Evaluation of concrete self-healing with different fly ash contents and cracking ages by means of ultrasonic pulse velocity and compressive strength tests

Need of construction is increasing due to increase in population growth rate. The geopolymer concrete is eco-friendly than ordinary concrete. Current experimental investigation was conducted on ordinary and geopolymer concrete using nondestructive testing (NDT) tests like ultrasonic pulse velocity (UPV) test and rebound hammer (RH) test. Cube specimens of dimensions 150 mm × 150 mm × 150 mm are used to conduct these tests at 7, 14, and 28 days. Proportions considered for concrete are cement-fly ash-river sand (100-0-100% and 60-40-100%), cement-fly ash-robo sand (100-0-100% and 60-40-100%) whereas geopolymer concrete fly ash-metakaolin is taken in proportions of 100-0%, 60-40%, and 50-50%. Alkaline activators (sodium hydroxide and sodium silicate with molarity 12M) were used in preparing geopolymer concrete. The major objective of the current study is to obtain relation between compressive strength of concrete and UPV values.

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Transport Properties and Resistance Improvement of Ultra-High Performance Concrete (UHPC) after Exposure to Elevated Temperatures

Buildings ◽

10.3390/buildings11090416 ◽

2021 ◽

Vol 11 (9) ◽

pp. 416

Author(s):

Yunfeng Qian ◽

Dingyi Yang ◽

Yanghao Xia ◽

Han Gao ◽

Zhiming Ma

Keyword(s):

Compressive Strength ◽

Transport Properties ◽

High Temperatures ◽

High Performance ◽

High Performance Concrete ◽

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

Capillary Absorption ◽

Self Healing

Ultra-high performance concrete (UHPC) has a high self-healing capacity and is prone to bursting after exposure to high temperatures due to its characteristics. This work evaluates the damage and improvement of UHPC with coarse aggregates through mechanical properties (compressive strength and ultrasonic pulse velocity), transport properties (water absorption and a chloride diffusion test), and micro-properties such as X-ray diffraction (XRD), Mercury intrusion porosimetry (MIP), and Scanning electronic microscopy (SEM). The result demonstrates that polypropylene (PP) fibers are more suitable for high temperature tests than polyacrylonitrile (PAN) fibers. The result shows that 400 °C is the critical temperature point. With the increase in temperature, the hydration becomes significant, and the internal material phase changes accordingly. Although the total pore volume increased, the percentage of various types of pores was optimized within 400 °C. The mass loss gradually increased and the ultrasonic pulse velocity gradually decreased. While the compressive strength first increased and then decreased, and the increase occurred within 25–400 °C. As for the transport properties, the chloride migration coefficient and capillary absorption coefficient both increased dramatically due to the higher sensitivity to temperature changes. The results of the property improvement test showed that at temperatures above 800 °C, the compressive strength recovered by more than 65% and the ultrasonic pulse velocity recovered by more than 75%. In terms of transport properties, compared to the results before self-healing, the chloride migration coefficient decreased by up to 59%, compared with 89% for the capillary absorption coefficient, after self-healing at 800 °C. With respect to the enhancement effect after exposure to high temperatures, the environment of a 5% Na2SO4 solution was not as good as the clean water environment. The corresponding changes in microstructure during the high temperatures and the self-healing process can explain the change in the pattern of macroscopic properties more precisely.

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Effect of alkali content and slag content on the fresh and hardened properties of air-cured alkali activated mortar containing fly ash

Proceedings of International Web Conference in Civil Engineering for a Sustainable Planet ◽

10.21467/proceedings.112.48 ◽

2021 ◽

Author(s):

Thushara Raju ◽

Namitha S ◽

Muhammed Nabil K ◽

Mohammed Rafeeque N. V ◽

Reshma Sundhar ◽

...

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Construction Material ◽

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

Alkali Content ◽

Hardened Properties ◽

Alkali Activated ◽

Slag Content

Alkali Activated Material (AAM) is introduced as a pioneering construction material in the construction diligence to trim down the utilization of Ordinary Portland Cement (OPC) and to curtail the amount of carbon dioxide released during the production of OPC. Modestly refined industrial by products or natural materials rich in alumino silicates are the binding agents used in AAM. Generally, heat curing is needed for the alkali activated mortar to achieve the required hardened properties and this difficulty can be overcome by adding slag to the mix. In this experimental analysis, the alkali activated mortar mixes with different proportions of glassy granulated slag and Class F fly ash were prepared without the usage of superplasticizers, with alkali to binder (a/b) ratios of 0.7, 0.8 and 0.9. The rheological characteristics of mortar were studied using flow table apparatus and hardened properties were studied using compressive strength test and ultrasonic pulse velocity (UPV) test by testing cylindrical specimens of size 25 mm diameter and 50 mm height. The mortar specimens were air-cured, and the compressive strength and UPV test were conducted after 3 and 7 days. The test results showed that due to the presence of higher alkali content and the decrease in slag content, the workability of alkali activated mortar was improved, but the measure of strength decreased. The mix with 100% slag and a/b ratio of 0.8 had the best UPV value, indicating its quality among the various mortar mixes studied. This study portrays the significance of optimising the alkali and slag content in tailor making an alkali activated mortar system with good hardened properties.

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Characteristics of Preplaced Aggregate Concrete Fabricated with Alkali-Activated Slag/Fly Ash Cements

Materials ◽

10.3390/ma14030591 ◽

2021 ◽

Vol 14 (3) ◽

pp. 591

Author(s):

Salman Siddique ◽

Hyeju Kim ◽

Hyemin Son ◽

Jeong Gook Jang

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Water Absorption ◽

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

Cement Grout ◽

Aggregate Concrete ◽

Alkali Activated ◽

Alkali Activated Cement

This study assesses the characteristics of preplaced aggregate concrete prepared with alkali-activated cement grout as an adhesive binder. Various binary blends of slag and fly ash without fine aggregate as a filler material were considered along with different solution-to-solid ratios. The properties of fresh and hardened grout along with the properties of hardened preplaced concrete were investigated, as were the compressive strength, ultrasonic pulse velocity, density, water absorption and total voids of the preplaced concrete. The results indicated that alkali-activated cement grout has better flowability characteristics and compressive strength than conventional cement grout. As a result, the mechanical performance of the preplaced aggregate concrete was significantly improved. The results pertaining to the water absorption and porosity revealed that the alkali-activated preplaced aggregate concrete is more resistant to water permeation. The filling capacity based on the ultrasonic pulse velocity value is discussed to comment on the wrapping ability of alkali-activated cement grout.

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Evaluation of Freeze-Thaw Durability of Silica Fume Concrete with Spraying Inorganic Coating Using Ultrasonic Testing

Mathematical Problems in Engineering ◽

10.1155/2021/5598611 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Wujian Yan ◽

Fuhang Niu ◽

Xinxin Tian

Keyword(s):

Compressive Strength ◽

Ultrasonic Testing ◽

Concrete Strength ◽

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

Freeze Thaw ◽

Strength Tests ◽

Inorganic Coating ◽

External Coating

To study the antifreezing durability of internal coating silicon fume concrete with different external coatings, fast freeze-thaw (FT) cycle testing was performed for three types of external coatings applied to the internal coatings of silicon fume concrete. Using ultrasonic testing and compressive strength tests, we analysed the relationships between the ultrasonic pulse velocity and the mechanical and physical properties of concrete under freeze-thaw action. The results show that the compressive strength and pulse velocity of the studied concrete changed little before the first 100 FT cycles but varied significantly after being subjected to 100 FT cycles and diminished linearly with increasing FT cycles. The dynamic elastic parameters of the concrete were inferred using pulse velocity calculations, and the dependence on FT cycles was very similar to that of ultrasonic pulse velocity. The concrete strength was strongly and positively correlated with ultrasonic pulse velocity. The linear regression model of between ultrasonic pulse velocity, kinetic coefficient, and compressive strength of concrete was also established. The damage incurred to the external coating material (XT-HPA + XT-SS and XT-HPS) was small, and the good performance of the concrete with the added inorganic coating after freeze-thaw cycles indicates good frost resistance.

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Using Ultrasonic Pulse Velocity Test to Assess the Effect of Water-Cement Ratio on the Compressive Strength of Concrete

Journal of Engineering ◽

10.31026/j.eng.2019.05.06 ◽

2019 ◽

Vol 25 (5) ◽

pp. 79-86 ◽

Cited By ~ 1

Author(s):

Ziwar Zebari

Keyword(s):

Compressive Strength ◽

Material Science ◽

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

Cement Ratio ◽

Water Cement Ratio ◽

Effect Of Water ◽

Strength Tests ◽

Compressive Strength Of Concrete

This study aims to find the effect of water-cement ratio on the compressive strength of concrete by using ultrasonic pulse velocity test (UPVT). Over 230 standard cube specimens were used in this study, with dimensions of 150mm, and concrete cubes were cured in water at 20 °C. Also, the specimens used in the study were made of concrete with varied water-cement ratio contents from 0.48 to 0.59. The specimens were taken from Diyarbakir-Turkey concrete centers and tested at the structure and material science lab, civil engineering, faculty of engineering from Dicle University. The UPV measurement and compressive strength tests were carried out at the concrete age of 28 days. Their UPV and compressive strength ranged between (3.89-4.66km/s) and (17.74-40.56MPa) respectively. The experimental results showed that although the UPV and the compressive strength of concrete are related, also, the UPV and compressive strength have a relation with the rate of the water-cement ratio of concrete.

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Performance of Fly Ash Geopolymer Concrete Incorporating Bamboo Ash at Elevated Temperature

Materials ◽

10.3390/ma12203404 ◽

2019 ◽

Vol 12 (20) ◽

pp. 3404 ◽

Cited By ~ 2

Author(s):

Ishak ◽

Lee ◽

Singh ◽

Ariffin ◽

Lim ◽

...

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Control Sample ◽

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

Air Cooling ◽

Geopolymer Concrete ◽

Water Cooling ◽

Control Samples

This paper presents the experimental results on the behavior of fly ash geopolymer concrete incorporating bamboo ash on the desired temperature (200 °C to 800 °C). Different amounts of bamboo ash were investigated and fly ash geopolymer concrete was considered as the control sample. The geopolymer was synthesized with sodium hydroxide and sodium silicate solutions. Ultrasonic pulse velocity, weight loss, and residual compressive strength were determined, and all samples were tested with two different cooling approaches i.e., an air-cooling (AC) and water-cooling (WC) regime. Results from these tests show that with the addition of 5% bamboo ash in fly ash, geopolymer exhibited a 5 MPa (53%) and 5.65 MPa (66%) improvement in residual strength, as well as 940 m/s (76%) and 727 m/s (53%) greater ultrasonic pulse velocity in AC and WC, respectively, at 800 °C when compared with control samples. Thus, bamboo ash can be one of the alternatives to geopolymer concrete when it faces exposure to high temperatures.

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Effect of Treated Sago Pith Waste Ash and Silica Fume to the Mechanical Properties of Fly Ash-Based Geopolymer Brick

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.879.100 ◽

2021 ◽

Vol 879 ◽

pp. 100-114

Author(s):

Izwan B. Johari ◽

Md Azlin Md Said ◽

Mohd Amirul B. Mohd Snin ◽

Nur Farah Aqilah Bt. Ayob ◽

Nur Syafiqah Bt. Jamaluddin ◽

...

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Silica Fume ◽

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

Partial Replacement ◽

Rebound Hammer ◽

Compressive Strength Test ◽

Sago Pith Waste

This paper investigates the effect of partial replacement of fly ash with sago pith waste ash and silica fume in fabricating the geopolymer mortar concrete. The mixtures of geopolymer mortar concrete were prepared by replacing sago pith waste ash and silica fume at 5% of total weight of fly ash. There were six specimens of geopolymer mortar cubes and bricks fabricated in this study. The specimens are tested with compressive strength test, rebound hammer test and ultrasonic pulse velocity test. The results from the tests are compared with some existing published works as to clarify the effect of replacing the fly ash with sago waste and silica fume on the strength of concrete. Comparisons had been made and concluded that the molarity of alkaline solution, Al3O2 and CaO influenced the development of compressive strength along the curing time of fly ash based geopolymer concrete.

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

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.594-595.648 ◽

2013 ◽

Vol 594-595 ◽

pp. 648-655 ◽

Cited By ~ 1

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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