Building Codes, Trade Standards and Common Sense trump manufacturers instructions

When ABT channel drain manufacturer installation instructions clearly violate the building codes and accepted trade practices, then common sense should prevail... that is if the contractor has any.

ABT Channel Drains

The installation instructions and components for the ABT Channel Drain system, instructs the installer to drive rebar directly into the soil.  Alternatively, the instructions state that a galvanized U bracket can be used directly against the earth as a brace.

Click on image to view a larger version

These instructions violate every tenant of concrete construction, building codes and accepted trade practices.  Just because a company came up with a "brilliant marketing idea" does not make it acceptable or correct. 

Click on the image to see a larger image of the rebar in direct contact with the earth.

What is a Contractor to do?

First and foremost, the building codes ALWAYS prevail.  The International Building Code (IBC) has adopted and incorporated the American Concrete Institute Standard ACI 318, directly into the building code.

ACI 318 states that reinforcing steel in concrete shall maintain minimum clearances to earth.  Driving reinforcing bars directly into the earth, clearly violates both the IBC and ACI 318.

Secondly, common sense should prevail.  Though it may be fast and easy, a manufacturer's instructions should not be followed when they clearly violate the law.

A Solution?

Had the manufacturer supplied or specified a non-corrosive plastic stake, then all would have been good.

Alternatively, smooth bar dowels could have been used as stakes and removed once the channels were secured with concrete.

The contractors reasoning, "That's what they sell.  Besides, it will be 20 years before the rebar rusts and the concrete cracks," is lame.  

Especially when he knows that he is violating the building code.

Paolo Benedetti, SWD 
Aquatic Artist, Watershape Consultant, Expert Witness, International Construction Management 
"Creating water as art."™ 
Aquatic Technology Pool and Spa©
Contact the author at: info@aquatictechnology.com or 408-776-8220 

©www.aquatictechnology.com All rights reserved.

MINUMUM Swimming Pool Strength Shotcrete Gunite PSI MPA

There are minimum specifications for the strength of swimming pool shotcrete.  

What ever you call it, it's all Shotcrete
All pneumatically applied (sprayed) concrete is called shotcrete, regardless if they are using the wet or dry mix method.  The term "gunite" is often incorrectly used to describe the dry mix method.  The American Shotcrete Association (ASA), which is a sub-organization of the American Concrete Institute (ACI) only recognize the term shotcrete.  And they only refer to the shotcrete "wet" or "dry" methods.

Specifications are the LAW
ACI 318 is incorporated and included in every state building code in the United States.  By statute, this makes the standards of ACI 318 MANDATORY.  So, regardless of the concrete strengths that a structural engineer can justify with their calculations, ACI 318 dictates the minimum strengths.  This is exactly where the problems start... structural engineers think that they are doing their clients and contractors a favor by specifying a lesser strength concrete.  

Concretes that are specified above 2500 PSI require strength validation by a testing laboratory.  The testing lab will obtain samples from the job site and then test them to verify that the proper strengths are met.  2500+ PSI concretes also require that an independent special (deputy) inspector observe the entire shotcrete placement process.  Structural engineers think that they are doing everyone a favory specifying sub-standard 2500 PSI concrete to avoid these additional quality assurance measures.

ACI 318-11 Durability Standards
As can be seen in the chart below, ACI 318-11, 4.2.1 specifies durability requirements for concrete (which includes shotcrete):


                  
Swimming pools by their very nature are always a Permeability Class P1.  They are always in contact with water where low permeability is required.

Corrosion protection for swimming pools more than likely fall into the Corrosion Classification C2, due to their exposure to both water and chlorides (this includes pools treated with chlorine, salt chlorinators or chlorine compounds).  ACI does not specify a MINIMUM level of chloride exposure, to require a C2 classification.  In any case, the C1 classification would be the absolute minimum level of corrosion protection required for swimming pools.

So swimming pools must meet the P1 and C1/C2 durability requirements.

Concrete Strengths for P1 & C1/C2 Classifications

It is clear from the following chart from ACI 318-11, 4.3.1, that swimming pool shotcrete should have a minimum strength of 4,000 PSI to satisfy Classification P1.
Classification C1 allows for the use of 2500 PSI concrete, while C2 requires the use of 5,000 PSI.
                                            

Therefore, swimming pools should be either 4,000 or 5,000 PSI, with 4,000 PSI being the ABSOLUTE MINIMUM STRENGTH.

Don't let your structural engineer do you any favors.  If there are any issues with the performance of the pool structure in the future, substandard concrete will come back to haunt everyone involved!

The Uniform Building Code, Uniform Swimming Pool and Spa Code and the California Building Codes all recognize the requirements of ACI 318.

Paolo Benedetti, SWD Aquatic Artist, Watershape Consultant, Expert Witness, International Construction Management 
Contact the author at: info@aquatictechnology.com or 408-776-8220 "Creating water as art."™ 
Aquatic Technology Pool and Spa© ©www.aquatictechnology.com 
All rights reserved.
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