High Performance Concrete in NYC, Successes, Problems, and Solutions

From The Concrete Contractors Perspective

D. Thomas RutturaPresident

Ruttura and SonsConstruction Co. Inc.

How do we achieve a successful project and avoid problems?

Track data from testing laboratories.Track data about concrete suppliers and use the right supplier for the project.Understand limitations of concrete construction.Provide a forum for the exchange of ideas about current concrete design and construction techniques with the design and construction team.

Track the data from the testing laboratories

When does anyone review the concrete testing results?Only when there is a low break!Testing results can give us warnings long before we have a problem.

What Can the Results Tell Us?

Set #1 has a range of 1620 psi, this indicates that the samples were handled or made poorly.Set #2 has a range of 0 psi, this could also indicate something?Neither is likely to be a problem with the concrete.

4750 6370 5980 5980

Set #1 Set #2

F’c= 8000 psi

What Can the Results Tell Us?

The concrete seems to have a strength problem, but if someone looked at the results early it may have prevented a lot of grief.

Ready Mix Supplier

The concrete supplier is one of the most important members of our team. He can be the difference between a successful project and seeing the inside of a court room.

What Can the Results Tell Us?

Set #1 and #2 have ranges of 160 to 170 psi, this indicates that the samples were handled and made very well.The deviation between the 2 sets is 245 psi, this indicates the supplier is very consistent. Looking at the data will help you select the right supplier.

5430 5260 5510 5670Set #1 Set #2

F’c= 4000 psi

Pre-Concrete Conference, What are the goals we are looking the achieve?

Develop a construction process that will result in a product that will meet the quality and expectations of the Owner.Share current, knowledge concerning design, and construction of concrete structures and slabs.Provide a forum for the exchange of ideas about current concrete structure design and construction techniques.Promote attention to detail

Who should be included?

OwnerArchitectStructural EngineerGeneral ContractorConcrete ContractorConcrete ProducerAdmixture SupplierConcrete Pumping ContractorTesting LaboratoryInspection Agency

Everybody!

Prepare for the Meeting

Schedule the meeting in advance of any concrete placement. We try and do it more then 4 weeks before placement.I like to start our conference about 11:00 am, and have lunch delivered about 12:00.

What should be discussed ?

Everything that goes into building the project

Pre Concrete Conference

If we discuss the expectations of the owner, designer, and the contractor we can build great structures

The Pre-Construction ConferenceKey to a Successful Project

Promote a forum for open discussionKeep an open mindBe prepared to compromise for the good of the projectUnderstand the limitations of the teamPut everything on the tableTraining the people involved in our project to succeed!Issue Minutes

Slab Flatness and Levelness understand the limitations of

concrete constructionFlatness and Levelness

SpecifiedOverall Value –Ff 50, Fl 35Minimum Local Value –Ff 35 / Fl 25

This is not unreasonable for a slab on grade. But the problem is, it’s specified for a structural slab with low head room. This limits the equipment the contractor can use.

Slab Flatness and Levelness understand the limitations of

concrete constructionShould Fl be applied to suspended slabs? (slab on deck)

NO“the concrete flooring contractor cannot control elevations of steel or precast concrete members upon which concrete slabs are cast.”(ACI 117- R4.4.1)

Slab Flatness and Levelness understand the limitations of

concrete constructionCan the owner expect a level slab on deck?

Its not likely!The concrete contractor cant control

the deflection of the metal deck or the beams that he is placing on.

The owner should be made aware of what the end product will look like.

Site Concreteunderstand the limitations of

concrete constructionSidewalks and Ramps

Review the elevations and “Maximum 8.3 % slope”“in practice, 8.3 percent is rarely treated as a

maximum but is used as the design standard that does not allow for construction tolerances. Therefore, rather than using 8.3 percent for designing curb ramp grade, a grade of 7.1 percent is recommended to allow a construction tolerance.”(Federal Highway Administration)

Site ConcreteSidewalks and Ramps

This will surely end up in a contractor replacing concrete, and an owner asking everyone why he’s replacing his landscaping on opening day!

Key to a Successful Project

Training for success!