When all local traditional methods for stabilization of the brick structures at Angkor Wat had been exhausted. ConSpec was consulted by the Conservator based on our knowledge and representation of numerous masonry stabilization and strengthening means, methods and materials. To provide the most effective and least intrusive solution we traveled to the site and installed the HeliFix DryFix anchors for their review.
Portland Cement Skin over Masonry – BAD
FACT – Place a dense material such as Portland Cement Stucco/System over a more permeable substrate such as brownstone or even worse, masonry, and FAILURE is guaranteed. As the moisture attempts to exit the building in the colder months, when it hits the interface, by definition, water has to build up at the denser interface so with freeze/thaw the weaker of the two has to fail and delamination occurs. If it is latex or resin modified the process is only accelerated.
This holds true whether it is a Brownstone re-skin or a Portland Cement based FRCM. While great for concrete, if you value your masonry please take this into consideration on your next masonry stabilization or strengthening project. Use of a material such an an inorganic cement which is made to be sympathetic to masonry substrates is always preferred.
Means, Methods and Materials – Idea to Spec to Implementation – The Process
For almost 15 years I have said that of 100 civil or structural engineers there are less than 5 that truly understand the repair, restoration, strengthening and stabilization of exiting projects using Stabilize-In-Place principles rather than a Rip-Out-And-Replace mentality (SIP vs ROAR). I have now come to the conclusion that the same can be said of restoration contractors regarding the acceptance and implementation of new concepts especially when they are not specified but rater fill a need or provide a better way on a project.
Recently I had the please of providing a material on a project, to a major restoration contractor, where I had tried to get them to consider using for almost 4 years resulting in the comment “I wouldn’t use anything else!” which was the subject of my last article. On another project I worked on a spec for a new rehabilitation concept for almost two years and am now waiting for it to come out to bid while just this past week I was called out on a similar project, suggested this same concept then; 1) The contractor immediately called his structural engineer, 2) The concept was accepted immediately by the structural engineer even though it was his first introduction to the product/process, 3) The change in product/process will be installed within the next two weeks and again, also reinforces the validity of the SIP vs ROAR concept, resulting in considerable savings in both time and money while maintaining the structural integrity and fabric of the structure.
When the right Means, Methods and/or Material, even new in concept, are proposed for a particular repair or stabilization application, time should not be the limiting factor rather implementation of the item proposed when it is sound, based a structural, process, sustainability and/or cost basis.
Ruredil PBO (Carbon Fiber) considered for repair of second Prestress Plank Parking Structure in NYC – Storm Damaged Areas also under Consideration
After being specified for a Prestress Plank Parking Structure in CT which also employed spray applied Zinc based upon the breath-ability of the Ruredil Cement Based System, a second application is now being considered for a New York Project. A Class A Fire Rating, ease or application, ability to be applied in damp or wet conditions as well as a ductile failure mode make it the preferred system over its resin alternative systems.
Another parking garage repair was also started in Jerusalem and an application on a 3 hr fire rated mechanical room concrete slab in Seattle will be done this month.
Attributes not available with resin systems make Ruredil the preferred product. While Ruredil’s Carbon Fiber is used primarily for masonry strengthening and repair , which makes it a primary consideration for distressed masonry structures in storm damage areas, its Class A Fire Rating and ease of application have it gaining ground for concrete applications. Storm ravaged areas considering their “saturated” condition will allow Ruredil to be immediately applied to all distressed concrete and masonry applications, unlike their resin alternatives. The fact that any qualified mason who can handle a trowel, can apply Ruredil, is also a major consideration. Basically if you can install a stucco or a EIFS system you can install Ruredil.
What makes a Structural Engineer a Restoration Engineer?
It is the structural engineer who has a true understanding of the materials within the Built Environment when approaching a restoration project and can cause the least insult to those materials that is the true Restoration Engineer.
Consider the Acronym “SIP vs ROAR” (Stabilize-In-Place vs Rip-Out-And-Replace) as it relates to;
- Cost to the material of the structure
- Cost to the environment with removal rather than stabilization
- Cost to the owner
- Time extension for completion
- Inconvenience to occupants
- Encroachment on adjacent properties
- Additional support structures during restoration
- And the list goes on!
Before our BOMA members pick their Engineer for the next LL11 Cycle think about asking the following two questions to you prospective engineer.
- Do flexible wall ties need to be replaced with more flexible wall ties during a restoration where they are found deficient and ask for reasoning for either response? Are rigid ties acceptable?
- Your building is in Manhattan and your parapet shows signs of distress. Which one, two, three or all of the following typically face the most distress; 78th Street side, 77th Street side, Madison Avenue side or Park Avenue side?
Europe has been training restoration engineers both in school and on the job for more years than our country has existed. While there are currently several efforts underway by engineers like Michael Drerup to establish graduate programs here in the United States we are only recently beginning that effort so most restoration engineers trained here in the US are validated by their time in the field. If your potential engineering firm does less than 50 percent of their work in restoration you may want to reconsider. It is not the building’s they have built, rather the buildings they have saved.