaio 2013): 107–12. http://dx.doi.org/10.3846/13923730.2012.734853.

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Today, concrete comprises more than 65% of the total volume of building constructions. As it undergoes degradation and buildings require refurbishment, the volume of concrete increases at disposal sites. Due to a lack of non-renewable resources and due to high prices of energies, the reuse of concrete seems to be more than desirable. It is common knowledge that in concretes made from recycled concrete, the strengths of the original concretes can hardly be achieved. The addition of dispersion additives and mineral admixtures into the freshly mixed concrete can contribute to improving the mechanical properties of concretes made from recycled concrete. Potential composite action of the recyclate, mineral admixtures and dispersion additives in increasing the compressive strength of concretes made from recycled concrete remains to be a question.

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Gunay, Ahmet Reha, Sami Karadeniz e Mustafa Kaya. "An Experimental Study on the Dynamic Behavior of an Ultra High-Strength Concrete". Applied Sciences 10, n. 12 (17 giugno 2020): 4170. http://dx.doi.org/10.3390/app10124170.

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Ultra-high-strength concrete is a newly developed construction material that has a minimum 120 MPa or higher compressive strength. Recently, the usage of high-strength and ultra-high-strength concretes has become widespread due to the enhancement of the concrete technology. Many civil engineering structures constructed by using concrete materials are usually subjected to, in addition to static loads, dynamic loads due to earthquakes, wind and storm, impact and blast, which take place under high energy and high strain rate values. The effects of such loadings on the structure must be understood thoroughly. In recent years, the withstanding of a structure on these loading conditions has become a crucial issue for its impact on the economy and human safety. One of the approaches to fulfill these requirements is to develop high-strength or ultra high-strength concretes (UHSCs). In this study, an ultra-high-strength concrete with a compressive strength of 135 MPa was designed and developed. In order to determine the dynamic behavior of this UHSC, the specimens at three height/diameter ratios (approximately, 0.6, 1.0 and 1.2) were extracted from the prepared concrete mixtures. These concrete specimens were tested to determine both the quasi-static and dynamic compressive behaviors of the developed concrete. In the quasi-static compression tests, cylindrical specimens and a conventional compressive testing machine were used. In order to study the dynamic compressive behavior, a Split Hopkinson Pressure Bar (SHPB) test setup was used. In this test system, the time variations of compressive strength, the strain and strain rates under uniaxial pressure loading were experimentally evaluated and the deformation and fracturing processes of the specimens were recorded using a high-speed camera. The test results, based on the testing of 21 different specimens, have shown that the dynamic compressive strength values of the developed concrete varied in the range of 143 to 253 MPa, while the strain rate values varied in the range of 353 s−1 to 1288 s−1. Using the data generated in the SHPB tests, the parameters present in a Johnson–Holmquist–Cook concrete material model, which is used in numerical studies on the high strain rate behavior of concretes, were evaluated.

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Kong, Xu Wen, Long Cui e Jin Shan Wang. "Experimental Study of Green High Performance Concrete Strength Testing by Rebound Method". Applied Mechanics and Materials 71-78 (luglio 2011): 737–43. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.737.

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Abstract (sommario):

Compare experiment analysis effect of material, slump, carbonation depth on green high performance concrete strength by rebound method, analysis under questions based on microstructure: (1)Basic reason for additives and admixtures etc. impact rebound testing; (2) Significant differences of pumping concrete and plastic concrete; (3) Concrete carbonation depth impact rebound value. Provide the method for improving testing accuracy of green high performance concrete strength testing by rebound method.

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Yi, Wei Jian, e Yan Mei Lv. "Experimental Study on Shear Failure of High-Strength Concrete Beams with High-Strength Stirrups". Key Engineering Materials 400-402 (ottobre 2008): 857–63. http://dx.doi.org/10.4028/www.scientific.net/kem.400-402.857.

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19 RC beams with shear span-to-depth equal to 3 were tested under a stiff testing facility, and complete load-deflection curves including the post-peak branch were obtained. Based on the test results the effects of concrete strength, stirrups strength, inclined stirrup angle, the amount of longitudinal reinforcement on failure mode, shear ductility index and shear capacity were analyzed. The test results were compared with the shear design approaches of Chinese Code and American Code. The results indicate that the shear failure of beam with appropriate web reinforcement has finite ductility. High-strength concrete beams with high-strength stirrups can increase not only the shear capacity, but also the shear ductility. The shear capacity of beams with high-strength concrete and stirrup can be designed with Chinese Code, but shear capacity of high-strength concrete beams without stirrups, or with the smaller amount of longitudinal reinforcement, and normal strength concrete beams with high-strength stirrups may be over-estimated by the Code.

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Yu, Le Hua, Shuang Xi Zhou e Hui Ou. "Experimental Investigation on Properties of High Performance Concrete with Mineral Admixtures in Pavement of Highway". Advanced Materials Research 723 (agosto 2013): 345–52. http://dx.doi.org/10.4028/www.scientific.net/amr.723.345.

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To meet demand of highperformance pavement concrete in highway, differentproportional concretes incorporating 30%—40% ground granulatedblast furnace slag and (or) fly ash were investigated on engineering properties in laboratory. Workability offresh concrete was evaluated by result of testing slump, mechanical property ofconcrete by flexural strength, abrasion resistance of concrete by index ofabrasion resistance and durability of concrete by chloride diffusioncoefficient and value of charge passed. The results indicate that measuredcharacteristics of concretes are superior to the relevant requisitions in specificationof highway. It was revealed that partial substitution ofmineral admixtures increased workability of fresh concrete, abrasion resistanceand durability of concrete. Addition of groundgranulated blast furnace slag is more favorable to flexural strength ofconcrete than that of fly ash, in particular for early-term to avoid delaying construction time with lower strength caused in use of greatvolume admixture.

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Elbasha, N., e M. N. S. Hadi. "Experimental testing of helically confined high-strength concrete beams". Structural Concrete 6, n. 2 (giugno 2005): 43–48. http://dx.doi.org/10.1680/stco.2005.6.2.43.

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Kumar, C. Naga Satish, e T. D. Gunneswara Rao. "Fracture parameters of high-strength concrete – mode II testing". Magazine of Concrete Research 62, n. 3 (marzo 2010): 157–62. http://dx.doi.org/10.1680/macr.2010.62.3.157.

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Thomas, C., J. Sainz-Aja, J. Setien, A. Cimentada e J. A. Polanco. "Resonance fatigue testing on high-strength self-compacting concrete". Journal of Building Engineering 35 (marzo 2021): 102057. http://dx.doi.org/10.1016/j.jobe.2020.102057.

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Gaidhane, Ms Sakshi Harish. "“Testing of High-Performance Concrete using Recycled Aggregates”". International Journal for Research in Applied Science and Engineering Technology 9, n. 9 (30 settembre 2021): 495–98. http://dx.doi.org/10.22214/ijraset.2021.37970.

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Abstract: Tons of waste is produced in the world on every day basis which sometimes gets really hard to manage and. The waste from demolished structures is one of them. Recycling waste consume energy and produces pollution that can lead to many adverse effects on the environment and human life. The disposal of waste is also very dangerous for the environment. Using waste materials like waste aggregates, broken bricks, stones and other material in concrete can help in eliminating the waste and save the environment getting polluted. It is also very much economical and encourages green concrete industry. The literature study consists of testing of high-performance concrete using waste aggregates by replacing 100 % natural aggregates. Also, silica fume and plasticizer are used as admixture to obtain more effective results. The tests were carried out on 3, 7 and 21 days of curing. The results were tallied using graphs between comparison of compressive strength and tensile strength of natural and recycled aggregates. The cement and natural aggregates and sand was obtained from a local store in a nearby market. The recycled aggregates were obtained from a nearby demolished building. The quantities were taken in a proper proportion according to IS codes to avoid any defects while constructing the cubes and while curing and performing various tests. Keywords: Recycled Aggregates, Natural Aggregates,Concrete Strength, High Performance Concrete, Properties of Concrete, Cost Effective

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Lee, Taegyu, Jaehyun Lee e Hyeonggil Choi. "Assessment of Strength Development at Hardened Stage on High-Strength Concrete Using NDT". Applied Sciences 10, n. 18 (9 settembre 2020): 6261. http://dx.doi.org/10.3390/app10186261.

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This study proposes model formulae for predicting the strength of concrete by analyzing the relationships between the results of nondestructive testing (NDT) methods and the compressive strength of concrete specimens at the hardened stage. Further, NDT of concrete molds and mock-up specimens was conducted using NDT methods (rebound hammer, ultrasonic pulse velocity). The water/cement (W/C) ratios were set to 0.48, 0.41, and 0.33 to achieve concrete strengths within the compressive strength range of 24–60 MPa. The evaluation parameters included the fresh concrete properties, compressive strength (mold and core), temperature history, maturity, rebound value, and ultrasonic pulse velocity. Evaluation results indicated that the reliability of existing models, based on the rebound and ultrasonic pulse velocity, is significantly low on high-strength concrete of 40 MPa or higher, and cannot satisfy the ±20% error range. Consequently, this study proposes a regression equation of the concrete strength based on the experimental rebound and ultrasonic pulse velocity values in a 24–60 MPa range, which offers satisfactory reliability.

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Wang, Zheng Jun, e Felix Zhao. "Applying Research on Testing Compressive Strength of High Performance Concrete with Rebound Method". Advanced Materials Research 452-453 (gennaio 2012): 106–9. http://dx.doi.org/10.4028/www.scientific.net/amr.452-453.106.

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Abstract (sommario):

In order to grasp timely and accurately quality of high performance concrete, detection of compressive strength of high performance concrete can be non-destructively, rapidly and accurately tested that is very testing index. The paper did some research on compressive strength of high performance concrete applying redound method that it established several estimation models between rebound value and compressive strength. Experiment shows that rebound method can effetely test compressive strength of high performance concrete. Construction quality of Cement concrete structure can timely grasp applying the method.

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Baranova, Al'bina, e Ol'ga Yazina. "FOAM CONCRETES BASED ON HIGH-STRENGTH BINDERS". Modern Technologies and Scientific and Technological Progress 2018, n. 1 (23 marzo 2020): 97–98. http://dx.doi.org/10.36629/2686-9896-2020-2018-1-97-98.

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Flores, Elsy Y., Jordan Varbel, Craig M. Newtson e Brad D. Weldon. "Ultra-High-Performance Concrete Shear Keys in Concrete Bridge Superstructures". MATEC Web of Conferences 271 (2019): 07006. http://dx.doi.org/10.1051/matecconf/201927107006.

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Many existing bridges have adjacent girders that utilize grouted shear keys to transfer loads laterally across the superstructure. Cracking and leaking often cause degradation of the shear key and the girder. This work investigates the potential for using non-proprietary ultra-high performance concrete (UHPC) as a grouting material for repair of deteriorated shear keys by testing bond strength between UHPC and substrate concrete surfaces that were either formed or scarified by chipping. Bond strengths were adequate for both surface textures even though texture depth was substantially less than recommended by ACI 546. Scanning electron microscopy has also been used to investigate the bonded area. This microscopic scanning has shown fly ash residue remaining on the substrate after bond failure, indicating that the supplementary cementitious materials produce much of the bond. Ongoing work for this project also includes full-scale testing of UHPC shear keys between pre-stressed channel girders.

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Wardi, Adil Hadi, Gökhan Tunç e Khalil Ibraheem. "Structural behavior of shear connectors embedded in different types of concrete". Challenge Journal of Structural Mechanics 6, n. 4 (20 dicembre 2020): 160. http://dx.doi.org/10.20528/cjsmec.2020.04.001.

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Push-out tests are used to determine shear connectors’ properties where two small reinforced concrete walls are attached to the top and bottom flanges of an I-section through four shear studs located on both its flanges. In this study, the structural behavior of shear connectors was examined by testing a total of 36 push-out specimens. In these specimens, various test parameters were used. The types of shear connectors and their strengths, their connection types, and the strength of the concrete in which they were embedded were all investigated. Headed, L-shaped, and C-shaped studs were selected in this experimental study to represent different types of shear connectors. These shear connectors were assumed to be either ordinary or high strength steel-embedded in three different types of concrete: ordinary, high strength, and reactive powder concretes. In these tests, the shear connectors were connected through welding or epoxy bonding. The objective of this study was to investigate the structural behaviors of these different types of shear connectors by focusing on their shear force capacities and slip values. The test results indicate that the reactive powder concrete increased the mechanical properties of concrete as the concrete age increased. The specimens with C-shaped studs made of high-strength steel with welded studs embedded in normal weight, high strength and reactive powder concretes, generated the maximum shear resistance values.

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Mohtasham Moein, Mohammad, Ashkan Saradar, Komeil Rahmati, Arman Hatami Shirkouh, Iman Sadrinejad, Vartenie Aramali e Moses Karakouzian. "Investigation of Impact Resistance of High-Strength Portland Cement Concrete Containing Steel Fibers". Materials 15, n. 20 (14 ottobre 2022): 7157. http://dx.doi.org/10.3390/ma15207157.

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Impact resistance of Portland cement concrete (PCC) is an essential property in various applications of PCC, such as industrial floors, hydraulic structures, and explosion-proof structures. Steel-fiber-fortified high-strength concrete testing was completed using a drop-weight impact assessment for impact strength. One mix was used to manufacture 320 concrete disc specimens cured in both humid and dry conditions. In addition, 30 cubic and 30 cylindrical specimens were used to evaluate the compressive and indirect tensile strengths. Steel fibers with hooked ends of lengths of 20, 30, and 50 mm were used in the concrete mixtures. Data on material strength were collected from impact testing, including the number of post-first-crack blows (INPBs), first-crack strength, and failure strength. Findings from the results concluded that all the steel fibers improved the mechanical properties of concrete. However, hooked steel fibers were more effective than crimped steel fibers in increasing impact strength, even with a smaller length-to-diameter ratio. Concrete samples containing hybrid fibers (hooked + crimped) also had lower compressive strength than the other fibers. Comparisons and analogies drawn between the test results and the static analyses (Kolmogorov–Smirnov and Kruskal–Wallis) show that the p-value of the analyses indicates a more normal distribution for curing in a humid environment. A significant difference was also observed between the energy absorptions of the reinforced mixtures into steel fibers.

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Zhang, Nan, Juan Liao, Tao Zhang, Wen Zhan Ji, Bao Hua Wang e Dong Hua Zhang. "The Effect of Mineral Admixtures on Mechanical Properties of High Performance Concrete at very Low Temperature". Applied Mechanics and Materials 584-586 (luglio 2014): 1509–13. http://dx.doi.org/10.4028/www.scientific.net/amm.584-586.1509.

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Abstract (sommario):

The effect of very low temperature on high performance concrete (HPC) mechanical properties is studied by using a reasonable testing method. The results show that the compressive strengths of concrete are increasing with lower temperatures. Fly ash (FA), compared to ground granulated blast-furnace slag (GGBFS), is positive to the compressive strength increasing at low temperature. The splitting tensile strengths of concrete appear a maximum at-40°C~-80°C. The compound replacement by GGBFS and FA makes the splitting tensile strength present the extreme value at higher temperature. At very low temperature, the single or compound replacement by mineral admixtures can result in the difference of the relationship between compressive strength and splitting tensile strength, and the degradation of concrete subjected to cold-thermal shocks.

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31

Korolev, Evgeniy Valerjevich, e Alexandr Sergeevich Inozemtcev. "Preparation and Research of the High-Strength Lightweight Concrete Based on Hollow Microspheres". Advanced Materials Research 746 (agosto 2013): 285–88. http://dx.doi.org/10.4028/www.scientific.net/amr.746.285.

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The paper presents the results of research aimed at development of nanomodified high-strength lightweight concrete for construction. The developed concretes are of low average density and high ultimate compressive strength. It is shown that to produce this type of concrete one need to use hollow glass and aluminosilicate microspheres. To increase the durability of adhesion between cement stone and fine filler the authors offer to use complex nanodimensional modifier based on iron hydroxide sol and silica sol as a surface nanomodifier for hollow microspheres. It is hypothesized that the proposed modifier has complex effect on the activity of the cement hydration and, at the same time increases bond strength between filler and cement-mineral matrix. The compositions for energy-efficient nanomodified high-strength lightweight concrete which density is 1300...1500 kg/m3 and compressive strength is 40...70 MPa have been developed. The approaches to the design of high-strength lightweight concrete with density of less than 2000 kg/m3are formulated. It is noted that the proposed concretes possess dense homogeneous structure and moderate mobility. Thus, they allow processing by vibration during production. The economic and practical implications for realization of high-strength lightweight concrete in industrial production (in particular, for construction of high-rise buildings) have been justified. The results of industrial testing of new compositions in precast concrete technology are shown.

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32

Oh, Bo Hwan, Hong C. Rhim e Hyo Seon Park. "Effect of Confining Pressure on Modeling High Early Strength Concrete under Uniaxial Loading". Key Engineering Materials 321-323 (ottobre 2006): 367–70. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.367.

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Abstract (sommario):

Better understanding of concrete behavior is beneficial to the determination of concrete strength and detection of cracking using nondestructive testing techniques such as ultrasonic and acoustic emission. For advanced nondestructive evaluation of high early strength concrete under triaxial compression loading, stress-strain relationship in axial as well as in radial directions needs to be described in explicit form. This paper presents empirical models developed for high early strength concrete under active confinement to explore the effect of confining pressure. Empirical model for axial stress-strain relationship is determined first. Transverse deformation model is automatically generated from the given axial stress-strain model using plastic strain rate. Parameters used in the model are identified and their recommended values are provided. Compressive strength of 24 MPa and 45 MPa concretes are considered along with four different levels of confining pressures.

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33

A.M. Mhamoud, Hassan, e Jia Yanmin. "Effect of different additives on high temperatures of concrete". Journal of Structural Fire Engineering 9, n. 2 (11 giugno 2018): 161–70. http://dx.doi.org/10.1108/jsfe-01-2017-0021.

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Abstract (sommario):

Purpose This study aims to investigate the effectiveness of different additives (individual effects) in improving the strength of concrete to resist temperatures of up to 60ºC. Design/methodology/approach In all, 13 different mixtures with a constant water/binder ratio of 0.36 and grade M40 were prepared by using ordinary Portland concrete alone, or with partial replacement by fly ash (FA), blast-furnace slag, silica fume (SF) and a combination of all three. After 7 and 28 days under water, their strength and residual strength were measured. Findings The results of testing revealed that the addition of 10 per cent SF was found to result in the greatest increase in compressive strength and flexural strength along with decreased the residual strengths. The addition of FA increased the compressive strength and enhanced the residual compressive strength. However, it also decreased the residual flexural strength. Originality/value The addition of slag achieved better flexural strength and the best residual compressive strength. The combination of additives also enhanced the compressive strength but was not found to be better than using SF alone.

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34

Li, Cao, e Wang Qing Gao. "Experimental Study on Rebound Curve of High-Strength Concrete". Key Engineering Materials 881 (aprile 2021): 137–41. http://dx.doi.org/10.4028/www.scientific.net/kem.881.137.

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Abstract (sommario):

As the application of high-strength concrete in civil engineering becomes more and more extensive in our country, it needs to cooperate with the popularization and application of new high-strength concrete technology so as to solve the practical problems of high-strength concrete in the engineering application of the strength detection and master the national strength measurement curve of high-strength concrete. A representative commercial concrete manufacturer in Guangzhou was selected for the detection accuracy of this area. And the general raw materials in Guangzhou were used to make concrete specimens. The 4.5J high-strength rebound tester and 5.5J high-strength rebound tester were used for testing the rebound value of the specimen and the compressive strength of the specimen at different ages. The basic research results can be used as an important basis for establishing the strength curve of high-strength concrete areas.

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35

Stepanova, V. F., G. V. Chehniy, I. M. Parshina, S. A. Orekhov e A. I. Kruglov. "Study into the freeze-thaw/ frost-salt resistance of high-strength B60–B100 concrete". Bulletin of Science and Research Center of Construction 33, n. 2 (19 aprile 2022): 183–93. http://dx.doi.org/10.37538/2224-9494-2022-2(33)-183-193.

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Abstract (sommario):

Introduction. The development of the Arctic Region and oil and gas fields in the North Atlantic Ocean leads to an increase in the production of high-strength concrete structures. Thus, it is becoming increasingly vital to make such low-permeability concretes more freeze-thaw resistant.Aim. To conduct experimental studies for obtaining reliable data required to develop a standardized approach to the normalization of freeze-thaw / frost-salt resistance parameters characterizing high-strength concretes.Materials and methods. The study was performed using concretes of eight compositions (B60–B100 compressive strength grades). The freeze-thaw/frost-salt resistance of high-strength concretes was determined using the third rapid method involving the saturation, freezing, and thawing of samples in a 5 % sodium chloride solution, as well as assessment of freeze-thaw resistance in terms of strength, mass variation, and the dynamic modulus of elasticity. A variety of methods for increasing the water saturation of highstrength concrete were examined in order to expedite the testing process of high-strength concrete for freeze-thaw resistance.Results. The studies into the freeze-thaw/frost-salt resistance of high-strength B60-B100 concretes revealed their high freeze-thaw resistance. Following 37 freeze-thaw cycles, the lower confidence limit for the strength of test samples was higher than that of control samples multiplied by a coefficient of 0.9. The frost-resistance grade of these concretes is above F2 300. No critical decrease in the dynamic modulus of elasticity is observed, which indicates a significant freeze-thaw/frost-salt resistance of all tested highstrength concrete compositions.Conclusions. The freeze-thaw resistance studies of high-strength concretes carried out at NIIZHB named after A.A. Gvozdev yielded experimental data required to subsequently develop a standardized approach to the normalization of freeze-thaw/frost-salt resistance parameters characterizing high-strength concretes.

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36

Varona, Francisco B., Francisco Baeza-Brotons, Antonio J. Tenza-Abril, F. Javier Baeza e Luis Bañón. "Residual Compressive Strength of Recycled Aggregate Concretes after High Temperature Exposure". Materials 13, n. 8 (23 aprile 2020): 1981. http://dx.doi.org/10.3390/ma13081981.

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Abstract (sommario):

Sustainability requirements are gaining importance in the construction industry, which needs to take specific measures in the design and construction of concrete structures. The use of recycled aggregates in concrete may be of special interest. Recycling a construction waste will close the life cycle of the original materials (e.g., concrete). Thus, environmental benefits would come from the lower waste generation, and from a lower necessity of raw materials for new structures. The current Spanish code for structural concrete considers the use of recycled aggregates in replacement rates up to 20% by aggregate mass, assimilating their properties with those of concretes without aggregate replacement. Higher substitution percentages would require further testing. In this work, substitution of coarse aggregate for recycled aggregates (with replacement percentages of 25%, 50% and 100%) has been studied, and the concrete’s residual properties after exposure to high temperatures (between 350 °C and 850 °C) have been assessed. Compressive strength and capillary water absorption tests were made after heating, and the experiments showed higher residual strength in concretes with the greatest content of recycled aggregates. However, a statistical analysis made with additional data available in the literature seemed to predict otherwise, and the recycled aggregate replacement would have a negative effect on the residual strength.

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KUTSYK, Olena, e Oleksandr ZHURAVSKYI. "EXPERIMENTAL AND THEORETICAL STUDIES OF REINFORCED CONCRETE BENDING ELEMENTS MADE OF HIGH-STRENGTH CONCRETE". Building constructions. Theory and Practice, n. 9 (28 dicembre 2021): 87–93. http://dx.doi.org/10.32347/2522-4182.9.2021.87-93.

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Abstract (sommario):

The use of quality materials is necessary for the manufacture of load-bearing reinforced concrete structures that are subject to heavy loads. To meet such requirements, it is necessary to use high-strength concrete, which has high compressive strength, water and gas tightness, corrosion resistance due to its dense structure. The use of high-strength concrete makes it possible to reduce the cross-sectional dimensions of structures, thereby reducing the weight of structures compared to structures of traditional classes of concrete.The results of experimental and theoretical researches of work of reinforced concrete beams from high-strength and ordinary concrete at crossbending are resulted in work.A program of experimental research has been developed, which includes the manufacture and testing of concrete samples of prisms and cubes todetermine the strength and deformation characteristics of concrete of different composition, the manufacture and testing of experimental reinforcedconcrete beams for transverse loading. Three series of rays were tested, four in each. The composition of the concrete mixture for high-strength concreteusing metakaolin and hyperplasticizer is proposed.The proposed algorithm for calculating the bearing capacity of bending elements, based on the method of deformation, allows obtaining resultswith sufficient accuracy. The calculation is performed according to the developed algorithm, which is implemented in the Mathcad program.The analysis of experimental and theoretical values of bearing capacity of reinforced concrete beams from high-strength and usual concrete attransverse bend.

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38

Rizkiasari, Anggia Eta, e Abdul Rouf. "Analisis Hubungan Kecepatan Gelombang Dengan Kuat Tekan Beton Menggunakan Metode UPV". IJEIS (Indonesian Journal of Electronics and Instrumentation Systems) 10, n. 1 (30 aprile 2020): 11. http://dx.doi.org/10.22146/ijeis.33414.

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Abstract (sommario):

Until now the use of concrete as a building material is still widely used for building structures. It is important to do concrete compressive strength testing as one of the factors to know the quality of a concrete. NDT (Non-Destructive Testing) is a method of solid quality testing without damaging the object. Testing with the NDT method is considered more efficient than the destructive test method. One method for performing NDT testing is by utilizing UPV (Ultrasonic Pulse Velocity).UPV is a method for estimating concrete compressive strength based on the ultrasonic pulse velocity relationship through concrete with the concrete compressive strength itself. UPV testing works by emitting ultrasonic pulses of 40 kHz through concrete to obtain the travel time of the pulse. Then the resulting time will be calculated the value of its speed and then will be converted into concrete compressive strength.Concrete compressive strength measurement system for high-quality concrete using UPV method can be designed by utilizing relation between ultrasonic pulse velocity with concrete compressive strength. Based on the test results, the average error value of concrete compressive strength testing is 3.04% with a maximum error of 6.63%.

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39

Hosseini Mehrab, Alireza, Seyedmahdi Amirfakhrian e M. Reza Esfahani. "Fracture characteristics of various concrete composites containing polypropylene fibers through five fracture mechanics methods". Materials Testing 65, n. 1 (1 gennaio 2023): 10–32. http://dx.doi.org/10.1515/mt-2022-0210.

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Abstract (sommario):

Abstract This paper investigates and compares the experimental results of fracture characteristics in various polypropylene fiber-reinforced concretes (high strength concrete, lightweight concrete, and engineered cementitious composite) on 90 three-point bend (notched and un-notched) beams. Five widely used fracture mechanics testing methods, such as work of fracture method, stress-displacement curve method, size effect method, J integral method, and ASTM E399, were used to investigate the fracture behavior. Results have demonstrated that fracture energy and fracture toughness improved as the dosage of polypropylene fibers increased in concretes. However, this improvement was different in concretes owing to various results of fracture mechanics testing methods and different properties of each concrete. Aggregates played significant role in the performance of polypropylene fibers on the fracture behavior of concretes. Among testing methods, the ASTM E399 showed the lowest values for the fracture toughness of concretes. Both work of fracture and stress-displacement curve methods exhibited appropriate results for the fracture energy of polypropylene fiber-reinforced concrete composites. The accuracy of size effect method was acceptable for determining size-independent fracture parameters of plain high strength and lightweight concretes. Furthermore, the J integral method showed more relevant results for the fracture toughness of polypropylene fiber-reinforced engineered cementitious composite.

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40

Huang, Peng Fei. "Patent Analysis of Concrete Testing Technology". Key Engineering Materials 726 (gennaio 2017): 120–24. http://dx.doi.org/10.4028/www.scientific.net/kem.726.120.

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Abstract (sommario):

Discover Patent existing concrete performance test technology at home and abroad in the field of analysis of the existing concrete performance test technical features, difficulties and trends, noted that the current domestic patent technology in concrete performance test encountered utilization, protection and disputes, high durability and lightweight concrete and avoid patent risk recommendations for the structure to adapt to the development of the next building needs and provide research and development of high strength.

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41

Lee, Ming Gin, Yung Chih Wang, Wan Xuan Xiao, Ming Ju Lee e Tuz Yuan Huang. "Effect of CO₂ Curing on the Strength of High Strength Pervious Concrete". Key Engineering Materials 846 (giugno 2020): 207–12. http://dx.doi.org/10.4028/www.scientific.net/kem.846.207.

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Abstract (sommario):

This study was conducted to assess the effect of CO2 curing on the compressive strength of high strength pervious concrete. The factors studied to evaluate compressive strength of concrete on CO2 curing pressure, curing time, and age of specimen at testing. Three Aggregate sizes, three CO2 curing pressures, three CO2 curing time, and three testing ages were used in this investigation. The research tried to produce a high strength pervious concrete and use carbon dioxide for curing to find out whether it could enhance the compressive strength. The results show that the compressive strength of the control group increases rapidly and its 90-day compressive strength closed to 60 MPa. The 1-day compressive strength has a major impact after CO2 curing and their strength decreased by about 0% to 50% as compared to the control group. However, it is observed that there is only slight difference in relationship between modulus of elasticity and compressive strength obtained from 100 by 200mm cylinders with CO2 curing.

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42

Yue, Zhong Wen, Hui Zhang e Bo Yang Dou. "Industrial Test on Outer Frozen Shaft Wall of High Strength and High Performance Concrete". Advanced Materials Research 179-180 (gennaio 2011): 569–74. http://dx.doi.org/10.4028/www.scientific.net/amr.179-180.569.

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Abstract (sommario):

To study the industrial technology for application of the C100 High strength and high performance concrete which is in freezing shaft lining of thick overburden, the industrial test of the shaft wall of high strength and high performance concrete is carried out under the engineering background of auxiliary shaft in Yuncheng coal mine of Juye coal mining area in Shandong Province. The verified laboratory testing results comported with the results of industrial technology from macro-mechanics, failure fractal, resultant morphology and pore characteristics. And the quality control system of high performance concrete and construction technology can be established. The results show that the experimental formula and construction technology of C100 high strength and high performance concrete can meet the requirement of field concrete shaft lining and achieve the high level of quality control. The industrial application and study results accord with the field requirement. Furthermore, the study results also provide experimental basis and industrial production data for industrial application of C100 high strength and high performance concrete.

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43

Wang, Jiantao, e Qing Sun. "Cyclic testing of Q690 circular high-strength concrete-filled thin-walled steel tubular columns". Advances in Structural Engineering 22, n. 2 (14 agosto 2018): 444–58. http://dx.doi.org/10.1177/1369433218790769.

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Abstract (sommario):

Under seismic action, the severe damage in critical regions of structures could be ascribed to the cumulative damage caused by cyclic loading. This article describes an investigation of the hysteresis behaviour of Q690 circular high-strength concrete-filled thin-walled steel tubular columns with out-of-code diameter-to-thickness ratios. A total of eight specimens were tested under constant axial compression and cyclic lateral loading. The study results of phase I testing consisting of a benchmark test were summarized to examine the seismic behaviour under standard loading, and those of the phase II testing that considered different fatigue loading modes and different concrete strengths were summarized to investigate the low-cycle fatigue behaviour. The load–displacement hysteretic curves, energy dissipation, strength and stiffness degradation were discussed in detail. A simplified method was proposed to predict the low-cycle fatigue life, which can be applied in the damage-based seismic design of circular concrete-filled steel tubular structures.

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44

Siregar, Atur P. N. "Experimental investigation of the flexural ductility of singly reinforced concrete beam using normal and high strength concrete". Journal of Sustainable Engineering: Proceedings Series 1, n. 2 (30 settembre 2019): 218–24. http://dx.doi.org/10.35793/joseps.v1i2.30.

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Abstract (sommario):

This paper discusses and reports based on the experimental investigation of the flexural ductility of singly reinforced normal strength and high strength concrete beams. Compressive concrete strength of 40 and 95 MPa were employed to create singly reinforced normal strength and high strength concrete beams, respectively. Fourteen samples made of normal and high strength concrete were engaged to observe the flexural ductility behaviour of beams on the basis of four point bend testing. Analysis on the basis of the flexural cracking, ultimate failure and curvature ductility were carried out to derive the comparison of singly reinforced normal strength and high strength beams. The beams using high strength concrete revealed a higher ductility ratio than that of normal strength concrete, i.e. 4.50 for high strength concrete and 2.60 for normal strength concrete.

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45

Liu, Feng, Gui Xuan Chen e Li Juan Li. "Performance of Rubberized High Strength Concrete after Fire". Advanced Materials Research 163-167 (dicembre 2010): 1403–8. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.1403.

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Abstract (sommario):

The effects of recycled rubber powder on working abilities, density and compressive strength of high strength concrete (HSC) at room temperature were studied in this paper. The characteristics of rubberized high strength concrete (RHSC) after fire was investigated by surface observation, weight loss and retained strength testing. The sieve number of rubber powder used in test is No.40 (420μm), No.60 (250µm) and No.80 (178µm), and the content of rubber powder filled in RHSC is 1%, 2%, 3% and 4% with respect to cementation material respectively. Test results show that the increase in rubber powder content reduces the concrete strength, while the decrease in compressive strength of RHSC is less than 10% when the content of rubber powder is within 2%. RHSC with small content of rubber (1%) can restrain the spalling failure of concrete under high temperature.

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46

Ali, A., Z. Soomro, S. Iqbal, N. Bhatti e A. F. Abro. "Prediction of Corner Columns’ Load Capacity Using Composite Material Analogy". Engineering, Technology & Applied Science Research 8, n. 2 (19 aprile 2018): 2745–49. http://dx.doi.org/10.48084/etasr.1879.

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Abstract (sommario):

There are numerous reasons for which concrete has become the most widely used construction material in buildings, one of them being its availability in different types, such as fiber-reinforced, lightweight, high strength, conventional and self-compacting concrete. This advantage is specially realized in high-rise building construction, where common construction practice is to use concretes of different types or strength classes in slabs and columns. Columns in such structures are generally made from concrete which is higher in compressive strength than the one used in floors or slabs. This raises issue of selection of concrete strength that should be used for estimating column capacity. Current paper tries to address this issue by testing nine (09) sandwich column specimens under axial loading. The floor concrete portion of the sandwich column was made of normal strength concrete, whereas column portions from comparatively higher strength concrete. Test results show that aspect ratio (h/b) influences the effective concrete strength of such columns. A previously adopted methodology of composite material analogy with some modifications has been found to predict well the capacity of columns where variation in floor and concrete strength is significant.

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Dvořák, Richard, Zdeněk Chobola e Ivo Kusák. "Acoustic non-destructive testing of high temperature degraded concrete with comparison of acoustic impedance". MATEC Web of Conferences 219 (2018): 03003. http://dx.doi.org/10.1051/matecconf/201821903003.

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Abstract (sommario):

The paper is focused on non-destructive measurement of high temperature degraded concrete test specimens of three mixtures different by the use of coarse aggregate. Testing is done by ultrasonicpulse velocitymethod and Impact-Echo method. Non-destructive results are compared with destructive tests. Ultrasonic pulse velocity, dominant resonance frequency and acoustic impedance are discussed and compared with changes in density, cubic compressive strength, and tensile strength of concrete. The paper suggests possible assessment of degraded concrete by the change in acoustic impedance dependent on residual tensile strength.

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48

Liu, Guan Guo, Guo Rong Zhang, Yun Sheng Zhang e Lu Lu. "Study on Tensile Creep Characteristics of High Strength Concrete". Applied Mechanics and Materials 835 (maggio 2016): 535–41. http://dx.doi.org/10.4028/www.scientific.net/amm.835.535.

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Abstract (sommario):

A set of concrete tensile creep testing apparatus was constructed. The tensile creep characteristics of concrete under different loading ages (1d, 3d and 7d), different water-binder ratio (0.29, 0.33 and 0.37) and different fly ash proportion (0%, 20% and 40%) were researched. The results show that tensile creep increases with increasing of water-binder ratio obviously as well as with decreasing of loading ages. The tensile creep is inhibited by addition of fly ash, and the inhibition effect increases with the increase of fly ash proportion. Free shrinkage is counteracted 42%~62% by tensile creep. The internal tension of concrete is effectively relieved so that the possibility of cracking of concrete is decreased at early ages.

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49

Kadam, Shriganesh Shantikumar, V. V. Karjinni e C. S. Jarali. "Prediction of Fiber Reinforced Concrete Strength Properties by Micromechanics Method". Civil Engineering Journal 5, n. 1 (27 gennaio 2019): 200. http://dx.doi.org/10.28991/cej-2019-03091238.

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Abstract (sommario):

High strength steel fiber reinforced concrete (HSSFRC) was prepared with the help of steel fiber. 0.5%, 1.0%, and 1.5% steel fiber by volume of concrete specimen was used in concrete for present investigation. Compressive strength test and flexural strength test were conducted on cubical and prismatic specimens respectively.The main objective of the research work is to validate the experimental out comes by a numerical technique such as micromechanics approach. A high strength steel fiber reinforced concrete whose compressive strength is greater than 60 N/mm2 was prepared and tested on concrete testing machine. Flexural strength test was conducted on universal testing machine to evaluate the bending properties of concrete. It was observed that with increase in the percentage of steel fiber volume the compressive strength and flexural strength also increases. However the workability of concrete declines and concrete is no longer in working condition. Micromechanics technique helps to predict the strength properties which save time required for casting and such technique was found to be beneficial.

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50

Del Savio, Alexandre Almeida, Darwin La Torre e Juan P. Cedrón. "Experimental Volume Incidence Study and the Relationship of Polypropylene Macrofiber Slenderness to the Mechanical Strengths of Fiber-Reinforced Concretes". Applied Sciences 12, n. 18 (11 settembre 2022): 9126. http://dx.doi.org/10.3390/app12189126.

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Abstract (sommario):

An experimental study was conducted to examine the mechanical strengths of concretes with straight high-strength knurled polypropylene macrofibers. Incidences of concrete mechanical strengths were determined for three different fiber dosages and lengths. In addition, compressive, indirect-splitting-test tensile, and flexural strengths were determined through testing. The results showed no statistically significant correlation between the volume and length of fibers with the compressive strength of polypropylene fiber-reinforced concrete (PPFRC). However, there was a statistically significant correlation between the split tensile strength, the volume, and the length of the fibers when the volume was greater than 0.80%, and the length of the fibers was greater than 50 mm. Furthermore, the modulus of rupture increased when the volume of fibers was greater than 0.80% and the length of the fibers was 60 mm. Finally, equations were proposed to determine the tensile strength by split test and the modulus of rupture as a function of the mixture’s resistance without fibers, the fibers’ volume and length.

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