skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Title: Evaluation of Precision Statements for Physio-mechanical Characterization Tests on GFRP Bars
Abstract Glass fiber reinforced polymer (GFRP) bars are composite materials that, in the field of civil engineering, serve as an alternative for the internal steel reinforcement of concrete structures. The study and development of these material systems in construction are relatively new, requiring targeted research and development to achieve greater adoption. In this scenario, research and standardization play crucial roles. The development and publication of new test methods, material specifications, and other standards, as well as the improvement of the existing ones, allow for quality control, validation, and acceptance. One of these improvements is the evaluation of precision statements of the different ASTM standards related to the physical-mechanical and durability characterization of GFRP bars used as internal concrete reinforcement. Precision refers to how closely test results obtained under specific conditions agree with each other. A precision statement allows potential users to assess the test method’s general suitability for their intended applications. It should provide guidance on the type of variation that can be expected between test results when the method is used in one or more competent laboratories. The present study aims to enhance the precision statements in ASTM standards pertaining to the geometric, material, mechanical, and physical properties required for GFRP bars in concrete reinforcement, including ASTM standards like ASTM D7205M-21, Standard Test Method for Tensile Properties of Fiber Reinforced Polymer Matrix Composite Bars; ASTM D7617M-11(2017), Standard Test Method for Transverse Shear Strength of Fiber-Reinforced Polymer Matrix Composite Bars; and ASTM D7913M-14(2020), Standard Test Method for Bond Strength of Fiber-Reinforced Polymer Matrix Composite Bars to Concrete by Pullout Testing, while in accordance with the statistical procedures and calculation methods outlined in ASTM Practices ASTM E177-20, Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods, and ASTM E691-22, Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method.  more » « less
Award ID(s):
1916342
PAR ID:
10538742
Author(s) / Creator(s):
; ; ; ;
Publisher / Repository:
ASTM International
Date Published:
Journal Name:
Journal of Testing and Evaluation
Volume:
52
Issue:
4
ISSN:
0090-3973
Page Range / eLocation ID:
2055 to 2068
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Beckwith, S.; Flinn, B.; Dustin, J. (Ed.)
    A novel additive manufacturing process utilizing the laminated object manufacturing (LOM) technology with woven natural fiber-reinforced biopolymer is investigated in this paper. Traditional synthetic composite materials are products from nonrenewable crude oil with limited end-of-life options, and therefore not environmentally friendly. The continuous woven natural fiber is used to significantly strengthen the mechanical properties of biocomposites and PLA biopolymer as the matrix made the material completely biodegradable. This is one of the promising replacements for synthetic composites in applications such as automotive panels, constructive materials, and sports and musical instruments. A LOM 3D printer prototype has been designed and built by the team using a laser beam in cutting the woven natural fiber reinforcement and molten PLA powder to bind layers together. Tensile and flexural properties of the LOM 3D printed biocomposites were measured using ASTM test standards and then compared with corresponding values measured from pure PLA specimens 3D printed through FDM. Improved mechanical properties from LOM 3D-printed biocomposites were identified by the team. SEM imaging was performed to identify the polymer infusing and fiber-matrix binding situations. This research took advantage of both the material and process’s benefits and combine them into one sustainable practice. 
    more » « less
  2. Recycling glass fiber reinforced polymer (GFRP) composite materials has been proven to be challenging due to their high mechanical performance and high resistance to harsh chemical and thermal conditions. This work discusses the efforts made in the past to mechanically process GFRP waste materials by cutting them into large-sized (cm scale) pieces, as opposed to pulverization, for use in concrete mixtures. These pieces can be classified into two main categories—coarse aggregate and discrete reinforcement, here referred to as “needles.” The results from all the studies show that using GFRP coarse aggregate leads to significant reductions in the compressive strength and tensile strength of concrete. However, GFRP needles lead to sizable increases in the energy absorption capacity of concrete. In addition, if the glass fibers are longitudinally aligned within the needles, these elements can substantially increase the tensile strength of concrete. Processing GFRP waste into needles requires less energy and time than that for producing GFRP coarse aggregate. Also, compared to pulverized GFRP waste, which consists of broken and separate particles of glass and resin that at best can be used as low-quality fillers, GFRP needles are high strength composite elements 
    more » « less
  3. This paper reports on a combined experimental and numerical modeling investigation of cracking of concrete slabs with GFRP reinforcement. At this stage of the project, attention is given to early-age cracking driven by plastic shrinkage, preceding longer term considerations of cracking resistance over the service life of field applications. Of interest is the effectiveness of GFRP reinforcement in restricting plastic shrinkage cracking. Nine small-scale slab specimens were subjected to controlled evaporation rates. Images of crack development were acquired periodically, from which crack width estimations were made. Comparisons were made between slabs reinforced with conventional steel and those reinforced with GFRP, along with control specimens lacking reinforcement. During the period of plastic shrinkage, the time of crack initiation and subsequent crack openings do not appear to be influenced by the presence of the reinforcing bars. To understand this behavior, six early-age bond tests were conducted for both types of the bars after 1, 2, and 3 h exposure to the controlled evaporation rate. In addition, concrete strength development and time of settings were measured using penetration resistance tests on a representative mortar. The numerical modeling component of this research is based on a Voronoi cell lattice model; in this approach, the relative humidity, temperature, and displacement fields are discretized in three-dimensions, allowing for a comprehensive investigation of material behavior within the controlled environment. Based on the measured bond properties, our simulations confirm that the reinforcing bars restrict crack development, though they do not prevent it entirely. 
    more » « less
  4. The mechanical properties of woven natural fiber reinforced polymers additively manufactured through Laminated Object Manufacturing (LOM) technology are investigated in this paper. The benefits of both the material and manufacturing process were combined into a sustainable practice, as a potential alternative to traditional synthetic composite materials made from nonrenewable crude oil with limited end-of-life alternatives. Woven jute fiber reinforcements are used to strengthen both synthetic and bio- thermoplastic polymers in creating highly biodegradable composite structures. Such materials, as one of the prospective alternatives for synthetic composites, can be used in many engineering fields such as automobile panels, construction materials, and commodity and recreational products including sports and musical instruments. A LOM 3D printer prototype was designed and built by the authors. All woven jute/polymer biocomposite test specimens made using the built prototype in this study had their mechanical (both tensile and flexural) properties assessed using ASTM test standards and then compared to similar values measured from pure polymer specimens. Improved mechanical characteristics were identified and analyzed. Finally, SEM imaging was performed to identify the polymer infusion and fibermatrix bonding conditions. 
    more » « less
  5. null (Ed.)
    As part of the effort to improve the seismic performance of buildings in Alaska (AK), many of the deficient structures in Anchorage, AK, were retrofitted—some with externally bonded fiber-reinforced polymer (EBFRP) composite systems. The 2018 magnitude 7.1 Cook Inlet earthquake that impacted the same region offered an opportunity to evaluate the performance of EBFRP retrofits in a relatively high-intensity earthquake. This study summarizes the following findings of this field investigation: (1) the performance of EBFRP-retrofitted structures in the Cook Inlet earthquake and (2) the observations concerning the condition of FRP retrofits from over a decade of exposure in a subarctic environment. A deployment team from the National Institute of Standards and Technology (NIST) in collaboration with the University of Delaware (UD) Center for Composite Materials conducted post-earthquake inspections of EBFRP retrofits in multiple buildings to assess their performance during the earthquake and condition with respect to weathering. EBFRP debonding was documented with infrared thermography and acoustic sounding and the bond quality between EBFRP and concrete was assessed using pull-off tests. Visual inspections showed no major signs of earthquake damage in the EBFRP-retrofitted components. However, evaluation of debonding and pull-off test results suggested that outdoor conditions may have led to bond deterioration between EBFRP and concrete from installation defects that grew over time, freeze–thaw expansion from moisture present at the FRP/concrete interface, differences in thermal expansion of the materials, or a combination thereof. The carbon fiber–reinforced polymer (CFRP) bond to concrete was found to be more vulnerable to outdoor exposure than the glass fiber–reinforced polymer (GFRP) bond. Earthquake effects on FRP/concrete bond could not be assessed due to the lack of baseline data. 
    more » « less