scholarly journals Mechanical Properties and Sulfate Resistance of High Volume Fly Ash Cement Mortars with Air-Cooled Slag as Fine Aggregate and Polypropylene Fibers

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 469 ◽  
Author(s):  
Jun Kim ◽  
Abdul Qudoos ◽  
Sadam Jakhrani ◽  
Atta-ur-Rehman ◽  
Jeong Lee ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Polypropylene Fiber ◽  
High Volume ◽  
Sulfate Solution ◽  
Ultrasonic Pulse Velocity ◽  
Pulse Velocity ◽  
Phase Changes ◽  
Fine Aggregate ◽  
Natural Sand

The depletion of natural sand and production of the huge amount of cement in the construction industry are serious threats to the environment, which can be reduced by the utilization of by-products as cement replacement material. In this study, cement was replaced with fly ash up to 45% (by weight). In addition, the natural fine aggregate was replaced with air-cooled blast furnace slag aggregate (here referred to as “slag aggregate”) at a level of 50% and 100% (by weight). Polypropylene fiber was also added, at a dosage of 0.25% of binder weight. Mortar specimens were prepared and analyzed using tests for compressive, flexure, and splitting tensile strength, as well as for microhardness, and ultrasonic pulse velocity. In addition, the specimens were exposed to sulfate solution and investigated for changes in length, mass, and compressive strength. Electron microscopy and X-ray diffraction analysis were performed to examine the microstructure and phase changes of mortar specimens exposed to sulfate solution. The results indicate that mortar specimens made with 50% slag aggregate and 0.25 % fiber showed enhanced mechanical properties. The performance of slag aggregate mortars under sulfate attack was improved significantly.

scholarly journals Comparative study on physical and mechanical properties of high slump and zero lump high volume fly ash concrete (HVFAC)

2013 ◽  
Vol 15 (4) ◽  
pp. 578-584 ◽  
Keyword(s):  
Experimental Investigation ◽  
Fly Ash ◽  
Physical And Mechanical Properties ◽  
High Volume ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Fly Ash Concrete ◽  
High Volume Fly Ash ◽  
Class F Fly Ash

<p>An experimental investigation was carried out to compare the compressive strength of zero slump and high slump concrete with high volume fly ash. 40% to 70% replacements of OPC (by weight) with class F fly ash have been incorporated. Superplasticizer was added at 1% of binder (cement + fly ash) to the zero slump mixture to get a slump in the range of 140 to 180mm and cubes were cast without compaction. The results showed that the apparent porosity and water absorption were higher for zero slump concrete than high slump concrete. Zero slump concrete showed better compressive strengths than superplasticized concrete with 40 to 60% fly ash addition for all curing times tested (3,7 and 28 days). Ultrasonic pulse velocity results categorized all mixes as of &lsquo;EXCELLENT&rsquo; concrete quality. Based on the present experimental investigation, it can be concluded that high volume fly ash concrete is suitable for general construction applications.</p>

scholarly journals Studies on manufactured sand effect on mechanical properties of geopolymer concrete as replacement of river sand in fine aggregate

2021 ◽  
Vol 309 ◽  
pp. 01114
Author(s):  
K. Veera Babu ◽  
T. Srinivas ◽  
Mahathi Tummala
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Construction Material ◽  
Environmental Concerns ◽  
Fine Aggregate ◽  
Geopolymer Concrete ◽  
River Sand ◽  
Natural Sand ◽  
Manufactured Sand ◽  
Low Calcium

Concrete is the most adaptable, long-lasting, and dependable construction material on the planet. There are numerous environmental concerns associated with the production of OPC, and natural sand is becoming more expensive and scarce as a result of unlawful river sand dredging. The greatest replacement material for traditional concrete is geopolymer concrete with low calcium fly ash. The purpose of this paper is to investigate the mechanical properties of geopolymer concrete of grades G30 and G50, which are equivalent to M30 and M50, when river sand is substituted in various quantities with manufactured sand, such as 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%. When compared to the equivalent grades of controlled concrete, geopolymer concrete improves mechanical properties such as compressive, tensile, and flexural strengths.

scholarly journals PHYSICAL AND MECHANICAL PROPERTIES RESEARCH AND ANALYSIS OF CONCRETE WITH BIOFUEL COMBUSTION FLY ASH SUPPLEMENT

2019 ◽  
Vol 11 (0) ◽  
pp. 1-5
Author(s):  
Deividas Augutis ◽  
Džigita Nagrockienė
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Physical And Mechanical Properties ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Ash Content ◽  
Closed Porosity ◽  
Freeze Thaw ◽  
Materials Used

Materials used for the study: Portland cement CEM I 42,5 R, 0/4 fraction sand, 4/16 fraction gravel, biofuel fly ash, superplastizer ViscoCrete D187 (V) and water. Seven compositions of concrete were designed by replacing 0%, 5%, 10%, 15%, 20%, 25% and 30% of cement with biofuel fly ash. The article analyses the effect of biofuel fly ash content on the properties of concrete. Studies have shown that the increase of biofuel fly ash content up to 15% increases concrete density and compressive strengh after 28 days of curing, compressive strength, ultrasonic pulse velocity, closed porosity, concrete forecasted freeze-thaw cycles and decreases water absorbtion, open porosity.

scholarly journals Mechanical Properties of Na2CO3-Activated High-Volume GGBFS Cement Paste

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Taewan Kim ◽  
Yubin Jun
Keyword(s):  
Mechanical Properties ◽  
Water Absorption ◽  
High Volume ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Strength Development ◽  
X Ray Diffraction ◽  
Granulated Blast Furnace Slag ◽  
Dry Shrinkage

The use of Na2CO3 to improve the mechanical properties of high-volume slag cement (HVSC) is experimentally investigated in this study. Ordinary Portland cement (OPC) was replaced with 50, 60, 70, 80, and 90% ground-granulated blast-furnace slag (GGBFS) by weight. Na2CO3 was added at 0, 1, 2, 3, 4, and 5 wt.% of HVSC (OPC + GGBFS). The compressive strength, water absorption, ultrasonic pulse velocity, dry shrinkage, and X-ray diffraction spectra of the Na2CO3-activated HVSC pastes were analyzed. The results indicate that Na2CO3 was effective for improving the strength of HVSC samples at both early and later ages. There was a trend of increasing HVSC sample strength with increasing Na2CO3 content. The 5% Na2CO3-activated HVSC (50% OPC + 50% GGBFS) paste had the best combination of early to later-age strength development and exhibited the highest UPV and the lowest water absorption among the Na2CO3-activated HVSC samples at later age.

scholarly journals Mechanical Properties of High Volume Fly Ash Concrete Reinforced with Hybrid Fibers

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Rooban Chakravarthy ◽  
Srikanth Venkatesan ◽  
Indubhushan Patnaikuni
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Polypropylene Fiber ◽  
Basalt Fiber ◽  
High Volume ◽  
Single Type ◽  
Hybrid Fibers ◽  
Brittle Behavior ◽  
Fly Ash Concrete ◽  
High Volume Fly Ash

Fly ash substitution to cement is a well-recognized approach to reduce CO2emissions. Although fly ash concrete is prone to brittle behavior, researchers have shown that addition of fibers could reduce brittle behavior. Previous research efforts seem to have utlised a single type of fiber or two types of fibers. In this research, three types of fibers, steel, polypropylene, and basalt as 0%, 0.50%, 0.75%, and 1% by volume of concrete, were mixed in varying proportions with concrete specimens substituted with 50% fly ash (class F). All specimens were tested for compressive strength, indirect tensile strength, and flexural strength over a period of 3 to 56 days of curing. Test results showed that significant improvement in mechanical properties could be obtained by a particular hybrid fiber reinforcement combination (1% steel fiber, 0.75% polypropylene fiber, and 0.75% basalt fiber). The strength values were observed to exceed previous research results. Workability of concrete was affected when the fiber combination exceeded 3%. Thus a limiting value for adding fibers and the combination to achieve maximum strengths have been identified in this research.

scholarly journals Eco-Friendly Chopped Tire Rubber as Reinforcements in Fly Ash Geopolymer Concrete

2020 ◽  
Keyword(s):  
Fly Ash ◽  
Mechanical Performance ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Industrial Wastes ◽  
Fine Aggregate ◽  
Geopolymer Concrete ◽  
Tire Rubber ◽  
Naoh Solution

<p>One of the major challenges faced by researchers is to recycle industrial wastes in a manner that reduces their environmental impact in nature. An experimental study was carried out to determine the suitability of using chopped tire rubber as reinforcements in green and sustainable geopolymer concrete, with the purpose of using them as nonstructural products. The geopolymer mixture was made by mixing of fly ash powder, fine aggregate, and Superplasticizer in Na2SiO3/NaOH solution. Mixtures were divided into four different groups, with constant water to fly ash ratio of 0.12 and alkaline dosage of 45% by weight of fly ash, based on the recycled chopped tire rubber (CTR) content: 0, 10, 20, and 30% by volume of fine aggregate with two maximum sizes (2 and 4mm). Hardened properties of resulted geopolymer like compressive strength, density; and ultrasonic pulse velocity were examined at 28d. Besides that, X-Ray diffractometer and Scanning Electron Microscope were used in order to observe the microstructure of the resulted geopolymer concrete. In view of the consequences for this study, it is preferable to replace no more than 10% of fine aggregate in geopolymer concrete by CTR. In addition, according to SEM photographs, increasing the CTR content more voids will be pronounced and thus, decreasing the mechanical performance.</p>

scholarly journals Post-Fire Mechanical Properties of Concrete Reinforced with Spanish Broom Fibers

2021 ◽  
Vol 5 (10) ◽  
pp. 265
Author(s):  
Sandra Juradin ◽  
Lidia Karla Vranješ ◽  
Dražan Jozić ◽  
Ivica Boko
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Polypropylene Fiber ◽  
Compressive Load ◽  
Ultrasonic Pulse Velocity ◽  
Optical Microscope ◽  
Pulse Velocity ◽  
Concrete Mixture ◽  
Cross Sectional ◽  
Residual Properties

In this study, we conducted an initial investigation of the post-fire mechanical properties of concrete reinforced with Spanish broom fibers. The mechanical properties were determined at room temperature, and the post-fire mechanical properties were determined at elevated temperature, so that the fire resistance of the concrete could be determined. Five mixtures were considered: three with differently treated Spanish broom fibers, a polypropylene fiber mixture, and a reference concrete mixture. The concrete and reinforced concrete samples were first dried to 100 °C, then heated to 400 °C, and left to cool to room temperature. The samples were tested immediately and 96 h after cooling. The compressive strength, weight loss, ultrasonic pulse velocity, and dynamic modulus of elasticity were determined and compared. The cross-sectional images of the concrete samples captured through an optical microscope were observed and analyzed. The changes in fiber structure were monitored by TG/DTG analysis. The results of the study indicate that even the reference concrete mixture did not have satisfactory residual properties. The reinforced concretes did not improve the residual properties of the reference concrete, but reduced the spalling and explosive failure performance under a compressive load. The concrete reinforced with Spanish broom fibers showed improved residual properties compared with concrete reinforced with polypropylene fibers.

The Effect of Chloride Environment on Mechanical Properties Geopolymer Binder with Fly Ash

2013 ◽  
Vol 594-595 ◽  
pp. 648-655 ◽  
Author(s):  
Muhammad Sigit Darmawan ◽  
Ridho Bayuaji ◽  
Boedi Wibowo ◽  
Nur Ahmad Husin ◽  
Srie Subekti
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Design Method ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
National Standard ◽  
Vacuum Saturation ◽  
Chloride Environment

This study is conducted to determine the effect of five variables on mechanical properties of geopolymer binders. These five variables are chloride environment, NaOH molarity, Na2SiO3/NaOH ratio, fly ash/alkaline activator (FA/AA) ratio and superplasticizer (SP) addition. The mechanical properties considered are compressive strength, porosity and density. Taguchi experimental design method is used to compile the binder composition of geopolymer to achieve the maximum compressive strength. Specimens binder used is a cylinder with 25 mm diameter and 50 mm height. Compressive strength test is performed at 28 days using SNI 03-6825-2002 (Indonesian National Standard) and porosity of the binder is determined using vacuum saturation apparatus similar to that developed by RILEM. The density of the binder is measured using Ultrasonic Pulse Velocity (UPV). This study concludes that the chloride environment has a beneficial effect on the compressive strength of the binder. In addition, the FA/AA ratio and NaOH molarity give a significant effect on the compressive strength of geopolymer binders.

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