ASA administers the Shotcrete Contractor Qualification as a review service for shotcrete contractors, providing them with objective, experienced review of their projects, equipment, and company structure for project owners who might have less experience evaluating shotcrete work. This review is conducted by the Review Task Group within the Contractor Qualification Committee, whose members have extensive experience in successful shotcrete work. This qualification program provides a distinct service to the industry by assuring specifiers that shotcrete contractors reviewed here have a proven work record for completion of successful projects of similar work and scope. This qualification program is based on the ASA Board Position Paper, “Qualifications of the Shotcrete Construction Team.” 

Structural Levels of Qualification:

There are two structural levels of qualification, Level I and Level II in the process(es), i.e. wet-mix or dry-mix, to the work performed by applicant.

  • Qualified Shotcrete Contractor – Structural Level I (QSC – SI) Shotcrete Contractor (Level I) – Representative projects which have thin, lightly-reinforced shotcrete sections that can be easily accessed and placed would be considered “Level I”.
  • Qualified Shotcrete Contractor – Structural Level II (QSC – SII) Shotcrete Contractor (Level II) – Representative projects which have thick, heavily-reinforced sections or sections with difficult access would be considered “Level II”.

Program Requirements:

  • Identify a Qualifying Individual (QI) to attend the required CQ Seminar and successfully complete the required written exam. Please contact ASA for the next available seminar: [email protected] | 248/983.1702. (The seminar will also provide helpful insights for completion of the CQ application.)
  • Documentation of company equipment and shotcrete staff, including list of certified shotcreters (previously known as nozzlemen)
  • Documentation of FIFTEEN (15) projects successfully completed in the last 3 – 5 years (per level pursued) representative of the level of qualification pursued in the application.

Click here to review the full policy for help in completing your application

If you have any questions, please contact ASA at 248.983.1702 or [email protected]

Copyright © American Shotcrete Association

Contractor Qualification Program - Part 1

Begin Application

Are You a Member?

All Those Small Numbers We Ignore – What Do They Mean?

We have all seen those small letters and numbers that mark practically everything we use in construction. To most, these are meaningless markings that are meant for someone else. However, with shotcrete, nothing could be farther from the truth.

Getting Back to Work

The COVID-19 Pandemic affected our lives in ways none of us have ever experienced in our lifetimes. I’ve been in construction for 45 years and I have never seen our economy shut down, businesses closed, or people required to stay at home. In 2001, the attacks of September 11th temporarily shut down air travel and the stock market, but the American economy remained intact and air travel resumed within a couple of weeks. However, COVID-19, has affected our lives in ways that we could never have imagined. Schools and universities were closed; professional, collegiate and high school sports seasons were suspended and canceled; and restaurants and businesses were closed. We were told to stay home and work remotely, if possible, and businesses across the country followed those directives.

OSHA’s Respirable Crystalline Silica Rule on Shotcrete Operations – Revisited

This is a revised version of the original article printed in the Summer 2016 of Shotcrete magazine before the OSHA rule was put in place. This revision has added site measured values for air monitoring of crew members on shotcrete projects, as well as ASA’s response to OSHA’s request for information in August 2019. Also, included is a short section on applicable respirators. With this revision our intent is to put the current information you need about the OSHA rule and its impact on shotcrete operations in one place for ready reference.

Please discuss the differences in curing/shrinking cracking challenges for wet-mix shotcrete versus dry-mix shotcrete (gunite). In my limited experience, wet-mix shotcrete tends to crack easier than dry-mix shotcrete. In general terms, or on average is gunite more porous, but less likely to show cracks?

Both wet-mix and dry-mix shotcrete when using proper materials, equipment and placement techniques will produce high strength, low permeability concrete in-place. Dry-mix shotcrete will tend to have a lower w/cm since water is added to the dry concrete materials at the nozzle. Wet-mix needs a higher w/cm and a fairly high cement paste content to facilitate pumpability. This can make wet-mix more susceptible to plastic or drying shrinkage cracking than dry-mix. However, cracking in either dry-mix or wet-mix shotcrete can be controlled by using fogging of freshly finished surfaces and then early curing of exposed shotcrete surfaces.

Wet-mix still has very low w/cm (0.40 to 0.45) to allow vertical and overhead placement without sloughing or falling out and is lower than much of the form-and-poured concrete. The low w/cm and high velocity impact produces excellent compressive strength and low permeability. Properly placed dry-mix will have similar compressive strength and permeability as wet-mix. strength gain.

I would like to know how could I obtain an expert opinion from ASA stating that a particular person specializes in gunite (dry-mix shotcrete) operations and that the person is amply qualified to perform such work?

ASA is the international trade association dedicated to advancement of shotcrete placement. The American Concrete Institute (ACI) has a long history of certification of individual craftsmen in concrete construction. Nearly 20 years ago ASA worked closely with ACI to establish the ACI Shotcrete Nozzleman certification program to evaluate a nozzleman’s ability to place quality shotcrete. ASA is the primary group that conducts the ACI Nozzleman Certification sessions around the world. We provide a full day of education before the formal ACI certification and have a team of examiners with proven shotcrete expertise to rigorously conduct the sessions to ACI’s high standards. Many engineers specify that all the nozzlemen on their projects must have ACI Nozzleman Certification. Many concrete-related codes, specifications and standards require ACI-certified shotcrete nozzleman for shotcrete placement of structural concrete.

Thus, ASA doesn’t offer an expert opinion on individuals as an association but provide the ASA education and ACI certification upon request. You will find full details of the session services we can provide on our website at shotcrete.org/ education then clicking on the “Shotcrete Nozzleman Certification Program” link. An article that covers in greater detail the overall shotcrete nozzleman education and certification process ACI Nozzleman Certification—Why, Who, When, and How can be found on our website: shotcrete.org/ wp-content/uploads/2020/05/2018Win_Hanskat.pdf

Also, many of our corporate members offer consulting services. You can find them in our free, online Buyer’s Guide at Shotcrete.org/BuyersGuide. On the web page you can select the category, subcategory and geographic location to narrow your search.

 

We are working on a design-build project located in southern California of which the perimeter walls of the underground parking structure are planned to be shotcrete. Do you recommend any particular ACI publication that would be applicable to the shotcrete operation or does ASA have their own publications, similar to ACI, that are more appropriate to shotcreting?

ACI Committee 506 is the technical committee responsible for creating and maintaining the ACI documents related to shotcrete. ACI 506R-16 Guide to Shotcrete is an excellent resource for shotcrete information including materials, equipment, crew composition and placing techniques. It is a non-mandatory document that is very descriptive and readable. ACI 506.2-13 (18) Specification for Shotcrete is another excellent resource that has mandatory requirements for the contractor’s shotcrete placements. Additionally, the ACI 318-19 Building Code Requirements for Structural Concrete directly addresses shotcrete for use in buildings.

A past article in Shotcrete magazine describes the additions to cover shotcrete in ACI 319-19: shotcrete.org/wp-content/ uploads/2020/06/2019Fal_HanskatHollandSuprenant.pdf

Another past article dealing with Shotcrete Testing—Who, Why, When, and How can be found on our website here: shotcrete.org/wp-content/uploads/2020/01/2011Sum_Hanskat.pdf

 

 

Do you have any case studies or applications where Ground Granulated Blast Furnace Slag (GGBFS) cement was successfully used in the concrete mix?

Shotcrete is a placement method for concrete. Concrete mixtures that have been shotcreted have used all different supplemental cementitious materials (SCM) including slag. Silica fume, and fly ash are also widely used. Generally geographic availability and cost of the slag are a deciding factor on if slag is included in a concrete mixture design. Concrete using alternative binders or cements have been used for specialized applications like refractory, or extremely high early strength gain. Here are links to past articles from our Shotcrete magazine that have considered slag in shotcreted concrete mixtures:

The Use of Slag Cement, Alkali-Free Accelerator, and Macro-Synthetic Fibers – https://shotcrete.org/wp-content/ uploads/2020/05/2016Spr_Yurdakul-etal.pdf

Sustainable Shotcrete Using Blast-Furnace Slag – https://shotcrete.org/wp content/uploads/2020/05/2013Fal_Sustainability.pdf

I am looking for information on where, when and why welded wire mesh (WWF) would be recommended in lieu of structural steel reinforcement, or with steel reinforcement, or guidance on how to determine which option or combination is the preferred one.

WWF should only be used when the area of reinforcing provides the required reinforcement area. It may serve as supplemental reinforcement to bars, or entirely replace reinforcing bars as long as the required area of reinforcing steel is provided in the concrete section. Where multiple sheets (more than 2 at say a corner) overlap you may need to cutout one or more of the layers to allow good encasement. Don’t use steel fibers with WWF as they tend to bunch up where the wires cross.

WWF can be used to provide reinforcing in double curved sections where it would be hard to bend and place reinforcing bars. Also, it may be used where you have a thick concrete cover or unreinforced thickness of a repair area that you wanted to get some reinforcing in place to control depth of any surface or shrinkage cracking.

If the mesh is just being provided to help support shotcrete being shot overhead you may not worry about the area of steel, just adding it in addition to the original design reinforcing. Then a lighter mesh might be used since you aren’t really worried about its ability to be reinforcing.

 

 

Dealing with COVID-19 Article

This year, 2020, we have been challenged in a manner unlike anything we have experienced in America since the 1918 influenza pandemic that killed millions worldwide. The coronavirus (COVID-19) was identified in Wuhan, China, after initially being reported as a cluster of pneumonia cases in December 2019. Despite efforts to contain the virus, it rapidly spread to Italy and the rest of Europe and eventually the United States. As a result, on February 26, the first cases of COVID-19 began to appear in the Seattle,
Wash. area. Acting rapidly, many state governors issued
emergency restrictions and stay-at-home orders. Across
America we all watched the coronavirus task force briefings and New York Governor Andrew Cuomo’s morning
broadcasts, as the response unfolded in especially
hard-hit New York. In Pennsylvania we were issued
stay-at-home orders by our Governor Tom Wolf for all
but life-sustaining businesses. Which resulted in PennDOT closing down construction projects. In the months
that followed, state governors began to reopen their
economies. With the return to work there are protocols
and procedures we will need to follow to keep our crews
safe and well. Below are some guidelines and information that I hope you will find helpful.
INTENT OF PROGRAM
COVID-19 is an easily transmitted disease, especially
in group settings. It is essential that positive actions be
implemented to slow or stop the spread of the virus to
safeguard the public safety. Construction is vital to our
nation’s economy. Recognizing this, we need to find
ways to accomplish our work while not endangering
our employees. This requires several precautions to
protect our workers, their families, and members of
the community. It is necessary that all businesses in
the construction industry conducting person-to-person
activities follow the directives and requirements of their
state governments. Other local political units or privately
owned companies may elect to impose more stringent
requirements. In such cases we must adhere to the
client or owner’s requirements.
Recommended Guidelines
• Follow all applicable provisions that your State
government has provided for business safety
measures.
• Requiring that every person present at a work
site wear a face mask or face coverings.
Dealing with COVID-19
in Construction
By Ted W. Sofis
Fig. 1: Social distancing with mask inside Fig. 2: Hand Sanitizer and Disinfectant Wipes
shotcrete.org Spring 2020 | Shotcrete 35
• Establish protocols for action to be taken when
cases or probable cases of COVID-19 are
discovered or whenever people in the company
could have possibly been exposed to someone
who may have the virus.
• Require social distancing with a 6 ft (2 m) minimum distance between workers, unless the safety of the workers makes an exception necessary,
(for example, team lifting.)
• Follow other Department of Health (DOH) and
Centers for Disease Control and Prevention
(CDC) guidance.
• Provide hand washing stations at appropriate
locations on your job sites, such as building entrances, break areas, offices, trailers and job site
egress areas.
• Implement cleaning or sanitizing protocols at all
construction sites and projects. Identify and regularly clean and disinfect areas that are high risk
for transmission. Establish requirements to clean
common areas and regularly trafficked areas
periodically.
• Ensure all gatherings are limited to no more than
the maximum gathering size mandated by the
state where your project is located. Maintain 6 ft
(2 m) social distancing at all times when required
to meet, even when meeting outside.
• Use virtual meetings and distribute information
electronically whenever possible.
• Stagger shifts, work breaks, work areas, and
different trades, wherever feasible, to minimize
the number of workers on site.
• Limit tool sharing and sanitize tools or equipment
if they must be shared.
• Employ jobsite screening based on CDC guidance to determine if employees should be
working. Prohibit employees with any symptoms
of Covid-19 from working. Encourage any sick
employees to stay at home.
• Prohibit unnecessary visitors to any project
or work site and limit the number of supplier
deliveries.
• Limit access to enclosed spaces as much as
possible.
• Ensure workers are traveling to and from the
jobsite in separate vehicles. Whenever possible,
make sure that they do not share a vehicle.
• Identify a Coronavirus Safety Officer for each
project or work site, or (on a large-scale project)
for each contractor or subcontractor at the site.
The primary responsibility of the Safety Officer is
to convey, implement and enforce the social distancing and other requirements of the company
program for the protection of employees, suppliers, and other personnel at the site.
Fig. 3: Social distancing with mask outside
36 Shotcrete | Spring 2020 shotcrete.org
Ultimately, as a contractor, I realize the difficulties
involved in implementing and following coronavirus
guidelines, while at the same time trying to efficiently
perform and complete our projects. The reality is
that we have no other option. This pandemic is so
widespread and highly contagious that it forced
the shutdown of our nation’s economy for months.
Nothing like this has ever happened before in our
lifetimes. To ignore this, we jeopardize the lives of
our employees and their families. For the safety of
everyone involved and the communities where we
live, we need to get through this together. A vaccine
for COVID-19 will be developed and therapeutic
medications for treating the virus will become
available. In the interim, we need to find ways to
be safe and productive. I hope that you find these
guidelines helpful. More importantly, it is my hope that
all of you and all of your employees make it through
this construction season safely and in good health.
Ted Sofis and his brother, William J.
Sofis Jr., are the Principal Owners of
Sofis Company, Inc. After he received
his BA in 1975 from Muskingum College,
New Concord, OH, Ted began working
full time as a shotcrete nozzleman and
operator servicing the steel industry. He
began managing Sofis Company, Inc., in
1984 and has over 40 years of experience in the shotcrete
industry. He is a member of various ASA committees and an
ACI Shotcrete Nozzleman Examiner for shotcrete certification. Over the years, Sofis Company, Inc., has been involved
in bridge, dam, and slope projects using shotcrete and
refractory installations in power plants and steel mills. Sofis
Company, Inc., is a member of the Pittsburgh Section of the
American Society of Highway Engineers (ASHE) and ASA.
Fig. 4: Face mask protection in close proximity Fig. 5: The respiratory protection worn during gunning operations
fulfills the COVID-19 face mask directive.