- Safety: Due to loss of life from failure of anchor systems (Boston Tunnel, 2007) further measures are needed to ensure that they perform to their designed capacity. The NTSB report n the Boston Tunnel collapse stated that, in addition to other factors, lack of thorough cleaning of holes was a probable cause of what the report called a “slow creep” failure of the anchors. Cored samples showed a layer of debris creating a barrier between the epoxy and the existing concrete thus reducing the bond. Cleaned holes verses un-cleaned holes more than doubles the pull-out value of epoxy anchor systems. The Vortabrush tool thoroughly cleans holes. Thus it has the potential to actually save lives.
- Consistency and thoroughness in cleaning: The traditionally approved methods of cleaning holes drilled in concrete and masonry for installation of anchors varies for many different reasons. The thoroughness of cleaning can vary depending on the laborer doing the work, the number of holes being cleaned, and the condition of the hole before cleaning. Many times the laborer assigned to do the job of cleaning holes is the newest person on the crew. He may have explained to him the process but does not understand the importance of cleaning every hole thoroughly. And, let’s face it, it is a boring job. After cleaning a large number of holes (I inspected one job that had over 12,000 rebar dowels) the laborers will often become less diligent in their work. Other times, holes have become damp or wet after drilling. This creates a silica paste that cannot be removed with dry brushing and blowing. The Vortabrush solves all of these issues. It is easy. Anyone can do it and it works the same way every time regardless of how many times it is repeated. The Vortabrush also offers the option of cleaning wet holes with an attachment that can be used to flush out the paste left behind in a damp hole.
- Cost: Simply put, the Vortabrush is very fast. Each dry hole typically takes less than 15 seconds total to clean. If you are familiar with the manufacturer prescribed cleaning methods, you know that it takes a lot of time and very often involves 2 laborers, one brushing and the other blowing out the holes. On one job site I witnessed 450 nine inch deep by 7/8” holes cleaned in 2 hours with the Vortabrush! This is a massive savings in time and thus labor cost.
- New OSHA requirements began being enforced on September 23, 2017 for all Silica dust producing tools used on jobsites. All such tools must make available a dust collection system that will not allow silica dust to be dispersed in the open air.
I am an ICC/WABO Special Inspector and in 15 years in the industry have witnessed many thousands of holes being cleaned. I have watched the frustration of contractors. And I have nearly fallen asleep many times watching this slow and boring process. Then it is frustrating to learn that even when done as directed there are still failures due to lack of cleaning. It is time for the industry to step up and allow change by adopting the use of the Vortabrush.
REPORT FROM THE WORLD OF CONCRETE 2018
Self-Cleaning Vacuum Drill Bit Systems.
Do they pass inspection in the field?
That is a hard question to answer with a simple response.
First let’s look at the claims that these systems present. Their ESR’s claim that “without any further cleaning after drilling”, that structural epoxy can be placed with all thread or rebar anchors.
Is that “always” the case? Not according to John Nehisal and Michael Morrison of the American Concrete Institute. They stated that: “If the holes are found to be dirty after this initial cleaning system is used, further cleaning may be required by the Special Inspector. Using the standard blow, brush, blow, brush, blow method.”
Does this happen on jobsites where these systems are used? Ask most Special Inspectors and they will say “yes”. It is not uncommon for drilled holes to be found in a dirty condition even after these “approved” vacuum drill bit systems are used.
The makers of these systems will pull out their ESR report and protest. But according to Mr. Nehisal and Mr. Morrison, the inspector has both the right and the obligation to ensure that the holes are properly cleaned before the anchors can be placed.
My question is; In the case of failure, who is liable? It will fall on the contractor and the drill bit vacuum system maker if they have refused to clean the holes any further if asked by the Special Inspector. Even though they have a “report”, do they really want to accept this responsibility?
Jaimie D. Gordon
ACI, ICC, WABO Special Inspector (Retired)