Swimming Pool Rebar Clips - Expert evaluates suitability for swimming pool reinforcment steel

Not all products are suitable for their intended purpose.  Take plastic clips used securing reinforcement steel for instance.

Plastic is non-conductive


Because the plastic is not electrically conductive, the clips isolate the pieces of rebar from each other.  Why is this bad?

Electrocution.

Bonding grid



An equipotential bonding grid is required around all swimming pools and spas.  This includes ALL of the steel in the pool structure and surrounding concrete decks.

Non-compliant plastic rebar clips - cannot be used around swimming pools

Using plastic clips to secure the rebar, electrically isolates the bars from each other, defeating the continuity of the bonding grid.

Liability

Just because a salesman demonstrated their ease of use, and said that they were approved by the building codes, does not make it so.
If it cannot be proven that every bar is electrically bonded, then there exists a potential for electrocution.

This is exactly why epoxy coated rebar is not permitted for use in swimming pools - the epoxy (plastic) coating isolates each bar from the next.

Go ahead any use plastic rebar clips - if you want to pay to to remove and replace the entire pool someday.  It's your gamble...

Paolo Benedetti, SWD, Principal

Aquatic Technology Pool and Spa 
© http://www.AquaticTechnology.com 
International Aquatic Consultant, Watershape Engineering, Expert Witness, Hydraulic Designer, Landscape Design, Owner's Rep
Office: 408-776-8220 
Email: info@aquatictechnology.com 
Major Markets Serviced: 
San Francisco, Palo Alto, Atherton, Hollywood Hills, Beverly Hills, Malibu, Los Angeles, San Diego, San Clemente, Pacific Palisades, Escondido, Scottsdale, Seattle, Phoenix, Tempe, Portland, Aspen, Vail, Park City, Chicago, Dallas, Houston, Austin, New Orleans, Madison, Detroit, East Hamptons, South Hamptons, Cape May, Ft. Lauderdale, Orlando, Raleigh, Chapel Hill, Cherry Hill, Toms River, Salt lake City, Boise, Denver, Santa Barbaara, Carmel, Carmel Valley, Monterey, Pebble Beach, Oceanside, Big Sur, Napa, Sonoma, Sausalito, Danville, Belvedere, Montecito, Palm Springs, Midland, Manhattan, Greenwich Village, Osaka, Paris, Madrid, Barcelona, London, Seoul, Sydney, New York, Tokyo, Cairo, Istanbul, Athens, Rome, Lisbon, Bonn.

Construction Defects - Failure to Notify

The duty to notify the owner or their representative, belongs to all contractors and sub-contractors on a project.

Duty to Notify

When a party observes a deficiency on a project and fails to make a notification, they become partially responsible for that mistake.

If a stucco plasterer observes inadequate flashing around a door, they have a responsibility to report it.
If a tile contractor realizes that the waterproof membrane in a shower is insufficient, they have a responsibility to notify the owner.
If a painter sees that the drywall in a bathroom is not the proper waterproof variety, they have a duty to make a notification.

If a trade covers up the inferior work of a previous trade without making notice, then they become responsible for the errors as well.

Bottom Line

When a tradesman observes errors in the preceding stages of construction, they have a duty to notify the of the deficiencies.  Most of the time this is the contractor who hired them.  

If the General Contractor then fails to take corrective action, then they share the joint responsibility for correcting the mistakes.
 
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.

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.

ANSI A108.5 Exterior Floor Tiles Require 95% Thinset Mortar Contact

Loose or hollow sounding floor tiles are usually a result of improper tile installation practices.

ANSI A108.5 (2005) 

The American National Standards Institute (ANSI) has established trade standards for the installation of Ceramic Tiles.  This standards also includes quarry pavers (natural stone tiles).  It has been in effect for decades, and was most recently reaffirmed in 2005.

ANSI A108.5, Section 3.3.2 states that in exterior or shower installations, the average uniform contact area shall not be less than 95% (upon the inspection of three tiles).

Shortcuts

Let's face it, humans beings are like electricity and water - they will take the path of least resistance and effort.

Tile setters must be reminded that tiles installed in exterior floor and shower applications, must achieve 95% contact with the setting material.

This means that the tile setter must knock down the trowel gauge marks on ceramic tiles, quarry pavers and natural stone tiles.  Leaving the trowel marks in place will mean only 50% contact.  

Why do they do this?  It saves them 50% on their thinset costs.  They are lazy.  No one ever taught them how to do it correctly.  They have never been involved in a construction defect case.

Improperly Set Travertine Quarry Tiles - click on image to enlarge

Improperly Set Marble Quarry Tiles - click on image to enlarge

Additionally, it will leave voids behind the tiles where moisture will collect.  This moisture can lead to freeze damage, saturated or loosening thinset.  Loose thinset may result in cracked tiles.  

Porous tile or natural stones, such as terracotta or marble, may develop or exhibit efflorescence.  The efflorescence will bleed up through the tile from this moisture trapped underneath.  By ensuring a solid void free substrate, there will be little place for the water to collect, nor air pockets to foster efflorescence.  

Efflorescence requires calcium, water and air in order to form.  Since efflorescence crystals cannot push into the concrete deck, they will manifest themselves on the surface of the tiles or the grout.  The efflorescence will continue to form until all of the calcium has been activated.  That means that it may never actually cease.

Sound Practices equal Sound Tiles
 
If quarry tiles are not gauged (cut to a consistent thickness), it means that the masons may need to back buttered the tiles as well, to ensure complete contact.

Well cleaned and saturated tiles will also ensure a good tight bond with the substrate.  No thinset mortar will adhere to dust, dirt or dry tiles.

A little care and periodic inspection of tiles as they are set (lifting installed tiles to inspect the contact coverage), will verify and ensure that your clients enjoy a trouble free deck for years to come.

Paolo Benedetti, SWD 
 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.

ANSI/APSP-12 Swimming Pool Plaster Workmanship Standards

ANSI/APSP-12 Swimming Pool Plaster Workmanship Standards 

The general public and pool industry at large need to know how and why, otherwise unacceptable workmanship finds it’s way into becoming “the minimally acceptable standard.”

In July 2014, the APSP (Association Pool & Spa Professionals) and the NPC (National Plaster's Counsel) announced a “joint” committee to write a new plaster workmanship standard, under the guise of APSP/ANSI-12.  

Because APSP is aligned with ANSI (American National Standards Institute), the resulting standards to would in effect become “statute” in many regions of the country.  Through ANSI's affiliation with the ICC (the International Code Counsel ironically publishes the International Building Code, which has been adopted across the US), this may just become law in your state. 

You can see where this is going.  It is a end around run on consumer rights and justifiable workmanship.  This forces consumers to settle for inferior workmanship, just because it meets the industry's own minimum acceptable level.  

Their proposals for this standard include defining acceptable "deviations" and explanations as to why pool plaster cannot achieve the levels of performance delivered by other plaster trades. 

These defined deviations will be governed by "accepted trade practices" and not by the BEST AVAILABLE PRACTICES.   

Again, locate and identify the lowest common level of performance and make that acceptable.  If a consumer has a project with poor workmanship, they will be forced to accept poorest quality job that the NPC can justify.

Fox in the Hen House

Trade associations writing their own workmanship standards is self-serving and against the general interest of the American public.  Even if a standard is written with the absolute lack of personal biases and interests, the end result will still be a self-serving document.   

This is what I take offense with… putting the fox in charge of the hen house.

In other words, "how bad can it get and still be defensible?"

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.

International Swimming Pool Codes and Standards

Miami Swimming Pool Design and Construction

The underlying problem in this country, is that trade associations write minimum performance standards for their own members.  Volunteers with egos, contractors and manufacturers sit on these committees, pushing personal agendas in order to validate their antiquated products, inferior trade practices or poor workmanship.  The resulting standards end up catering to the lowest common denominator.

These minimum workmanship standards then get absorbed into the building codes as law or adopted by state contractors licensing boards the performance standards.  This has happened with almost every association published code in this country.

Does this process really serve the American public?  It certainly serves the industry, manufacturers and contractors.

MINIMUM STANDARDS

People need to realize that building codes and industry performance & workmanship standards are not the ceiling to strive for, but are the foundation upon which to build upon.  They are the minimum acceptable level of performance.

To date only 2 major standards have evolved beyond being self-serving – the ACI and NEC.  Every one of their standards is based upon science and the evaluation of practical field experiences and failures.

Swimming Pool Plaster Workmanship Standards

The National Plaster Counsel (NPC) needs to get scientific with their standards.  For example, maximum water-cement (W/C) ratios are not specified by the NPC.  Instead the NPC Techinical Manual (section 2.1) is ambiguous about water content, leaving it up to the on-site crews to determine. 

I have never seen concrete finishers, stucco applicators or venetian plasterers "re-temper" their work by splashing water on it.  They all know that this destroys the finish, causes discoloration, and that the localized addition of water invalidates the W/C ratios.  But the NPC continues to endorse this improper practice.

The technical bulletins for integral cement pigments from Davis, Scofield, Solomon and most others all state in BOLD TYPE "calcium chloride shall not be used."   What is so special about pool plaster that makes it exempt from the prohibition on the addition of calcium chloride?

Steel troweled stucco finishes and Venetian plaster are installed virtually free of trowel marks, waviness and unevenness.  I see these finishes almost daily.  These other trades deliver hand finished & troweled surfaces that are virtually flawless.  They are precariously perched on scaffolding or working overhead as they trowel.  Yet, the NPC workmanship standards promote surfaces with these flaws.  Their standards are subjective and not quantitative, thereby in effect validating bad installations.  Why not hold the industry to a standard that contains a defined +/- variance?

Precise batching, W/C ratios and basic cement chemistry are beyond the comprehension of a mere mortal plaster crew.  We're lucky to have high school graduates on the plaster crews, let alone someone who understands cement chemistry.

It's time for the NPC to set a new bar - HIGH.

If the tide rises, all of the boats will have to float with it.  If we drain the seas, they will all sit on the ocean floor and will go nowhere.

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.

Phoenix Swimming Pool Expert Witness Aquatic Consultant Watershape designer

Now what?

You just had your dream pool built to beat the Scottsdale heat.  But, things just don't seem to be working properly since the pool was finished.

The swimming pool builder is unresponsive to your concerns.  The equipment is noisy, the pool seems to be losing a lot of water, efflorescence is bleeding out of retaining walls, stone and tile work and the decks are cracking all over.

State Licensing Board Experts

State contractor's licensing boards will provide experts to evaluate workmanship complaints.  However, the state provided experts are usually medium to lower quality contractors, who are seeking extra money or are in retirement.

These "experts" are usually not up to date on the latest codes, industry standards and construction technology.


Limited Scope of Investigation

In fact, most state laws forbid the state provided expert from "discovering" additional defects in a project.  They are only allowed to report findings on issues in the original complaint.  

Unless the property owner is already an industry or construction expert, many flaws and defects will go undisclosed and unresolved.

How to Protect Yourself

By hiring your own independent expert to evaluate your project for defects in materials and workmanship, there are no limitations on the investigation.

Anything and everything is subject to inspection.  Hidden defects that the property owner was not even aware of, may come to light.  Substandard practices and shortcuts will be uncovered.

Fully Armed

Armed with a complete evaluation of their project, a property owner can make a complaint to the state license agency.

The state agency will have all of the information they need to proceed.  In fact, a lot of their leg work has been done for them.

If warranted, the state agency may send out their own expert to validate the findings of the property owner's hired expert.  And the state expert can now provide an opinion on defects that were previously unknown by the property owner.

The state agency is now armed with TWO complete independent evaluations of the project.  

Now, the offending contractors and sub-contractors have some explaining to do...

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

Swimming Pool Design, Watershapes Consulting, Expert Witness

International swimming pool design, watershape consulting, swimming pool construction, hydraulic design, structural engineering, plans and specifications, and construction documents.

If it has anything to do with water, we can design or build it anywhere in the world.

We provide feasibility studies, design services from conception to completion, design details, construction specifications and documents, materials selections and even construction management. 

Clients include architects, landscape architects, developers and property owner's worldwide.  Our international aqua design team should be a part of any project involving water.

Our experience performing over a hundred project inspections and construction defect cases, provides a unique insight into code compliance, hydraulic design, sanitization systems, mechanical and filtration systems design brings an unparalleled level of experience to every project.

Our practical experience actually operating and maintaining watershapes, swimming pools and aquatic facilities lends a unique "end users" viewpoint to our designs.  This hands-on operational experience translates into design elements that will ease the operation and maintenance of any aquatic facility.

Our experience with the service and maintenance of the support equipment, heaters, pumps and filtration systems, allows us to specify equipment that will provide the maximum return on your investment.

As owner's representatives we have reviewed countless plans of so other so called "aquatic international design" firms.  Their lack of actual construction experience and practical facilities operations, resulted in plans that were in direct violation of the building, electrical and mechanical codes, hydraulically deficient and unsound structurally.

Don't be penny wise and pound foolish... spending a few dollars on your design and initial capital investment can save you thousands of dollars later.

Experience how our practical know-how, training and knowledge can benefit your next project - whether it be a residential backyard, estate, mansion basement, oceanfront resort or rooftop hotel project.

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.

Aqua Designer International Swimming Pool Consultant and Expert Witness

From the surf of Malibu and Southern California to the sunny beaches of Miami and the Caribbean and the cool waters of the Hamptons and upstate New York and all points in between, Aquatic Technology Pool and Spa brings a superior level of support services to high-end upscale projects and luxury pools.

Our Principal

Our founder, Paolo Benedetti, is an internationally recognized expert in the field of swimming pool and watershape construction.  He has consulted or designed projects on every major continent.

Paolo's vast experience and knowledge translates into economical solutions for construction and design dilemmas.  Paolo can honestly say, "been there, seen that, done that."  Instead of reinventing the wheel, your project can progress in a timely manner by drawing upon his knowledge and experience to solve those issues.
And, at a cost no more than those who claim to be his peers.

Products & Services

• swimming pool construction
• design consultations
• hydraulic design
• owner's representative
• quality assurance
• construction specifications
• project details
• CAD drawings 
• construction documents
• equipment specifications 
• international watershape consulting
• knife edge swimming pools
• vanishing edge swimming pools
• negative edge swimming pools
• infinity edge swimming pools
• glass tile swimming pools
• glass mosaics
• glass tiles
• glass tile mosaics
• swimming pool consultants
• swimming pool designers
• expert witness
• construction defects
• watershape designer
• construction management
• structural engineering
• aqua design
• sanitization
• chlorine free alternatives
• construction details 
• indoor pools
• rooftop pools
• waterfront pools
• basement pools
• dehumidification systems
• alternative energy systems
• geothermal heating
• solar heating
• photovoltaic heating and energy
• home automation integration

For no more cost than his supposed peers - don't you deserve the VERY BEST?


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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Interactive Splash Pad Fountain Sanitization Requirement

Whether in New York, Los Angeles, Miami, San Francisco, Dallas or the Hamptons, any water source that people interact with needs to be treated to keep them safe.

Simple Logic

Health codes require wading pools, swimming pools and spas all require filtration and sanitization.  It is common sense that any water that people touch, run through, or play in - also be treated.  Yet, health laws in all states do not require water treatment.

Filtration and Sanitization

To protect the public safety, fountains where people touch the water, all need to have the water kept safe.

Fountains where children run through the water are the worst offenders.  These fountains, whether designed for this purpose or not, need to assume public contact with the water.


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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Swimming Pool Water Loss - Perimeter Overflow

As a Swimming Pool Construction Defects Expert Witness, I recently consulted on a newly completed perimeter overflow swimming pool in Florida.

The owners had a number of concerns regarding their new pool.  Their issues related to the operating levels of the surge tank and suspected water loss.

• Excess water consumption - Their homes water use increased 8,000+ gallons a month following completion of the pool.
• When the solar system activated, the surge tank level dropped so much that the fill line turned on.
• For a while each day after the systems shut off, water backs up out of the slot and onto the pool decks.

Because the pool builder did not understand the relationship of the various components of the swimming pool and surge tank, the project will waste over 100,000 gallons of water every year. 

The bottom line - The hydraulics of this project were not planned or executed properly.

Surge Tank Sizing


The surge tank was too small and was installed at the wrong elevation relative to the pool.  The surge tank was also not sized sufficiently to accommodate the draw down for the solar system.

Due to the tank being under sized, when the solar panels filled, the tank's operating level dropped and the fill line sensor activated.  The tank would then eventually return to it's proper operating level with make-up water from the water meter.

However, when the systems shut off, the water in the solar panels would drain down into the tank.  Now the tank is too full.  

As the level in the tank rose above the overflow line, it backed up into the gravity drain line and out of the perimeter overflow slot.  The water collects on the pool deck the until the tank's overflow line can drain water to waste.  Repeat this process everyday, and it amounts to over a hundred thousand gallons of wasted water.

Not to mention the wasted money for the water, energy to heat and filter that water and the chemicals to treat it.

Bather Displacement

When bathers swim in the pool, their body mass and movements displace water into the surge tank.

The relative shallowness of the surge tank, cause the tank's water level to rise above the over flow line.  Valuable water is needlessly discharged into the storm drain, just from swimming in the pool.

Proper Calculations

There is no such thing as a surge tank that is too large.

Proper sizing of a surge tank needs to provide freeboard (excess empty tank volume) below the over flow line, so that the pool can actually be swam in without discharging water into the storm drains.  Imagine, people actually swimming in a pool... what a novel idea!

The surge tank also needs to have sufficient volume of water in storage, to allow for the draw down effect that occurs when the system first starts up each day.  Since the pumps draw from the tank, the level in the tank will continue to drop until that water reaches the pool, fills the gutter and gravity drains back to the surge tank.  This volume of water is called water in transit.  

Additionally, an amount of water must be stored for other demands that will be placed upon the surge tank.  If fountains, solar panels or water feature pumps will also draw from the same surge tank, then a volume of water in transit must also be provided for these features.

Finally, a protective level of water must be maintained in the tank to prevent any of the pumps from running dry.  This is called the minimum operating level (MOL).  This level is usually 12 inches, but it may need to be deeper depending upon the size of the pumps.  High horsepower pumps can easily vortex in 12 inches of water.

The sensor for the auto-fill will be set just above the MOL.  This is to ensure that the water level in the tank never drops below this safe level.

Surge Tank Elevation

The slope of the gravity drain lines and the distance of the surge tank from the pool, will determine the entry point of the gravity drain line into the surge tank.  The further away from the pool the surge tank is place, the deeper below grade it will enter the tank.  Obviously this also increases the cost of a site fabricated tank.  Manways, ladders or increased tank heights all contribute to additional costs.

The maximum operating volume of the tank is the tank's volume that exists below the entry point of this gravity drain line.  So if the gravity drain line penetrates the surge tank too low, the tank capacity is greatly diminished.

The solution?  Build the surge tank deeper below the entry point of the gravity drain line.

Planning

Of course getting all of these volumes and elevations correct requires a lot of planning.  Perimeter overflow pools cannot be designed without creating cross-sectional drawings.  

The locations of the various pipes (overflow and fill lines, sensor stand pipes, suction drains, vacuum port) and the entry point of the gravity drain line must all be carefully calculated.

Always a Solution

Sometimes the surge tank needs to be relocated closer to the pool, in order to raise the entry point of the gravity drain line.  

When space is limited, our firm builds the surge tank adjacent to the pool.  This allows for sharing a common wall and reducing construction costs.

If the tank size and depth is constrained by project parameters, then we may specify balancing valves.  Of course balancing valves only work if the tank can be built slightly above the pool, say in a nearby planter or in an elevated portion of the patio.

Knowledge and Planning... FOR SALE HERE.

Paolo Benedetti, Pool Designer, 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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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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