scholarly journals Performance of Epoxy Resin Polymer as Self-Healing Cementitious Materials Agent in Mortar

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1255 ◽  
Author(s):  
Ghasan Fahim Huseien ◽  
Abdul Rahman Mohd Sam ◽  
Iman Faridmehr ◽  
Mohammad Hajmohammadian Baghban
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Epoxy Resin ◽  
Healing Process ◽  
Microstructural Analysis ◽  
Ultrasonic Pulse Velocity ◽  
Cementitious Materials ◽  
Pulse Velocity ◽  
Self Healing ◽  
Dry Conditions

This research investigated the application of epoxy resin polymer as a self-healing strategy for improving the mechanical and durability properties of cement-based mortar. The epoxy resin was added to the concrete mix at various levels (5, 10, 15, and 20% of cement weight), and the effectiveness of healing was evaluated by microstructural analysis, compressive strength, and non-destructive (ultrasonic pulse velocity) tests. Dry and wet-dry conditions were considered for curing, and for generating artificial cracks, specimens at different curing ages (1 and 6 months) were subjected to compressive testing (50 and 80% of specimen’s ultimate compressive strength). The results indicated that the mechanical properties in the specimen prepared by 10% epoxy resin and cured under wet-dry conditions was higher compared to other specimens. The degree of damage and healing efficiency index of this particular mix design were significantly affected by the healing duration and cracking age. An optimized artificial neural network (ANN) combined with a firefly algorithm was developed to estimate these indexes over the self-healing process. Overall, it was concluded that the epoxy resin polymer has high potential as a mechanical properties self-healing agent in cement-based mortar.

PERFORMANCE OF EPOXY RESIN AS SELF-HEALING AGENT

2015 ◽  
Vol 77 (16) ◽  
Author(s):  
Abdul Rahman Mohd Sam ◽  
Nur Farhayu Ariffin ◽  
Mohd Warid Hussin ◽  
Han Seung Lee ◽  
Mohamed A. Ismail ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Epoxy Resin ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Self Healing ◽  
Fine Aggregates ◽  
Healing Agent ◽  
Initial Reading ◽  
External Intervention

Formation of cracks due to the shrinkage effects during curing and mechanical loading can deteriorate the concrete performance especially in terms of durability aspect. Chemical and harsh solutions will easily penetrate into the concrete and cause damage to the concrete. In order to solve this problem, researchers have introduced a self-healing concrete; the mechanism of automatically repairing concrete cracks without external intervention. Nowadays, the self-healing concrete by using bacteria as a healing agent had gained interest among researchers. In contrast, this paper presents the study on performance of epoxy resin without hardener as a self-healing agent in concrete. Mortar specimens were prepared with mass ratio of 1:3 (cement: fine aggregates), water-cement ratio of 0.48 and 5 to 20% epoxy resin of cement content. All tested specimens were subjected to wet-dry curing; where compressive strength, apparent porosity and self-healing evaluation were measured. Result shows that, the compressive strength of mortar with addition of epoxy resin by 10% increased significantly compared to normal mortar. Epoxy resin as a healing agent was found to be functioned well as the compressive strength and ultrasonic pulse velocity regain the initial reading with prolonged curing time. These results together with microstructure test indicate that epoxy resin can be used as a self-healing agent.

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

Buildings ◽  
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.

scholarly journals Self-healing bacterial cementitious concrete composites: development and performance evaluation

2021 ◽  
Author(s):  
Sini Bhaskar
Keyword(s):  
Compressive Strength ◽  
Bacillus Subtilis ◽  
Statistical Modelling ◽  
Energy Dispersive Spectrum ◽  
Ultrasonic Pulse Velocity ◽  
Pulse Velocity ◽  
Self Healing ◽  
Chloride Permeability ◽  
Sporosarcina Pasteurii ◽  
Subtilis Subsp

The principal objective of the research is to contribute towards attaining the goal of developing self-healing cementitious concrete composites by incorporating bacteria as healing agent. Since the root cause of the majority of structural failure is attributed to concrete cracking, there is a compelling economic incentive to develop a concrete that can treat and repair the damage all by itself. Even though some research has been carried out in this area, a major breakthrough in identifying the types of bacteria, modes to protect this bacteria from high pH concrete environment and nutrients for effective healing are yet to materialise. For the present study, three different bacteria namely, Sporosarcina ureae, Sporosarcina pasteurii and Bacillus subtilis subsp. spizizenii and two protective vehicles such as zeolite and pumice were selected to determine the best combination among them for self-healing. Normal and fibre reinforced mortar and engineered cementitious composite (ECC) specimens were employed for the study. In order to develop self-healing bacterial concrete based materials, it is crucial to understand whether the introduction of mineral producing bacteria and nutrients adversely affect the properties. Thus, various concentrations of bacteria and nutrients were tested to determine the best possible combinations without sacrificing concrete properies. Evaluation of healing effect was determined by comparing compressive strength, sorptivity and rapid chloride permeability (RCPT), four point bending and ultrasonic pulse velocity (UPV) properties of sound and damaged specimens at different ages. Healing associated with crack closure was visualised and analysed using scanning electronmicroscopy (SEM), Energy Dispersive Spectrum Energy (EDS) and X-ray diffraction (XRD) studies. Finally, an attempt was made to employ statistical models for parameter optimization of self-healing characteristics in terms of compressive strength, sorptivity, RCPT and UPV by design and analysis of experiments. Evaluation of results to determine self-healing efficiency indicated that a significant amount of self-healing was achieved by all three selected bacteria, out of which Sporosarcina pasteurii and Bacillus subtilis subsp. spizizenii found to be promising choices. Both zeolite and pumice turned out to be effective protective vehicles. Statistical modelling of the experiment proved to be the ideal choice for modelling self-healing characteristics.

SYNTHESIS AND CHARACTERIZATION OF SELF-HEALING MORTAR WITH MODIFIED STRENGTH

2015 ◽  
Vol 76 (1) ◽  
Author(s):  
Gassan Fahim Huseien ◽  
Jahangir Mirza ◽  
Nur Farhayu Ariffin ◽  
Mohd Warid Hussin
Keyword(s):  
Early Stage ◽  
Polymeric Materials ◽  
Building Blocks ◽  
Ultrasonic Pulse Velocity ◽  
Cementitious Materials ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Diglycidyl Ether ◽  
Self Healing ◽  
Research Initiative

Cementitious materials being the most prospective building blocks achieving their absolute strength to avoid the deterioration in the early stage of service life is ever-demanding. Minimizing the labor and capital-intensive maintenance and repair cost is a critical challenge. Thus, self-healing mortars with modified strength are proposed. Lately, self-healing of micro-cracks by introducing bacteria during the formation of mortar or concrete became attractive. Self-healing with polymeric admixtures is considered to be relatively more durable and faster process. Certainly, the self-healing of synthetic polymeric materials is inspired by biological systems, where the damage triggers an autonomic healing response. This emerging and fascinating research initiative may significantly improve the durability and the safety limit of the polymeric components potential for assorted applications. In this work, using epoxy resin (diglycidyl ether of bisphenol A) without any hardener as admixture polymeric-cementitious materials is prepared. These epoxy-modified mortars are synthesized with various polymer-cement ratios subjected to initial wet/dry curing (WDC) together with long term dry curing (DC). Their self-healing function and hardening effects are evaluated via preloading and drying of the specimens, chemical analysis, and ultrasonic pulse velocity testing. It is demonstrated that 10% of polymer is the best proportion for polymer-cement ratio. Furthermore, the wet/dry curing is established to be superior process for healing hairline cracks present in the mortar. The excellent features of the results suggest that our novel method may constitute a basis for improving the compressive strength and self-healing features of mortars.    

COMPRESSIVE STRENGTH EVALUATION OF LIGHTWEIGHT CONCRETE WITH EXPANDED GLASS AGGREGATE BY ULTRASONIC PULSE VELOCITY METHOD

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Christopher Collins ◽  
Saman Hedjazi
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Normal Weight ◽  
Unit Weight ◽  
Normal Weight Concrete

In the present study, a non-destructive testing method was utilized to assess the mechanical properties of lightweight and normal-weight concrete specimens. The experiment program consisted of more than a hundred concrete specimens with the unit weight ranging from around 850 to 2250 kg/m3. Compressive strength tests were performed at the age of seven and twenty eight days. Ultrasonic Pulse Velocity (UPV) was the NDT that was implemented in this study to investigate the significance of the correlation between UPV and compressive strength of lightweight concrete specimens. Water to cement ratio (w/c), mix designs, aggregate volume, and the amount of normal weight coarse and fine aggregates replaced with lightweight aggregate, are the variables in this work. The lightweight aggregate used in this study, Poraver®, is a product of recycled glass materials. Furthermore, the validity of the current prediction methods in the literature was investigated including comparison between this study and an available expression in the literature on similar materials, for calculation of mechanical properties of lightweight concrete based on pulse velocity. It was observed that the recently developed empirical equation would better predict the compressive strength of lightweight concrete specimens in terms of the pulse velocity.

scholarly journals Experimental Evaluation of Untreated and Pretreated Crumb Rubber Used in Concrete

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 558
Author(s):  
Hamad Hassan Awan ◽  
Muhammad Faisal Javed ◽  
Adnan Yousaf ◽  
Fahid Aslam ◽  
Hisham Alabduljabbar ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Water Treatment ◽  
Mechanical Performance ◽  
Strength Loss ◽  
Ultrasonic Pulse Velocity ◽  
Crumb Rubber ◽  
Pulse Velocity ◽  
Unit Weight ◽  
Lime Treatment

The present research aims at evaluating the mechanical performance of untreated and treated crumb rubber concrete (CRC). The study was also conducted to reduce the loss in mechanical properties of CRC. In this study, sand was replaced with crumb rubber (CR) with 0%, 5%, 10%, 15%, and 20% by volume. CR was treated with NaOH, lime, and common detergent for 24 h. Furthermore, water treatment was also carried out. All these treatments were done to enhance the mechanical properties of concrete that are affected by adding CR. The properties that were evaluated are compressive strength, indirect tensile strength, unit weight, ultrasonic pulse velocity, and water absorption. Compressive strength was assessed after 7 and 28 days of curing. The mechanical properties were decreased by increasing the percentage of the CR. The properties were improved after the treatment of CR. Lime treatment was found to be the best treatment of all four treatments followed by NaOH treatment and water treatment. Detergent treatment was found to be the worse treatment of all four methods of treatment. Despite increasing the strength it contributed to strength loss.

scholarly journals Effect of Hollow Corundum Microspheres Additive on Physical and Mechanical Properties and Thermal Shock Resistance Behavior of Bauxite Based Refractory Castable

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4736
Author(s):  
Rimvydas Stonys ◽  
Jurgita Malaiškienė ◽  
Jelena Škamat ◽  
Valentin Antonovič
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Thermal Shock ◽  
Modulus Of Elasticity ◽  
Thermal Shock Resistance ◽  
Visual Analysis ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Shock Resistance

This paper analyses the effect of hollow corundum microspheres (HCM) on both physical-mechanical properties (density, ultrasonic pulse velocity, modulus of elasticity, and compressive strength) and thermal shock resistance behavior of refractory medium cement castable with bauxite aggregate. Moreover, the scanning electron microscopy (SEM) results of HCM and refractory castable samples are presented in the paper. It was found that the replacement of bauxite of 0–0.1 mm fraction by HCM (2.5%, 5%, and 10% by weight of dry mix) had no significant effect on the density and compressive strength of castable, while the modulus of elasticity decreased by 15%. Ultrasonic pulse velocity (Vup) values and the visual analysis of the samples after thermal cycling showed that a small amount of HCM in composition of refractory castable could reduce the formation and propagation of cracks and thus increase its thermal shock resistance.

scholarly journals Analysis of damage failure in uniaxial compressive of cemented paste backfill by ultrasonic pulse velocity test

2021 ◽  
Vol 37 (2) ◽  
Author(s):  
B. Wang ◽  
L. Li ◽  
Y. Yu ◽  
B. Huo ◽  
J. Liu
Keyword(s):  
Mass Fraction ◽  
Damage Mechanics ◽  
Microstructural Analysis ◽  
Ultrasonic Pulse Velocity ◽  
Cementitious Materials ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Experimental Results ◽  
Cemented Paste Backfill ◽  
Paste Backfill

Cemented paste backfill (CPB) is prepared by mixing cementitious materials, tailings and water. Uniaxial compressive strength (UCS) is one of the most commonly used indicators for evaluating the mechanical performance of CPB. Ultrasonic pulse velocity (UPV) testing which is a non-destructive measurement, can also be applied to determine the mechanical properties of cement-based materials such as CPB. In order to study the failure mechanism of CPB,144 CPB samples prepared at different mass fraction and cement-tailing ratios were subjected to the UCS and UPV tests at 7,14 and 28 days of curing age. The effect of cement-tailing ratio and mass fraction on the UCS and UPV of CPB samples were obtained, the UCS values were correlated with the corresponding UPV data. Microstructural analysis was also performed on CPB samples to understand the effect of microstructure on the UCS data. The results show that the UCS and UPV values of CPB increased with cement-tailing ratio, mass fraction and curing time. Based on the experimental results, the damage constitutive equations and the damage evolution equations of different backfills were proposed on the basis of damage mechanics. Moreover, comparative analysis of constitutive model and experimental results were made to verify the reliability of the damage model. The results acquired by this paper provide a scientific basis for the rational strength design of backfill mine.

scholarly journals Self-healing bacterial cementitious concrete composites: development and performance evaluation

2021 ◽  
Author(s):  
Sini Bhaskar
Keyword(s):  
Compressive Strength ◽  
Bacillus Subtilis ◽  
Statistical Modelling ◽  
Energy Dispersive Spectrum ◽  
Ultrasonic Pulse Velocity ◽  
Pulse Velocity ◽  
Self Healing ◽  
Chloride Permeability ◽  
Sporosarcina Pasteurii ◽  
Subtilis Subsp

The principal objective of the research is to contribute towards attaining the goal of developing self-healing cementitious concrete composites by incorporating bacteria as healing agent. Since the root cause of the majority of structural failure is attributed to concrete cracking, there is a compelling economic incentive to develop a concrete that can treat and repair the damage all by itself. Even though some research has been carried out in this area, a major breakthrough in identifying the types of bacteria, modes to protect this bacteria from high pH concrete environment and nutrients for effective healing are yet to materialise. For the present study, three different bacteria namely, Sporosarcina ureae, Sporosarcina pasteurii and Bacillus subtilis subsp. spizizenii and two protective vehicles such as zeolite and pumice were selected to determine the best combination among them for self-healing. Normal and fibre reinforced mortar and engineered cementitious composite (ECC) specimens were employed for the study. In order to develop self-healing bacterial concrete based materials, it is crucial to understand whether the introduction of mineral producing bacteria and nutrients adversely affect the properties. Thus, various concentrations of bacteria and nutrients were tested to determine the best possible combinations without sacrificing concrete properies. Evaluation of healing effect was determined by comparing compressive strength, sorptivity and rapid chloride permeability (RCPT), four point bending and ultrasonic pulse velocity (UPV) properties of sound and damaged specimens at different ages. Healing associated with crack closure was visualised and analysed using scanning electronmicroscopy (SEM), Energy Dispersive Spectrum Energy (EDS) and X-ray diffraction (XRD) studies. Finally, an attempt was made to employ statistical models for parameter optimization of self-healing characteristics in terms of compressive strength, sorptivity, RCPT and UPV by design and analysis of experiments. Evaluation of results to determine self-healing efficiency indicated that a significant amount of self-healing was achieved by all three selected bacteria, out of which Sporosarcina pasteurii and Bacillus subtilis subsp. spizizenii found to be promising choices. Both zeolite and pumice turned out to be effective protective vehicles. Statistical modelling of the experiment proved to be the ideal choice for modelling self-healing characteristics.

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