Journal articles on the topic 'Concrete blocks Effect of temperature on Testing'
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1
Bai, Yin, Yue Bo Cai, Jian Tong Ding, and Xi Ning Guo. "Study on the Damage Risk of Dam Concrete Suffering Alkali-Silicareaction Based on 7 Years Outdoor Field Exposure Testing, Part I: The Influence of Maximum Size of Aggregate." Key Engineering Materials 768 (April 2018): 341–46. http://dx.doi.org/10.4028/www.scientific.net/kem.768.341.
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Alkali-aggregate reaction is one of the most serious concrete durability problems threating the safety of dam. Some accelerated test methods with high temperature and high alkalinity are usually used in laboratory to evaluate the reactivity of aggregates or the effectiveness of suppression measures. In this paper, an outdoor field exposure station was built to objectively assess the damage risk of real dam concrete suffering alkali-silica reaction. 25 concrete blocks measuring 450 by 450 by 450 mm in size were tested at first stage, all immersed into water to simulate the environment of dam concrete. The influences of the size of aggregate and the amount of cementing materials were tested at the same time. After 7 years field exposure testing, the results showed that: the crack risk of blocks was not proportional to the expansion rates, but influenced by the maximum diameter of aggregate. The block with bigger aggregate had smaller expansion rate, but cracked more easily. If the sizes of aggregate were the same, less cementing materials would cause bigger expansion. The constraint effect is bigger than the effect of alkali content increasing caused by increasing the amount of cementing materials.
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Peng, Haoyang, Peng Lin, Yunfei Xiang, Jinwu Hu, and Zongli Yang. "Effects of Carbon Thin Film on Low-Heat Cement Hydration, Temperature and Strength of the Wudongde Dam Concrete." Buildings 12, no. 6 (May 26, 2022): 717. http://dx.doi.org/10.3390/buildings12060717.
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Research on the mechanism of carbon thin film (CTF) is a hot issue in the field of concrete materials and is of great significance to the temperature control and crack prevention of concrete structures, but little research has been conducted regarding this issue. In this paper, the composition of CTF and its influence on cement hydration, concrete temperature and strength are studied in the context of the Wudongde (WDD) dam project. Through observations of hand specimens, rock slice identification and X-Ray Fluorescence (XRF) analysis, it was shown that the CTF has the same chemical composition as the limestone component, except for the presence of low-crystalline graphite. Based on hydration testing using TAM Air, it was found that CTF promotes the dissolution of cement and the hydration of C3A in the very early stage but exerts a lowering effect on the second exothermic peak of cement hydration. In addition, the greater the CTF content, the greater the hydration heat release. According to temperature measurements of the Wudongde (WDD) dam, CTF could promote an increase in the maximum temperature of concrete blocks. Finally, compressive strength analysis revealed that the content of CTF was proportional to the compressive strength of concrete specimens and provides a reference for the effect of CTF on the performance of low-heat cement concrete.
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Mathi1, A. Mathu, and G. Lavanya. "Study on the Light Weight Geopolymer Concrete Made of Recycled Aggregates from Lightweight Blocks." International Journal for Research in Applied Science and Engineering Technology 10, no. 8 (August 31, 2022): 1551–59. http://dx.doi.org/10.22214/ijraset.2022.46440.
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Abstract: This study studied the properties of lightweight geopolymer concrete that contained recycled lightweight block aggregate. The recovered blocks are classified as coarse aggregates after being crushed.To reduce greenhouse gas emissions, geopolymers have the potential to be used to create new, environmentally beneficial materials. A new class of building materials called geopolymer concrete (GPC) has a replacement for regular Portland cement concrete (OPCC) and are capable of revolution in the construction sector. The impact of On the strength characteristics, alkaline activators have been investigated. Used fly ash was obtained for this study from a nearby thermal power plant. Samples were produced from low-calcium fly ash through activation with a combination of sodium silicate solution and sodium hydroxide. Fly ash was added to the concrete with a ratio of 0.5. Using a mix proportion and 5,10,15 Molar of sodium hydroxide solution, geopolymer specimens were cast. The samples underwent compression testing. test with ambient temperatures for curing. From the analysis ofLiterature suggests that the combination of the aforementioned ingredients is healing. FromAccording to a review of the literature, the amalgamation of the aforementioned elementshas a favorable effect on the strength properties of geopolymer concrete. Since fly ash is viewed as a waste product, geopolymer concrete made from low-calcium fly ash costs less than Portland cement concrete as a result. Lowcalcium fly ash-based geopolymer concrete has good compressive strength, very little drying shrinkage and minimum creep, great resistance to sulphate attack, and superior acid resistance.
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Girskas, Giedrius, Džigita Nagrockienė, and Gintautas Skripkiūnas. "The effect of synthetic zeolite admixture on the durability of concrete paving blocks." Baltic Journal of Road and Bridge Engineering 11, no. 3 (September 30, 2016): 215–21. http://dx.doi.org/10.3846/bjrbe.2016.25.
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Concrete paving blocks that were started to be used in the last century have become very popular. They became an alternative to the natural stone. Concrete paving blocks are used for the paving of pedestrian and vehicle zones. Durability is one of the main characteristics in the production of high-quality concrete paving blocks in the Baltic region climate zone. The article describes tests with concrete paving blocks, the top layer of which contains 5% of synthetic zeolite admixture obtained by means of low temperature synthesis in laboratory conditions. This zeolite admixture is obtained from aluminium fluoride production waste. The durability of concrete paving blocks was tested according to abrasion resistance, tensile splitting strength, absorption and frost resistance. The test results revealed that 5% of zeolite admixture added to the top layer of concrete paving blocks reduce the absorption, increase the tensile splitting strength by more than 10%, and decrease abrasion by 6.5%. The zeolite admixture used in concrete paving blocks reduces the scaling about 4 times after 28 freeze-thaw cycles when 3% NaCl is used as the freezing solution. The tests revealed that synthetic zeolite admixture can be used in concrete elements production by means of vibropressing (pavement elements) to increase their durability.
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Yao, Ze Liang, Guo Liang Bai, and Fa Ning Dang. "Analysis on a Steel-Concrete Hybrid Structure Temperature Effect and Supporting Block Design." Applied Mechanics and Materials 29-32 (August 2010): 1862–65. http://dx.doi.org/10.4028/www.scientific.net/amm.29-32.1862.
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The steel-concrete hybrid structure is a new special industrial structure in large thermal power plants. It is composed of a spatial steel truss and steel-concrete tubular columns. Its stiffness and mass is highly non-uniform at vertical direction. Its temperature effect is obvious because its steel truss is a high order statically indeterminate structure. Types and characteristics of temperature load prescribed in codes are introduced. Temperature effect of the steel-concrete hybrid structure is calculated by FEM analysis software SAP2000 in four different supporting blocks. The structural internal force and distortion under temperature effect is analyzed. The influence of supporting blocks on the structual temperature effect is analyzed. The structural supporting block form to advantageously release its temperature effect is presented. Some advice is presented based on the analysis results.
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Lee, Mi Hwa, Bae Su Khil, and Hyun Do Yun. "Thermal Analysis of Hydration Heat in Mass Concrete with Different Cement Binder Proportions." Applied Mechanics and Materials 372 (August 2013): 199–202. http://dx.doi.org/10.4028/www.scientific.net/amm.372.199.
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This study is conducted to evaluate analytically the effect of cement binder proportions (ordinary Portland cement, blast-furnace slag and fly ash) on the hydration heat of mass concrete with specific compressive strength of 30 MPa. Two types of blended concretes were mixed; binder of PSLB_352 consists of ordinary Portland cement (OPC) : blast-furnace slag (BFS) : fly ash (FA) = 3 : 5 : 2 and binder of PSLB_442 comprise OPC : BSF : FA = 4 : 4 : 2. For comparison, a control concrete mixture was mixed with commercial low-heat cement. To measure temperature characteristics due to hydration heat of each mixture, large concrete blocks were cast and temperature within concrete blocks was measured until the equilibrium temperature was reached. Finite element model was developed for predicting hydration heat of mass concrete based on thermal characteristics of mass concrete derived from large concrete blocks. The effect of cement binder proportions on the hydration heat of mat foundation was evaluated by developed finite element model.
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B. Abdurrahman, R., Z. A. Mohammed, and Dr A. H. Ahmed. "Effect of High Temperature on Engineering Properties of Light Weight Blocks Concrete." AL-Rafdain Engineering Journal (AREJ) 18, no. 6 (December 28, 2010): 1–9. http://dx.doi.org/10.33899/rengj.2010.35165.
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Konrád, Petr, Peter Gallo, Radoslav Sovják, Šárka Pešková, and Jan Valentin. "Effect of Various Input Parameters on Compressed Earth Block’s Strength." Key Engineering Materials 838 (April 2020): 81–87. http://dx.doi.org/10.4028/www.scientific.net/kem.838.81.
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In the framework of this study, compressed earth blocks (CEB) were produced using waste materials and various parameters. Material parameters included waste soil, recycled concrete, fly ash, cement, admixtures and water contents. Manufacturing parameters were vibration during manufacturing, confinement pressure, curing environment and curing time. Specimens used in this study were cubes and compressive strength testing was used to evaluate different mixtures and manufacturing methods. In terms of compressive strength, compressed earth blocks made of these materials could be used for manufacturing bricks and other structural elements.
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Dong, Shu Hui, De Cheng Feng, Shou Heng Jiang, and Wei Zhong Zhu. "Effect of Freezing Temperature on the Microstructure of Negative Temperature Concrete." Advanced Materials Research 663 (February 2013): 343–48. http://dx.doi.org/10.4028/www.scientific.net/amr.663.343.
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The pore size distribution and the microstructure of negative temperature concrete was studied with different temperature, combining with some testing methods, such as MIP and SEM. Moreover, the change of the compressive strength was also studied with different ages. In addition, the relationship between the microstructure and the macro-mechanical properties on negative temperature concrete was explored further with different freezing temperature. It indicated that the lower the early curing temperature, the looser the original structure of cement paste; the total volume of gel pore whose pore size was less than 20nm was decreasing apparently, and the compressive strength declined. When changing to standard curing, the pore size trended to be thinner, the compressive strength was increasing sharply. The concrete was cured from -5°C to standard curing, the volume of pore that was less than 200nm was equal to that of the concrete with the standard curing in the age of 28d, so was the compressive strength. However, the volume of the macro pore of the concrete curing under -10°C and -15°C was greater than the concrete curing the standard condition, the compressive strength was less.
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Almusawi, Aqil Mousa, Rana Shabbar, and Qusay A. Jabal. "Effect of Elevated Temperature on the Physical and Mechanical Properties of Crushed Clay Bricks Aggregate Concrete." Key Engineering Materials 924 (June 30, 2022): 223–31. http://dx.doi.org/10.4028/p-372w5h.
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In this study concrete block was produced with waste crushed clay bricks (CCB). CCB is used as a conventional coarse aggregate replacement with the range of 0, 25, 50 and 75%. Physical and mechanical properties of concrete blocks were examined at room temperature (25°C) and elevated temperatures of 400, 600 and 800°C. The results indicated that concrete specimens with 50% CCB exhibited the greatest flexural strength characteristics compared to that containing natural aggregates, whereas a slight decline indicated at the density and compressive strength. However, the specimens with 75% CCB have the highest residual strength at an elevated temperature of 800°C. Accordingly, it is suitable for load-bearing wall application when exposed to elevated temperature in confirmation to ASTM-C55. Keywords: Concrete Masonry Units; Crushed Clay Bricks; Elevated Temperature; Coarse Aggregate Replacement.
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Zhu, Zhen Yang, Sheng Qiang, Min Zhi Liu, and Hai Bo Wang. "Cracking Mechanism of RCC Dam Surface and Prevention Method." Advanced Materials Research 295-297 (July 2011): 2092–96. http://dx.doi.org/10.4028/www.scientific.net/amr.295-297.2092.
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Using low placement temperature and proper water pipe cooling water, the cracks are rarely appears in the interior of the dam, but the surface of the dam is prone to cracking. During the construction, the surface of the dam may be wet due to several factors such as creep, maintenance and so on, so the effect of the heat preservation is always been over-estimated. For those concrete blocks constructed in cold season, without proper heat preservation, the cracks are easy to appear soon after construction. For those concrete blocks constructed in hot period, under the influence of air temperature, the temperature of those concrete within about 5.0m of the dam surface are hard to control. So the key point to prevent the dam surface constructed in cold period is to take heat preservation measure suiting the on-the-spot situation. And for those dam blocks constructed in hot period, water cure on the surface of the dam can greatly reduce the risk of dam surface cracking.
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Deelaman, Woranuch, Kantima Chaochanchaikul, and Kitiyot Tungsudjawong. "Effect of Banana Fibers on Mechanical and Physical Properties of Light Weight Concrete Blocks." Applied Mechanics and Materials 879 (March 2018): 151–55. http://dx.doi.org/10.4028/www.scientific.net/amm.879.151.
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This work was to investigate the mechanical and physical properties of light weight block with addition of banana fiber. The formulation series of concrete block were divided into two groups: banana fiber for replacing cement and sand, respectively. Banana fibers were varied from 0.0 to 7.5 %wt. and were evaluated by compressive testing, density and water absorption and changing length at water immersion of 28 days. Optimum formulation of concrete adding banana fiber is ratio of sand: cement: lime: gypsum: aluminum powder: banana fibers: 50: 27.5: 9: 9: 2: 2.5, respectively. The increase of water absorption and changing length were found with increase of fiber content whereas the density decreased. However, the mechanical and physical properties of banana fiber/concrete block were subject to standard according to Thai Industrial Standard 1505-2541. From this study, it indicates that banana fiber can be used as an alternative precursor material for producing the light weight and cost effectiveness block.
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CHANDIO, Ali Dad, Shahid Hussain ABRO, Asif Ahmed SHAIKH, Haseeb AHMED, Baber FAROOQI, Faraz MAHMOOD, Yousra KHAN, and Areeba SOHAIL. "Effect of Concrete Admixtures on Structural Properties and Corrosion Resistance of Steel Reinforcements." Materials Science 27, no. 3 (August 23, 2021): 354–60. http://dx.doi.org/10.5755/j02.ms.26369.
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Concrete structural properties are compromised largely due to corrosion susceptibility of steel reinforcements. This results in weakening and eventual failure of structures. Several strategies have been employed in past to control corrosion and increase mechanical strength of concretes, in particular for structural applications. In this study, fly ash and polypropylene fibers were utilized as the admixtures for preparation of concrete blocks with variable water-cement (w/c) ratios i.e. 0.45, 0.5 and 0.65. Three different grades of cements were selected in this study namely OPC 43, OPC 53 and sulfate resistant one. Also, two different steel alloys were used i.e. ASTM-615 and ASTM-706, since both of them are very common reinforcement materials (rebars). The curing time of 56 consecutive days was employed before testing and characterization. The results suggest remarkable improvement in the mechanical properties of blocks upon the incorporation of admixtures. However, rebars exhibited highest corrosion rate in the presence of OPC 43 cement at w/c ratio of 0.65.
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Li, Chunbao, Xiaotian Li, Shen Li, Di Guan, Chang Xiao, Yanyan Xu, Valentina Y. Soloveva, Hojiboev Dalerjon, Pengju Qin, and Xiaohui Liu. "Effect of Maintenance and Water–Cement Ratio on Foamed Concrete Shrinkage Cracking." Polymers 14, no. 13 (July 1, 2022): 2703. http://dx.doi.org/10.3390/polym14132703.
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This is a study on how to reduce shrinkage and improve crack resistance of foamed concrete. By selecting different curing temperatures and humidity, six different curing conditions were analyzed. The shrinkage deformation and maximum crack width of foamed concrete blocks with water–cement ratios of 0.4 and 0.5, under six curing conditions, were measured by a comparator and optical microscope, and the cracking time was recorded. The effects of curing temperature, humidity and water–cement ratio on the shrinkage and crack resistance of the foamed concrete were analyzed by comparing the experimental results of each group. We studied the primary and secondary order of the three factors affecting the drying shrinkage of foamed concrete. The results show that: temperature is the primary factor that changes the drying shrinkage performance of foamed concrete, followed by the water–cement ratio, and finally humidity. The interaction of these three factors is not obvious. The shrinkage of foamed concrete increases with the increase in temperature; increasing the humidity of curing can control the water loss rate of foamed concrete and reduce shrinkage. Lower humidity and higher temperature will make cracks appear earlier; with an increase in the water–cement ratio, the initial cracking time is shortened and the cracking property of foamed concrete is improved.
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Le, Quang X., Vinh TN Dao, Jose L. Torero, Cristian Maluk, and Luke Bisby. "Effects of temperature and temperature gradient on concrete performance at elevated temperatures." Advances in Structural Engineering 21, no. 8 (December 8, 2017): 1223–33. http://dx.doi.org/10.1177/1369433217746347.
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To assure adequate fire performance of concrete structures, appropriate knowledge of and models for performance of concrete at elevated temperatures are crucial yet currently lacking, prompting further research. This article first highlights the limitations of inconsistent thermal boundary conditions in conventional fire testing and of using constitutive models developed based on empirical data obtained through testing concrete under minimised temperature gradients in modelling of concrete structures with significant temperature gradients. On that basis, this article outlines key features of a new test setup using radiant panels to ensure well-defined and reproducible thermal and mechanical loadings on concrete specimens. The good repeatability, consistency and uniformity of the thermal boundary conditions are demonstrated using measurements of heat flux and in-depth temperature of test specimens. The initial collected data appear to indicate that the compressive strength and failure mode of test specimens are influenced by both temperature and temperature gradient. More research is thus required to further quantify such effect and also to effectively account for it in rational performance-based fire design and analysis of concrete structures. The new test setup reported in this article, which enables reliable thermal/mechanical loadings and deformation capturing of concrete surface at elevated temperatures using digital image correlation, would be highly beneficial for such further research.
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Xin, Jianda, Siqing Lin, Nannan Shi, Jianshu Ouyang, and Dahai Huang. "Effect of Reinforcement on Early-Age Concrete Temperature Stress: Preliminary Experimental Investigation and Analytical Simulation." Advances in Materials Science and Engineering 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/231973.
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For concrete under short-term loading, effect of reinforcement on concrete crack resistance capability is usually negligible; however, recent research results show that extension of this viewpoint to concrete under long-term loading (temperature variation) may be unsuitable. In order to investigate this phenomenon, this paper presents the experimental and analytical results of early-age reinforced concrete temperature stress development under uniaxial restraint. The experiments were carried out on a temperature stress testing machine (TSTM). Experimental results show that the coupling of reinforcement and concrete creep behavior influenced the concrete temperature stress development, and nearly 16% of concrete stress was reduced in the current research. Moreover, the cracking time of reinforced concrete was also delayed. Finally, based on the principle of superposition, analytical simulations of effect of reinforcement on concrete temperature stress have been performed.
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Pukhkal, Viktor, and Vera Murgul. "Effect of aerated concrete blockwork joints on the heat transfer performance uniformity." E3S Web of Conferences 33 (2018): 02002. http://dx.doi.org/10.1051/e3sconf/20183302002.
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Analysis of data on the effect of joints of the aerated concrete blocks on the heat transfer uniformity of exterior walls was carried out. It was concluded, that the values of the heat transfer performance uniformity factor in the literature sources were obtained for the regular fragment of a wall construction by approximate addition of thermal conductivities. Heat flow patterns for the aerated concrete exterior walls amid different values of the thermal conductivity factors and design ambient air temperature of -26 °C were calculated with the use of “ELCUT” software for modelling of thermal patterns by finite element method. There were defined the values for the heat transfer performance uniformity factor, reduced total thermal resistance and heat-flux density for the exterior walls. The calculated values of the heat transfer performance uniformity factors, as a function of the coefficient of thermal conductivity of aerated concrete blocks, differ from the known data by a more rigorous thermal and physical substantiation.
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Araujo, Antonio S., Ana C. F. Coriolano, Rafaely A. F. Bandeira, and Regina C. O. B. Delgado. "Preparation and Compressive Strength Evaluation of Concrete Containing Oil Sludge as Additive." Materials Science Forum 930 (September 2018): 148–52. http://dx.doi.org/10.4028/www.scientific.net/msf.930.148.
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Concretes were prepared containing oil sludge additive to produce new materials for construction. The oil sludge and concrete have previously been characterized in terms of chemical composition of the elements present in the materials. The concrete blocks were produced with a defined amount of oily sludge of 3.0 mass% on cement/water factor. All samples were cured at room temperature and then heated at 200 °C for 3 hours and 292 °C for 2h. The surfaces of the samples were subjected to previously grinding for the compressive strength testing. These tests were conducted in a press of 2000 kN load capacity. It was found that concrete containing additive showed a positive response in all the compressive strength tests, compared to concrete without the additive
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Terzic, Anja, and Ljubica Pavlovic. "Determination of the apparent porosity level of refractory concrete during a sintering process using an ultrasonic pulse velocity technique and image analysis." Chemical Industry and Chemical Engineering Quarterly 16, no. 1 (2010): 79–87. http://dx.doi.org/10.2298/ciceq090910012t.
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Concrete which undergoes a thermal treatment before (pre-casted concrete blocks) and during (concrete embedded in-situ) its life-service can be applied in plants operating at high temperature and as thermal insulation. Sintering is a process which occurs within a concrete structure in such conditions. Progression of sintering process can be monitored by the change of the porosity parameters determined with a nondestructive test method - ultrasonic pulse velocity and computer program for image analysis. The experiment has been performed on the samples of corundum and bauxite concrete composites. The apparent porosity of the samples thermally treated at 110, 800, 1000, 1300 and 1500 ?C was primary investigated with a standard laboratory procedure. Sintering parameters were calculated from the creep testing. The loss of strength and material degradation occurred in concrete when it was subjected to the increased temperature and a compressive load. Mechanical properties indicate and monitor changes within microstructure. The level of surface deterioration after the thermal treatment was determined using Image Pro Plus program. Mechanical strength was estimated using ultrasonic pulse velocity testing. Nondestructive ultrasonic measurement was used as a qualitative description of the porosity change in specimens which is the result of the sintering process. The ultrasonic pulse velocity technique and image analysis proved to be reliable methods for monitoring of micro-structural change during the thermal treatment and service life of refractory concrete.
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Rashid, Muhammad Harunur, Md Maruf Molla, and Imam Muhammad Taki. "Effect of Elevated Temperature on Bond Strength of Concrete." Materials Science Forum 972 (October 2019): 26–33. http://dx.doi.org/10.4028/www.scientific.net/msf.972.26.
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In the case of exposure of reinforced concrete structure to accidental fire, an assessment of its residual capacity is needed. Bond strength of concrete was observed under elevated temperatures (150°, 250°, 350° and 500°C) in this study. Cylindrical specimens were prepared for pull-out tests to find out the bond behavior and to observe the mechanical properties of concrete. All the specimens were 100 mm diameter and 200 mm height. The pull-out specimens contain a 10 mm steel bar at its center. The specimens were tested at 52 days age following a 28 days water curing. Samples were preheated for 3 hours at 100°C temperature and then put into the furnace for 1 hour at the target temperature. Samples were tested before preheating as controlled specimens. In case of mechanical properties and the bond strength of concrete, there were no remarkable changes due to elevated temperature up to 150°C. However, the mechanical properties and bond strength were decreased gradually after 150°C temperature. Maximum reduction of bond strength observed was 52.13% and 49.8% at 500°C for testing within 1 hour and after 24 hours of heating respectively when compared to the controlled specimens. Bond strength was found to reduce at a greater rate than compressive strength due to the elevated temperature.
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Dan, Jian, Cong Yu, and Chang Wu Xu. "Experimental Analysis of the Sectional Temperature Distribution of CFST under Variable Temperature Effect." Advanced Materials Research 971-973 (June 2014): 249–54. http://dx.doi.org/10.4028/www.scientific.net/amr.971-973.249.
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The concrete filled steel tubular (CFST) structure takes full advantages of the interaction of two materials in the process of loading, while the thermal performance parameters between steel tube and concrete are different, and the outside temperature changes makes the structural section produce a greater temperature gradient, which leads to the uncoordinated deformation between them. In this paper, the thermal conductivity of experimental system is carried on the theoretical analysis, then the distribution regularities of sectional temperature are obtained through the testing its of CFST under variable temperature effect, and the larger temperature difference will produce the temperature stress, which affects the bonding performance of structural interface. So in order to better analyze the influence which is impacted on the mechanical performances of structure by the combination effect of multiple factors such as temperature and load, such paper can provide the theoretical and experimental foundation.
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Lee, Jong Won, Sang Hyuk Lee, Young Il Jang, and Hee Mun Park. "Evaluation of Reducing NO and SO2 Concentration in Nano SiO2-TiO2 Photocatalytic Concrete Blocks." Materials 14, no. 23 (November 25, 2021): 7182. http://dx.doi.org/10.3390/ma14237182.
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The use of titanium dioxide in concrete block pavements is a promising approach to reduce air pollution in the roadside. When TiO2 is used as an additive of cement concrete or mortar, it is not dispersed uniformly due to agglomeration between particles causing the degradation of photocatalytic reaction. To improve the photocatalytic performance of TiO2, the Nano SiO2-TiO2 (NST) has been developed by coating TiO2 with SiO2 as a support using the sol-gel method. The environmental performance of concrete blocks incorporating NST as an additive was evaluated using both laboratory and full-scale chamber experiments. It was observed from laboratory environment chamber testing that the NO reduction efficiency of concrete blocks with 4% NST ranged from 16.5 to 59.1%, depending on the UV intensity. Results of the full-scale chamber test on NST concrete blocks indicated that the NO and SO2 reduction efficiencies were 22.3% and 14.4% at a 564 W/m2 of solar radiation, respectively. It was found that the increase in UV intensity and solar radiation had a positive effect on decreasing NO and SO2 concentration. In the future, the NST will be applied at in-service photocatalytic block pavements to validate the environmental performance in field conditions.
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Powęzka, Aleksandra, Jacek Szulej, and Paweł Ogrodnik. "Effect of High Temperatures on the Impact Strength of Concrete Based on Recycled Aggregate Made of Heat-Resistant Cullet." Materials 13, no. 2 (January 18, 2020): 465. http://dx.doi.org/10.3390/ma13020465.
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The article presents results obtained during testing of concrete based on CEM I 42.5R Portland cement, fine and coarse aggregate, glass, volatile ash, and superplastifier. The concrete mixture was modified using filler consisting of bromosilicate heat resistant cullet. Recycled aggregate was added to the batch. Samples for the need of testing were produced as (100 × 100 × 100) mm cubes. Before commencing proper tests, samples have been heated within the temperature range of 20–800 °C. Tests carried out during the proper testing procedure included tests of compressive strength, elevated temperature, impact strength, as well as macroscopic tests of the contact area. The obtained test results have provided proof of there being a possibility of producing special concrete, modified by products obtained from heat resistant cullet. This type of is generally characterized by satisfactory performance parameters. The average compressive strength for concrete modified by a 10% of heat resistant cullet was determined as 43.6 MPa and 48.3 MPa respectively after 28 and 180 days of curing.
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Suleymanov, K., I. Pogorelova, and I. Ryabchevskiy. "INCREASING THE THERMAL UNIFORMITY OF WALLS MADE OF CELLULAR CONCRETE BLOCKS." Bulletin of Belgorod State Technological University named after. V. G. Shukhov 7, no. 5 (May 11, 2022): 17–24. http://dx.doi.org/10.34031/2071-7318-2022-7-5-17-24.
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The development of effective protecting structures is currently one of the most popular areas in the construction industry. Masonry made of aerated concrete blocks is used in conditions of ensuring energy efficiency and environmental safety in the construction of civil buildings as enclosing structures. It has high thermal protection properties. The issue of filling through seams of aerated concrete masonry is acute, since adhesive and cement-sand mortars in masonry have low thermal conductivity and are temperature bridges. The authors have developed a two-row energy-efficient wall masonry made of aerated concrete blocks using polyurethane glue as a filler for through and dressing joints. The article discusses the effect of horizontal through joints made of cement-sand mortar and blocking of blocks on the resistance to heat transfer of masonry from aerated concrete blocks. In addition, it presents a study of the reduced resistance to heat transfer of the enclosing structure, taking into account heat-conducting inclusions, presented in the form of a traditional two-row aerated concrete masonry through a row, made on a thin-layer adhesive solution, as well as the masonry developed by the authors. It is concluded that the energy efficiency of the developed wall fencing is ensured due to the increased thermal homogeneity of the masonry.
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Zhang, Nan, Juan Liao, Tao Zhang, Wen Zhan Ji, Bao Hua Wang, and 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 (July 2014): 1509–13. http://dx.doi.org/10.4028/www.scientific.net/amm.584-586.1509.
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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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Won, Moon. "Improvements of Testing Procedures for Concrete Coefficient of Thermal Expansion." Transportation Research Record: Journal of the Transportation Research Board 1919, no. 1 (January 2005): 23–28. http://dx.doi.org/10.1177/0361198105191900103.
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The coefficient of thermal expansion (CTE) of concrete has a significant effect on the performance of portland cement concrete pavement. Concrete with a higher CTE is more prone to cracking, additional warping, and spalling. To improve PCC pavement performance, several districts of the Texas Department of Transportation (TxDOT) currently limit the CTE of concrete. To support this policy, efforts have been made to improve the accuracy and repeatability of the testing procedures for CTE. The current AASHTO Test Method TP 60 has been evaluated, its shortcomings identified, and improvements made. The improvements include CTE determination from regression analysis of temperature and displacement measurements. The effects of a number of variables on concrete CTE were investigated. The effect of the rate of heating and cooling is negligible. Concrete age and specimen size also have a negligible effect. Coarse aggregate content in the concrete mix has an effect on the test results. This test procedure was used to evaluate coarse aggregates from 32 sources in Texas. The results show that coarse aggregate type has a significant effect on concrete CTE. The proposed testing procedure for concrete CTE provided more accurate results than the AASHTO TP 60. TxDOT plans to implement this test procedure and to develop appropriate steel design standards for continuously reinforced concrete pavement and other construction-related requirements such as different curing methods for concrete with varying CTEs. This implementation should result in better concrete pavement performance.
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Yeom, Yun-Taek, Yeong-Won Choi, Hak-Joon Kim, Hun-Hee Kim, Jae-Suk Park, Sung-Woo Ryu, and Sung-Jin Song. "Containment Liner Plate Void Defect Detection Technique Using Phased Array Ultrasonic Testing and Acoustic Resonance Method." Materials 15, no. 4 (February 11, 2022): 1330. http://dx.doi.org/10.3390/ma15041330.
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The CLP (containment liner plate) of a nuclear power plant protects the internal system from the external environment and sudden changes in internal pressure or temperature, and it is a structure that blocks and protects radioactive materials leaking inside and outside in the event of a nuclear accident and is composed of a liner plate, reinforcing bars, tendons, and concrete. Recently, corrosion on the rear side of the liner plate and concrete voids has emerged as a severe defect in nuclear power plants across South Korea. Therefore, in this study, we proposed a new inspection method that a line-type inspection method applied phased array ultrasonic testing and the area inspection method applied acoustic resonance method using developed moveable tapper. The acoustic signals were signal-processed and reproduced to a mapping image following the inspection area, and with the image, it was possible to determine the type of defect. Furthermore, an automated inspection system for within the CLP was proposed.
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Razak, Siti Nooriza Abd, Nasir Shafiq, Laurent Guillaumat, Mohamed Mubarak Abdul Wahab, Syed Ahmad Farhan, Nadzhratul Husna, and Fouad Ismail Ismail. "Fire Performance of Fly Ash-Based Geopolymer Concrete: Effect of Burning Temperature." IOP Conference Series: Earth and Environmental Science 945, no. 1 (December 1, 2021): 012062. http://dx.doi.org/10.1088/1755-1315/945/1/012062.
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Abstract Geopolymer concrete (GEO) is a cementless concrete produced from the reaction of an aluminosilica-rich material, in particular, fly ash, with an alkaline solution, which can either be sodium or potassium-based. In light of the potential of fly ash-based GPC as an alternative to Ordinary Portland Cement (OPC)-based concrete as a green building material, an investigation on the fire performance of GEO, in comparison to OPC-based concrete, is essential. The results of an experimental study on the fire performance of fly ash-based GEO that was subjected to a flame test using a methane burner torch, after 28 days of curing, to simulate a real fire event, are presented. Concrete specimens were exposed to a fire flame at 500 °C and 1200 °C for two hours and subsequently cooled to the ambient temperature, prior to testing. Visual inspection was performed on the specimens to observe for any cracking, spalling and change in colour. Losses of mass and residual compressive strength were measured. The results were compared with those of OPC-based reference specimens. The findings revealed that, in contrast to OPC-based concrete, the strength of GPC increased when exposed to fire at 500 °C. GEO also suffered a smaller loss of mass as compared to OPC-based concrete due to the smaller amount of loss in moisture from burning. It was also observed that no spalling had occurred on the GEO, with less cracking on the exposed surface in relation to OPC-based concrete, hence indicating that the structural integrity of GEO was successfully maintained.
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Zhang, Yajun, Yao Wang, and Zhaoqing Ren. "Experimental Study on the Properties of Mixed-Fiber Concrete Shield Tunnel Segments Subjected to High Temperatures." Fire 6, no. 1 (January 6, 2023): 17. http://dx.doi.org/10.3390/fire6010017.
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In order to study the mechanical and damage behavior of concrete shield tunnel segments under a high temperature, two self-compacting concrete and three mixed-fiber (steel and polypropylene fiber) self-compacting concrete test blocks were designed. The influence of several key factors, including fire duration, pre-loading, and concrete type, on the fire behavior of concrete shield tunnel segments were studied. The results show that the type of fiber and pre-loading have an important influence on crack development in concrete shield tunnel segments. Compared with undoped segments, cracks in segments with steel fibers and polypropylene fibers appeared later, and the average crack spacing decreased. The pre-loading has an important effect on the vertical deformation before and after the temperature rise. As the load level increases, so does the deformation after the temperature rise. The influence of the initial load level should be considered when designing the fire resistance of the segment.
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Xin, Jian Da, Yi Liu, Guo Xin Zhang, Zhen Hong Wang, Ning Yang, and Yu Qiao. "Thermal Stress of Early-Age Concrete Made with Different Cement Compositions." Key Engineering Materials 923 (June 28, 2022): 157–61. http://dx.doi.org/10.4028/p-849817.
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A temperature stress testing machine (TSTM) was used to investigate effect of cement composition and temperature history on thermal stress of concrete. Results show that the benefit of higher amount of C3S on concrete strength enhancement was compromised by the relatively higher temperature rise at early age, leading to a lower temperature difference. However, by means of a delicate design of cooling history, the deficiency of concrete with higher amount of C3S can be compensated and the cracking sensitivity was closer to that of concrete with lower amount of C3S.
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Kumar, Virendra. "Effect of temperature on stress–strain behaviour of pre-damaged confined concrete." Journal of Structural Fire Engineering 11, no. 1 (July 22, 2019): 67–99. http://dx.doi.org/10.1108/jsfe-03-2019-0019.
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Purpose This paper aims to study the residual test results under uni-axial compression of tie confined pre-damaged normal strength concrete short columns subjected to elevated temperatures. Design/methodology/approach The test variables included temperature of exposure, spacing of transverse confining reinforcement and pre-damage level. An experimental program was designed and carried out involving testing of hoop confined concrete cylindrical specimens exposed to elevated temperatures ranging from room temperature to 900 °C. Findings The test results indicate that the residual strength, strain corresponding to the peak stress and the post-peak strains of confined concrete are not affected significantly up to an exposure temperature of 300 °C. However, the peak confined stress falls and the corresponding strain increase considerably in the temperature range of 600 to 900 °C. It is shown that an increase in the degree of confinement reinforcement results in an increased residual strength and deformability of pre-damaged confined concrete. Research limitations/implications It is applicable in finding the residual strength and strain of the pre-damaged confined concrete in uni-axial compression after exposure to elevated temperature. Practical implications The practical implications is that the test result is applicable in finding the residual strengths of pre-damaged confined concrete under uni-axial compression after exposure to elevated temperature. Social implications The main aim of the present investigation is to provide experimental data on the residual behaviour of pre-damaged confined concrete subjected to high temperatures. Originality/value The results of this study may be useful for developing the guidelines for designing the confinement reinforcement of reinforced concrete columns against the combined actions of earthquake and fire, as well as for designing the retrofitting schemes after these sequential disasters.
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Babu, J. Chinna, M. Sandeep Kumar, Prabhu Jayagopal, V. E. Sathishkumar, Sukumar Rajendran, Sanjeev Kumar, Alagar Karthick, and Akter Meem Mahseena. "IoT-Based Intelligent System for Internal Crack Detection in Building Blocks." Journal of Nanomaterials 2022 (June 13, 2022): 1–8. http://dx.doi.org/10.1155/2022/3947760.
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Cracks that are detected in concrete structures represent significant damage, and they can lead to a detrimental effect on the structure’s durability. Their identification in a timely manner can help ensure structural safety and guide in-depth maintenance operation. Automatic detection of such cracks has been proposed using internal crack detection utilizing ultrasonic sensors in concrete. Cracks within the concrete can be detected using ultrasonic sensors. In this investigation, we introduced an intelligent method that is aimed at developing a crack detection scheme using ultrasonic sensors. These ultrasonic sensors are used for the detection of cracks in buildings which cannot be seen with our naked eyes; they are capable of alerting authorities via SMS message and providing the cracks’ location via GSM and GPS modules. To monitor internal cracks in the concrete cubes and cylinders, the ultrasonic sensors can be fixed at the centre of the cube which will be used for interval crack monitoring based on crack detection technology. The grade of concrete used for testing is M25, and it is well mixed with the ingredients of cement, fine aggregate, coarse aggregate, and water. The concrete is placed in the cube moulds having the dimensions 150 mm × 150 mm × 150 mm . The cylinders used in the case of the experimental analysis are of the dimensions of 150 mm diameter and 300 mm height. These specimens are cast and kept in the curing tank for 28 days to attain the maximum strength. After completion of the curing period, the specimens were taken out from the tank and weighed. After this weighing process, the cubes and cylinders are about 8.884 kg and 13.399 kg, respectively. The information about the cracks can be displayed on the LCD, and also, the transmitted short message about the cracks can be exchanged between the devices using IoT.
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Kadium, Nazar Sajad, and Saad Isaa Sarsam. "Evaluating Asphalt Concrete Properties by the Implementation of Ultrasonic Pulse Velocity." Journal of Engineering 26, no. 6 (June 1, 2020): 140–51. http://dx.doi.org/10.31026/j.eng.2020.06.12.
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In past years, structural pavement solution has been combined with destructive testing; these destructive methods are being replaced by non-destructive testing methods (NDT). Because the destructive test causes damage due to coring conducted for testing and also the difficulty of adequately repairing the core position in the field. Ultrasonic pulse velocity was used to evaluate the strength and volumetric properties of asphalt concrete, of binder course. The impact of moisture damage and testing temperature on pulse velocity has also been studied. Data were analyzed and modeled. It was found that using non-destructive testing represented by pulse velocity could be useful to predict the quality of asphalt concrete, the good correlation between the pulse velocity and the volumetric and strength properties. The potential benefit of using the wave parameters is for condition assessment of asphalt concrete. The moisture damage exhibits a negative influence on pulse velocity by 13%, while the testing temperature shows an effect on the pulse velocity.
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Utepov, Yelbek, Aleksej Aniskin, Assel Tulebekova, Aliya Aldungarova, Shyngys Zharassov, and Assel Sarsembayeva. "Complex Maturity Method for Estimating the Concrete Strength Based on Curing Temperature, Ambient Temperature and Relative Humidity." Applied Sciences 11, no. 16 (August 21, 2021): 7712. http://dx.doi.org/10.3390/app11167712.
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The maturity method is deservedly considered one of the reliable indirect methods for determining the strength at the early stages of concrete curing. The main parameter in the calculation is the internal temperature of concrete that accumulates during the chemical reaction of concrete curing, while external factors such as ambient temperature and relative humidity are fallaciously omitted. In this work, the complex maturity method was developed based on ASTM C1074, accounting for the influence of ambient temperature and relative humidity and coefficients indicating their influence weight. The laboratory testing to measure the concrete strength by compression method and non-destructive sclerometer method were performed on concrete samples according to ASTM C109, GOST 22690, and GOST 10180. According to the calibration dependence of the existing and proposed methods results in comparison with the strength of cubic samples, the highest coefficient of determination R2 = 0.976 was revealed for the complex method of maturity, which indicates its reliability in contrast with sclerometer and traditional maturity methods. The determination of complex maturity allows for an evaluation of the current state of concrete strength, but also reduces the waiting time for concrete curing and increases the economic effect during construction.
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Shoukry, S. N., G. W. William, M. Y. Riad, and J. C. Prucz. "Effect of FWD Testing Position on Modulus of Subgrade Reaction." Applied Mechanics and Materials 518 (February 2014): 53–59. http://dx.doi.org/10.4028/www.scientific.net/amm.518.53.
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This paper discusses the variation of the Modulus of subgrade reaction (k) backcalculated from slab deflection basins, interactive with the location of the Falling Weight Deflectometer (FWD) load pulse, and curling of slabs due to daily temperature variations. The k-value was calculated following the AASHTO design guides procedures, while deflection basins were recorded at an interval of 3 to 4 hours along the day on an instrumented concrete pavement test section in West Virginia. The state of deformation of the slabs are continuously monitored, through dowel bar bending measurements and records of the temperature gradient profiles through the slab thickness, as well as joint openings every 20 minutes. The results indicated that the backcalculated k-values are greatly affected by the positive temperature gradient, and the least variation in (k) was found in the slab center. In order to minimize errors in back-calculations of k-values, it is recommended to perform the FWD test for recording deflection basins in the interior of the slab during late evening or in the early morning.
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Luan, Li Qiang, and Xiao Ge Tian. "Fatigue Life Analysis of Asphalt Mixture Coupling with Loading Intermittent Time." Applied Mechanics and Materials 204-208 (October 2012): 3852–58. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.3852.
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Repeated loading will produce cumulative damage to asphalt concrete, because of the visco-elastic property of asphalt concrete, a certain degree of self-healing may occurred in case the loads being taken away.( the healing effect is more obvious under higher temperature or pressure),this process can be indicated through adding the intermittent time factor to fatigue test of asphalt concrete .This study adds intermittent time factor to asphalt concrete fatigue testing through universal testing machine,, deeply analyzing the effect of intermittent time, confirming that 0.5 second intermittent time is a key time point to fatigue process ,fatigue rate under 15 °C is slower than that under 20 °C,and introducing the effect factor to the fatigue equation.
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Wang, Dang Zai, Jian Da Xin, and Zhen Hong Wang. "Creep Behavior of Early-Age Concrete Made with Different Cement Compositions under the Controlled Temperature History." Key Engineering Materials 923 (June 28, 2022): 163–68. http://dx.doi.org/10.4028/p-03013y.
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A temperature stress testing machine (TSTM) was used to investigate effect of cement composition on cracking sensitivity and creep behavior of concrete. Results show that the cracking sensitivity of concrete varied with the ratio of C3S/C2S and it is observed that the temperature difference of concrete linearly increased with smaller ratio of C3S/C2S. Furthermore, it is also found that concrete with higher ratio of C3S/C2S had weaker creep behavior based on the specific creep deduced from results of TSTM.
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Yang, Hailu, Kai Yang, Yinghao Miao, Linbing Wang, and Chen Ye. "Comparison of Potential Contribution of Typical Pavement Materials to Heat Island Effect." Sustainability 12, no. 11 (June 10, 2020): 4752. http://dx.doi.org/10.3390/su12114752.
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Pavement materials have significant influence on the urban heat island effect (UHIE). This paper presents a study on the potential effects of pavement materials on UHIE in a natural environment. Three typical pavement materials, including cement concrete, dense asphalt concrete and porous asphalt mixture, were selected to evaluate their anti-UHIE properties by testing. In this paper, heat island potential (HIP) is proposed as a new index to analyze the influence of pavement materials on UHIE. It is shown that the temperature inside a pavement distinctly depends on the depth, and varies, but is usually higher than the air temperature. Solar radiation in the daytime significantly contributes to the temperature of pavement surface and the upper part. The correlation becomes weak at the middle and the bottom of pavements. Among the three materials tested in this study, the anti-UHIE performance of cement concrete is significantly higher than that of the other asphalt mixtures, while the porous asphalt mixture is slightly better than the dense asphalt concrete in anti-UHIE.
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Chen, Xiaoming, Guohui Zhang, Wei Zhou, Hongchuan Liu, and Shiqiang Yang. "Experimental Research on Dehydration Process and Strength of Concrete Influenced by Drying Temperature and Concrete Size." Advances in Materials Science and Engineering 2022 (May 18, 2022): 1–8. http://dx.doi.org/10.1155/2022/5680910.
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Moisture has a significant effect on the properties of concrete, and drying concrete in an oven is a common method to obtain specimens with different moisture content. In this paper, C30 concrete specimens with different sizes were oven-dried at constant temperatures of 60, 80, 105, 120, and 150 °C, respectively. The change of specimen mass, ultrasonic testing, and compressive and splitting tensile strength were tested before and after drying. The size effect and the size effect law (SEL) of concrete were analysed. The results indicated that the maximum drying rate and water loss ratio of the specimens with different sizes under the same drying temperature are basically the same. The larger the size, the longer the drying time. After drying, the concrete compressive and splitting tensile strength have increased to varying degrees, and the smaller the size, the greater the increase. For C30 concrete with different sizes, the drying temperature that has the minimal influence is 105 °C. The SEL was modified by introducing drying temperature, and the formulas were obtained after drying.
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Alwetaishi, Mamdooh, Mostafa Kamel, and Nidal Al-Bustami. "Sustainable applications of asphalt mixes with reclaimed asphalt pavement (RAP) materials: innovative and new building brick." International Journal of Low-Carbon Technologies 14, no. 3 (June 4, 2019): 364–74. http://dx.doi.org/10.1093/ijlct/ctz023.
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Abstract This paper presents an experimental study to evaluate the effect of various percentages of RAP on the properties of asphalt mixtures. Moreover, the thermal characteristics of using asphalt mixes with RAP in asphalt concrete blocks for sustainable application in building construction was also studied. For this issue, four mixtures, which were the combination of different ratios of RAP materials viz, 0%, 30%, 60%, 90% and virgin aggregates, were studied in this research. A comprehensive experimental program was conducted to find out the highest ratio of RAP in asphalt mixes that retains an acceptable level of physical and mechanical properties. This revealed that 90% RAP has such an acceptable level. Finally, the thermal characteristics of asphalt concrete blocks for walls in building construction were analytically investigated using TAS EDSL. This software was initially validated by building a real model of walls with asphalt concrete blocks where temperature and humidity measurements were taken through data loggers for both the indoor and outdoor spaces. A comparative study was conducted to find out the energy efficient behaviour of this material in four different climate conditions. It was concluded that the asphalt concrete mixes with 90% RAP are beneficial materials for use as a thermal mass in building construction and it is suitable only for cold weathers.
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Rezende, Maria Luiza de Souza, José Wallace Barbosa do Nascimento, Gelmires de Araujo Neves, and Heber Carlos Ferreira. "The effect of metakaolin on the durability of concrete hollow blocks used in masonry: evaluation of degradation caused by driving rain." Rem: Revista Escola de Minas 68, no. 1 (March 2015): 21–27. http://dx.doi.org/10.1590/0370-44672015680076.
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Driving rain, considered one of the major factors in the degradation of external seals, may cause esthetic problems and material decomposition to facades and masonry. In the present research, the production of concrete hollow blocks for masonry underwent testing for which 20 years of exposure have been considered, taking into account the annual precipitation in the State of Paraíba. This was assessed by replacing 10, 15 and 20% of cement for metakaolin using as parameter the specimen’s mass loss at end of the test. It has was found that the concrete with metakaolin revealed values of weight loss greater than those of the reference concrete, without metakaolin, and that these values increased as the level of substitution increased. However, for mixtures with lower cement content, the use of 10% by metakaolin promoted results that have been considered similar to the reference. The test results are, therefore, consistent with those reported in literature for assessment studies on actual exposure situations; however, further studies will be developed to correlate the laboratory results obtained and from the resulting exposure to natural weather conditions.
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Bech, Nathan D., and Julie M. Vandenbossche. "Relationship between Backcalculated and Estimated Asphalt Concrete Dynamic Modulus with Respect to Falling Weight Deflectometer Load and Temperature." Transportation Research Record: Journal of the Transportation Research Board 2674, no. 9 (July 7, 2020): 887–97. http://dx.doi.org/10.1177/0361198120932560.
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There are several methods for determining the stiffness of asphalt concrete in an existing pavement. The three primary methods are: dynamic modulus testing in the laboratory, predictive equations, and falling weight deflectometer (FWD) testing. Asphalt over asphalt (AC/AC) overlay design procedures allow the use of multiple methods to characterize fatigue damage in the existing asphalt concrete. Therefore, understanding the difference between these methods is critical for AC/AC overlay design. The differences between the methods for determining asphalt concrete stiffness and how these differences are related to FWD load magnitude and asphalt temperature are examined. Data from the Federal Highway Administration’s Long-Term Pavement Performance Program (LTPP) are used in this investigation. It is found that the stiffness determined through FWD testing and backcalculation is generally less than that estimated using the Witczak predictive equation and binder aging models. Furthermore, it is found that both FWD load magnitude and asphalt temperature have a significant effect on the difference between backcalculated and estimated stiffness of asphalt concrete. Backcalculated stiffness increases relative to estimated stiffness as FWD load and temperature increase. These effects must be considered when multiple methods of determining asphalt concrete stiffness are used interchangeably for overlay design.
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Zhang, Zu Peng, Shui Wen Zhu, and Guo Ping Chen. "Study on Thermal Performance for Straw Fiber Concrete Hollow Block." Advanced Materials Research 953-954 (June 2014): 1596–99. http://dx.doi.org/10.4028/www.scientific.net/amr.953-954.1596.
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In this paper, based on ansys studies for thermal performance of concrete hollow block which were conducted on the content of 5% and 15% of the straw plant fiber, and get temperature distribution and the law of heat of the blocks which suffer the load of convection, then calculate the mean coefficient of thermal conductivity and thermal resistance based on the data block obtained. The results show that mixed plant fiber can effectively improve thermal performance for the concrete hollow block,and better insulation effect,thus can provide the basis for the promotion of plant fiber building block materials.
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Xu, Lina, Daohan Song, Ning Liu, and Wei Tian. "Study on Mechanical Properties of Basalt Fiber-Reinforced Concrete with High Content of Stone Powder at High Temperatures." Advances in Materials Science and Engineering 2021 (December 17, 2021): 1–15. http://dx.doi.org/10.1155/2021/7517049.
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Concrete materials are an important part of global structure, and their fire resistance directly affects the safety of buildings and tunnels. In this study, basalt fiber was used to reinforce concrete with high content of stone powder in order to enhance its high-temperature performance. The mechanical properties and ultrasonic characteristics at different temperatures were studied using the cube compressive strength test and nonlinear ultrasonic test. The results indicated that the addition of basalt fiber in specimens improved their compressive strength; however, this strength did not continuously increase with increases in the fiber length and fiber content, and the optimal values for fiber length and fiber content were determined to be 12 mm and 1 kg/m3 at 600°C, respectively. With increases in temperature, the unconfined compressive strength increased first and then decreased. When the temperature was 400°C, the unconfined compressive strength of the specimens reached their highest values and then decreased. When the temperature was 400°C and 600°C, the strength of the stone powder concrete with fiber was higher than that without fiber, which shows that fiber can improve the mechanical properties of concrete at high temperatures. Based on the Box-Behnken design (BBD) method, the unconfined compressive strength response regression model of basalt fiber-reinforced concrete with high content of stone powder, which follows parameters including fiber content, fiber length, and temperature at high-temperature environments, was established, and it was found that the interaction of fiber content, fiber length, and the temperature was significant based on multifactor interaction analysis. The analysis of ultrasonic signals based on the S transform showed that, with increases in temperature, the amplitudes of the acoustic response signals, the corresponding frequency spectrum, and the time-frequency spectrum were clearly reduced. At the same temperature, the amplitudes of the acoustic response signals of different concrete testing blocks did not change much and remained at the same level.
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Li, Na, Dong Sheng Zhang, Wei Wei Han, and Ai Qin Shen. "Experimental Study on Effect of Recycled Asphalt Mixture Particles on Properties of Concrete." Advanced Materials Research 857 (December 2013): 75–80. http://dx.doi.org/10.4028/www.scientific.net/amr.857.75.
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To study the effect of different dosage of recycled asphalt mixture particles on the performance of concrete, the mechanical characteristics, shrinkage performance and durability testing were performed, the results show that the compressive strength and flexural strength of concrete are decreased with the increase of dosage recycled asphalt mixture particles, while still meet the regulatory requirements; the capability of plastic shrinkage resistance can be improved by incorporated recycled asphalt mixture fine particles, yet slight effective on the temperature shrinkage; the durability of concrete changes as a result of incorporation of recycled asphalt mixture fine particles, the durability of concrete with a dosage of 20% is considered in the optimal state, so the recommended dosage is 20%.
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Zeng, Haoyu, Chao Lu, Li Zhang, Tianran Yang, Ming Jin, Yuefeng Ma, and Jiaping Liu. "Prediction of Temperature Distribution in Concrete under Variable Environmental Factors through a Three-Dimensional Heat Transfer Model." Materials 15, no. 4 (February 17, 2022): 1510. http://dx.doi.org/10.3390/ma15041510.
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Temperature distribution in concrete is significant to the concrete structure’s macro properties and different factors affect the heat transfer in concrete, and therefore influence the temperature distribution. This work established a three-dimensional transient heat transfer model coupled with various environmental factors, using the finite element method for calculating the results and real-measured data for testing accuracy. In addition, a sensitivity evaluation of various factors was conducted. Due to various environmental factors, the results revealed that the prediction of temperature distribution in concrete by the three-dimensional model had great accuracy with an error of less than 4%. A particular hysteresis effect of temperature response in the concrete existed. Considering heat transfer in different spatial directions, the model can predict the temperature change of each spatial point instead of the spatial surface in different depths, proving the shortcomings of a one-dimensional heat transfer model. A greater solar radiation intensity caused a more significant temperature difference on the concrete surface: the surface temperature difference in July was twice as significant as that in December. Wind speed had a cooling effect on the concrete surface, and stronger wind speed accompanied with a stronger cooling effect made the surface temperature closer to the ambient temperature. Material properties had different effects on the temperature distribution of the surface part and internal part: the specific heat capacity determined the speed of the outer layer temperature change while the thermal conductivity determined the speed of the inner layer temperature change.
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Rojas-Duque, Oriana, Lina Marcela Espinosa, Rafael A. Robayo-Salazar, and Ruby Mejía de Gutiérrez. "Alkali-Activated Hybrid Concrete Based on Fly Ash and Its Application in the Production of High-Class Structural Blocks." Crystals 10, no. 10 (October 17, 2020): 946. http://dx.doi.org/10.3390/cryst10100946.
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This article reports the production and characterization of a hybrid concrete based on the alkaline activation of a fly ash (FA) of Colombian origin, which was added with 10% Portland cement (OPC) in order to promote the compressive strength development at room temperature. The alkali-activated hybrid cement FA/OPC 90/10 was classified as a low heat reaction cement (type LH), according to American Society of Testing Materials, ASTM C1157; the compressive strength was of 31.56 MPa and of 22.68 MPa (28 days) at the levels of paste and standard mortar, respectively, with an initial setting time of 93.3 min. From this binder, a hybrid concrete was produced and classified as a structural type, with a compressive strength of 23.16 MPa and a flexural modulus of rupture of 5.32 MPa, at 28 days of curing. The global warming potential index (GWP 100), based on life cycle analysis, was 35% lower than the reference concrete based on 100% OPC. Finally, its use was validated in the manufacture of a solid block-type construction element, which reached a compressive strength of 21.9 MPa at 28 days, exceeding by 40.6% the minimum strength value established by the Colombia Technical Standard, NTC 4026 (13 MPa) to be classified as high class structural blocks.
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Xiao, Kai Tao, Jia Zheng Li, and Hua Quan Yang. "Study of Crack Resistance Property of Polyvinyl Alcohol Fiber Reinforced Concrete." Advanced Materials Research 287-290 (July 2011): 178–82. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.178.
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The strength, ultimate tensile value, compressive elastic modulus and drying shrinkage of polyvinyl alcohol fiber reinforced concrete were studied by tests, and its crack resistance property was also studied by plate method and temperature stress testing machine. The test results showed that PVA fiber could improve the tensile strength and ultimate tensile value of concrete, lower its compressive elastic modulus and drying shrinkage, restrain its early plastic shrinkage and drying shrinkage cracks, reduce its cracking temperature and improve the crack resistance property of concrete, moreover, the effect of long PVA fiber was better.
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Gress, David L., and Ronald L. Kozikowski. "Accelerated Alkali-Silica Reactivity Testing of Recycled Concrete Pavement." Transportation Research Record: Journal of the Transportation Research Board 1698, no. 1 (January 2000): 1–8. http://dx.doi.org/10.3141/1698-01.
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Techniques and procedures are investigated for assessing the alkali–silica reactivity (ASR) expansion potential of concrete that was made from recycled concrete aggregate, was known to have ASR, or was capable of ASR under conditions of increased alkalinity. Laboratory tests included evaluating prisms characterized by variable surface-to-volume ratios, increased temperature, microwave energy, increased alkali content, and ultrasonic energy. Standard 280-mm (11-in.) prisms with 76.2-mm (3-in.) faces, which were cast with four 6.35-mm (0.5-in.) parallel longitudinal holes, were shown to accelerate ASR and to lower the coefficient of variation of the expansion data. The expansions of 76.2-mm (3-in.) concrete cubes were found to be greatly accelerated, compared with standard prisms. Concrete prisms were subjected to AASHTO T303 and ASTM 1293 conditions and were compared to modified versions of the same tests. Modified AASHTO T303 and modified ASTM 1293 conditions were found to effectively accelerate ASR in concrete prisms cast with holes. Prisms that were sealed in evacuated plastic bags with water were found to effectively accelerate ASR expansion. Testing to date has eliminated the use of ultrasonic energy because it was shown to have no effect on ASR acceleration.
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Hager, Izabela, and Katarzyna Mróz. "Role of Polypropylene Fibres in Concrete Spalling Risk Mitigation in Fire and Test Methods of Fibres Effectiveness Evaluation." Materials 12, no. 23 (November 23, 2019): 3869. http://dx.doi.org/10.3390/ma12233869.
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The explosive behaviour of concrete in fire is observed in rapidly heated concrete. The main factors controlling the occurrence of spalling are related to the material’s low porosity and high density as well as the limited ability to transport gases and liquids. Thus, for high-strength, ultrahigh-strength, and reactive powder concrete, the risk of spalling is much higher than for normal-strength concrete. The paper presents the discussion on the leading hypothesis concerning the occurrence of concrete spalling. Moreover, the methods for spalling prevention, such as polypropylene fibre application, which has been found to be an effective technological solution for preventing the occurrence of spalling, are presented. Various tests and testing protocols are used to screen concrete mixes propensity toward spalling and to evaluate the polypropylene fibres’ effectiveness in spalling risk mitigation. The most effective testing methods were selected and their advantages were presented in the paper. The review was based mainly on the authors’ experiences regarding high performance concrete, reactive powder concrete testing, and observations on the effect of polypropylene fibres on material behaviour at high temperature.