The mechanical properties of fly ash concrete prepared and cured at high temperatures

Results of an experimental investigation on the effect of fly ash content, water cement (w/c) ratio of concrete prepared and cured at temperatures of ambience, 40°C and 60°C are presented in this paper. The mechanical properties investigated here include its workability, its behaviour under compression and splitting tension. Microscopic investigations were also carried out using SEM micrographic images to gain understanding of concrete at its microstructural level.The results indicate that high temperature increases early compressive strengths of concrete, but has decreasing effects on the strengths at later ages. The use of fly ash in concretes cast and cured at elevated temperatures improves the physical and mechanical properties of fresh as well as those of hardened concrete.Various mathematical models describing the properties of such concretes are considered at the end of this paper. The strength properties of high temperature fly ash concrete were best represented by a simple exponential function of time, while its stress-strain relationship could be best described by an exponential function of strain of a more complicated form.

Download Full-text

Mechanical Properties and Thermal Resistance of High Volume Fly Ash Concrete for Energy Efficiency in Building Construction

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.678.99 ◽

2016 ◽

Vol 678 ◽

pp. 99-108 ◽

Cited By ~ 3

Author(s):

B. Balakrishnan ◽

A.S.M. Abdul Awal

Keyword(s):

Mechanical Properties ◽

High Temperature ◽

Fly Ash ◽

Elevated Temperatures ◽

Value Added ◽

High Volume ◽

Building Construction ◽

Strength Development ◽

Fly Ash Concrete ◽

High Volume Fly Ash

The utilization of waste materials in concrete is one of the best value added solutions to the construction industry. With the aim of sustability development, high volume fly ash (HVFA) were tested in concrete by substituting 40, 50 and 60% of OPC with fly ash. Properties studied in this research includes fresh concrete properties, mechanical properties and the resistance of concrete exposed to high temperature. The test result indicates that HVFA concrete positively influenced the workability; however, the setting times of the concrete were longer. It has been found that the development of strength of high volume fly ash concrete was relatively slower, but ahigher strength development at later ages was observed in concrete containing HVFA. The performance of concrete at elevated temperatures reveals that concrete without any fly ash has better resistance than HVFA concrete at high temperature. The use of high volume fly ash results in an acceptable concrete performance, which grants high potential for energy saving in the building construction.

Download Full-text

Mechanical and Microstructural Characterization of Quarry Rock Dust Incorporated Steel Fiber Reinforced Geopolymer Concrete and Residual Properties after Exposure to Elevated Temperatures

Materials ◽

10.3390/ma14226890 ◽

2021 ◽

Vol 14 (22) ◽

pp. 6890

Author(s):

Muhammad Ibraheem ◽

Faheem Butt ◽

Rana Muhammad Waqas ◽

Khadim Hussain ◽

Rana Faisal Tufail ◽

...

Keyword(s):

Mechanical Properties ◽

Weight Loss ◽

Compressive Strength ◽

Fly Ash ◽

Mechanical Strength ◽

Elevated Temperatures ◽

Strength Properties ◽

Steel Fibers ◽

Geopolymer Concrete

The purpose of this research is to study the effects of quarry rock dust (QRD) and steel fibers (SF) inclusion on the fresh, mechanical, and microstructural properties of fly ash (FA) and ground granulated blast furnace slag (SG)-based geopolymer concrete (GPC) exposed to elevated temperatures. Such types of ternary mixes were prepared by blending waste materials from different industries, including QRD, SG, and FA, with alkaline activator solutions. The multiphysical models show that the inclusion of steel fibers and binders can enhance the mechanical properties of GPC. In this study, a total of 18 different mix proportions were designed with different proportions of QRD (0%, 5%, 10%, 15%, and 20%) and steel fibers (0.75% and 1.5%). The slag was replaced by different proportions of QRD in fly ash, and SG-based GPC mixes to study the effect of QRD incorporation. The mechanical properties of specimens, i.e., compressive strength, splitting tensile strength, and flexural strength, were determined by testing cubes, cylinders, and prisms, respectively, at different ages (7, 28, and 56 days). The specimens were also heated up to 800 °C to evaluate the resistance of specimens to elevated temperature in terms of residual compressive strength and weight loss. The test results showed that the mechanical strength of GPC mixes (without steel fibers) increased by 6–11%, with an increase in QRD content up to 15% at the age of 28 days. In contrast, more than 15% of QRD contents resulted in decreasing the mechanical strength properties. Incorporating steel fibers in a fraction of 0.75% by volume increased the compressive, tensile, and flexural strength of GPC mixes by 15%, 23%, and 34%, respectively. However, further addition of steel fibers at 1.5% by volume lowered the mechanical strength properties. The optimal mixture of QRD incorporated FA-SG-based GPC (QFS-GPC) was observed with 15% QRD and 0.75% steel fibers contents considering the performance in workability and mechanical properties. The results also showed that under elevated temperatures up to 800 °C, the weight loss of QFS-GPC specimens persistently increased with a consistent decrease in the residual compressive strength for increasing QRD content and temperature. Furthermore, the microstructure characterization of QRD blended GPC mixes were also carried out by performing scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS).

Download Full-text

Influences of high temperature on mechanical properties of fly ash based geopolymer mortars reinforced with PVA fiber

10.7764/rdlc.20.2.393 ◽

2021 ◽

Vol 20 (2) ◽

pp. 393-406

Author(s):

Mehmet Kaya ◽

◽

Fuat Köksal ◽

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

High Temperature ◽

Fly Ash ◽

High Temperatures ◽

Physical And Mechanical Properties ◽

The Other ◽

Polyvinyl Alcohol Fiber ◽

Pva Fiber ◽

High Temperature Effect

In this study, a geopolymer composite containing PVA fiber was produced to recycle waste fly ash and obtain an eco-friendly binder. Mechanical properties of geopolymer mortars, produced by using F class fly ash which was activated with NaOH (sodium hydroxide), and reinforced by PVA (polyvinyl alcohol) fiber were investigated after high temperature effect. Geopolymer mortar samples produced by mixing with fly ash, sand, water and NaOH were placed in standard molds of 40×40×160 mm3. PVA fibers were used at percentages of 0,5%, 1% and 1,5% by volume in the experiment. Tests were performed on mortars exposed to high temperatures of 200°C, 400°C, 600°C and 800°C for physical and mechanical properties. For the specimens not subjected to high temperatures, an increase in the compressive strength of mortars containing PVA fibers was observed in comparison to mortar without PVA fiber. On the other hand, it was concluded that losses in compressive strength were less for mortar without PVA fiber when compared with the mortars containing PVA fibers. As a result of the modeling, the PVA ratio, which gives the optimum flexural and compressive strength, was determined as 1,47%. As a result of melting of PVA fibers under the effect of high temperature, 83,58% loss of compressive strength was determined in samples containing 1,5% PVA after 800ºC temperature.

Download Full-text

High Temperature Mechanical Properties of High-Strength Fly Ash Concrete with and without Fibers

ACI Materials Journal ◽

10.14359/51684164 ◽

2012 ◽

Vol 109 (6) ◽

Cited By ~ 1

Keyword(s):

Mechanical Properties ◽

High Temperature ◽

Fly Ash ◽

High Strength ◽

Fly Ash Concrete ◽

High Temperature Mechanical Properties

Download Full-text

BRUSH ALLOY 3

Alloy Digest ◽

10.31399/asm.ad.cu0454 ◽

1983 ◽

Vol 32 (3) ◽

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Corrosion Resistance ◽

Physical Properties ◽

Copper Alloy ◽

Elevated Temperatures ◽

Physical And Mechanical Properties ◽

Heat Treating ◽

Good Resistance ◽

Good Corrosion Resistance

Abstract BRUSH Alloy 3 offers the highest electrical and thermal conductivity of any beryllium-copper alloy. It possesses an excellent combination of moderate strength, good corrosion resistance and good resistance to moderately elevated temperatures. Because of its unique physical and mechanical properties, Brush Alloy 3 finds widespread use in welding applications (RWMA Class 3), current-carrying springs, switch and instrument parts and similar components. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fatigue. It also includes information on corrosion resistance as well as casting, forming, heat treating, machining, joining, and surface treatment. Filing Code: Cu-454. Producer or source: Brush Wellman Inc..

Download Full-text

Effect of Elevated Temperature on Mechanical Properties of High-Volume Fly Ash-Based Geopolymer Concrete, Mortar and Paste Cured at Room Temperature

Polymers ◽

10.3390/polym13091473 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1473

Author(s):

Jun Zhao ◽

Kang Wang ◽

Shuaibin Wang ◽

Zike Wang ◽

Zhaohui Yang ◽

...

Keyword(s):

Mechanical Properties ◽

Elevated Temperature ◽

Fly Ash ◽

Residual Strength ◽

Elevated Temperatures ◽

High Volume ◽

Sem Analysis ◽

Geopolymer Concrete ◽

Ordinary Concrete ◽

Exposure Temperature

This paper presents results from experimental work on mechanical properties of geopolymer concrete, mortar and paste prepared using fly ash and blended slag. Compressive strength, splitting tensile strength and flexural strength tests were conducted on large sets of geopolymer and ordinary concrete, mortar and paste after exposure to elevated temperatures. From Thermogravimetric analyzer (TGA), X-ray diffraction (XRD), Scanning electron microscope (SEM) test results, the geopolymer exhibits excellent resistance to elevated temperature. Compressive strengths of C30, C40 and C50 geopolymer concrete, mortar and paste show incremental improvement then followed by a gradual reduction, and finally reach a relatively consistent value with an increase in exposure temperature. The higher slag content in the geopolymer reduces residual strength and the lower exposure temperature corresponding to peak residual strength. Resistance to elevated temperature of C40 geopolymer concrete, mortar and paste is better than that of ordinary concrete, mortar and paste at the same grade. XRD, TGA and SEM analysis suggests that the heat resistance of C–S–H produced using slag is lower than that of sulphoaluminate gel (quartz and mullite, etc.) produced using fly ash. This facilitates degradation of C30, C40 and C50 geopolymer after exposure to elevated temperatures.

Download Full-text

Physical and Mechanical Properties of Cement Paste Were Used Partially with Fly Ash and Kaolin Waste

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.866.199 ◽

2017 ◽

Vol 866 ◽

pp. 199-203

Author(s):

Chidchanok Chainej ◽

Suparut Narksitipan ◽

Nittaya Jaitanong

Keyword(s):

Mechanical Properties ◽

Fly Ash ◽

Room Temperature ◽

Physical And Mechanical Properties ◽

Partial Replacement ◽

X Ray Diffraction ◽

X Ray ◽

Lime Water ◽

Diffraction Patterns ◽

Iron Mold

The aims of this research were study the microstructures and mechanical properties for partial replacement of cement with Fly ash (FA) and kaolin waste (KW). Ordinary Portland cement were partially replaced with FA and KW in the range of 25-35% and 10-25% by weight of cement powder. The kaolin waste was ground for 180 minutes before using. The specimen was packing into an iron mold which sample size of 5×5×5 cm3. Then, the specimens were kept at room temperature for 24 hours and were moist cured in the incubation lime water bath at age of 3 days. After that the specimens were dry cured with plastic wrap at age of 3, 7, 14 and 28 days. After that the compounds were examined by x-ray diffraction patterns (XRD) and the microstructures were examined by scanning electron microscopy (SEM). The compressive strength was then investigated.

Download Full-text

Effects of Elevated Temperatures on the Compressive Strength of HFCC

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.261-263.416 ◽

2011 ◽

Vol 261-263 ◽

pp. 416-420 ◽

Cited By ~ 1

Author(s):

Fu Ping Jia ◽

Heng Lin Lv ◽

Yi Bing Sun ◽

Bu Yu Cao ◽

Shi Ning Ding

Keyword(s):

Compressive Strength ◽

Elevated Temperature ◽

Fly Ash ◽

Room Temperature ◽

Elevated Temperatures ◽

Relative Strength ◽

Ordinary Concrete ◽

Residual Compressive Strength ◽

Fly Ash Concrete ◽

The Relationship

This paper presents the results of elevated temperatures on the compressive of high fly ash content concrete (HFCC). The specimens were prepared with three different replacements of cement by fly ash 30%, 40% and 50% by mass and the residual compressive strength was tested after exposure to elevated temperature 250, 450, 550 and 650°C and room temperature respectively. The results showed that the compressive strength apparently decreased with the elevated temperature increased. The presence of fly ash was effective for improvement of the relative strength, which was the ratio of residual compressive strength after exposure to elevated temperature and ordinary concrete. The relative compressive strength of fly ash concrete was higher than those of ordinary concrete. Based on the experiments results, the alternating simulation formula to determine the relationship among relative strength, elevated temperature and fly ash replacement is developed by using regression of results, which provides the theoretical basis for the evaluation and repair of HFCC after elevated temperature.

Download Full-text