YOSE-PRES_1(14)_CoringReport2-6-13.pdf

YOSEMITE NATIONAL PARK BRIDGE / TUNNEL PRESERVATION

CA PRA/NPS YOSE BRIDGE PRES 2(12)

YOSEMITE TUNNEL CORING REPORT

February 6, 2013

Report by:

Yeh and Associates

5700 East Evans Avenue Denver, Colorado 80222

Project No. 212-124

Prepared for:

Jacobs Engineering Group, Inc.

707 17th Street, Suite 2300

Denver, Colorado 80202 Attn: Mr. James Mills, P.E.

Federal Highway Administration

Central Federal Lands Highway Division

Lakewood, Colorado

TABLE OF CONTENTS

Executive Summary …………......………………….…………………….…….…… 1

1.0 Introduction ..............…………………………….……………………………….. 2

2.0 Project History......…………………….………………………………………..… 2

3.0 Purpose .................……………………………………………………………….. 2

4.0 Field Sampling .........................................................……..…….…….….….… 2

5.0 Field Observations ………......................................……………………………. 4

5.1 Honeycomb and Seepage

5.2 Shotcrete

5.3 Concrete thickness and Void

6.0 Petrographic Analysis ….................…………………………………………….. 8

7.0 Conclusions

8.0 Recommendations

8.1 Concrete Repair

8.2 Joint Sealing

9.0 Limitations …….……………………………………….…………..……….……. 10

10.0 References

LIST OF TABLES

Table 1 - Summary of Core Properties ……………………….……....................… 4

APPENDICES

Appendix A - Tunnel and Core Locations Appendix B - Yosemite Tunnel Core Data Appendix C - Petrographic Analysis Report

Yosemite National Park Tunnel Preservation Project: CA PRA/NPS YOSE BRIDGE PRES 2(12) Yeh Project 212-124

Executive Summary

Four highway tunnels located within Yosemite National Park are scheduled for rehabilitation in the near future. The Wawona Tunnel located on Wawona Road (CA Route 41) and Big Oak Flat Tunnels #1, #2, and #3 are located on Big Oak Flat Road (CA Route 120).

In order to determine if there are any special requirements for repair needed on the concrete lined sections of these tunnels, cores were taken from the walls and tested for compressive strength and also submitted for petrographic examination to determine if there are any problems related to chemical attack or aggregate silica reactivity.

Cores were taken for each of the four tunnels and the range of compressive strength of the cores ranged from 5,148 psi to 9,111 psi. These strengths are considered adequate.

The petrographic analysis showed that the concrete represented by the cores is sound and intact. The cores show no evidence of cracking or significant micro cracking and no evidence of damage related to durability mechanisms such as free-thaw, sulfate attack or aggregate silica reactivity. Two of the core locations did contain honeycombing to a depth of 2 to 3 inches into the tunnel wall. There were no significant deposits of ettrigite which indicates that concrete has not been exposed to significant moisture from infiltration of or seepage of water.

The test results show that standard repair materials and methods can be used in the rehabilitation of these tunnels.

Yosemite National Park Tunnel Coring Report

1.0 Introduction

Four tunnels, located within Yosemite National Park are scheduled for rehabilitation in the near future. All of the tunnels are located along major routes into Yosemite National Park in Mariposa County, California. The tunnels include the Wawona Tunnel (Structure No. 8800- 031P) on NPS Route 014 Wawona Road (CA Route 41) and Big Oak Flat Tunnel #1 (Structure No. 8800-032P), Big Oak Flat Tunnel #2 (Tunnel No. 8800-033P) and Big Oak Flat Tunnel #3 (Structure No. 8800-034P) all located on NPS Route 013 Big Oak Flat Road (CA Route 120).

This geotechnical investigation was to sample the concrete from the tunnel walls and to evaluate the existing concrete for strength, aggregate reactivity and the concrete compatibility with repair materials for spalled concrete sections, power washing lined sections, repairs to spalled concrete, sealing leaking joints and cracks and replacing deteriorated shotcrete lining.

2.0 Project History

The Federal Highway Administration (FHWA), Central Federal Lands Highway Division (CFLHD) in cooperation with the National Park Service (NPS) / Yosemite National Park, is proposing rehabilitation of the tunnel lining, drainage and pavement of the four tunnels within Yosemite National Park.

The general scope of improvements is to rehabilitate the tunnel concrete walls, address any failing sections, and clean and provide for long lasting rehabilitations of the tunnel walls.

3.0 Purpose

This geotechnical report is to provide results of sampling and testing of the tunnel wall concrete, and to recommend any special methods needed to rehabilitate the concrete walls. Testing included compressive strength of the concrete and also petrographic examination of the concrete to determine if there are any reactive aggregate problems or other evidence of chemical attack on the concrete.

4.0 Field Sampling

Traffic control personnel from Safety Network, Inc. closed the east bound lane of CA Route 41 at the Wawona Tunnel at 10:00 PM on July 23, 2012. Personnel from Yosemite National Park requested that the closures begin not sooner than 10:00 PM and that the lanes be completely open by 5:00 AM. The time limitations caused the work to be extended over two nights.

Tunnel coring locations were previously identified by representatives from Jacobs Engineering, and the stations and exact locations were identified based on the stations previously marked on the tunnel curbs. A minimum of one core was extracted from the reinforced wall section of each tunnel. All of the samples were taken at a height of approximately 6 feet above the tunnel walkway except Core BOF 3-2 which was taken at a specific location directed by the Jacobs inspection team. The tunnel location map and also the core locations are presented in

Appendix A.

A Model CT-4950A Micro Covermeter manufactured by ELE International/SoilTest was used to locate reinforcing steel so that it could be avoided during coring.

Coring was conducted by personnel from the Penhall Company of Anaheim, California. Four inch diameter cores taken with a 4.25 X 14 inch core barrel.

To insure retrieval of a minimum 10 inch core length to provide samples long enough for both strength testing and petrographic analysis, 12 inches was marked on the core barrel and coring stopped when the 12 inch depth was reached. The cores were then broken loose and retrieved.

Coring slurry was collected in a bucket as seen in Photograph 1. This method was very effective in keeping slurry from draining onto the tunnel walls and floor. The slurry was collected in buckets and disposed of outside the park by the coring contractor from Penhall.

Photograph 1 - Slurry capture method

Core samples were returned to the laboratory and prepared for compressive strength testing as well as sawing of the top section of cores to be submitted to DRP Consulting, Inc. for petrographic analysis.

Appendix B contains photographs that document the core condition immediately after retrieval as well as the exact station within each tunnel. A second photograph was taken to document the core condition prior to testing and the third photograph of each core documents the type of break indicating that samples were properly prepared and tested for compressive strength.

For each core a photograph was taken prior to sawing to prepare samples for testing in the laboratory and after compression strength testing. The center section was used for compressive strength testing and the top (inside tunnel side) was submitted for petrographic examination. The bottom section was removed to provide a vertical cut section for compression strength testing. The bottom was also sent to the petrographer for examination.

Table 1 presents the length of core extracted from each tunnel wall and the compressive strength measured on the center section of each core. Appendix B contains the original compressive strength test report.

Table 1 - Summary of Core Properties

Core Number Retrieved Length

(inches) Compressive Strength (psi)

Comments

W-1 11 3/4 9,111 Honeycomb - 3" inside tunnel face W-2 11 1/2 6,744

BOF 1-1 12 1/2 8,211 Slight honeycomb - 2" inside tunnel face

BOF 2-1 12 6,665

BOF 3-1 12 5,148

Separated at shotcrete/concrete interface

BOF 3-2 11 1/2 6,791

BOF 3-3 12 6,106 20 inch void behind concrete wall

5.0 Field Observations

5.1 Honeycomb and Seepage

The first core taken was Core W1 from the south wall at Station 1+30 in the Wawona Tunnel.

Photograph 2 - Seepage within the wall at W1.

The area appears to have honeycombing and Photograph 2 shows core water leaking down the wall several feet from the core location. Note that the core barrel in only about 1/3 of the full depth of 12 inches of core.

Photograph 3 shows the condition of Core W-1. Approximately the top 3 inches contain honeycomb and fell apart during the coring process. The remainder of the core appears to be well consolidated and had adequate compressive strength.

Photograph 3 - Core W1-Sta. 1+30 south side of Wawona Tunnel

The only other core which exhibited honeycombing was Core Number BOF 1 which was extracted from the north wall of Big Oak Flat Tunnel Number 1.

Photograph 4 - BOF 1-1 Sta. 100+19 north wall

In the area of core BOF 1-1, the surface finish on the core broke off, about 1/4 inch thick, but remainder of the core was retrieved intact.

Photograph 5 - BOF 1-1 Sta. 100+19 seepage at joint

At the same location of the core in Big Oak Flats Core #1 additional seepage at the joint, at approximately 1/2 the finished core depth, was generated by the coring operation.

At this location, reinforcing steel was encountered on lower left of core at a depth of approximately 1 inch, so the core barrel was moved approximately 1 inch right and coring continued. Following completion, the reinforcing steel was slightly nicked on right side. The steel spacing was very close at this location, approximately 6 inch spacing of vertical steel based on Micro Covermeter readings.

5.2 Shotcrete

Photograph 5 - W-3 shotcrete from north wall of Wawona Tunnel Sta. 6+94.

Shotcrete was also cored in two locations in the Wawona Tunnel. Photograph 5 shows an 8 inch diameter core with some texture variation from several applications of shotcrete but the core is solid and no distress was identified at this location.

On July 24, 2012, the area suspected to have sheet metal (Station 41+75) behind the shotcrete was visited during the day, and using the Micro Covermeter, the signal indicated that continuous metal was behind the shotcrete to at least as high as 8 feet. We suspect that the sheet metal was used as a form for a rebar cage while new concrete was poured. The upper arch on the south side appears to be rebar cage which was shotcreted into place.

Following completion of coring at the Wawona Tunnel, traffic control was then moved to Big Oak

Tunnel 3 and coring resumed on the south wall at approximately 3:00 AM July 24, 2012.

Photograph 6 - Core BOF 3-3 - Sta. 318+87 south side Big Oak Tunnel 3

The concrete sampled at this location as well as the other two cores from Big Oak Flat Tunnel

#3 were well consolidated. Photograph 6 shows well consolidated concrete and similar compressive strength for all the cores from Big Oak Flat Tunnel #3.

At the location of core BOF 3-3, Sta. 318+87, the core went through the cast concrete wall. The core removal exposed a void behind the wall to a depth of 32 inches which means that there is a void of approximately 20 inches behind the concrete at this location. Based on visual observation using a flashlight, the back wall appeared to be a shotcreted rock face.

Core BOF 3-1 from the north side of the tunnel also broke through the concrete collar, but the break point appeared to be at a concrete / shotcrete interface. Two of the three cores taken from the walls of Big Oak Flat Tunnel #3 broke through at a thickness of 12 inches indicating the vertical reinforcing walls are 12 inches thick. All of the cores from the other tunnels broke within the concrete section, so the exact thickness was not determined.

Tunnels Big Oak Flats #1 and #2 were cored on the night of July 25, 2012 with no problems and the cores were similar in visual appearance to the cores from the other tunnels.

6.0 Petrographic Analysis

Both cores from the Wawona Tunnel and the top and bottom sections of one core from each of the Big Oak Flat Tunnels were submitted to DRP Consulting, Inc. for petrographic analysis to determine if there were any reactive aggregate problems or problems from some other source such as chemical attack.

The executive summary from that report states:

"The cores do not show evidence of cracking or significant micro-cracking. No evidence of damage related to durability mechanisms such as freeze thaw damage, sulfate attack or aggregate silica reaction (ASR) was observed in any core. The cores lack significant deposits of ettringite, which indicates the concrete was not exposed to significant moisture from infiltration or seepage of water. There is evidence if significant honeycombing at the outer end of Core W-1 and BOF-1-1, but neither core shows evidence of cracking, micro cracking or any other distress that resulted from the honeycombing (although there is deep carbonation around some of the honeycombing). While all cores show evidence of significant carbonation, no cracking or micro cracking due to corrosion was observed."

The complete petrographic report is presented in Appendix E.

7.0 Conclusions

The tests performed on the cores from the formed concrete collars in the tunnel walls indicate that the concrete is sound with compressive strengths within the range expected for older structural concrete. Two of the seven core locations contained honeycomb to a depth of 2 to 3 inches, but the concrete behind the honeycombing was sound and compressive strengths ranged from 5,148 psi to 9,111 psi which is within the expected range. The petrographic analysis results found that at the core locations, the concrete had not been subject of alkali silica or other chemical caused deterioration. Numerous locations were observed where the surface finish was deteriorated and laitance was very visible on the surface of the concrete tunnel walls. In some locations, the surface finish was peeling from cast concrete tunnel wall.

Photograph 7 - South wall of Big Oak Flats Tunnel 1

As seen in Photograph 7, there are isolated locations where the concrete has spalled away from the reinforcing steel and a deep repair may be recommended.

Photograph 8 - South wall of Big Oak Flats Tunnel 3

Another distress that is prevalent in many locations is the laitenance (white deposits) on the walls. Photograph 8 shows the laitenance and also some minor spalling on the lower wall in Big

Oak Flats Tunnel #3.

8.0 Recommendations

8.1 Concrete Repair

Since no special problems were indicated in the quality of concrete samples taken from the tunnel walls, we believe that the repairs can be completed using standard concrete products.

Deep patches can be completed with standard concrete containing fine aggregate after removal of the concrete in the repair areas and/or replacement of reinforcing steel as required. The honeycombed areas can be treated with partial removal and a standard concrete mix with an appropriate epoxy bonding agent conforming to the requirements of ASTM C881.

When all of the structural or honeycomb repairs have been completed the surface of the cast concrete collars can be cleaned using sand blasting or high pressure water blasting and given a

Class 2 Rubbed Finish in accordance with Section 552.16 of the FHWA Federal Lands Highway

Standard Specifications of Construction of Roads and Bridges, (FP-03). We recommend water blasting followed by compressed air to dry the surface because the visibility problems associated with sand blasting may cause traffic safety problems.

8.2 Joint Sealing

The joints that run parallel to the roadway at a height of about 5 feet above the curb and the joints below these relief joints should be filled. We recommend that a non-sagging silicone joint sealant similar to those for concrete pavements be used. The Dow Corning 790 Silicone

Building Sealant with backer rod or approved equal appears to be appropriate for this application. All joints will need to be cleaned in accordance with the manufacturer's instructions and application procedures strictly followed to have a successful sealant application and performance.

9.0 Limitations

This study has been conducted in accordance with generally accepted geotechnical engineering practices in this area. The conclusions and recommendations submitted in this report are based upon the data obtained from exploratory cores, field reconnaissance, and the proposed type of construction. The nature and extent variations from one tunnel to another may not become evident until repair work is performed. If during construction conditions appear to be different from those described herein, this office should be advised at once so re-evaluation of the recommendations may be made.

10.0 References

Standard Specifications for Construction of Roads and Bridges on Federal Highway Project, FP-03, US Department of Transportation, FHWA, 2003. Publication No. FHWA-FLH-03-002

Dow Corning Technical Manual, Dow Corning Corp, 2011. Form No. 62-11126-01

Appendix A - Tunnel and Core Locations

Yosemite Tunnel Coring Locations

Revised July 18, 2012

The center locations of 4-inch diameter by 10-inch long cores to be extracted from Yosemite National

Park tunnels are listed below. Prior to coring, locate vertical and horizontal reinforcing bars in the tunnel at specified core locations using a pachometer or similar device so that coring does not cut or damage the reinforcing bars. Core locations may be modified if they conflict reinforcing bars. Core center locations should be at least 12-inches away from any horizontal or vertical construction joint.

Stations at 25-foot intervals are marked on the north side curb of the Wawona Tunnel and on south side curbs for Big Oak Flat Tunnel No.1 and Big Oak Flat Tunnel No. 3.

Wawona Tunnel:

Core W1

• Station 1+30

• South side of the tunnel (up-station on the right-hand side)

• 6-feet above the top of the safety walk

Core W2

• Station 6+42

• North side of tunnel (up-station on the left hand side)

Core W3 (no testing required)

The preferred method here is to remove the shotcrete by sawing an 8-inch by 8-inch square to determine the shotcrete thickness and configuration of the corrugated steel behind the shotcrete. If sawing can not be achieved, using coring methods. If the shotcrete is cored, it is impetrative the core hole be sealed properly to prevent water from entering the tunnel.

• Station 4+75

• North side of tunnel (up-station on the left hand side)

• 6-feet above the top of the safety walk (through shotcrete)

Core W4 (no testing required, similar to W3)

• Station 4+75

• South side of tunnel (up-station on the right hand side)

• 6-feet above the top of the safety walk (through shotcrete)

Yosemite Tunnel Coring Locations

Big Oak Flat Tunnel No. 1:

Core BOF1-1

• Station 100+19

• North side of the tunnel (up-station on the right-hand side)

Big Oak Flat Tunnel No. 2 :

Core BOF2-1 (Optional)

• Station 201+98

• North side of the tunnel (up-station on the right-hand side)

• 6’-feet above the top of the safety walk

Big Oak Flat Tunnel No. 3:

Core BOF3-1 (Optional)

• Station 301+00 +/-

• North side of tunnel (up-station on the right-hand side)

• 6’-feet above the top of the safety walk

Core BOF3-2

• Station 303+25

• North side of the tunnel (up-station on the right-hand side)

• 12-inches above the horizontal reveal/joint and 16-inches up-station from the vertical reveal/joint

Core BOF3-3

• Station 318+87

• South side of the tunnel (up-station on the left-hand side)

Appendix B - Yosemite Tunnel Core Data

Yosemite Tunnel Coring CA PRA/NPS YOSE BRIDGE PRES 2(12) Yeh 212-124

Yosemite Tunnel Core History

Core W-1 / Wawona Tunnel / Sta. 1+30 South Wall / 6 ft. above walk

Core immediately after extraction from wall. Note: honeycomb left

Core W-1 / Wawona Tunnel / Sta. 1+30 South Wall / 6 ft. above walk / Length: 11 3/4 inches

Core in lab prior to sawing: Section on left and right went for petrographic examination, center section used for compressive strength tests. Core did not break through lining.

Core W-1 / Wawona Tunnel Sta. 1+30 South Side / 6 ft. above walk

Compressive strength = 9,111 psi (Type 1 Break with correction factor applied for length)

Core W-1

Core W-2 / Wawona Tunnel / Sta. 6+42 North Wall / 6 ft. above walk

Core immediately after extraction from wall.

Core W-2 / Wawona Tunnel / Sta. 6+42 South Wall / 6 ft. above walk / Length: 11 1/2 inches

Core in lab prior to sawing. Center section used for compressive strength tests. Top and bottom combined with W-1 for petrographic examination.

Core W-2 / Wawona Tunnel / Sta. 6+42 South Wall / 6 ft. above walk / Length

Compressive strength = 6,744psi. (Type 1 Break)

Core BOF-1-1/ Big Oak Flat Tunnel #1 / Sta. 100+19 North Wall / 6 ft. above walk

Core immediately after extraction from wall. Note: honeycomb left

Core BOF-1-1/ Big Oak Flat Tunnel #1 / Sta. 100+19 North Wall / 6 ft. above walk / Length 12 1/2 inches

Core BOF-1-1/ Big Oak Flat Tunnel #1 / Sta. 100+19 North Wall / 6 ft. above walk

Compressive strength = 8,211 psi (Type 2 Break)

Core BOF-2-1/ Big Oak Flat Tunnel #2 / Sta. 201+98 North Wall / 6 ft. above walk

Length 12 inches

Core BOF 2-1

Compressive strength = 6,665 psi (Type 1 Break)

Core BOF-3-1/ Big Oak Flat Tunnel #3 / Sta. 301+00 North Wall / 6 ft. above walk

Core in lab prior to sawing: Section in center section used for compressive strength tests.

Compressive strength = 5,148 psi (Type 1 Break)

Core BOF-3-2/ Big Oak Flat Tunnel #3 / Sta. 303+25 North Wall / 12 inches above horizontal reveal joint and 14 inches left of vertical reveal/joint

BOF-3-2/ Big Oak Flat Tunnel #3 / Sta. 303+25 North Wall / Length =11 1/2 inches section used for compressive strength tests.

Compressive strength = 6,791 psi (Type 2 Break)

Core BOF-3-3/ Big Oak Flat Tunnel #3 / Sta. 318+87 South Wall / 6 ft. above walk

Core in lab prior to sawing: Section in center section used for compressive strength tests.

Compressive strength = 6,106 psi (Type 1 Break)

Appendix C - Petrographic Analysis Report

Petrographic Investigation of Concrete Cores From Tunnel Linings in Yosemite National Park, California

Prepared for: Mr. Robert F. La Force, P.E.

Yeh & Associates, Inc.

Denver, Colorado

Prepared by: David Rothstein, Ph.D., P.G., FACI Report No.: DRP12.1005

5 OCTOBER 2012

DRP Consulting, Inc. 3200 Carbon Place #104 Boulder, CO 80301 www.drpcinc.com http://www.drpcinc.com http://www.drpcinc.com

EXECUTIVE SUMMARY

Five (5) concrete cores extracted from concrete tunnel linings at Yosemite National Park, California are subjects of petrographic examination to assess the general condition of the concrete represented by the cores. The findings from this scope of work indicate that the concrete represented by all the cores is sound and intact. All the cores lack air entrainment and contain portland cement with no fly ash or other supplemental cementitious materials. However, the cores represent distinctly different concrete mixtures made with different coarse aggregates.

The cores do not show evidence of cracking or significant microcracking. No evidence of damage related to durability mechanisms such as freeze-thaw damage, sulfate attack or ASR was observed in any core. The cores lack significant deposits of ettringite, which indicates the concrete was not exposed to significant moisture from infiltration or seepage of water. There is evidence of significant honeycombing at the outer end of Core W-1 and Core BOF 1-1, but neither core shows evidence of cracking, microcracking or any other distress that resulted from the honeycombing (although there is deep carbonation around some of the honeycombing).

While all the cores show evidence of significant carbonation, no cracking or microcracking due to corrosion was observed. None of the cores contain embedded steel.

Core BOF 2-1 is the only core to show evidence of ASR. In this core the observed ASR is negligible, with one deposit of gel observed next to a particle of andesite from the coarse aggregate. Core BOF 2-1 contains aggregate that is rich in siliceous volcanic rocks such as andesite and rhyolite, which are potentially susceptible to ASR. The aggregate in Core BOF 2-1 differs from the other cores, which consisted of more granitic rocks. No evidence of cracking, microcracking or any other forms of distress attributable to ASR were observed in Core BOF 2-1.

Yosemite National Park Tunnel Linings Core Petrography! Report No. DRP12.1005 Summary Report! 5 October 2012 drpcinc.com ! i

1.0 INTRODUCTION

Mr. Robert F. LaForce, P.E. of Yeh and Associates, Inc. (YAI) located in Denver, Colorado requested DRP Consulting, Inc. (DRP) to investigate the condition of concrete represented by cores extracted from concrete tunnel linings in Yosemite National Park, California for YAI project number 212-124. On 17 August 2012 DRP received five (5) concrete cores from YAI.

Table 1 summarizes information regarding the identification and location of these cores.

Table 1. Summary of core identifications and locations.Table 1. Summary of core identifications and locations.Table 1. Summary of core identifications and locations.Table 1. Summary of core identifications and locations.

Client ID DRP No. Location Condition Observed in Field W-1 16YD5521 Wawona Tunnel South Wall STA 1 + 30 Honeycombing & seeping observed

W-2 16YD5522 Wawona Tunnel North Wall STA 6 + 42 Well consolidated area

BOF 1-1 16YD5523 Big Oak Tunnel North Side STA 301 + 00 Separated at shotcrete interface

BOF 2-1 16YD5524 Big Oak Tunnel North Wall STA 303 + 25 Offset at vertical joint

BOF 3-2 16YD5525 Tunnel lining core Large void at shotcrete contact

Mr. LaForce reported that the cores represent concrete placements that date to the 1930s. No information was available regarding the project specifications for the concrete, the concrete mix design, or the results of testing during construction.

2.0 SCOPE OF WORK

The testing involved petrographic analysis of the cores according to ASTM C856 [1]. This report summarizes the findings of this scope of work. Appendices A-D contain the notes, photographs and photomicrographs from the petrographic examinations. Because of the poor recovery witih Core W-1, it was combined with Core W-2 to provide a representation of the material in thw Wawona Tunnel. Appendix E describes the procedures used to complete these tests.

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1 Standard Practice for Petrographic Examination of Hardened Concrete. Annual Book of ASTM Standards, Vol. 4.02., ASTM C856-11.

3.0 FINDINGS

The following findings are relevant to the concrete represented by the cores.

3.1 Orientation, Dimensions & As-Received Condition All the cores are horizontal in orientation; they measure 105 mm (4 ⅛ in.) in diameter and range in length from 45-105 mm (2 ¾- 4 ⅛ in.; Figure 1). The cores span from an outer formed surface to an inner surface that was fractured. The central region of the cores were removed and tested for compression before their delivery to DRP, so the cores represent the outermost and innermost sections of the wall linings they were extracted from. The cores show skim coats and repair mortar on the outer formed surfaces. The concrete is hard and compact.

No embedded steel was observed.

(a) (b)

(c) (d)

Figure 1. Photographs showing the outer surface and sides of cores in their as-received condition. (a) Core W-1. (b) Core BOF 1-1. (c) CoreBOF 2-1. (d) Core BOF 3-1. The yellow scale bar is ~ 150 mm (6 in.) long.

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3.2 Components: Paste The paste fraction of all the cores consists of hydrated cement with no fly ash, slag cement or other supplemental cementitious materials observed (Figure 2). The hydration is normal in all the cores but is significantly more advance in Core BOF 1-1. The paste has relict and residual cement grains that consist primarily of belite rimmed by interstitial aluminate and ferrite observed most commonly. Calcium hydroxide is typically coarse-grained and irregularly distributed.

(a) (b) (c)

(d) (e) (f)

Figure 2. Examples of paste properties in (a)-(c) Core BOF 1-1, which showed very advanced hydration, and (d)-(f) Core W-2, which showed less advanced hydration. (a), (d) Reflected light photomicrographs of polished surface showing paste texture and luster in the middle of the core. Transmitted light photomicrographs of thin section showing detail of paste in (b), (e) plane-polarized and (c), (f) cross-polarized light. The red arrows in (b) and (e) indicate relict and residual cement grains; in (c) and (f) they indicate calcium hydroxide. The yellow arrows in (f) indicate carbonated paste.

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3.3 Components: Air All the cores lack air-entrainment and have less than 3% air based on visual estimation (not measured by ASTM C457 [2]). Core W-1 shows poor consolidation and honeycombing throughout the outer piece of the core (outside the area that was trimmed for compressive strength testing). Core BOF 1-1 shows poor consolidation and honeycombing for ~ 65 mm (2 ½ in.) from the formed surface.

Figure 3. Photographs showing poor consolidation and honeycombing in Core W-1 and Core BOF 1-1. The photographs are of (a) the polished surface and (b) as-received fracture surface in Core W-1 and (c) the polished surface and (d) side of the core in Core BOF 1-1. The yellow scale in (a) and (b) is about 150 mm (6 in.) long and the scale in (c) and (d) is in millimeters.

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2 Standard Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete, Annual Book of ASTM Standards, Vol. 4.02, ASTM C457-10.

3.4 Components: Aggregates The aggregates are siliceous in all the cores but there are variations in the types of rocks (Figure 4). The aggregates in all the cores are natural river gravels with a 25 mm (1 in.) nominal top size (although most particles are 19 mm (¾ in.) or less) except Core BOF 3-1, which has a quarried, crushed aggregate with a 12.5 mm (½ in.) nominal top size. In Core W-1/W-2 the aggregate consists mostly of granitic rocks but dioritic rocks, quartzite and gneiss are also significant components. In Core BOF 1-1 the aggregate consists primarily of granitic rocks but volcanic rocks such as andesite and rhyolite and siliceous rocks like chert also serve as significant components.

In Core BOF 2-1 the aggregate consists primarily of volcanic rocks that are mafic (mostly andesite) to siliceous (rhyolite). Granitic rocks and siliceous metasedimentary rocks such as metagraywacke are also present. In Core BOF 3-2 the aggregate consists of granitic rocks with minor granodiorite. All the cores have fine aggregates that consist primarily of granitic rocks, often with minor amounts of dioritic and volcanic rocks as well. The finer fractions of the fine aggregates have significant amounts of biotite, chlorite and amphibole.

Figure 4. Photographs showing the outer surface and sides of cores in their as-received condition. (a) Core W-1. (b) Core BOF 1-1. (c) CoreBOF 2-1. (d) Core BOF 3-1. The scale bar is in millimeters in all the photos.

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3.5 Cracking and Microcracking No significant cracking or microcracking was observed except in Core W-1, which is cut in the outer portion by a sub-horizontal crack.

However, this crack appears associated with poor consolidation and honeycombing. In the other cores cracking is limited to near the outer surface and appears related to drying shrinkage and consolidation or placement (tearing cracks) except in Core W-2, where sub-vertical cracks (sub-parallel to the formed surface) were observed within 3 mm (⅛ in.) of the formed surface (Figure 5). These sub-vertical cracks ranged from 250-500 µm (10-20 mil) wide and are up to 19 mm (¾ in.) wide. Microcracking is minor in all the cores. No evidence of cracking or microcracking due to durability-related mechanisms was observed.

Figure 5. (a) Photograph of the polished surface of Core W-2 showing sub-vertical crack (red arrows); the scale is in millimeters. (b) Reflected light photomicrograph of tearing cracks (red arrows) near the outer surface (indicated by blue arrow) of Core BOF 3-2.

Yosemite National Park Tunnel Linings Core Petrography! Report No. DRP12.1005 drpcinc.com ! Page 6 of 9

3.6 Secondary Deposits Pervasive carbonation was observed in the outer portions of all the cores (Figure 6). Minor deposits of ettringite were observed in voids; no evidence of microcracking or other distress was observed in association with ettringite mineralization. The lack of extensive deposits of ettringite in all the cores indicates that they were not exposed to pervasive infiltration or seepage of water during their service life. Core BOF 2-1 showed a trace deposit of ASR gel; none of the other cores showed evidence of ASR (Figure 7, 8). None of the cores produced exudations of gel after exposure to elevated temperature/relative humidity (T/RH) conditions (40ºC T/100% RH) except Core BOF 2-1, where the exudation occurred in the same area where gel was identified before the exposure test.

Figure 6. Photographs of the phenolphthalein stained surfaces. (a) Core W-1. (b) Core BOF 1-1. (c) CoreBOF 2-1. (d) Core BOF 3-1. The scale is in millimeters in (b)-(d).

Yosemite National Park Tunnel Linings Core Petrography! Report No. DRP12.1005 drpcinc.com ! Page 7 of 9

Figure 7. Reflected light photomicrographs of polished surface of Core BOF 2-1 showing deposit of ASR gel

(a) before exposure to elevatedT/RH conditions and (b) after removal of the sample from the test chamber.

Note that the gel swelled above the polished surface in the elevated T/RH chamber.

Figure 8. Backscatter electron micrograph of deposit removed from area indicated by green arrow in Figure 7a and EDX spectrum from this material. The spectrum is consistent with ASR gel.

Yosemite National Park Tunnel Linings Core Petrography! Report No. DRP12.1005 drpcinc.com ! Page 8 of 9

4.0 CONCLUSIONS

The findings described above indicate that the concrete represented by all the cores is sound and intact. All the cores lack air entrainment and contain portland cement with no fly ash or other supplemental cementitious materials. However, the cores represent distinctly different concrete mixtures made with different coarse aggregates.

The cores do not show evidence of cracking or significant microcracking. No evidence of damage related to durability mechanisms such as freeze-thaw damage, sulfate attack or ASR was observed in any core. The cores lack significant deposits of ettringite, which indicates the concrete was not exposed to significant moisture from infiltration or seepage of water. There is evidence of significant honeycombing at the outer end of Core W-1 and Core BOF 1-1, but neither core shows evidence of cracking, microcracking or any other distress that resulted from the honeycombing (although there is deep carbonation around some of the honeycombing).

While all the cores show evidence of significant carbonation, no cracking or microcracking due to corrosion was observed. None of the cores contain embedded steel.

Core BOF 2-1 is the only core to show evidence of ASR. In this core the observed ASR is negligible, with one deposit of gel observed next to a particle of andesite from the coarse aggregate. Core BOF 2-1 contains aggregate that is rich in siliceous volcanic rocks such as andesite and rhyolite, which are potentially susceptible to ASR. The aggregate in Core BOF 2-1 differs from the other cores, which consisted of more granitic rocks. No evidence of cracking, microcracking or any other forms of distress attributable to ASR were observed in Core BOF 2-1.

This concludes work performed on this project to date.

David Rothstein, Ph.D., P.G. FACI

Yosemite National Park Tunnel Linings Core Petrography! Report No. DRP12.1005 drpcinc.com ! Page 9 of 9

Yosemite National Park Concrete Tunnel Lining Core Petrography

Appendices

Appendix A! ! Core W-1/W-2 Petrography (ASTM C856) Appendix B! ! Core BOF 1-1 Petrography (ASTM C856) Appendix C !! Core BOF 2-1 Petrography (ASTM C856) Appendix D! ! Core BOF 3-2 Petrography (ASTM C856) Appendix E! ! Procedures drpcinc.com

1. RECEIVED CONDITION1. RECEIVED CONDITION

ORIENTATION

Horizontal cores taken through tunnel linings measure 105 mm (3 ¾ in.) in diameter (Figure A1, A2). Core W-1 is 105 mm (4 ⅛ in.) long and Core W-2 is 45 mm (1 ¾ in.) long.

SURFACES

Outer surfaces are formed and inner surfaces are fractures such that they represent partial thickness of the tunnel wall. The cores were trimmed after the initial inspection for compression strength testing. The provided samples represent the outermost and inner sections of the cores.

The outer section spans from a formed surface to a saw cut and the inner section spans from a saw cut to a fracture.

GENERAL

CONDITION

The concrete is hard and compact and rings lightly when sounded with a hammer.

Core W-1 shows poor consolidation and significant honeycombing (Figure A3). A light skim coat up to 1 mm (40 mil) thick was observed on the outer surface of the cores that is adhered to Core W-1 but detaches easily from Core W-2. Core W-2 has a skim coat on the outer surface and moderate scaling that exposes coarse aggregate particles to a depth of 2-3 mm (80-120 mil) over about one third of the surface (Figure A4).

2. EMBEDDED OBJECTS2. EMBEDDED OBJECTS

GENERAL None observed.

3. CRACKING3. CRACKING

MACROSCOPIC

A through-going sub-horizontal crack cuts Core W-1 in two pieces (Figure A3).

Core W-2 shows sub-vertical cracks sub-parallel to and within 3 mm (⅛ in.) of the formed surface (Figure A5). The cracks cut around and through aggregate particles, are 250-500 µm (10-20 mil) wide and 19 mm (¾ in.) long and are free of secondary deposits.

MICROSCOPIC

Minor microcracks cut orthogonally to the formed surface near the outer end of Core W-2 (Figure A6). The microcracks are 25-50 µm (1-2 mil) wide and up to 2 mm (80 mil) long, cut around aggregates and are free of secondary deposits.

4. VOIDS4. VOIDS

VOID SYSTEM

Concrete is not air-entrained and contains less than 3% air by visual estimation (not determined following ASTM C457). Elongated bleed voids observed occasionally.

Core W-1 shows extensive honeycombing throughout most of the sections provided to DRP (Figure A3). Core W-2 is well-consolidated.

VOID FILLINGS Voids are usually free of secondary deposits but occasional voids contain deposits of ettringite.

5. COARSE AGGREGATE5. COARSE AGGREGATE

PHYSICAL

PROPERTIES

Natural river gravel with 25 mm (1 in.) nominal top size but most particles are 19 mm (¾ in.) or less (Figure A7). The rocks are hard and competent. The particles are sub-equant to oblong in shape with round to sub-round edges. The grading and distribution is somewhat uneven.

ROCK TYPES*

The aggregate is siliceous in composition and consists primarily of igneous rocks with occasional metamorphic rocks. The rock types include granitic rocks (50%), diorite (20%), quartzite (12.5%), gneiss (7.5%), schist (5%) and granodiorite (5%). Many of these rock types are potentially susceptible to alkali-silica reaction (ASR).

OTHER FEATURES

No deleterious coatings or incrustations observed. No low w/c mortar coatings observed. No reaction rims, internal microcracking, deposits of gel or other evidence of ASR observed.

*Modal abundance based on visual estimation.*Modal abundance based on visual estimation.

APPENDIX A: Yosemite National Park Tunnel Lining Core Petrography Report No. DRP12.1005 Sample ID: Core W-1 (16YD5521)/Core W-2 (16YD5522) Date: 2 October 2012 drpcinc.com A1

6. FINE AGGREGATE6. FINE AGGREGATE

PHYSICAL

PROPERTIES

Natural river sand consists of rocks that are hard and competent (Figure A8). The particles are sub-equant to tabular in shape with angular to sub-angular edges. The grading and distribution are relatively even.

ROCK TYPES

The sand is siliceous in composition and consists of granitic rocks, mafic intrusive rocks, and metamorphic rocks similar to those observed in the coarse aggregate, suggesting they were derived from a common geological source. The finer fractions of the sand have abundant biotite, chlorite and amphibole.

OTHER FEATURES

No deleterious coatings or incrustations observed and no low w/c mortar coatings observed. No evidence of ASR observed.

7. PASTE OBSERVATIONS7. PASTE OBSERVATIONS

POLISHED

SURFACE

Core W-2 was used to examine the paste due to the extensive honeycombing in Core W-1. Paste is light gray (Munsell 10YR/7/1), has a granular texture and a dull to sub-vitreous luster (Figure A9). The paste is moderately hard (Mohs ~ 3). The paste in the outer 9.5 mm (⅜ in.) of Core W-2 is pale brown (10YR/6/3), has a granular texture and dull luster and is hard (Mohs ~ 4).

THIN SECTION*

The paste contains hydrated portland cement; no fly ash, slag cement or other SCM were observed (Figure A10). The hydration is normal with 4-8% RRCG that consist mostly of belite and interstitial aluminate and ferrite. CH makes up 10-15% of the paste, is coarse-grained and unevenly distributed. Pervasive carbonation and partial carbonation was observed over much of the thin section.

FRESH FRACTURE

SURFACE

Fracture surface is light gray, has a hackly texture and a sub-vitreous luster. The surface cuts primarily through aggregate particles.

* Abbreviations as follows: RRCG = relict and residual cement grains; SCM = supplemental cementitious materials; CH = calcium hydroxide; ITZ = interfacial transition zone. Modal abundances are based on visual estimations.

* Abbreviations as follows: RRCG = relict and residual cement grains; SCM = supplemental cementitious materials; CH = calcium hydroxide; ITZ = interfacial transition zone. Modal abundances are based on visual estimations.

8. SECONDARY DEPOSITS8. SECONDARY DEPOSITS

PHENOLPHTHALEIN

No staining to very pale purple staining for up to 25 mm (¼ in.) from exposed surface (honeycombed) in Core W-1 (Figure A11). In Core W-2 no staining was observed for up to 6 mm (¼ in.) from the formed surface (Figure A12).

DEPOSITS

Extensive carbonation observed in areas not stained by phenolphthalein in both cores. Minor deposits of ettringite observed in voids. No deposits of ASR gel observed.

APPENDIX A: Yosemite National Park Tunnel Lining Core Petrography Report No. DRP12.1005 drpcinc.com A2

FIGURES

(a)

(b)

Figure A1. Photographs showing (a) oblique view of the outer surface and side of Core W-1 with identification labels and (b) the outer surface of the core. The red and blue dots in (a) show the orientation of the saw cuts used to prepare the sample.

APPENDIX A: Yosemite National Park Tunnel Lining Core Petrography Report No. DRP12.1005 drpcinc.com A3

(c)

(d)

Figure A1 (cont’d). (c) Photograph showing the inner surface of Core W-1. (d) Photograph showing oblique view of the outer surface and side of Core W-2 with identification labels

APPENDIX A: Yosemite National Park Tunnel Lining Core Petrography Report No. DRP12.1005 drpcinc.com A4

(e)

(f)

Figure A1. Photographs showing (e) outer surface of Core W-2 and (f) the inner surface of Core W-2. The red and blue dots in (a) show the orientation of the saw cuts used to prepare the sample.

APPENDIX A: Yosemite National Park Tunnel Lining Core Petrography Report No. DRP12.1005 drpcinc.com A5

(b)

Figure A2. Photograph showing the polished surface of (a) Core W-1 and (b) Core W-2.

APPENDIX A: Yosemite National Park Tunnel Lining Core Petrography Report No. DRP12.1005 drpcinc.com A6

Figure A3. Photograph showing detail of honeycombing on as-received fracture surface from Core W-1.

Figure A4. Photograph of outer surface showing of Core W-2 showing detail of transition from the skim coat to the scaled surface; scale in millimeters.

APPENDIX A: Yosemite National Park Tunnel Lining Core Petrography Report No. DRP12.1005 drpcinc.com A7

Figure A5. (a) Photograph and (b) reflected light photomicrograph of polished surface of Core W-2 showing sub-vertical crack (red arrows) at the outer end of the core. Scale in millimeters in (a). The yellow bar in (b) measures the depth of paste discoloration associated with carbonation.

APPENDIX A: Yosemite National Park Tunnel Lining Core Petrography Report No. DRP12.1005 drpcinc.com A8

Figure A6. Reflected light photomicrographs of polished surface of Core W-2 showing orthogonal microcracks (red arrows) at the outer end of the core.

APPENDIX A: Yosemite National Park Tunnel Lining Core Petrography Report No. DRP12.1005 drpcinc.com A9

Figure A7. Photograph of the polished surface of Core W-2 showing coarse aggregate; scale in millimeters.

Figure A8. Reflected light photomicrograph of polished surface of Core W-2 showing the fine aggregate.

APPENDIX A: Yosemite National Park Tunnel Lining Core Petrography Report No. DRP12.1005 drpcinc.com A10

Figure A9. (a) Photograph of polished surface of Core W-2 showing overview of paste at the top of the core.

The scale is in millimeters. (b) Reflected light photomicrograph of polished surface of Core W-2 showing detail of paste texture and luster.

APPENDIX A: Yosemite National Park Tunnel Lining Core Petrography Report No. DRP12.1005 drpcinc.com A11

Figure A10. Transmitted light photomicrographs of thin section from the Core W-2 showing detail of paste in

(a) plane-polarized and (b) cross-polarized light. The red arrows in (a) indicate RRCG; in (b) they indicate CH. The yellow arrows in (b) show carbonated paste.

APPENDIX A: Yosemite National Park Tunnel Lining Core Petrography Report No. DRP12.1005 drpcinc.com A12

Figure A11. Photographs showing (a) overview of phenolphthalein stained surface and (b) detail of surface near the outer end of Core W-1. Scale in millimeters in (b).

APPENDIX A: Yosemite National Park Tunnel Lining Core Petrography Report No. DRP12.1005 drpcinc.com A13

Figure A12. Photographs showing (a) overview of phenolphthalein stained surface and (b) detail of surface near the outer end of Core W-2. Scale in millimeters in (b).

APPENDIX A: Yosemite National Park Tunnel Lining Core Petrography Report No. DRP12.1005 drpcinc.com A14

Horizontal core taken through tunnel lining measures 105 mm (3 ¾ in.) in diameter and 85 mm (3 ⅜ in.) long (Figure B1, B2).

SURFACES

Outer surface is formed and inner surface is a fracture such that the core represents a partial thickness of the tunnel wall. The core was trimmed after the initial inspection for compression strength testing. The provided samples represent the outermost section of the core, which spans from a formed surface to a saw-cut surface, and the inner section spans from a saw-cut surface to a fracture surface. The core appears to have been started and then shifted such that the outer wall is offset along a portion of the length of the core.

GENERAL

CONDITION

The concrete is hard and compact and rings lightly when sounded with a hammer.

A mortar layer measuring up to 3 mm (⅛ in.) thick is present on the outer surface; a portion of the surface is scaled and exposes a coarse aggregate particle in the concrete (Figure B3).

Segments of the contact between the mortar and the concrete show minor separation (Figure B4).

2. EMBEDDED OBJECTS2. EMBEDDED OBJECTS

GENERAL None observed.

3. CRACKING3. CRACKING

MACROSCOPIC None observed.

MICROSCOPIC No significant microcracking observed.

4. VOIDS4. VOIDS

VOID SYSTEM

Concrete is not air-entrained and contains less than 3% air by visual estimation (not determined following ASTM C457). The core shows extensive honeycombing in the outer 65 mm (1 ½ in.;

Figure B5).

VOID FILLINGS Voids are usually free of secondary deposits but occasional voids contain deposits of ettringite.

5. COARSE AGGREGATE5. COARSE AGGREGATE

PHYSICAL

PROPERTIES

Natural river gravel with 25 mm (1 in.) nominal top size but most particles are 19 mm (¾ in.) or less (Figure B6). The rocks are hard and competent. The particles are sub-equant to oblong in shape with round to sub-round edges. The grading and distribution is relatively even.

ROCK TYPES*

The aggregate is siliceous in composition and consists primarily of igneous rocks with occasional metamorphic rocks. The rock types include granitic rocks (30%), mafic intrusive rocks (dioritic, 30%), andesitic rocks (15%), quartzite (10%), very fine-grained siliceous rocks such as chert (10%), and rhyolite (5%). Many of these rock types are potentially susceptible to alkali-silica reaction (ASR).

OTHER FEATURES

No deleterious coatings or incrustations observed. No low w/c mortar coatings observed. No reaction rims, internal microcracking, deposits of gel or other evidence of ASR observed.

*Modal abundance based on visual estimation.*Modal abundance based on visual estimation.

APPENDIX B: Yosemite National Park Tunnel Lining Core Petrography Report No. DRP12.1005 Sample ID: Core BOF 1-1 (16YD5523) Date: 2 October 2012 drpcinc.com B1

PROPERTIES

Natural river sand consists of rocks that are hard and competent (Figure B7). The particles are sub-equant to tabular in shape with angular to sub-angular edges. The grading and distribution are relatively even.

ROCK TYPES

The sand is siliceous in composition and consists primarily of granitic rocks with minor siliceous metamorphic rocks and minor amounts of mafic intrusive rocks. The finer fractions of the sand have abundant biotite, chlorite and amphibole.

OTHER FEATURES

No deleterious coatings or incrustations observed and no low w/c mortar coatings observed. No evidence of ASR observed.

7. PASTE OBSERVATIONS7. PASTE OBSERVATIONS

POLISHED

SURFACE

Paste is lightly mottled from pale brown (Munsell 10YR/8/3) to light gray (10YR/7/1), has a granular texture and a dull luster (Figure B8). The paste is moderately hard (Mohs ~ 3). The paste in the inner 3-6 mm (⅛-¼ in.) is gray (10YR/4/1), has a smooth texture and is hard (Mohs ~ 4).