scholarly journals Mechanical and Impact Properties of Engineered Cementitious Composites Reinforced with PP Fibers at Elevated Temperatures

Fire ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 3
Author(s):  
Raad A. Al-Ameri ◽  
Sallal Rashid Abid ◽  
Mustafa Özakça
Keyword(s):  
Room Temperature ◽  
Elevated Temperatures ◽  
Impact Resistance ◽  
Ductile Failure ◽  
Cementitious Composites ◽  
Repeated Impact ◽  
Normal Concrete ◽  
Engineered Cementitious Composites ◽  
Impact Performance ◽  
The Impact

The repeated impact performance of engineered cementitious composites (ECCs) is not well explored yet, especially after exposure to severe conditions, such as accidental fires. An experimental study was conducted to evaluate the degradation of strength and repeated impact capacity of ECCs reinforced with Polypropylene fibers after high temperature exposure. Compressive strength and flexural strength were tested using cube and beam specimens, while disk specimens were used to conduct repeated impact tests according to the ACI 544-2R procedure. Reference specimens were tested at room temperature, while three other groups were tested after heating to 200, 400 and 600 °C and naturally cooled to room temperature. The test results indicated that the reference ECC specimens exhibited a much higher failure impact resistance compared to normal concrete specimens, which was associated with a ductile failure showing a central surface fracture zone and fine surface multi-cracking under repeated impacts. This behavior was also recorded for specimens subjected to 200 °C, while the exposure to 400 and 600 °C significantly deteriorated the impact resistance and ductility of ECCs. The recorded failure impact numbers decreased from 259 before heating to 257, 24 and 10 after exposure to 200, 400 and 600 °C, respectively. However, after exposure to all temperature levels, the failure impact records of ECCs kept at least four times higher than their corresponding normal concrete ones.

scholarly journals Residual Impact Performance of ECC Subjected to Sub-High Temperatures

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 454
Author(s):  
Raad A. Al-Ameri ◽  
Sallal Rashid Abid ◽  
Gunasekaran Murali ◽  
Sajjad H. Ali ◽  
Mustafa Özakça ◽  
...  
Keyword(s):  
High Temperatures ◽  
Reference Group ◽  
Impact Resistance ◽  
Impact Response ◽  
Repeated Impact ◽  
Impact Performance ◽  
Compressive And Flexural Strengths ◽  
Reference Specimens ◽  
Temperature Exposure ◽  
The Impact

Despite the fact that the mechanical properties of Engineered Cementitious Composites (ECC) after high-temperature exposure are well investigated in the literature, the repeated impact response of ECC is not yet explored. Aiming to evaluate the residual impact response of ECC subjected to sub-high temperatures under repeated drop weight blows, the ACI 544-2R repeated impact test was utilized in this study. Disk impact specimens (150 mm diameter and 64 mm thickness) were prepared from the M45 ECC mixture but using polypropylene fibers, while similar 100 mm cube specimens and 100 × 100 × 400 mm prism specimens were used to evaluate the compressive and flexural strengths. The specimens were all cast, cured, heated, cooled, and tested under the same conditions and at the same age. The specimens were subjected to three temperatures of 100, 200 and 300 °C, while a group of specimens was tested without heating as a reference group. The test results showed that heating to 100 and 200 °C did not affect the impact resistance noticeably, where the retained cracking and failure impact numbers and ductility were higher or slightly lower than those of unheated specimens. On the other hand, exposure to 300 °C led to a serious deterioration in the impact resistance and ductility. The retained failure impact numbers after exposure to 100, 200, and 300 °C were 313, 257, and 45, respectively, while that of the reference specimens was 259. The results also revealed that the impact resistance at this range of temperature showed a degree of dependency on the compressive strength behavior with temperature.

High-Performance Impact-Resistant Concrete Mixture for Transportation Infrastructure Applications

2019 ◽  
Vol 2673 (12) ◽  
pp. 628-635 ◽  
Author(s):  
Kamal Baral ◽  
Jovan Tatar ◽  
Qian Zhang
Keyword(s):  
Energy Absorption ◽  
High Performance ◽  
Impact Resistance ◽  
Absorption Capacity ◽  
Flexural Behavior ◽  
Cementitious Composites ◽  
Repeated Impact ◽  
Energy Absorption Capacity ◽  
Transportation Infrastructures ◽  
The Impact

Engineered cementitious composites (ECC) is a class of high-performance fiber-reinforced cementitious composites featuring metal-like strain-hardening behavior under tension and high ductility. The highly ductile behavior of ECC often results in high impact resistance and energy absorption capacity, which make ECC suitable for applications in structures that are prone to impact damages, like exterior bridge girders, bridge piers, and crash barriers. In a recent study, a new ECC mixture has been developed using domestically available polyvinyl alcohol (PVA) fibers and regular river sand in replacement of imported PVA fibers and fine silica sand that are normally used in other ECC mixtures. The newly developed mixture, with improved local accessibility of raw materials, enables structural-scale applications of ECC in transportation infrastructures. To evaluate the suitability of the mixture for impact-resistant structures, in this paper, the tensile and flexural behavior of the newly developed material were characterized under pseudo-static loading and high strain-rate loadings up to 10−1 s−1. Direct drop-weight impact test was also conducted to assess the impact resistance and energy absorption capacity of the material. It was ensured that the ECC mixture maintains high tensile strain capacity above 1.8% under all tested strain rates. Regarding the damage characteristics, energy absorption capacity and load-bearing capacity during repeated impact loadings, ECC was found to have 75% higher energy dissipation capacity compared with regular reinforced concrete specimens and superior damage tolerance. The research results demonstrated that the newly developed ECC has a great potential to improve the impact resistance of transportation infrastructures.

scholarly journals Residual Repeated Impact Strength of Concrete Exposed to Elevated Temperatures

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 941
Author(s):  
Raad A. Al-Ameri ◽  
Sallal R. Abid ◽  
G. Murali ◽  
Sajjad H. Ali ◽  
Mustafa Özakça
Keyword(s):  
High Temperature ◽  
Impact Strength ◽  
Elevated Temperatures ◽  
Impact Resistance ◽  
Test Results ◽  
Repeated Impact ◽  
High Temperature Exposure ◽  
Compressive And Flexural Strengths ◽  
Temperature Exposure ◽  
The Impact

Portland cement concrete is known to have good fire resistance; however, its strength would be degraded after exposure to the temperatures of fire. Repeated low-velocity impacts are a type of probable accidental load in many types of structures. Although there is a rich body of literature on the residual mechanical properties of concrete after high temperature exposure, the residual repeated impact performance of concrete has still not been well explored. For this purpose, an experimental study was conducted in this work to evaluate the effect of high temperatures on the repeated impact strength of normal strength concrete. Seven identical concrete patches with six disc specimens each were cast and tested using the ACI 544-2R repeated impact setup at ambient temperature and after exposure to 100, 200, 300, 400, 500 and 500 °C. Similarly, six cubes and six prisms from each patch were used to evaluate the residual compressive and flexural strengths at the same conditions. Additionally, the scattering of the impact strength results was examined using three methods of the Weibull distribution, and the results are presented in terms of reliability. The test results show that the cracking and failure impact numbers of specimens heated to 100 °C reduced slightly by only 2.4 and 3.5%, respectively, while heating to higher temperatures deteriorated the impact resistance much faster than the compressive and flexural strengths. The percentage reduction in impact resistance at 600 °C was generally higher than 96%. It was also found that the deduction trend of the impact strength with temperature is more related to that of the flexural strength than the compressive strength. The test results also show that, within the limits of the adopted concrete type and conducted tests, the strength reduction after high temperature exposure is related to the percentage weight loss.

scholarly journals Impact Resistance of Epoxy Composites Reinforced with Amazon Guaruman Fiber: A Brief Report

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2264
Author(s):  
Raphael H. M. Reis ◽  
Fabio C. Garcia Filho ◽  
Larissa F. Nunes ◽  
Veronica S. Candido ◽  
Alisson C. R. Silva ◽  
...  
Keyword(s):  
Fiber Composite ◽  
Impact Resistance ◽  
Fiber Composites ◽  
Epoxy Composites ◽  
Impact Performance ◽  
Electron Microscopy Analysis ◽  
Ballistic Properties ◽  
Microscopy Analysis ◽  
Izod Impact ◽  
The Impact

Fibers extracted from Amazonian plants that have traditionally been used by local communities to produce simple items such as ropes, nets, and rugs, are now recognized as promising composite reinforcements. This is the case for guaruman (Ischinosiphon körn) fiber, which was recently found to present potential mechanical and ballistic properties as 30 vol% reinforcement of epoxy composites. To complement these properties, Izod impact tests are now communicated in this brief report for similar composites with up to 30 vol% of guaruman fibers. A substantial increase in impact resistance, with over than 20 times the absorbed energy for the 30 vol% guaruman fiber composite, was obtained in comparison to neat epoxy. These results were statistically validated by Weibull analysis, ANOVA, and Tukey’s test. Scanning electron microscopy analysis disclosed the mechanisms responsible for the impact performance of the guaruman fiber composites.

scholarly journals Impact Response of Hammerhead Pier Fibrous Concrete Beams Designed with Topology Optimization

2020 ◽  
Author(s):  
Meivazhisalai Parasuraman Salaimanimagudam ◽  
Covaty Ravi Suribabu ◽  
Gunasekaran Murali ◽  
Sallal R. Abid
Keyword(s):  
Topology Optimization ◽  
Concrete Beams ◽  
Impact Load ◽  
Impact Resistance ◽  
Adaptive Mesh ◽  
Impact Response ◽  
Adaptive Meshing ◽  
Repeated Impact ◽  
Ductility Ratio ◽  
The Impact

Reducing the weight of concrete beams is a primary (beyond strength and durability) concern of engineers. Therefore, this research was directed to investigate the impact response of hammerhead pier concrete beams designed with density-based method topology optimization. The finite element topology optimization was conducted using Autodesk fusion 360 considering three different mesh sizes of 7 mm, 10 mm, and adaptive meshing. Three optimized hammerhead beam configurations; HB1, HB2, and HB3, respectively, with volume reductions greater than 50 %. In the experimental part of this research, nine beams were cast with identical size and configuration to the optimized beams. Three beams, identical to the optimized beams, were tested under static bending for verification purposes. In comparison, six more beams, as in the preceding three beams but without and with hooked end steel fibers, were tested under repeated impact load. The test results revealed that the highest flexural capacity and impact resistance at crack initiation and failure were recorded for the adaptive mesh beams (HB3 and HB3SF). The failure impact energy and ductility ratio of the beam HB3SF was higher than the beams HB1SF and HB2SF by more than 270 %. The results showed that the inclusion of steel fiber duplicated the optimized beam’s impact strength and ductility several times. The failure impact resistance of fibrous beams was higher than their corresponding plain beams by approximately 2300 to4460 %, while their impact ductility ratios were higher by 6.0 to 18.1 times.

Effect of Alkali Treatment and Molding Temperature on Flexural and Impact Properties of Coir-Fibre-Epoxy Composite

2015 ◽  
Vol 24 (4) ◽  
pp. 096369351502400
Author(s):  
C. K. Tai ◽  
R. Ahmad ◽  
H. M. Akil ◽  
M. M. Ratnam
Keyword(s):  
Room Temperature ◽  
Alkali Treatment ◽  
Flexural Modulus ◽  
Impact Resistance ◽  
Compression Molding ◽  
Impact Properties ◽  
Molding Temperature ◽  
Coir Fibre ◽  
Fibre Composites ◽  
The Impact

The combined effects of alkali treatment and compression molding temperature on the flexural strength and impact resistance of woven coir fibre composites are investigated. Ten pieces of composites plates made from single-layer woven coir fibre fabricated under different process parameters were used in the study. Five pieces of the coir woven fibre were treated with 6% sodium hydroxide (NaOH) solution while another five were left untreated. The compression molding temperature were varied between room temperature (25°C), 50°C, 75°C, 100°C and 125°C. The flexural properties of the composite were evaluated using the three-point flexural test, while the impact resistance was investigated by drop weight impact tests using a specially designed indenter. The indentation radius on each test specimen was measured using a 3-D metrology system and the depth of indentation was determined from the geometry of the indenter. The results show that the maximum flexural load to failure is improved by 38.9% when the fibres were treated and the compression molding temperature is increased to 125°C. The flexural modulus generally decreased with increase in the molding temperature. The depth of indentation in the treated coir woven composites is lower than that of untreated fibre composite at all molding temperatures. The impact resistance of both untreated and treated fibre composites decreased with the increase in the compression molding temperature. Composites fabricated by molding at room temperature, 50°C and 75°C using treated fibre produced the best impact properties.

scholarly journals Experimental Tests and Reliability Analysis of the Cracking Impact Resistance of UHPFRC

Fibers ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 74
Author(s):  
Hussain A. Jabir ◽  
Sallal R. Abid ◽  
Gunasekaran Murali ◽  
Sajjad H. Ali ◽  
Sergey Klyuev ◽  
...  
Keyword(s):  
High Performance ◽  
Steel Fiber ◽  
Impact Resistance ◽  
High Strength ◽  
Experimental Tests ◽  
Fiber Reinforced Concrete ◽  
Fiber Types ◽  
Impact Performance ◽  
High Performance Fiber ◽  
The Impact

Ultra-high performance (UHP) concrete is a special type of fibrous cementitious composite that is characterized by high strength and superior ductility, toughness, and durability. This research aimed to investigate the resistance of ultra-high performance fiber-reinforced concrete (UHPFRC) against repeated impacts. An adjusted repeated drop mass impact test was adopted to evaluate the impact performance of 72 UHPFRC disc specimens. The specimens were divided into six mixtures each of 12 discs. The only difference between the mixtures was the types of fibers used, while all other mixture components were the same. Three types of fibers were used: 6 mm micro-steel, 15 mm micro-steel, and polypropylene. All mixtures included 2.5% volumetric content of fibers, however with different combinations of the three fiber types. The test results showed that the mixtures with the 15 mm micro-steel fiber absorbed a higher number of impact blows until cracking compared to other mixtures. The mixture with pure 2.5% of 15 mm micro-steel fiber exhibited the highest impact resistance, with percentage increases over the other mixtures ranging from 25 to 140%. In addition, the Weibull distribution was used to investigate the cracking impact resistance of UHP at different levels of reliability.

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