Shooting the Shotcrete Test Panel

Shooting the shotcrete test panel and three compression test samples took 12 minutes to complete.

Preparation

Setting up the test took less than 30 minutes.  

Test panel is in position so it will be easy to shotcrete (and can stay in this location for several days).

Test panel is in position so it will be easy to shotcrete (and can stay in this location for several days).

Bill Brown’s team had the test panel in place near the front of the site and the shotcrete nozzlemen and pumper (with air compressor) were in position and ready.  The Graniterock truck, loaded with three yards of mix, arrived at 8:26 am.  Then, the special inspector from HP Inspections, Gary Stafford, arrived right on time at 8:30 am.  We had a quick meeting to coordinate the test.

The full team, including Bill Brown, discusses how the test will be conducted.

The full team, including Bill Brown, discussing how the test will be conducted.

One of the special inspector’s key activities was to review the reinforcing steel (rebar) placement in the test panel and identify where the densest area of rebar is located so he can specify where the core samples will be taken.

Gary Stafford conferring with Bill Brown regarding where the core samples should be taken from.

Gary Stafford conferring with Bill Brown regarding where the core samples should be taken from.

Shooting Shotcrete into the Test Panel

Each nozzleman had to shoot the shotcrete into the test panel, with the same pump operator and the same equipment that will be used when the retaining walls are completed.

First nozzleman completing half of the test panel.

First nozzleman completing half of the test panel.

Second nozzleman shooting shotcrete.

Second nozzleman shooting shotcrete.

Shooting the shotcrete is a bit noisy and messy.

Shooting the shotcrete is a bit noisy and messy.

The Graniterock truck loading the hopper for the pumper.

The Graniterock truck loading the hopper for the pumper.

The test panel required the full setup on the street.  The only difference between the test panel and the retaining walls will be the number of Graniterock trucks delivering concrete.

Graniterock truck and air compressor/pumper truck on Via Sereno.

Graniterock truck and air compressor/pumper truck on Via Sereno.

With concrete, the ‘slump’ is a key test to ensure the concrete mixture is delivered as specified.

HP Inspection's Gary Stafford, testing and measuring the slump of the concrete mix.

HP Inspection's special inspector, Gary Stafford, testing the concrete mixture and measuring the slump.

While the test panels will measure any voids in the shotcrete retaining walls, we also used the same shotcrete mix for three plugs, for destructive testing of the compressive strength of the concrete.

Shooting the shotcrete plugs for destructive testing of the compressive strength.

Shooting the shotcrete plugs for destructive testing of the compressive strength.

Completing the Shotcrete Test Panels and Plugs

With the test panel and plugs completed, Bill and Gary completed and signed the documention regarding the test procedures and observations.

Gary Stafford (left) and Bill Brown (right) completing and signing the documentaiton of the test procedures and observations.

Gary Stafford (left) and Bill Brown (right) completing and signing the documentaiton of the test procedures and observations.

Marking the locations for the core samples.

Marking the locations for the core samples.

Core samples will be taken from the three locations that were marked.

Core samples will be taken from the three locations that were marked.

Having completed inspecting the shooting of the shotcrete and identifying the locations where the core samples will taken, Bryan and Gary left the project site at 9:50 am to go to the City of Monte Sereno so Gary could present his qualifications to the Building Official.  That was completed by 10:05 am.

Completed Shotcrete Test Panel and Plugs

The procedures went quite well today.  Now, the shotcrete test panel and plugs need to cure and gain compressive strength before core samples are taken.

Completed test panel, curing and gaining compressive strength.

Completed shotcrete test panel, curing and gaining compressive strength.

Completed concrete plugs.

Completed shotcrete plugs.

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3 Responses to Shooting the Shotcrete Test Panel

  1. Kelvin says:

    does the same procedure apply for shotcrete of a wall versus a swimming pool

  2. bmek says:

    No, I do not believe so. A swimming pool uses gunite, which is a dry mixture; shotcrete is a wet mixture. With gunite, the cement and sand are premixed and then conveyed down a hose to a nozzle and pneumatically fired at the surface being coated. I do not believe there is a similar test for gunite. The shotcrete test was to ensure the structural strength of the shotcrete wall will be realized by the qualifications and ability of the nozzleman to shoot the shotcrete through the dense reinforcing steel (rebar) without leaving voids and the shotcrete mixture has the required compressive strength (PSI).

  3. Kelvin says:

    Today i have a shotcrete inspection for a swimming pool 1st i must make sure the nozzleman is qualified. 2nd do i need to do a test plug. 3rd and i must take a slump test at the concrete truck.

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