B08_Attachment_13_Upper_Plaza_Temp_Repairs-2011.pdf

PERRY'S VICTORY AND INTERNATIONAL PEACE

MEMORIAL

Additional Investigation

Put-in-Bay, South Bass Island, Ohio

Report October 7, 2011 WJE No. 2008.1261.6

Prepared for:

Mr. Rick Rampi Project Manager, Architect National Park Service, Denver Service Center

Prepared by:

Wiss, Janney, Elstner Associates, Inc.

330 Pfingsten Road Northbrook, Illinois 60062

847.272.7400 tel | 847.291.9371 fax

PERRY'S VICTORY AND INTERNATIONAL PEACE

MEMORIAL

Put-in-Bay, South Bass Island, Ohio

Harry J. Hunderman, AIA

Michael J. Scheffler, PE

Joshua D. Freedland

Report

WJE No. 2008.1261.6

Prepared for:

Mr. Rick Rampi Project Manager, Architect National Park Service, Denver Service Center

Prepared by:

Wiss, Janney, Elstner Associates, Inc.

330 Pfingsten Road Northbrook, Illinois 60062

847.272.7400 tel | 847.291.9371 fax

TABLE OF CONTENTS

Introduction Column

Observations Granite Joints Cleaning

Discussion Granite Joints Cleaning

Recommendations Interim Granite Repairs Cleaning

Upper Plaza Observations

Paving Structure

Discussion Paving Structure

Rotunda Observations Discussion Recommendations

Figures

APPENDICES

A. Petrographic Examination of Column cores

B. Drawings and Specifications for Interim Column Repairs

C. Trial Cleaning Products

D. Excerpts from 2008 WJE report on the condition of the structure

E. Bibliography from 2007 WJE Report

Perry's Victory and International Peace Memorial

Two previous reports prepared by WJE provided background for the current investigation:

Perry’s Victory and International Peace Memorial – Exterior Condition Assessment, dated February

12, 2007

Perry’s Victory and International Peace Memorial – Investigation, dated February 12, 2008

The close-up inspection confirmed that, as described in our previous reports, there are several types of granite distress present, including cracks, spalls, and incipient spalls and delaminations at cracks.

Examples of distress are shown in Figures 2 through 6. The separation of sizeable fragments of the stone along the surface of a crack results in a spall where the separated fragment is missing, or a delamination

(also called an incipient spall) where the separated fragment remains in place. Delaminations typically occur adjacent to a crack within a granite block or a joint between blocks. Delaminations indicate that a portion of the stone along the exposed surface of the block is separating from the main body of the granite block, usually along the plane of a crack that is visible on the exterior surface of the granite block. If not addressed, this condition allows the delaminating portion of the stone to loosen to the extent that it may become a falling hazard. At several locations adjacent to cracks, incipient spalls or delaminations were found to be loose or considered not to be reliably attached to the main body of the granite. Where possible, these portions of granite were removed during the inspection; where they could not be removed, these distress conditions were documented for future repair.

An existing large patch (Figure 7) was observed to be loose and not reliably attached and was removed during the inspection. Failed patches of this type that are not reliably attached also have the potential to fall, and were identified for future repair.

In general, granite cracks are open and not sealed or filled with mortar. In many locations, cracks had been previously repaired with sealant or mortar; however, several inches of crack length at the ends of many cracks were not sealed, indicating that the distress has continued to develop and worsen since the cracks were last repaired.

Cores were taken through the granite and into the concrete structure in three locations: at the D course of

Section 1, Flute 14 (Core 1); at the B course, Section 4, Flute 15 (Core 2); and at the F course, Section 7, Flute 16 (Core 3). A description of the cores and the findings of petrographic examination are provided in Appendix A.

Core 1 ‒ A 24 inch long by 4 inch diameter core was made at the location of a granite crack as shown in Figure 8. The core location was selected in an effort to identify the causes of the crack. The location was also selected to evaluate the properties of concrete backup material at a location near the base of the monument. The granite and concrete backup were largely removed intact. The core was taken centered on the granite unit near its top edge. Other than the crack being in alignment with the vertical joint between the granite units above, there was no direct evidence indicating the cause of the crack.

Core 2 ‒ An approximately 17 inch long by 4 inch diameter core was made at the location of a cracked granite unit at an area that sounded delaminated adjacent to the crack as shown in Figure 9.

The core location was also selected in an effort to identify the severity and causes of the distress. The location was selected to evaluate the material properties of joint mortar and concrete backup at a location near the mid-height of the monument. The granite and concrete backup were removed as numerous fractured pieces. Upon removal of the core a visible space was observed between the cracked portion of the granite unit and the mortar in the irregular joint, indicating that the granite unit was no longer in direct contact with the mortar in the joint and had likely shifted outward slightly after installation. The joint varies in width but is progressively wider at greater depths; ranging from approximately 3/8 inch wide at the face of the granite to more than 2 inches wide approximately 3 inches deep into the wall. The space between the mortar and the granite unit strongly suggests that the crack developed as a result of forces from freezing water that may have previously been present in the area immediately behind the granite. At the joints between granite units there are voids between the exterior joint mortar and the poured concrete structure behind.

Core 3 ‒ An approximately 17 inch long by 4 inch diameter core was made at the location of cracked granite unit at an area that sounded delaminated adjacent to the crack as shown in Figure 10. The core location was selected in an effort to identify the causes of the distress. The location was also selected to evaluate the material properties of joint mortar and concrete backup at a location near the upper portion of the monument. The granite and concrete backup were removed in a few pieces. Upon removal of the core, voids were observed in the mortar in the irregular joint between the granite units;

however, the mortar was in direct contact with the adjacent granite. The joint varies in width but is progressively wider at greater depths; ranging from approximately 3/8 inch wide at the face of the granite to more than 2 inches wide approximately 3 inches deep into the wall. There was no direct evidence observed that indicated the cause of the crack.

Joints

The joints between the granite units are assumed to have originally been bedded and pointed with a portland cement, lime, sand mortar. In 1952, the joints between the granite units were repointed with a mortar composed of 1 part portland cement, 0.5 part hydrated lime putty, and 3 parts sand. As part of the same project, composite patches consisting of “1 part special patching cement” and 3 parts pulverized granite were installed, and DRYWAL by Flidden Co. was applied to waterproof “undeveloped surface cracks” (WJE, 2007).

In 1963‒1964, the Column was again repaired. Repairs included removing the mortar and installing polysulfide sealant in the joints between granite units and coating the granite with Thoro 777 silicone waterproofing. Remnants of polysulfide sealant were identified using Fourier transform infrared (FTIR) spectroscopy by WJE in 2007. In 1983, another exterior repair campaign was implemented, which included removal and replacement of the polysulfide sealant with Dow 790 silicone sealant. Aggregate was broadcast into the sealant to more closely resemble the appearance of the original mortar joints.

Laboratory analysis conducted by WJE using FTIR spectroscopy confirmed that the existing sealant is silicone (WJE 2007).

The existing elastomeric joint sealant is debonded in many isolated locations along the length of the joints; however, these areas of debonded sealant are not a large percentage of the total length of joints. At many locations water and efflorescence stains exist directly below debonded portions of sealant where water and dissolved minerals are exiting the Column wall at the joints. This condition is more prevalent at lower levels and at the intersections of joints. Typically, the length of debonded sealant is short (a few inches or less); however, there are likely dozens if not hundreds of such occurrences, resulting in numerous locations where water can potentially penetrate and also exit the wall.

In areas where a portion of the sealant was removed to inspect the joint between the granite blocks, water drained from the wall, as shown in Figure 11.

Cleaning

Staining of the granite cladding has reportedly been a concern since construction and the Column has been cleaned using abrasive techniques at least four times. Following completion of the construction, the granite Column was sandblasted. In 1952, the Column was cleaned using 120 to 140 psi dry abrasive cleaning with flint shot silica sand. Calcium carbonate deposits were removed by hand using metal tools.

In 1963‒1964, the Column was cleaning using wet aggregate blasting at “low pressure.” In 1983, the

Column was cleaned using aggregate blasting techniques, although the documentation is conflicting as to whether wet or dry techniques were used at that time (WJE 2007).

Two predominant staining patterns were referenced historically and are currently visible: white deposits and dark staining adjacent to the joints. White deposits were observed on the exposed face of the granite throughout the monument. The following specific conditions were noted:

The white deposits were observed mainly at the top three courses of the Column directly below the echinus and at the bottom seventeen courses of the Column (Figure 12).

The deposits typically appear to emanate from the intersection of the head and bed joints at the granite units but are also found below horizontal joints (Figure 13).

The white deposits ranged from a thin (less than 1/16 inch) deposit to nearly 1 inch in thickness

(Figures 14 and 15).

At accessible areas, the sealant in joints above areas of white deposits was in poor condition and debonded from the granite.

At many areas of debonded sealant above the white deposits, the sealant joint was damp and at several locations water actively dripped from the joint.

There was no correlation of staining pattern relative to the orientation of the Column.

Dark staining below the joints was observed as early as 1916, according to later correspondence between the original general contractor, J. C. Robinson & Sons, and Joseph Prentice, the park superintendent, in

1955. J. C. Robinson & Sons attributed the dark stains below the joints to the leaching of a bituminous waterproof coating applied to the back and sides of the granite as part of original construction and the subsequent heating of the coating during warm weather.

During the current close-up inspection, the following conditions were observed with regard to the dark staining adjacent to the joints:

The dark staining was observed adjacent to both horizontal and vertical joints.

The dark stained areas of the granite did not exhibit hydrophobic properties.

The staining extended several inches from the joints.

No correlation was noted in the severity of the staining relative to height, orientation, or relationship to other staining or distress patterns.

In addition, some “wand marks” and other non-uniform appearance of the granite were observed, likely a result of uneven cleaning during previous abrasive cleaning campaigns.

Discussion

Granite

The recommended type of repairs and the extent of those repairs will vary depending on the goals for the work. For example, a minimal approach would be to address only safety issues such as the removal or stabilization of any loose or potentially loose pieces of stone (incipient spalls). Another approach would be to address service life as well as safety issues; for example, repairs could include pinning of cracked pieces of stone that are not presently in danger of falling, or sealing of cracks in the granite to limit the intrusion of water into the monument. This approach would be designed to provide interim repairs until a more comprehensive repair program can be initiated. A third approach would be a restoration repair program that could include replacement of all of the joint sealant, installation of dutchman units at incipient spall locations, repair of cracks, installing pin anchors at cracked granite, and cleaning of the granite.

Although the generic repair types and order-of-magnitude repair quantities can be determined from the current close-up inspection and other analysis already completed, in order to identify all the locations where distress is present on the Column, a detailed, close-up visual survey of all twenty flutes from a suspended scaffold is required. Based on the inspection conducted in July, a swingstage of similar size should be provided for close-up access by an architect/engineer to all remaining flutes; this would permit access to three flutes at a time. Accordingly, an estimated seven swingstage drops are required to obtain close-up access to all twenty flutes. During the detailed visual survey, cracked portions of granite should be tapped and sounded to identify delaminations and any unsafe conditions requiring repair. Based on the detailed survey, each repair location and repair type, including the layout and dimensions of the specific repairs, should be identified by the architect/engineer and documented with photographs and field survey sheets. This detailed survey will provide the contractor with the locations and types of required repairs.

The field survey sheets also will serve as a permanent record of the repair program and locations. In addition to the granite repairs, the locations where joint sealant requires replacement should also be identified by the architect/engineer during this inspection.

The scope of work for the Column as outlined below is designed to address current distress conditions.

Most of the recommended repairs, including the installation of anchors to stabilize cracked or delaminated stone or the installation of Dutchmen to replace portions of delaminated stone, are long term repairs that would not require significance maintenance for the foreseeable future.

The recommended scope of work, however, does not include those repairs required to address the root cause of the observed problem. Because the granite blocks were of irregular shape on the backside, and considering that the concrete was poured in 7 foot lifts, and as confirmed by the coring completed as part of this investigation, there appears to be an interconnected channel of voids between the back of the granite and the concrete structure. This network of voids allows water to move behind the stone and perhaps pool in cavities near the joints. This water can freeze, resulting in deterioration of the concrete, and can also put stress on the granite, leading to cracking. The collection of water behind the stone also leads to saturation of the concrete, resulting in damage from cyclic freezing and thawing as observed in the concrete removed from the cores (see Appendix A). These conditions can also cause distress and cracking in the stone. Another factor contributing to the observed distress may be non-uniform support and loading of the granite due to the poor and presumably variable strength of the concrete structure.

Certainly, keeping water out of the structure is the highest priority in preventing further damage, a consideration that has led others in the past to suggest the use of sealant in the joints between granite units. The problem with sealant as a joint fill material is that it also holds water in the wall, which can lead to deterioration of the stone and concrete. In addition, since silicones have been use in the past for sealing the joints, it may be problematic to install any other sealant or mortar in the joints in the future, as discussed below.

When repointing or resealing of the joints is undertaken in the future (with either mortar or sealant), consideration should also be given to grouting the voids behind the pointing mortar/sealant to retard the movement and collection of water behind the stone.

Joints

Since the exterior facade is constructed of a mass masonry wall, the use of sealant in all of the joints would not typically be recommended. If the joints between the granite units had remained filled with mortar, which is consistent with the original design, repointing the joints would be the recommended approach to repairing deteriorated joints. However, elastomeric sealant was installed over the mortar some time ago, and more recently silicone sealant was used for repair of the joints. The use of a silicone sealant may have led to the migration of plasticizers into the stone, which may negatively impact the adhesion of any new repointing mortar.

Restoring the weather resistance of the joints between the granite panels is important to reduce the rate of future water infiltration, distress, and soiling. Based on these considerations, two joint repair options exist for the granite panels following removal of the existing joint fill materials: installation of mortar or elastomeric sealant.

As discussed previously, using sealant between masonry units in a mass masonry wall is typically not advisable. However, the existence of elastomeric sealant (particularly silicone sealant) in the joints leads to consideration of this potential repair approach. This repair would require the removal and replacement of the existing sealant in the joints between granite units with a properly detailed silicone sealant joint.

The advantages to repairing the granite joints with sealant include:

Sealant joints will minimize water migration into the wall system.

The general adhesion properties of the sealant to the granite substrate are known.

A sealant joint will accommodate joint movement, resulting in a system that is more flexible than the original bonded mortar system. The use of sealant joints at selected locations in the facade (with mortar joints elsewhere) may allow natural movement to occur without cracking of mortar joints.

Considering the condition of the joints today, it is possible that only a portion of the sealant may need to be replaced in a comprehensive repair program.

The disadvantages to repairing the granite joints with elastomeric sealant include:

The use of elastomeric sealant in the joints, although embedded with sand, is inconsistent with the historic design and appearance of the building.

Effectively installed joint sealant will prevent the water from evaporating from the wall system.

It is unlikely that all the sealant can be installed perfectly without some small percent of the new sealant remaining unadhered to the stone substrate, particularly considering the amount of moisture that is already trapped in the wall. These small failures, as well as breaches that occur over time as the sealant ages, will allow water to enter the wall system.

This repair will require routine periodic monitoring, maintenance, and replacement of sealant to prevent water from entering the wall at breaches in the sealant joints.

Replacing the existing sealant joints with mortar is the preferred treatment of joints between the granite blocks, but it is unknown if the mortar will bond to the granite due to the presence and possible migration into the granite of plasticizers from silicone sealant. No hydrophobic zones adjacent to the joints were observed during the field investigation, suggesting the migration of plasticizers from the silicone sealant may be limited. Further in-situ trials are required to confirm the feasibility of achieving a consistent bond of the mortar to granite.

The advantage to repairing the granite joints with mortar includes:

Repointing with mortar is the original and historical treatment of the joint.

Mortar will allow absorbed moisture to evaporate to the exterior, allowing the mass masonry wall to manage water as originally designed.

Isolated failures in pointed joints, such as cracking and debonding of the mortar, are of less concern than minor sealant failures that can lead to entrapment of water behind the sealant joint.

The disadvantages to repairing the granite joints with mortar include:

The presence of plasticizers and plasticizer migration from sealant in the granite may interfere with mortar bond. Field trials may not identify the extent of plasticizer migration and therefore may be unsuccessful in predicting mortar bond.

Joint movement due to may be more extensive than mortar can accommodate, leading to premature separation and/or cracking of the mortar.

Mortar joints will require periodic repointing where mortar separations occur.

This repair will also require routine periodic monitoring, maintenance, and replacement of mortar to prevent water from entering the wall at breaches in the mortar joints.

The type and extent of staining observed was consistent with the staining observed throughout the history of the Column from shortly after completion of the monument to conditions noted in the 1981 masonry cleaning report.

While no laboratory analysis was conducted of the white deposits on the granite surface, these deposits are likely primarily calcium carbonate and may also contain other soluble mineral components from the back-up concrete and setting mortar.

As part of the 2007 WJE investigation, petrographic examination of concrete cores of the back-up concrete was performed. These studies indicated that many of the voids were partially to completely filled with secondary crystalline deposits; some of the cores had a higher cement content; and the concrete was typically uncarbonated throughout the depth of the core. Water percolating through the concrete dissolves minerals in the concrete (primarily from the paste) and deposits these minerals in the voids. The deposits on the face of the granite are the result of the same mechanism observed on a macro-scale. The uncarbonated nature of the concrete suggests that more readily water soluble components are available for this staining mechanism to occur. While a reduction in rate of deposition may be anticipated as the concrete carbonates, while the concrete remains uncarbonated there is not likely to be any reduction in the quantity of soluble components present in the concrete to create the white deposits.

Based on available documentation and the appearance of the monument, it is unclear if any of the abrasive cleaning techniques used historically were successfully in reducing or eliminating the dark perimeter staining observed. The parameters used during some of the cleaning programs did cause damage to the granite and unevenness in appearance, as noted by the wand marks currently visible. While

WJE did not perform any laboratory analysis of the dark staining adjacent to the joints in the granite as part of this study. Although the pattern and character of the dark staining resembles plasticizer migration, a problem that often occurs when silicone sealant is installed in masonry joints, the non-hydrophobic

Frank G. Matero, Report on Masonry Cleaning and Long-Term Testing. (Boston, Massachusetts: National Park

Service, North Atlantic Historic Preservation Center, August 1981).

nature of the granite at the stained areas suggests this may not be the cause. The potential leaching of the back-up waterproofing coating suggested by J. C. Robinson and Sons also seems unlikely. The 1981 masonry cleaning report hypothesized that the dark stain results from calcium silicates in the portland cement in the back-up concrete carried with water migrating through the open joints and being deposited near the edge of the joints. No deposits associated with the dark discoloration could be observed using field microscopy; however, the concentration of deposits that may be causing the discoloration may be extremely small and nearly imperceptible using microscopy and other laboratory techniques.

Based on our understanding of the staining, WJE performed several limited cleaning trials of the exterior granite. Cleaning trials were conducted using low pressure water at approximately 500 psi. The following trials were performed:

1. ABR Products, Inc., X-190 Limestone and Concrete Cleaner (three applications)

2. Prosoco Light Duty Concrete Cleaner diluted 1:2 parts volume/volume with water (three applications)

3. FTB-Remmers Arte Mundit Type I Peeling Cleaning Agent followed by FTB-Remmers Arte Mundit

Type V Peeling Cleaning Agent

4. Prosoco Limestone and Masonry Afterwash diluted 1:1 parts volume/volume with water

5. MasonRe Light Duty Rust Remover diluted 1:2 parts volume/volume with water

6. ABR Products Inc. 50 Rust Remover diluted 1:2 volume/volume with water

7. ABR Products Inc. 50 Rust Remover diluted 1:2 volume/volume with water (three applications)

8. MasonRe Light Duty Rust Remover diluted 1:2 parts volume/volume with water

The product data and material safety data sheets for the cleaners used during the trials are provided in

Appendix C. The acid based cleaners (Samples 1, 2, 4, 5, 6, 7, and 8) successfully removed a significant amount of the white deposits, although white deposits remained on the surface even after multiple applications at the severely stained areas (Figures 10, 17 and 18). In addition, ABR-190 Limestone and

Concrete Cleaner brightened the surface of the granite slightly. The non-acidic poultices (Sample 3) were ineffective at removing the staining. No trial was successful at removing or reducing the appearance of the dark perimeter staining.

Abrasive cleaning techniques were not attempted for several reasons, including the need for specialized equipment. Further, previous cleaning campaigns and trials on the granite using both wet and dry abrasive techniques as well as mechanical cleaning using metal tools in the 1950s have reportedly been successful at removing the white deposits from the granite surface.

Based on the cleaning trials conducted, weak acid based cleaners were successful to some degree at reducing the level of soiling; however, even after multiple applications, some white deposits were left on the surface. The weak acidic cleaners did not significantly change the appearance of the granite, which may permit the cleaning of isolated stones at the areas of most severe staining closest to grade rather than a comprehensive cleaning of the monument. A chemical cleaning process would, however, introduce water into the masonry system, which may exacerbate the reformation of the deposits. In addition, the weak acidic cleaners did not remove the dark staining adjacent to the joints.

The long-term success of a cleaning campaign to remove the white deposits will require resolving the water leakage that is occurring at the Column, since any water entering the back-up concrete will dissolve and redeposit staining components as the water leaves the system. Based on the staining pattern, water is exiting the wall primarily directly below the Observation Deck as well as at the bottom fifth of the

Column. The recently completed repairs to the waterproofing at the Observation Deck level will help in preventing additional staining particularly directly beneath this area, but the history of staining at the monument as well as the remaining open and failed joints between the granite units indicate that staining will remain an active problem.

As repeated cleaning will be required to remove the staining, it may be addressed as a maintenance item made more feasible by the installation of recently suspended scaffolding access system. While mild acidic chemical cleaning may be less effective than the abrasive cleaning campaigns conducted historically, these systems allow for spot cleaning without significantly changing the appearance of the Column.

Abrasive cleaning would likely clean the unstained granite more effectively and thus create a more dissimilar appearance to the granite if only localized areas are cleaned. Use of chemical cleaners, which require water for prewetting and rinsing, may introduce more water into the Column and accelerate the rate of formation of the deposits if the joints are not successfully repaired and maintained. Care must be taken to define the parameters of any abrasive cleaning system, as previous abrasive cleaning systems have caused damage to the granite.

Recommendations

As noted above, the recommended type of repairs and the extent of those repairs will vary depending on the purpose of the work. The interim granite repairs outlined below are designed to address current distress conditions. Additional work required on the Column long term should address treatment of the joints and cleaning of the granite.

Interim Granite Repairs

Based on the distress observed during our inspection of three flutes of the Column in July 2011, four general types of repair are recommended. Appendix B includes drawings and specifications for repairs to address safety and serviceability issues as noted above. This Appendix also includes a spreadsheet documenting quantities of repairs. A summary table of repair quantities is also provided below.

1. Removal of Small Incipient Spall. Small incipient spalls adjacent to joints can be removed and the missing stone portion filled in with sealant. Removal of the stone fragment is typically recommended where the spall is relatively small in size. Another factor for consideration in whether the spall location is left as is, filled with sealant, or repaired with a dutchman (see below) after spall removal is how visible the location will be once the spall has been removed. Many of the small spalls recommended for removal and sealant repair on the monument are located along joints between granite blocks and typically involve narrow fragments of stone that extend along the joint (Figure 2).

In these cases, the current sealant joint can easily be cut out and reinstalled as a wider joint to include the width of the spall as part of the sealed joint. A maximum of a 1 inch width of the spall is recommended for spalls to be removed and incorporated into the joint between blocks. This interim repair is designed to address safety issues but may be visible and will need to be addressed further during a comprehensive restoration program. Incorporation of spalls wider than 1 inch into the joint will likely have a negative effect on the overall appearance of the monument.

2. Pin Repair. When spalls are larger in size than a narrow strip of stone along a joint and where cracking is observed or delamination suspected, pinning of the incipient spall or delaminated area of stone is recommended. Pin repairs will secure large delaminated or cracked portions of the stone to the main portion of the granite unit (appropriate for conditions shown in Figures 2 through 6). Two types of pinning are included in the recommended scope of work for the monument Column.

a. Stainless steel rod set in epoxy. The first type of recommended pinning repair involves placement of a 1/4 inch diameter stainless steel threaded rod in a slightly larger hole drilled into a delaminated area of stone or incipient spall. The hole should be thoroughly cleaned prior to placement of the rod and injection of epoxy into the hole around the threaded rod. The exterior end of the threaded rod should be recessed a minimum of 3/8 inch from the surface of the stone to permit installation of sealant or grout over the end of the rod on the exterior stone surface. Use of the 1/4 inch diameter threaded rod should be limited to locations where the delaminated portion of the stone is a minimum of 1 inch in depth (Figure 5, as an example). The threaded rod should be inserted to a minimum depth of 2 inches beyond the plane of delamination into solid granite or back-up behind. An epoxy pin repair location is shown in Figure 5 where a sample repair was performed in July 2011.

b. Stainless steel expansion anchors. The second type of pinning repair recommended involves installation of specialty expansion type anchors for stone. The stone anchors are designed to secure spalls that extend more deeply into the granite block (appropriate for granite distress shown in Figure 19). When the plane of delamination within the stone is a minimum of 3 inches from the surface of the stone block, a stone expansion anchor should be installed to anchor the spalling stone to the solid back-up of the granite block. The anchors are designed to secure larger sections of stone than the shallower spalls that can be repaired with a threaded rod set in epoxy.

Stone expansion anchors utilize mechanical wedging action to secure the anchor into both the solid back-up of the granite block and also the spalling portion of the stone. The wedging action of the stone anchor is engaged after the anchor is inserted into a drilled hole of specified diameter and then torqued to a specified force, at both an inner expansion sleeve which engages the solid back-up stone and the exterior expansion sleeve which engages the spalled or delaminated portion of the stone at the surface of the granite block. During torquing of the anchor, the brass expansion sleeves expand as a wedge is driven up against each expansion sleeve. Anchors are readily available in lengths between 5-1/2 and 11-1/2 inches but may be specially ordered for other lengths as well. The exterior end of the stone anchor should be recessed a minimum of 3/8 inch from the surface of the stone to permit installation of sealant or grout over the end of the anchor on the exterior stone surface. The stone anchor should be inserted to a minimum depth of 2 inches beyond the plane of delamination into the solid back-up behind, to ensure that the anchor is fully engaged into the solid back-up beyond the plane of the crack in the stone. A typical stone anchor installation is shown in Figure 19, where a sample repair was performed at the time of the close-up inspection in July 2011.

3. Dutchman Repair. A dutchman repair involves cutting out and removing an existing section of deteriorated stone, such as around an existing spall location where a section of stone is currently missing. The section of stone cut out should have square edges and be a minimum 2 inches in depth and a maximum of 4 inches in width (because of the curve of the flutes). The minimum face dimensions are dependent on the ability to properly install a new piece of stone with at least two pins.

The minimum size may vary due to specific tools used on site.

The dutchman repair is anchored into place by two or more threaded rods along the top and bottom edge of the stone that drop into place only once the stone has been properly installed. A hole is drilled into the top and bottom edges of the opening as well as the top and bottom edges of the repair stone such that the holes align when the stone is properly set into place. A threaded rod is inserted and temporarily taped into place in both the drilled hole on the upper edge of the opening and the drilled hole on the bottom surface of the repair stone. Once the stone has been set into place, the tape is removed and the threaded rod drops into the holes on the bottom edge of the opening and the top edge of the repair stone. Holes are drilled to a depth such that when installed, a 4 inch threaded rod extends approximately 2 inches into the dutchman at the top and bottom and 2 inches into the adjacent stone beneath and above the dutchman. Once it is verified that the threaded drop pins are positioned properly, the narrow joint at the perimeter of the dutchman is filled with mortar in a fashion similar to a typical joint between granite blocks; however, the mortar is tooled flush with the adjacent stone surface.

A dutchman repair is recommended for a variety of conditions, which may include spalls where fragments of the stone are missing, incipient spalls that are difficult to anchor due to their location, or locations where a delaminated section has broken into multiple sections of stone. A dutchman repair may also be suitable to replace a previous repair that has failed or begun to degrade, or to repair a severely cracked portion of stone (Figure 20). A completed dutchman repair location is shown in

Figure 21, where a repair was performed at the time of the close-up inspection in July 2011.

4. Crack Repair

a. Repair with Sealant. Open cracks can be routed and sealed with elastomeric sealant to prevent water from penetrating into the monument Column (for example, appropriate for crack shown in

Figure 2). Many of these locations were not previously repaired; the cracks have extended further since the previous repair; or the previous repair has failed. At these locations the recommended repair is as follows:

Rout the crack along the entire crack length with a profile of 1/4 inch wide by 1/4 inch deep, centered on the crack.

Install bond breaker tape at the back surface of the square cut out joint covering the open crack.

Install and tool non-staining, non-bleeding elastomeric silicone joint sealant over the bond breaker tape to fill the cut out joint.

b. Repair with Grout. At some locations, it may be possible to install sanded or unsanded grout in the crack, particularly in smaller cracks without previous repairs however this would not be recommended if additional movement in the crack were anticipated. This may preclude the need to grind cracks to make them wider.

Table 1 provides a summary of granite distress conditions observed at the flute areas inspected. This table also provides an estimate of the quantity of distress conditions likely to be present at the entire Column of the monument, and the number of recommended repairs required, based on extrapolating the quantities of distress observed at the inspected area across the entire area of the Column.

Rout and seal crack (lin. in.)

Remove incipient spall

(number)

Epoxy pins

(number)

Expansion anchors

(number)

Dutchman repairs

(number)

Flute 15 324 7 19 20 0

Flute 16 431 8 18 4 2

Flute 17 216 10 10 10 2

Total (based on observation)

971 25 47 34 4

Extrapolated total for 20 column flutes

(539 lin. ft.)

167 313 227 27

Table 1 - Summary of Repair Quantities

Based on our survey, we estimate that, for the entire Column, there are likely to be approximately 500 cracked or spalled areas of granite of various sizes that result in portions of granite that are not reliably attached to the monument, some of which may present a falling hazard. These cracked or loose portions of granite will need to be identified and removed or secured in place prior to allowing public access to the monument.

Based on our general visual observations of joint sealant, it is estimated that in total, approximately 100 linear feet of sealant over the entire height of each of the 20 flutes is debonded from adjacent granite units, or is deteriorated, and requires replacement to help reduce water entry through these joints. In total, approximately 2,000 linear feet of sealant in total require replacement.

Removal and replacement of deteriorated joint sealant with new sealant will require cutting out the existing sealant (and backer rod, if present) with a razor knife, cleaning, and if necessary, lightly grinding the granite substrate within the joints to remove sealant remnants and residue. Because the sealant replacement anticipated for interim repairs will be very limited, it is anticipated that the new sealant will be the same sealant as that previously used, Dow Corning 790 silicone sealant. The new sealant should be placed against a newly installed bi-cellular foam non-absorbent backer rod to prevent adhesion to remaining internal joint mortar. It may be necessary to remove a significant amount of existing deteriorated mortar and also allow the joints to dry for an extended period of time before new sealant can be installed onto a dry substrate. The specific procedures required will need to be determined through sealant replacement mock-ups.

Prior to or during the sealant repair work described above, we recommend that a trial repair study be performed at a small area of the Column near the base of the monument to evaluate whether the existing silicone joint sealant can be replaced with mortar instead of sealant. Using mortar in joints may facilitate water that enters the wall from breaches that are very likely difficult to detect and will also likely to develop in the future to more readily exit the wall. Initial adhesion of the new joint mortar to the granite substrate should be evaluated, as well as long term performance monitoring of the mortared joints in the trial repair area over several years prior to full scale implementation. Preliminarily, trial repairs should include installing approximately 25 to 50 linear feet of each of several types of pointing mortar, including a range of several hydrated lime/portland cement based mortars, and possibly mortar additives to improve performance (such as acrylic modifiers to improve bond). As part of this repair, all deteriorated mortar behind the pointing mortar should be removed from the joints; the repointing effort may require deep pointing or grouting of any voids behind the joints. Mortar materials or grouts for deep pointing will need to be developed so that they have good flow characteristics and can be properly placed in the joint without formation of voids.

Proprietary gentle abrasive systems unavailable during previous cleaning campaigns, which have a higher degree of applicator control and use lower pressures (less than 50psi), should be considered for cleaning of the Column; however such a system would likely require cleaning of the entire monument to achieve a uniform appearance. Alternatively, spot cleaning using weak acidic cleaners may be used as a routine cyclical maintenance procedure. Regardless, unless the water migration through open joints is reduced, the deposits will continue to reform as they have historically.

UPPER PLAZA

Observations

Paving

Observations were made in July 2011 during the Observation Deck and Penthouse repair project that was currently underway at the top of the monument. Consequently, some areas of the plaza were not available for observation, including a large lay down area on the east side which was covered by plywood, and the area between the lower staging area and the Column and hoist which was covered by plywood at grade and a raised platform and staging.

Because the plaza has not been accessible to the public for several years, and because of the repair project underway last year and this, the condition of the Upper Plaza paving system and planters has deteriorated

(Figure 22). The granite pavers themselves are in generally in good condition with only a few cracked pavers. Several of the pavers were previously removed to facilitate the installation of the canopy from the stairs to the monument entrance, and for the installation of the hoist, walkway to the hoist, and the installation and demobilization of the shoring tower. The joints between the pavers have opened, dirt has accumulated in the joints, and vegetation has grown up. The planters have become overgrown. In addition, some of the pavers are displaced (Figure 23), creating potential tripping hazards.

Where the stone pavers were removed for inspection there was little if any bond between the paver and the mortar bed beneath (Figures 24 and 25). The mortar bed (where exposed) was in poor condition with little consolidation. The mortar bed will continue to deteriorate because water easily penetrates the joints and saturates the mortar; with freezing and thawing, the mortar eventually turns to sand-like consistency.

Much of the plaza was sounded during the current inspection and most of the pavers appear to be debonded from the mortar bed. Where the pavers are debonded, dirt and debris can get underneath the pavers. In addition, since the mortar bed has deteriorated into a sand-like consistency, the bedding material can shift or be washed away, further destabilizing the paver. Since the pavers are not bonded, they can easily become dislodged and move, creating uneven surfaces.

Structure

A visual survey and sounding of the concrete structure were performed at representative areas of the

Upper Plaza to compare the current condition of the reinforced concrete structure to that observed during previous inspections.

As noted in the previous WJE report (WJE 2008) notable conditions observed included concrete deterioration in the form of cracked, spalled, and delaminated concrete (Figures 26 and 27). Some areas of concrete sounded “dead” or hollow when tapped with a hammer, indicating delaminations, freeze thaw deterioration, or other defects. In areas of spalled concrete, reinforcing steel was observed to exhibit corrosion but not significant loss of cross-sectional area. Areas of previously installed patches were noted.

Sound testing of the repairs indicated that some areas may be delaminated and/or debonded. Evidence of water leakage through the deck structure in the form of water staining and efflorescence (mineral deposits) was observed on the underside of the structural slab. Although visual evidence of severe freeze thaw deterioration was not observed at all areas of the slab, beams, and girders, visible freeze thaw deterioration was extensive. Somewhat less water staining and deterioration of the concrete were observed in the dropped slab areas of the plaza that support the planters.

Paving

As stated in the 2008 WJE report, “. . . if public access to the Upper Plaza is desired after repairs are made in the next few years to the Observation Deck and Column, the short term recommendation is to shore the structure after limited waterproofing and drain repairs are made to address ongoing water leakage and paver repairs are made to address deterioration and tripping hazards.” The disadvantages of this short term repair approach are that water leakage and freeze thaw damage may continue, depending on the effectiveness of these short-term repairs, and the concrete structure will continue to deteriorate. The structure will need to be evaluated periodically and the shoring will need to be examined and adjusted over time. Eventually, the structure will need to be replaced. The long term solution is to completely replace the concrete structure and install a new waterproofing membrane and surface.

The primary short term goal defined by the NPS is to allow public access (perhaps limited in numbers and only to selected areas) to the plaza. At a minimum, public access from the top of the stairs to the monument entrance is desirable to allow access to the monument and the Observation Deck.

A secondary goal for any repairs to the plaza should be to improve drainage off the Upper Plaza to help slow the rate of leakage into the concrete structure and the associated deterioration of the concrete structure. There may be several options to address the Upper Plaza accessibility in the short term, including the following:

1. Repair the existing paving system by:

Cleaning out the joints of dirt, vegetation and debris.

Broadcasting sand into the joints (this would probably have to be done on a periodic basis as the sand will wash away).

Resetting those pavers that are displaced relative to the adjacent paver by more than 1/4 inch, using sand to reset the paver.

Remove the existing brick pavers and install a temporary exposed aggregate concrete pad.

At a minimum, the pavers surrounding all the existing drains should be removed, the drain bodies inspected, and the waterproofing patched to insure good drainage. Resetting the pavers would incorporate a screen or other device to allow water flow but prevent the sand from being washed away under the pavers adjacent to the drains.

Advantages

This approach would be fairly inexpensive.

If applied over the entire plaza, it would allow public access to larger area.

Disadvantages

This would be an ongoing maintenance issue because the cause of the problem is not addressed by this repair. It should be anticipated that resetting of individual pavers and re-sanding of the joints would have to be completed at least annually.

Continued deterioration of the paving system, waterproofing system, and concrete structure would occur, as this option would not fully address the current drainage problems.

2. Install an overlay on the existing system without implementing other repairs. The overlay could consist of a wood deck, composite rubber tiles, or some other system.

This system could likely be installed rapidly.

Use of a custom colored pattern could provide a more finished look.

Disadvantages

Depending on its weight, any overlay system will need to be anchored to the existing structure.

The lighter the system, the more anchorage necessary to address uplift. This anchorage would be expected to penetrate the waterproofing, requiring special detailing to prevent water infiltration.

Any system that overlays the existing pavers could telescope the unevenness of the pavers beneath unless they are reset

Water (dirt and debris) will continue to enter and saturate the existing paving system, leading to the potential for vegetation growing through the overlay and increased leakage into the structure and basement, resulting in further deterioration of the concrete structure.

Although the overlay system might possibly be custom-colored, it is unlikely it could be made to match the existing historic pattern, color, and overall appearance.

This system will have potentially higher costs that the other options

Elevation differences would need to be addressed at the top of the stairs and at the entrance to the monument.

3. Remove the existing paving system, salvaging the granite pavers, and perform…