Wake Island Concrete and Masonry Structures Feb 2020.pdf

February 28, 2020

To: Willie Willenbrink

From: Grant Thorson, PE

RE: Wake Island Concrete and Masonry Structures

North Wind Infrastructure and Technology (North Wind), through coordination with the 611 CES, Pacific Air Forces Regional Support Center (PRSC) has been asked to inspect and provide assessments, short term repair solutions, and long-term recommendations for degraded and damaged concrete and masonry of structures at Wake Island.

1. Introduction

The inspections were performed during a site visit in February of 2020 and include most concrete and masonry structures on the island. The inspections and repair recommendations are limited to structural components of the buildings. This site visit was in part a result of previous recommendations that structural inspections and assessments should occur regularly in order to track known deficiencies and identify changes in condition of the structures. The scope of this effort included structures of concern identified by 611 CES engineers and site managers. Many, but not all structures were inspected. Structures that were inspected are mentioned in the following text and their location shown in figures. Buildings that were not inspected are not identified. This report includes assessment of structural aspects of the buildings only.

In preparation for this task, North Wind reviewed the report produced by the US Army Corps of Engineers (USACE) dated 4 August 2017 titled Engineering Assessment of Dormitory Buildings, Wake Island and concurs with its assessment and recommendations. Analysis and testing of the dormitory structures including failure modes, causes, concrete chemical and strength tests, and recommendations are found in the USACE report and provide significant context to the assessments and recommendations provided herein. Many of the historical, environmental, and maintenance concerns found in the USACE report can be extended to apply to all structures on the island.

Inspection of the buildings included the following:

- Visual inspection of the exterior of the structure

- Visual inspection of the interior where possible

- Hammer soundings of select structural features

Figure 1 Wake Island Location

Figure 2 Wake Island Overall

Wake Island

Downtown Area

Airfield and Support

Marina Area

Figure 3 Downtown Area

Figure 4 Airfield and Support

Figure 5 Marina Area

2. General Observations

The Wake Island Installation Design Guide indicates that the facilities should be designed for an expected lifespan of 40 – 50 years. Although the structures have various construction dates, most have reached and exceeded their design life.

The source of concrete aggregate for the existing structures was primarily local coral aggregates and beach sand. Testing done as part of the USACE report shows the concrete to be of superior strength. The chemical makeup of the concrete is however variable with some areas being above the typical limits for chloride content. This would explain the variations in concrete conditions around the island. Although these aggregates can be successfully used, these aggregates make the concrete susceptible to reinforcement corrosion when moisture is present. This appears to be the principle cause of the cracked, spalled, and damaged concrete. The swelling of the reinforcing steel as it oxidizes is the primary cause of large cracks in the concrete. In some locations the concrete has cracks more than ½” wide and completely spalled off in others. In areas where the concrete has cracked and has fallen or been removed, some reinforcing steel has oxidized the point of complete disintegrations. In a conversation with craftsmen currently performing some repairs it was described that when removing concrete to expose good rebar, the zone of deterioration often extends several feet beyond what appears damaged on the surface.

Moisture control interior and exterior of structures has been observed to be a constant struggle.

The exteriors of the buildings have experienced exposure to and intrusion of storm water and sea water. The interiors of some buildings have inadequate ventilation that has allowed high humidity and condensation. Concrete around openings for windows and vents appears to be especially vulnerable due to increased surface exposure and horizontal surfaces. In addition, plumbing in some buildings has corroded and leaks. Much, but not all piping has been replaced.

This interior moisture has resulted in oxidation of rebar and delamination of the concrete in localized areas, specifically around many windows, in some pipe chases, and around some floor drains.

3. Dormitories

Description The dorm buildings are located in the Downtown Area and are identified as structures 1115, 1116, 1117, 1118 and 1120. The buildings are two story concrete structures and are primarily used for temporary and extended term housing. Buildings 1115 and 1117 are constructed as two-bedroom apartments. Buildings 1116, 1118, and 1120 are constructed as single room units with shared bathroom and shower facilities. A portion of building 1116 is used as billeting management, another portion of 1116 is used for the island’s medical clinic. The buildings were constructed in the early 1960’s and have exceeded their design life. The dorms were previously assessed by the US Army Corps of Engineers (USACE) in 2017.

The buildings are constructed using a cast in place concrete beam and column frame with select cast in place concrete walls and floors over cast in place concrete floor beams. In addition, some bays of the structure are case concrete or filled using masonry block.

Figure 6 Building 1115, Building 1117 Similar

Figure 7 Building 1116

Figure 8 Building 1118, Building 1120 Similar

Observations and Condition In agreement with the previous USACE inspection, the structures are exhibiting severe degradation of concrete and steel reinforcing especially around the exterior of the buildings.

Exterior beams are showing cracking in most locations with severe cracking and likely reinforcement oxidation of many beams. This is evident in almost all at grade beams (foundations) as well as beams under the upper floor level and at the roof level of the structures.

Columns are showing similar failures in some locations.

Cracking has been identified to be a result of exposure to the elements including the introduction of water into the already vulnerable high chloride concrete. This has resulted in oxidation of the reinforcing steel and severe degradation of the concrete. The failure has been described as delamination or spalling but is better understood as bursting of the concrete due to the expansion of the reinforcing steel as it oxidizes. Most of the severe beam cracking is covered by plywood.

Facility staff describes the reason for the plywood being that the cracks are large enough that rain water infiltrates the cracks and damages the interior wood and sheetrock below. Second story floor level beams also have a short stem wall directly over them. This stem wall is also experiencing similar failures.

Of note also is the style of construction of the dorm buildings. These buildings are deteriorating faster that other structures on the island. The form of construction of the dorm buildings is different from the other buildings in that it includes horizontal ledges of concrete at the beams and in the trim of the wood panels used to fill the bays. Other concrete structures on the island have vertical concrete columns with tilt up or cast in place concrete walls with minimal horizontal concrete surfaces. These horizontal ledges have likely contributed to the deterioration of the structures as it allows water to remain standing on the concrete and eventually permeate the concrete causing the reinforcement oxidation. Design of future structures should minimize or eliminate exposed horizontal ledges of concrete or other materials.

Figure 9 Cracked Beam and Stem Wall

Figure 10 Plywood Covered Beam and Stem Wall

Figure 11 Cracked Foundation

Many of the rooms and areas were observed to contain mold and have a musty smell. Moisture intrusion has also resulted in ongoing mold mitigation with several spaces being deemed uninhabitable due to mold.

Figure 12 Building 1118 South Pipe Chase Ceiling Figure 13 Building 1118 South Pipe Chase Column

Interior concrete appears to be significantly intact with low levels of cracks, spalling, or delamination with three exceptions:

In Building 1118, the south pipe chase on the bottom level, and in Building 1120, both pipe chases on the bottom level have severe delamination of the ceiling concrete. The condition is similar in all three cases. The 2nd story floor above the pipe chases is constructed as a single slab of reinforced concrete. The slab is 7” thick with both a top and bottom mat of concrete. The damaged concrete is approximately 2 feet wide by 10 feet long in each case. The concrete below the bottom mat has delaminated and has fallen. The deterioration includes some damage to the floor beam and column adjacent to the slab. The cause of the damage is inadequate moisture controls including leaking pipes and inadequate ventilation. In the pipe chase in Building 1118 there is an existing corroded pipe from the bathroom floor above that has failed completely and has not been replaced. In all cases there is no sign of failure or deflection of the floor from above. The floor slab is currently supported in part by the stud wall framing between the pipe chase and the bathroom.

In Building 1118 South Pipe chase the ceiling, floor beam, and column are all showing concrete delamination due to the rebar oxidation.

Floor Beam Damage

Figure 15 Building 1120 South Pipe Chase Floor Beam Figure 16 Building 1120 South Pipe Chase Column

In Building 1120 south pipe chase the ceiling, floor beam, and column are showing concrete delamination due to rebar oxidation.

Figure 14 Building 1120 South Pipe Chase Ceiling

In Building 1120 North Pipe Chase the delamination and oxidation damage are limited to the ceiling with only minor cracking at the floor beam and column.

The method of construction used for the buildings provides an integrated system with redundancies as members are connected in a way that allows loads to be shared. These redundancies are significant to these buildings because they provide alternative load path in case of damage or during events such as earthquakes and storms. Currently these redundancies are functioning as primary members where primary members are damaged. Although several of the members and structural components are severely damaged, the buildings show little sign of deflection. These redundancies are providing alternative load paths. These load paths are not intended to provide primary support. With the passage of time or when an earthquake or storm event occurs, these alternative load paths will not react in a predictive manner and may fail.

Because of the nature of this construction (reinforced concrete in the 1960’s), the failure may be catastrophic, meaning the failure will come on suddenly.

As part of this inspection, an effort was made to quantify the damage in order to identify and prioritize the buildings that should be removed and replaced. The inspection identifies the damage as either minor or major. Minor damage included cracks less than 1/8” wide with no visible displacement of the concrete surface or member. Major damage includes cracks that are greater than 1/8” wide with concrete that was either spalled, delaminated, or displaced from the original form of the concrete. Portions of the building that have been covered in plywood were marked as major per discussion with maintenance personnel that those locations have the worst cracking.

Figure 17 Building 1120 North Pipe Chase Ceiling

Bldg 1115 Bldg 1116 Bldg 1117 Bldg 1118 Bldg 1120 Minor Major Minor Major Minor Major Minor Major Minor Major

Foundation 7 23 4 15 7 16 7 12 7 14 Columns 13 32 9 12 13 2 4 2 10 1 Beams 4 35 6 10 8 4 4 18 9 10 Upper Stemwall 3 13 6 14 10 3 6 15 7 9 Total 27 103 25 51 38 25 21 47 33 34 Priority 1 2 5 3 4

Table 1 Dormitory Damage Count and Priority

Recommendations The dormitory buildings should be demolished and replaced. If phased or staged construction is necessary, the buildings should be replaced in the order of priority shown above with building 1115 being the most urgent structural concern.

Repairs to the structural elements of the buildings would not adequately alleviate the safety concerns of the structures. Repairs would only extend the outdated design and construction methods and the result would be structures that would retain legacy safety concerns, would still not comply with current codes, and would continue to present operation and maintenance problems. The extent of the damage to the structures would require additional facility and infrastructure upgrades that make the repairs significantly more expensive than replacement.

Previous recommendations may still be pursued. Although these repairs would improve the performance of the structures, they should only be considered as a path forward to mitigate immediate concerns while the long-term plans can be arranged. Because little has changed with regard to the condition of the buildings, the short-term recommendations previously provided are not repeated here except for the following:

- Remove loose concrete from the damaged ceilings of the pipe chases and clean the floor area.

o Failure of the floor area above is not an immediate hazard.

o Short period entry is acceptable provided hard hats are worn.

o Clean the floor area of debris to allow ongoing identification of new spalled concrete

- Ensure additional moisture doesn’t continue to penetrate the building o Seal existing cracks by maintaining exterior paint (cracks <1/16”), concrete crack sealant (cracks <1/2”) or grout (cracks >1/2”) o Install, maintain and replace plywood covers over exterior concrete that has severe cracks, spalling or delamination as needed. This plywood should contain any loose concrete that may break away and fall as well as limit continued water intrusion

- Train facility staff to identify and notify administration of any signs of new damage, loose concrete, or deflection.

- Perform annual inspections of the concrete structures by a qualified individual to identify immediate safety hazards including settling, deflection of beams, column compression failures, or other severe damage.

4. Church Building 1181

Description Building 1181 functions as the non-denominational church building for the island. The building is primarily constructed with reinforced masonry walls with a wood framed roof. The building has a main chapel area with minor office/administration rooms and covered patio areas on each side. On the south side of the chapel is an additional administration and recreation area that has served several purposes. Most recently the area served as an electronics communications center for the Downtown Area.

Figure 18 Church Building

Figure 19 Church Building Rear View

The church building is three significant areas of failure.

The roof over the rear portion of the building has collapsed. The roof consists of 2x6 wood roof beams with some semblance of a truss configuration. The roof has a very shallow slope ~2:12.

The beams have failed due to overloading as well as termite damage. The connections to the masonry interior to the building did not appear adequate. Connections at the exterior of the structure could not be seen. The collapse of the roof has made the rooms below uninhabitable.

The communications equipment that was installed in the space has been removed and relocated to an adjacent trailer.

The rear portion of the building also includes masonry damage to the area behind the pulpit or altar. The interior of this space cannot be accessed. The exterior is visible from the rear rooms of the church under the collapsed roof where cracks in the masonry corner columns can be seen.

The cracks were measured to be as wide as 3/8”. The cells within the masonry contain some reinforcing steel. The cracks were observed over the last 7 years and have not expanded. The cause of the cracks is not apparent but they were possibly caused as a result of a fire that occurred in the interior void space. The cracks consist of a combination of vertical and step cracks.

Figure 21 Church Building Masonry Cracking Figure 20 Church Building Masonry Cracking

The church appears to have a bond beam or lintel that extends across the tops of doors and windows around the building. This beam is protected around the sides of the structure but exposed to the elements at the front. The beam at the front of the structure is deteriorating due to rebar oxidation. This is apparent over the front door where deformation of the door header is apparent. The deformation has the appearance of deflection but does not extend into block courses above the door header.

Figure 22 Church Front View

Figure 23 Church Front Door

Deteriorated bond beam/lintel Deteriorated bond beam/lintel

In addition, the church has other minor structural concerns.

The top block of a column supporting the north corner of the east side patio cover has broken.

Per conversation with personnel the break happened many years ago and appears to be due to unplanned side pressure on a cut block at the top of the column.

The roof support beam and column appear to be functioning despite the damage. The anchor bolt through the beam into the column is still intact.

This crack and spalling is located mid height on the east wall of the chapel. The crack may be associated with rebar oxidation but is localized.

This crack is located at the northeast corner of the structure and appears to be affecting only an architectural trim feature of the church. The crack does not appear to be affecting the structure of the building.

Figure 26 Crack in Masonry at Church

Figure 24 Broken Block at Top of Column

Figure 25 Spalling on East Wall of Chapel

Recommendations The roof over the rear portion of the building should be replaced. The replacement should be designed for the anticipated loadings and should be properly anchored to the masonry. The replacement could consist of wood trusses or appropriately sized wood or steel roof beams. If wood is used it should be treated and maintained to control termite damage.

The cracks in the masonry behind the altar area should be repaired by replacing the broken masonry at the corner columns. Whole units along the crack should remain and be cleaned in placed. The new masonry should be altered as little as possible to slide past the reinforcing steel and set with new mortar. The repaired corner cells should then be grouted solid or may be grouted solid as blocks are placed. There are several step cracks in the area that should be repaired by removing and replacing the mortar to a depth of 1½” (repointing). The masonry can then be painted or otherwise finished to match the adjacent wall surface.

The beam extending across the front of the church should be repaired. The repair should consist of replacing the rebar and block of the beam across the entirety of the front of the church. This should occur as follows:

1. Install jacks along the wall to support the upper wall weight during construction

2. Remove the front door, damaged concrete, and reinforcing steel

3. Replace reinforcing steel in kind using epoxy coated rebar. Expose good reinforcing at each end and include appropriate lap splices or embed new rebar into good masonry grout

4. Replace block including fully grouted beams in kind (this could alternatively be accomplished by forming and casting the beam as concrete)

5. Remove and repair jacking point holes

6. Replace the door

7. Refinish the wall to match adjacent wall

The column at the northeast corner with broken block at the top should be repaired in kind

1. Install jacks to support the roof load

2. Remove the broken 2 blocks at the top of the column

3. Retain or replace in kind the anchor bolt

4. Install new block, cut similar to existing

5. Fully grout the newly install column cells

6. Remove the support jack(s)

7. Finish the column surface to match adjacent columns

The spalled masonry on the east wall of the church should be removed and examined to determine the extents of the block and rebar that needs to be replaced. If the rebar is clean the spalling can be repositioned and bedded in mortar or masonry adhesive back in place as a superficial repair. If the rebar has rusted and is causing the crack, the rebar should be cleaned or replaced. The block can then be repaired by installing a new face of block only in a full grout and mortar bed. If the damage to the rebar and block is extensive, the replacement should be similar to the repair recommended for the front wall of the church.

The cracked block at the northeast corner of the structure may remain in place as it is not a structural feature. If desired, the crack can be filled and refinished. If full repair is desired the block can be removed and replaced with new mortar and the surface refinished.

5. Building 1519 Mezzanine

Building 1519 is used as a maintenance and storage facility for transportation. The building is a concrete structure with concrete columns and cast or tilt up concrete walls. Inside the building along the east wall is a small mezzanine structure. The mezzanine is approximately 18 feet square with a concrete stair access.

Figure 27 Building 1519 Transportation

Figure 28 Mezzanine and Stair Access

The mezzanine concrete deck and concrete beams appear in good condition.

The access stairs and a small portion of the deck near the stairs at the connection to the wall has cracked and concrete is broken and spalling. The damage extends along the connection to the wall and down the stairs. The cause of the damage is not apparent as there is very little if any deflection of the concrete. It was observed however that the method of construction for the wall includes joint at each side of the columns where the wall panels connect to the column. This joint could allow minor amounts of differential movement.

The mezzanine deck and stairs were placed after the wall was constructed. The mezzanine concrete and stairs appear to have been placed as a single pour without expansion or other joints that would match the movement of the walls and columns. It is most likely that the damage to the mezzanine deck and concrete stairs is due to minor movement between the walls and column. That movement could not be tolerated in the rigid concrete of the deck and stairs leading to the stair and deck concrete breaking.

Figure 29 Building 1519 Mezzanine Deck

Figure 30 Building 1519 Mezzanine Stairs

Recommendation It appears the damage to the mezzanine deck and stairs is due to pressure points that occurred as part of differential settling or movement of the structure. Assuming these pressure points have been resolved naturally over time, it is recommended that the stairs can be repaired by removing the cracked concrete and replacing it in kind. The concrete should be removed the full depth of the deck or stairs where the damage has occurred. The exposed rebar should be cleaned and repositioned as it was prior to the damage. The area can then be formed, and new concrete placed.

6. Supply Building 1402

Building1402 is used as for storage and supply of materials for the island. The building is made of reinforced concrete columns and concrete wall panels with a wood roof deck covered by a built-up asphalt roof.

Figure 31 Building 1402 Supply

The building is mostly in good shape with several of the windows and vent openings having moderate to severe concrete cracking. In many cases facility maintenance personnel have performed repairs on the cracked concrete. The repairs consisted of chipping out the bad concrete, installing Tapcon concrete screws with the heads left ½” or so from full embedment, then grout was used to patch the concrete.

The patches have resulted in mixed success depending on how degraded the rebar was and how extensive the concrete removal was.

Several areas have experienced additional deterioration including the door jambs at the southeast door, header over windows at the north corner and a column at the west corner.

Additional areas under windows, vents, columns and headers are exhibiting similar deterioration to a lesser degree.

Figure 32 Building 1402 Repaired Concrete

Figure 33 Building 1402 Door Jamb

Figure 34 Building 1402 West Corner

The building should be repaired and should be expected to continue to function adequately. In cases where minor damage has occurred, a superficial repair as has been done previously would be adequate. For other areas, the rebar and concrete should be repaired.

7. Terminal and Base Ops Building 1502

Building 1502 is a two-story concrete structure that serves as the airfield terminal, base operations, and island support offices.

The building has been modified in the past when a third story was removed.

Additional wood and steel enclosures have also been added to the concrete structure to house HVAC and other support systems.

The building is currently undergoing repair work to fix spalled concrete over windows and other select areas. The rebar in some locations has corroded and is bursting the concrete causing open cracks, loose concrete, and visible deformation of the concrete headers. As part of this report it was requested that we assess a beam over the main northeast entry/exit doors that was not identified in the work currently underway. The beam and roof over the entry area support an enclosed rooftop space where HVAC equipment is located.

The entry/exit doors at this location have been locked shut and the area has been cordoned off because of the severe cracks in the concrete of the beam. Wood support posts have been placed to support the beam from below. The cracks in the concrete have opened as much as ½ an inch. The failure is consistent with the cause of the damage throughout the building. The concrete does not appear to be failing due to the load above. A craftsman that is performing the other repair work suggested that by experience he can see that the column on the south side of the beam will likely also need to be repaired as part of this work.

Figure 35 Building 1502 Base Operations

Figure 36 Building 1502 Beam Over Entry

The beam and column should be repaired in a similar fashion to the other work on the building.

1. Install supports for the adjacent structure for the duration of the repair

2. Remove the concrete and reinforcing steel until sound concrete is found at each end.

Remove the beam in its entirety, full depth and wall to wall, for this repair.

3. Retain existing unoxidized reinforcing steel including connection to adjacent components as much as possible.

4. Replace reinforcing steel to match the size, spacing and arrangement of existing

a. Lap new rebar with existing or embed new epoxy coated reinforcing steel at each end or into adjacent concrete to be connected

b. Install new reinforcing

c. Install forms to match the shape and size of existing concrete

d. Place 3,000psi concrete (min)

5. Let concrete cure to 80% design strength before removing forms and support

6. Replace wall panels, windows, and interior finishes as appropriate

8. Other Structures

In addition to the structures mentioned above, other concrete structures were inspected briefly.

These inspections were intended to find items not previously identified. The following are brief descriptions of these buildings, findings, and recommendations.

Building 1705 is used for remote storage, bathroom, and break facilities at the marina area. The building is primarily masonry. There is moderate cracking throughout the building including damage around doors in two locations. The masonry should be monitored to ensure the damage does not progress. Repair of the building would be extensive and is not recommended unless damage progresses. The building should be maintained to seal existing cracks.

Figure 37 Building 1705 Marina

Building 1706 is used as bulk storage for the marina area. The building is generally in excellent condition but has several locations of isolated spalling.

The isolated spalling is not detrimental to the structure of the building but should be monitored if it becomes more extensive. There was one opening at the northeast corner of the building where the concrete around the vent opening has spalled and broken away exposing the reinforcing around the opening.

This area should be repaired.

Building 1128 functions as the gym facility as well as a portion of the building that is bunk style barracks.

The building is made of concrete columns with cast in place or tilt up concrete panels. Several cracks can be seen in the lower portion of the concrete panels. The cracks should be sealed to prevent continued moisture penetration and deterioration.

Figure 38 Building 1706 Storage

Figure 39 Building 1128

Building 1703 houses the laundry facility. The structure is cast in place concrete. The building is in good condition with the exception of one column that has a significant crack. The crack does not appear to pose a significant threat to the structure but should be sealed in order to protect the reinforcing.

Figure 41 Building 1103 Laundry Figure 40 Building 1103 Cracked Column

The following buildings were inspected briefly. No notable damage other than normal wear and tear were identified.

Building 1125 Building 1125 Building 1140

Building 1152 Building 1715 Building 1152

Building 1806 Building 1809

9. Buildings Not Inspected

As previously mentioned, not all buildings on the island were inspected. The inspection was for concrete and masonry buildings only and primarily focused on specific areas of concern.

10. General Maintenance and Repair Options

The following should be generally used for maintenance of concrete structures:

- Ensure that the exterior of the structures is sealed either by grouting cracks, painting, or other coating. This should seal cracks and prevent intrusion of water that will oxidize and swell the reinforcing steel.

- Maintain or install adequate ventilation systems to prevent high humidity environments.

- Create and maintain adequate drainage away from the foundations of buildings. Where soil surface is in contact with the structure. Per IBC, the soil should be sloped away from the structure at a minimum slope of 5% for the first 10 feet. This will help keep water and saturated soil from penetrating and deteriorating the foundation concrete and rebar.

Building 1811 Building 1812

If repair of portions of the concrete structures is pursued, the following methods should be used:

Repair by Replacement For beams, columns, and walls where cracking is measured larger than 1/8th of an inch, repair should consist of full replacement of the member.

7. Install supports for the structure for the duration of the repair

8. Remove the concrete and reinforcing steel until sound concrete is found at each end.

9. Retain existing unoxidized reinforcing steel including connection to adjacent components as much as possible.

10. Replace reinforcing steel to match the size, spacing and arrangement of existing

a. Lap new rebar with existing or embed new epoxy coated reinforcing steel at each end or into adjacent concrete to be connected

b. Install new reinforcing

c. Install forms to match the shape and size of existing concrete

d. Place 3,000psi concrete (min)

11. Let concrete cure to 80% design strength before removing forms

12. Replace wall panels, windows, and interior finishes as appropriate

Do not repair beams or columns in adjacent bays at the same time.

Repair by Epoxy Injection For beams, columns, and stem walls where cracking is measured less than 1/8th of an inch, repair may be comprised of epoxy injection. This method of repair should be reserved for locations where the cause of the crack is other than reinforcement oxidation. If this method is used where oxidation is the cause of the cracking, the crack will reappear, and the beam will eventually need to be replaced per above. Although epoxy injection can be used on cracks up to ~¼” depending on the product used, the cause of the larger cracks is more likely corrosion and is not recommend to be considered. Below is a general description of epoxy injection. In all cases, follow manufacturer’s recommendations.

1. Clean the surface adjacent to the crack to allow adhesion of the epoxy ports and sealing

2. Dry the crack to remove moisture

3. Use a moisture repellant epoxy material

4. Seal the crack surface with epoxy paste

5. Inject the epoxy until it can be seen comping out of the adjacent port

6. Inject epoxy port by port until all ports are filled and the crack is filled

7. Remove the ports and re-finish the surface

There is no requirement for when or how many epoxy injection repairs can be made at the same time.

Masonry Repair For beams, columns, and walls where masonry repair is pursued:

1. Install supports for the structure for the duration of the repair

2. Remove the masonry and reinforcing steel until sound grout is found at each end.

3. Retain existing unoxidized reinforcing steel including connection to adjacent components as much as possible.

4. Replace reinforcing steel to match the size, spacing and arrangement of existing

a. Lap new rebar with existing or embed new epoxy coated reinforcing steel at each end or into adjacent grout of members to be connected

b. Install new reinforcing

c. Install new blocks whole or with as little modification possible to install around reinforcing steel

d. Fully grout appropriate cells

5. Let grout cure to 80% design strength before removing supports

6. Replace wall panels, windows, and interior finishes as appropriate

Please let me know if you have any questions regarding the contents or findings of this letter.

Thank you.

Grant Thorson Project Engineer