Product Testing and Physical Properties Contents...process (HSRP). Neuvokas has identified specific...

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Neuvokas Corp.

Product Testing and Physical Properties

Contents

Product Testing and Physical Properties ............................................................................................. 1

1.0. Complete Test Plan ................................................................................................................... 1

2.0. Product Validation .................................................................................................................... 3

2.1. Longitudinal Tensile Strength and Modulus, ASTM D7205 .................................... 3

2.2. Bond Properties (in concrete), ASTM D944 or ACI 440.3R B.3, completed by George

Morcous, Ph.D., P.E., University of Nebraska-Lincoln ............................................................ 4

2.3. Shear Strength, ASTM D7617...................................................................................... 6

2.4. Interlaminar Shear Testing after Alkaline Exposure ............................................... 7

2.5. Accelerated testing for alkali resistance, Completed by Brahim Benmokrane,

Ph.D.,P.E., Universitie de Sherbrook ........................................................................................ 8

2.6. Durability Properties, ACI 440.3R-12 B.6 ................................................................ 10

2.7. Creep Resistance ....................................................................................................... 11

2.8. Fatigue Performance ................................................................................................ 14

2.9. Glass Transition Temperature ................................................................................. 14

2.10. Moisture Absorption ................................................................................................. 14

2.11. SEM Analysis ............................................................................................................... 15

2.12. Bond Dependent Coefficient ................................................................................... 16

1.0. COMPLETE TEST PLAN

Neuvokas manufactures basalt fiber reinforced polymer (BFRP) reinforcing bar for use in

reinforced concrete construction, using a patented, modified, high speed pultrusion

process (HSRP). Neuvokas has identified specific testing based on the American Concrete

Institute (ACI) 440.3R-12, Guide Test Methods for Fiber Reinforced Polymer (FRP)

Composites for Reinforcing or Strengthening Concrete and Masonry Structures. This

document lays out an extensive list of test procedures that can be necessary to complete

depending on final application of the FRP product. The general strategy developed by

Neuvokas is to initially focus on a select group of primary tests. These primary tests were

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selected by a Professional Civil Engineer as being critical for slab-on-grade and the tilt-up

wall concrete markets. These tests are listed below.

1. Longitudinal Tensile Strength and Modulus, ASTM D7205

2. Bond Properties (in concrete), ASTM D944

3. Shear Strength, ASTM D7617

4. Interlaminar Shear testing with alkaline resistance, ASTM D4475

Each of these tests has been completed and has allowed Neuvokas to establish

performance when compared to competitors’ (GFRP and BFRP) published performance

data. Table 1 shows the complete list of completed vs in-process testing.

Neuvokas has continued to evaluate product performance specific to the use of its product

in structural design. These applications may require additional test information that

Neuvokas has not fully completed at this time, but is in process and nearly complete.

These tests are listed below. Certain tests listed below have extensive time requirements

and these specifics tests have been identified and begun.

1. Creep Properties, ASTM D7337 (To complete creep testing lower load levels can

require up to 1 year to complete) In-process, begun August 2016

2. Durability Properties, ACI 440.3R-12 B.6, (on-going test)

3. Fatigue Properties, D3479, Completed, working on data comparison

4. Bond Dependent Coefficient Completed

In addition to product performance testing Neuvokas has completed the following material

characterization tests.

1. Coefficient of thermal expansion, ASTM E831

2. Glass transition temperature, ASTM E1356

3. Moisture Absorption (on-going test)

4. Volume Fraction, ASTM D3171

5. Alkaline Resistance of Fiber

6. Comparative SEM Analysis



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Table 1. Chart of completed vs. in process Neuvokas BFRP rebar tests

Neuvokas uses a combination of certain tests mentioned above to monitor the quality of rebar

that is produced. Tensile testing, shear testing, moisture absorption, resin percentages, and fiber

sizing content are all tests that are used to ensure a high quality product is being produced. Tests

such as glass transition temperature are completed periodically to ensure these material property

values do not change.

2.0. PRODUCT VALIDATION

2.1. LONGITUDINAL TENSILE STRENGTH AND MODULUS, ASTM D7205

Tensile testing is completed per ASTM D7205 specifications. Figure 1 contains an image of

a rebar sample loaded in a mechanical test frame and a failed sample after testing. ACI

440.6-08, Specification for Carbon and Glass Fiber-Reinforced Polymer Bar Materials for

Concrete Reinforcement, has requirements for the tensile strength of rebar products.

Neuvokas basalt rebar will meet or exceed the requirements for glass FRP rebar in all

cases. This ACI documents lists the required strength for glass FRP rebar, #3 size, at 110

ksi.

SpecificationLongitutal Tensile Strength and Modulus ASTM D7205 x

Bond Properties ACI 440.3R-12 B.3 x

Shear Strength ASTM D7617 x

Interlaminar Shear Testing x

Creep Properties ASTM D7337 x

Durability Properties ACI 440.3R-12 B.6 x x

Fatigue Properties ASTM D3479 x

Bond Dependent Coefficient x

Coefficient of Thermal Expansion ASTM E831 x

Glass Transition Temperature ASTM E1356 x

Moisture Absorption x

Volume Fraction ASTM D3171 x

Alkaline Resistance of Fiber x

Comparative SEM Analysis x

Secondary

Testing

Other

Material

Properties

In P

roce

ss

Comple

ted

Test Procedure

Primary

Testing



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Figure 1. Tensile sample tested to failure in test lab at Michigan Tech University

The industry standard for calculating a tensile strength that can be published as a

guaranteed tensile strength is to subtract three times the standard deviation from the

average strength. Neuvokas has tested over 150 samples and does testing weekly to

ensure a quality product is being manufactured. It can be seen in Table 2 that Neuvokas

has a guaranteed tensile strength of 145.6 ksi based on the latest data available. It can also

be seen in Table 2 the average elastic modulus (Young’s Modulus) is approximately 6000

ksi. This also meets the ACI specifications for glass FRP rebar.

Table 2. #3 Gatorbar Tensile Strength Summary This data is representative of basalt fibers

manufacturing into 3/8” diameter rebar via the HSRP process .

2.2. BOND PROPERTIES (IN CONCRETE), ASTM D944 OR ACI 440.3R B.3, COMPLETED BY GEORGE

MORCOUS, PH.D., P.E., UNIVERSITY OF NEBRASKA-LINCOLN

As part of the product development process Neuvokas has evaluated multiple coatings on

rebar. Concrete pullout testing was conducted per the procedure described in ACI 440.3R-

12 B.3.

Average Max Load 17966.4 lbs

Average Max Stress 162.8 ksi

Standard Deviation 5.7 ksi

Avg. -3stdev 145.6 ksi

Average Modulus 6061.8 ksi

#3 GatorBar Tensile Strength



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Typically there are three methods that the FRP industry uses to bond concrete to rebar.

These include surface deformations, externally wound fibers, or a secondary sand coating.

Neuvokas has produced multiple coatings both with a secondary process and an inline,

primary process. Concrete pull-out testing was used as a direct A vs. B comparison of

these coatings.

To complete this test the University of Nebraska was contracted. Dr. George Morcous has

completed this testing on other manufacturers FRP rebar products. To complete this test

the ACI procedure is followed and rebar is cast into 8” x 8” x 8” blocks of concrete. Figure 2

shows a Neuvokas rebar sample loaded into a tensile testing machine prior to testing.

Figure 2. Neuvokas rebar sample loaded in Tinius Olson Universal Testing Machine

Results from this testing can be seen in Table 3. As mentioned in previous paragraph the

primary coating is applied “in-line” and this results in a lower product cost. As can be seen

in Table 3 the secondary coating does have higher pullout values, but the performance of

the primary coating is still sufficient when compared to steel rebar at a typical 1400 psi.

The average bond stress using this loading is 2,047 psi for primary coating, and 3,753 psi

for secondary coating. Neuvokas continues to utilize concrete pullout testing to compare

coatings.



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Table 3. Results from second run of concrete pull-out testing, completed by George

Morcous, Ph.D., P.E., University of Nebraska -Lincoln

Neuvokas will be continuing additional concrete bond property testing that will compare the

primary sand coating to the bond of steel rebar directly. While this concrete bond test has been

developed to understand the rebar bond to concrete the various variables involved require a

direct A vs. B comparison. This testing will be completed within Q2 of 2017.

2.3. SHEAR STRENGTH, ASTM D7617

Shear testing shows Neuvokas material has consistent test-to-test results and test results

falling within the range of published industry standards for FRP rebar. In-fact as Table 4

shows Neuvokas GatorBar has slightly higher shear strength than other industry

competitors. The values in Table 4 are guaranteed values that have been calculated using

the same method as discussed in the tensile section of this report (Total Average – 3 *

Standard Deviation). The industry standard that ACI 440.6-4 requires is 18 ksi. See Table 4

and Figure 3.

Table 4. Shear test results compared with competitors

Shear Load

lbs

Shear Strength

ksi

Neuvokas #3 Bar 5,602 25.3

Hughes Brothers Aslan 100 4,400 22

V-rod Standard 5,500 25

Guaranteed Values



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Figure 3. Shear test fixture and tested samples

2.4. INTERLAMINAR SHEAR TESTING AFTER ALKALINE EXPOSURE

A test that was completed by Neuvokas to address the effect of alkalinity on rebar was

interlaminar shear (aka short beam test). This test is designed to look at interface

degradation and is done per ASTM D4475. As can be seen in Figures 4 and 5 there was no

effect on the epoxy matrix based on SEM image analysis. Table 6 shows the interlaminar

shear strength before and after conditioning. Again, the alkalinity seems to have had no

effect on interface degradation of Gatorbar.

Figure 4. Cross section view rebar after interlaminar shear before conditioning



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Figure 5. Cross section view of rebar after interlaminar shear after conditioning

Table 6. Interlaminar shear strength, before and after conditioning

When considering rebar durability alkaline resistance is still the primary concern. Based on

the testing completed Neuvokas basalt rebar will not be affected by alkalinity. The final

test that will be completed will evaluate the tensile strength after alkaline exposure.

2.5. ACCELERATED TESTING FOR ALKALI RESISTANCE, COMPLETED BY BRAHIM BENMOKRANE,

PH.D.,P.E., UNIVERSITIE DE SHERBROOK

Alkaline resistance (aka durability testing) has been used as a standardized test by the ACI

during the development of glass fiber products. Glass fiber is susceptible to degradation

when exposed to alkaline environments. Over the course of glass fiber product

development this has led to unique sizing materials that are placed on the fiber to improve

the resistance to alkalinity. These products are sold as ECR or boron modified fiber instead

of the standard E-glass. A key difference between basalt fiber and glass fiber is that basalt

is inherently more resistant to alkalinity. Neuvokas has received basalt fibers from multiple



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suppliers and the performance of each fiber was tested in multiple solutions following a

test procedure that was published by Owens Corning in 2011 for evaluating glass fiber

chemical resistance. As can be seen in Table 7 the first lot 1 of the China basalt showed

slightly higher weight loss after exposure to alkaline solutions. However, the weight loss

seen for all fibers was not significant.

Table 7. Effect of various solutions on basalt fiber (% weight loss)

The images below were taken with a scanning election microscope and show the condition

of basalt fiber both before and after conditioning with the various solutions. Images were

taken by the Universitie de Sherbrooke in Sherbrooke Quebec.

Figure 7. SEM images of A) Reference B) Deionized Water C) Alkaline Solution D) Acidic Solution E)

Saline Solution

Fiber Lot Deionized Water Alkaline Solution Acidic Solution Saline Solution

1 0.2 3.2 5.1 0.1

2 0.1 2.1 3.7 0

3 0.1 2 4.6 0



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2.6. DURABILITY PROPERTIES, ACI 440.3R-12 B.6

The final alkalinity exposure testing that has been mostly completed requires exposing

product to elevated pH and temperature. Samples are then tested via ASTM D7205 tensile

testing to measure the effect of the alkalinity on performance. This testing is not designed

to determine a long-term expected rebar life, but to simply understand how alkalinity will

affect performance. Minimum values for this testing have not been established via the

industry at this point, but Neuvokas has done comparisons to published data from

competitors such as Hughes Brothers.

Table 9. Effect of alkalinity after 30 days with Neuvokas Gatorbar

It can be seen in Table 9 that Neuvokas rebar had approximately 20% loss in tensile

strength after 30 days of exposure during this test. Earlier it was discussed how Neuvokas

rebar had no loss in inter-laminar shear strength after alkalinity exposure. Inter-laminar

shear evaluates the interface between resin and fiber where the tensile testing evaluates a

different material property of the resin system.

To further investigate the cause of tensile strength losses after durability testing Neuvokas

has completed water only and temperature only testing. It was discovered that after 30

days of only elevated water exposure that the loss in tensile strength was similar to that of

elevated high alkalinity water. Based on these results water absorption is the primary

factor degrading the epoxy matrix and this is responsible for the loss in tensile properties.

BaselineAfter 30 day

exposurePercent Loss

Average Max Load, lbs 18,200 14,110 22.5%

Average Max Stress, ksi 164 127.9 22.0%

Standard Deviation, ksi 3.6 1.8 N/A

Avg.-3stdev, ksi 153.1 122.4 20.0%

Average Modulus, ksi 5964.6 5951 0.2%



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Figure 9. Effect of elevated temperature and elevated temperature water on tensile strength

after 30 days

2.7. CREEP RESISTANCE

According to the ACI 440-.1R-10 FRP reinforcing bars that are subjected to a constant load over

time can suddenly fail. This is often called the endurance limit for these types of products.

Unfortunately there is not a lot of data available on the failure or performance of FRP reinforcing

using this test and Neuvokas wanted to determine if current assumptions from the ACI were

appropriate for GatorBar.

Michigan Tech built two test stands for creep testing and will build more once initial testing is

completed. These frames are designed to accommodate up to 20,000 lbs of tensile load on the

rebar samples. The first sample was loaded on February 8, 2016? with a load of 10,477 lbs. The

test evaluates the creep performance so samples are loaded and the machine will measure the

total hours until failure.



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Figure 10. Neuvokas BFRP loaded into creep test frame with 10,477 lb loa d on rebar.

Results from Neuvokas BFRP can be seen Figure 12. This data shows results between 1 hour and

6,500? HOW DO WE GET THIS? hours of data with the corresponding load values. A report

completed by the University of North Florida titled Degradation Assessment of Internal Fiber

Reinforcement in Concrete Environment discusses the typical issues with Creep and Relaxation

performance of FRP rebars. This report offers that there is a linear relationship between creep-

rupture strength and the logarithm of time for all load levels. Based on the extrapolation of short

term creep data this means that longer service lifetimes suggest that typical glass FRP rebars

should have rupture strengths of 29-55% of ultimate tensile strength over X YEARS.



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Figure 11. Neuvokas BFRP failed during creep testing

Figure 12. Neuvokas creep data

Using the data that be seen in Figure 12 Neuvokas and Michigan Tech will be completing more

testing that will allow a linear equation to be obtained from this data. Once this is complete an

estimated creep design value for a 50 year life will be obtained.



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2.8. FATIGUE PERFORMANCE

Fatigue testing is also being completed at Michigan Tech using a hydraulically operated tensile set-

up. This setup cycles rebar at 4 hz. The cycles to failure are recorded and plotted on a fatigue life

curve. This test began in January 2017 and it is not complete yet. Neuvokas will be performing

more testing at each load seen below to determine variability in the results.

Past studies by El-Ragaby et al. (2007) have shown GFRP-reinforced concrete bridge deck

specimens had better fatigue performance and longer fatigue life than steel-reinforcement

concrete bridge decks. Data shown below will be compared to other GFRP rebar products, but

based on the similar modulus of elasticity between BFRP and GFRP it is expected that this data

performance trend will remain consistent.

Figure 11. Chart showing the number of cycles to failure at multiple loads

2.9. GLASS TRANSITION TEMPERATURE

Neuvokas has measured its glass transition temperature of its resin per ASTM E1356 to be

225 F. ACI 440.6-3 has established a minimum value of 212 F.

2.10. MOISTURE ABSORPTION

Moisture absorption is used as a method to determine the quantity of voids present in the

FRP product. As previously discussed this is likely the most important factor in surability

considerations. The CSA has established a maximum value of .75% and the ACI has

established a maximum value of 1%. This is evaluated using ASTM D570 with a water

temperature of 122 F.



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Neuvokas is using this to evaluate each lot of rebar produced on its manufacturing line for

acceptance.

Figure 13. Snapshot of Gatorbar moisture absorption, showing .75% maximum value by the CSA.

2.11. SEM ANALYSIS

Neuvokas uses SEM images to determine fiber wet-out and volume fraction of each

component. Figure 11 shows a cross-section of the Neuvokas rebar and is used to

determine gross fiber wet out percent. Volume fraction of fiber, resin, and voids is also

used with great accuracy by using image analysis tools. Neuvokas has also utilized these

images for competitive analysis within the FRP industry for benchmarking purposes and

initial results have been extremely promising.

Figure 14. Neuvokas rebar sample at two magnifications



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Competitive SEM analysis was also completed and can be seen in Figure 12 and 13.

Samples from major competitors were set up and analyzed via SEM. Figure 13 shows that

each of these competitors does have porosity

Figure 15. Competitive samples of FRP rebar mounted for SEM analysis

Figure 16. SEM images of competing glass fiber FRP rebar products. Starting from top le ft, Aslan

FRP, FireP, and V-rod

2.12. BOND DEPENDENT COEFFICIENT

Bond dependent coefficient accounts for the amount of bond between FRP rebar and the

concrete it is embedded in. For FRP rebar having the same bond to concrete as steel the value is

defined as being 1.0 with less than 1.0 being better than steel and greater than 1.0 being worse

than steel. The ACI 440.1R document recommends using a conservative value of 1.4 when other

specific test data is not available.

Bond dependent coefficient testing was completed by the University of Nebraska. This test is set

up as a four point bend test with two point loading. Figure 17 shows the dimensions of the beam

and the test setup and Figure 18 shows a basalt FRP rebar beam during testing. Figure 19 shows



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the specifications for reinforcement in each beam. It can be seen here where the placement of

the reinforcement being studied is placed.

Figure 17. Beam and test set-up dimensions

Figure 18. Basalt FRP reinforced beam during testing



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Figure 19. Reinforcement specifications for each beam

The results from this testing are shown in Table 10. The values in this table are used in the

equation from ACI 440.1R-06 to calculate the bond dependent coefficient, kb. The standard

product offered by Neuvokas is the Surfaced BFRP in Table 10. This #3 rebar product had a kb

value of 0.80 and since this is lower than 1.0 it means better performance than its steel

counterpart.

Table 10. Results from bond dependent coefficient testing


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