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Arizona I-10 EB NGCS and CDG Test Section Draft Construction Report NGCS and CDG test sections were constructed on I-10 EB in the vicinity of Estrella Parkway interchange in Avondale, Arizona. Both the NGCS and CDG test sections were two lanes wide and 1250 ft in length. The work occurred between April 30 and May 3rd, 2010. Construction occurred during night shifts due to traffic levels. The NGCS and CDG sections had OBSI levels of 99.2 dBA and 102.1 dBA, respectively. The NGCS section had an IRI of 24 inches per mile. The NGCS surface was 4.3 dBA quieter than the project longitudinal tined texture and was 3.6 dBA quieter than the SR 101 ARFC test section placed for Scottsdale in 2002.

Photo of Arizona I-10 NGCS Test Section Texture

2010

ACPA Larry Scofield

6/12/2010

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Introduction Two test sections, a Next Generation Concrete Surface (NGCS) and a Conventional Diamond

Grinding (CDG), were constructed between Friday, April 30 and Tuesday May 4. All construction occurred at night due to the I-10 traffic volumes. Both test sections were two lanes wide by 1250 ft in length as indicated in Figure 1.

This section of highway was an ongoing construction project that had constructed the existing 12 ft wide lanes approximately one year earlier but these lanes were not currently open to traffic. Additional lanes were to be constructed to the outside of the current construction in the near future.

Figure 1 Test Section Construction Layout

Test Section Construction NGCS:

The NGCS test section consisted of grinding the entire test area first with a CDG grinding process to remove the existing longitudinal texture. This was accomplished by grinding with two PC 6000 grinding units. The first PC6000 operated as a conventional CDG grinder using 105 spacers. This unit operated several hundred feet in advance of the second PC6000 which constructed the NGCS texture with a single pass head; which both grooved and ground the pavement creating the NGCS texture. The PC6000 used a 4 ft wide head and 14” in diameter blades.

The NGCS test section construction began Friday night and was completed Saturday night (e.g. Sunday morning). The NGCS construction began in lane 2 of Figure 1 so construction could occur before the allowable traffic control shift.

When the NGCS construction first started it was evident that small aggregate were being plucked out of the concrete by the NGCS grinding process as indicated in Figures 2 & 3. It was also noted that the groove depth was 7/32” which is in excess of the 1/8” to 3/16” specified. At the time it was indicated that the head had been set up for a ¼” groove depth. The first pass of the CDG grinding was the right-most pass of lane 2 (see Figure 1). To remove all the existing longitudinal tining it was necessary for this pass to be approximately 3/8 inch deep on the outside edge. It was also observed that the existing concrete contained a high percentage of smaller aggregate sizes.

Three possible reasons that could be causing the aggregate pop outs are: First, there was significant surface removal prior to the NGCS grind so often times this resulted in ½ or more of the aggregate being removed since the concrete mix had a significant amount of smaller aggregate. Second,

Existing Lane No Traffic

Test Section Lane 2

Test Section Lane 1E.B. Traffic

Existing Traffic Lane

Existing Traffic Lane

1250 ft NGCS Test Section

1250 ft CDG Test Section

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the aggregate bond is questionable since sufficient surface area still existed on many aggregates to allow adequate bonding, and third, the groove depth was too deep. It was common for the aggregate to breakout from the bottom of the groove suggesting a possible initiation mechanism.

Figure 2 Night Time Photo of Aggregate Being Plucked from Pavement by NGCS Grinding

Figure 3 Daytime Photo of Land Breakage on NGCS Section

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Figures 4 & 5 indicate the view of the top of the aggregate and side view, respectively that were plucked from the pavement during the NGCS grinding operation. The aggregate was a river run aggregate with no fractured faces apparent on the reviewed fragments. Aggregate was also pulled out during the CDG grinding operation but to a much less degree. However, it should be noted that the aggregate removed during the CDG operation is also included in the resulting NGCS surface texture. That is, the final NGCS texture is a result of the total aggregate removed by both the CDG and NGCS operations.

Figure 4 Top of Aggregate Removed by the NGCS Grinding Process

Figure 5 Side View of Aggregate Removed by NGCS Grinding Process-Same Order as Fig. 4

Aside from the aggregate pull out issue, the construction went well and resulted in a very satisfactory NGCS surface. If additional aggregate loss does not occur when the section is placed in service, the pavement should provide an excellent riding surface. The average IRI was 24 inches per mile. Typical grinding speeds were 9 to 10 ft per minute. The cover photo indicates a good overall view of the completed NGCS surface. Figure 6 indicates a close up view of the resulting texture.

CDG: The CDG test section construction occurred primarily on Saturday night when Lane 1 was

constructed and on Monday night when Lane 2 was constructed. There was no work on Sunday night. The CDG construction also experienced aggregate loss during the grinding operation but to a lesser degree than the NGCS grinding. Figure 8 indicates a night photo indicating the aggregate loss during CDG operation. Figures 8 and 9 indicate the top and side view, respectively, of an aggregate that was removed during the CDG operation.

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Figure 6 Close-Up View of Completed NGCS Texture

Figure 7 Night Photo of Aggregate Removed During CDG Operation

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Figure 8 Top View of Aggregate Plucked from the Pavement Surface During CDG Operation

Figure 9 Side View of Aggregate Plucked from the Pavement Surface During CDG Operation

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Aside from the aggregate loss during CDG operation, the grinding went well and the resulting texture is evident in Figure 10. Even though the 105 spacers were used significant fin size resulted as indicated in Figure 11.

Figure 10 Close-Up View of CDG Texture

Figure 11 Night Photo of Large Fins Remaining in the CDG Texture Even with the 105 Spacers

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Field Testing OBSI Testing

OBSI testing was conducted on Lane 2 on May 5th and on Lane 1 on May 7th. The May 5th testing was conducted within the existing traffic control set up which presented a driving challenge to accomplish. The results of the OBSI testing for both dates are indicated in Figures 12 and 13. The May 7th testing was conducted after the traffic control had been relocated during the night of May 6th when the lane stripe was re-installed. During the May 7th testing only the NGCS section, Lane 1, was tested. The traffic control necessary for the ramp prevented driving in Lane 1 on the CDG section. In addition, debris covered much of the CDG Lane 1 section as indicated in Figure 14.

Figure 12 OBSI Level for Test Sections and Other Arizona Surfaces

Figure 13 1/3 Octave OBSI Spectra for Selected Arizona Surfaces

99.099.4

100.2

102.1102.8

103.2103.9

94

96

98

100

102

104

106

Soun

d In

tens

ity L

evel

, dB

A

Pavement Section

NGCSLane 1

CDG

Typical 4 -5 Yr Old

ARFC

2002 ARFC Test

Section

Longitudinal Tining

NGCS Lane 2

65

70

75

80

85

90

95

100

105

500 630 800 1000 1250 1600 2000 2500 3150 4000 5000

Soun

d In

tens

ity L

evel

, dB

A

1/3 Octave Band Center Frequency, Hz

NGCS Lane 2

CDG

Longitudinal Tined

2002 ARFC

Typical ARFC

NGCS Lane 1

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As indicated in Figure 12 the NGCS averaged 99.2 dBA which was approximately 2.9 dBA lower than the CDG section and 4.3 dBA lower than test values obtained on the project longitudinal tining. Two additional locations on US 60 and SR 101 ARFC were also tested to compare to the NGCS surface. The SR 101 location that was the test section constructed at the request of Scottsdale citizens to evaluate the ARFC strategy. This section was constructed in 2002 and presently tests 3.6 dBA louder than the NGCS test section. A typical 4-5 year old ARFC tests about 100 dBA. Once the sections are open, traffic will break down the CDG fins and the level will probably decrease approximately 1 dBA.

Figure14 Debris on Roadway (Lane 1 of CDG Section) During May 7th OBSI Test

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Texture Measurement AMES Engineering Texture Scanner

Ames Engineering loaned ACPA a texture measurement device and it was used to collect the texture data indicated in Table 1. Figure 16 indicates a photo of the device. The Ames device was used to collect texture data every one hundred feet in the NGCS and CDG sections and at random locations for the longitudinal texture, dense AC, and several ARFC textures located elsewhere in the Phoenix area. The overall results of this testing are indicated in Table 1 and the individual test results in Appendix 2. Figure 17 provides a graph of the estimated texture depths. As indicated in Table 1, the NGCS section produced the largest estimated texture depth followed by the CDG, Longitudinal Tining, ARFC, and dense AC surfaces. Using the average of the NGCS texture for both lanes, the overall average values of the other textures expressed as a percentage of the NGCS textures are as follows: CDG 87%, Long Tine 67%, ARFC 65 %, and dense AC 45%. As indicated, the dense AC texture is less than half of the NGCS texture and the ARFC texture is only approximately 2/3 of the texture developed by the NGCS surface

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Outflow Meter Results Outflow meter testing was conducted on the three concrete textures. A photo of the Outflow

meter is shown in Figure 19. The time to remove the specified amount of water from the outflow meter is an indication of the texture depth in the surface. The time for the NGCS surface was 2.6 seconds, the CDG surface 3.0 seconds, and the longitudinal tined surface 6.7 seconds. The less time required, the greater the mean texture depth.

TABLE 1 Ames Texture Meter Results (mm)

Figure 15 Ames Engineering Texture Meter

Surface Type Long Tined Dense AC ARFCLN 1 LN 2 LN 1 LN 2

MPD (mm) 1.64 1.58 1.37 1.57 1.17 0.59 0.93

ETD (mm) 1.51 1.47 1.30 1.46 1.13 0.67 0.97

RMS 0.06 0.06 0.02 0.02 0.05 0.01 0.02

Outflow Time (sec) 2.60 3.00 6.67

NGCS CDG

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Figure 16 Estimated Texture Depth From Ames Texture Scanner (mm)

Figure 17 Photo of Outflow Meter Testing

1.511.47

1.30

1.46

1.13

0.97

0.67

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

Estim

ated

Tex

ture

Dep

th (

mm

)

NGCSCDG

LongTined ARFC

ACDense

LN 1LN 1 LN 2 LN 2

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Circular Track Texture Meter (CT Meter) CT Meter testing was conducted on the NGCS section at 100 ft intervals at the same locations as

the Ames Texture Meter readings. The results of this testing are indicated in Table 2 and a photo of the C.T. Meter in Figure 18.

Table 2 CT Meter Texture Results

Station 1+00 2+00 3+00 4+00 5+00 6+00 7+00 8+00 9+00 10+00

ETD

Figure 18 Photo of C.T. Meter in Test Position

Profile Measurement

An Ames Lightweight Profiler was used to measure the surface profile of the NGCS test sections. The RoLineTM sensor was used to ensure that-aliasing in the signal processing would not occur as a result of the longitudinal grooves. The results of this testing are indicated in Table 3. The average of the NGCS section was an IRI of 24 inches per mile.

TABLE 3 IRI PROFILE RESULTS (inches per mile) Segment Length

(ft)

Lane 1 Lane 2

LWP RWP LWP RWP

528 32.2 19.04 33.15 28.70

528 20.45 17.13 15.99 22.71

194 16.53 18.16 16.19 28.41

Appendix 1 Construction Photos

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Penhall Equipment

Figure 1 Night Photo of PC6000 Grinding Equipment

CDG Grinding Head

Figure 2 Photo of CDG Grinding Head with 105 Spacers

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NGCS

Figure 3 Photo of NGCS Grinding Single Pass Grinding Head

Appendix 2 Ames Texture Data

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