Disaster Beneath the Floor: Preventing Catastrophic Slab Collapse

By -

 

Industrial Building Slab Failure 

My Geotechnical Firm performed a Geoforensic investigation of a recently built Industrial building constructed in the Houston area. They investigated the failing interior concrete slab.




They documented over 80 cracks from under 10’ to over 40’ in length and from .02” to .06” in width.









They core drilled the slab and performed compressive tests. The results weren’t good.


Through their laboratory analysis, they determined that 

1) Water was added at the project site, which affected the consistency of the mix. 

2) An inferior aggregate was used in the mix. 

3) The control spacing was measured from 15’ to 25’ and the depth was .25”.

ACI recommends that the control joint be ¼ the thickness of the slab. A 7” slab should have a control depth of 1.75”. Control joint spacing should be twice the thickness of the slab in feet. Therefore, for a 7” slab, the maximum joint distance should be 14’.

4) Based on the forklift that was present during their investigation, they determined that they would need a 10” slab. 

5) Rebar depth. On all of the cores, they found that the reinforcing steel was placed near the bottom of the slab.




Let's learn from our failures. The B-17 Flying Fortress crashed on its maiden voyage in 1935. They installed the Pre-flight checklist. Let's do it for our jobs.

Check out my blog below. 

Beyond the Pour: Your Ultimate Concrete Foundation Checklist Blog

 

Shettig Construction Management provides Professional Construction Management services from the inception of your project through completion. www.shettig.com

mshettig@gmail.com





























Comments

Post a Comment

Popular Posts

Build Faster, Smarter: Is the Design-Build Method Right for Your Project?

By -
Image
The Design-build method on your construction project versus the traditional Design, bid, build method. Project: Huntsman Chemical Computer Building Addition, Conroe, Texas  I met Huntsman in mid-August and reviewed their completed drawings for the project.   They required that their project be complete by December 1 st . Their design showed a 44’ x 40’ painted block addition, one story along with bar joists and a structural steel deck with poured concrete and a gable steel frame roof with metal roof panels.                                  Bar joists with metal deck and poured concrete deck. METAL BAR JOISTS SCHEDULE PROBLEM Bar joists require a 10–12-week delivery after the shop drawing review. This puts the delivery in early December. Their design is a 7-month schedule project, not the 3 months that they desired. REDESIGN OF THE PROJECT TO A STRUCTURAL STEEL FRAMING I discussed with them t...
Read more

Building Smarter: The Power of Pre-Construction in Design-Build

By -
Image
The Design-Build Method is an alternative in the building of your project.  In the Design-Build method, you will start an immediate collaboration with your Design-Build consultant (DBC) The Pre-Construction activities are the first part of the Design-Build Method. The pre-construction phase starts with a Preliminary drawing or sketch that can be generated by the Design-Build consultant or the Owner. Develop Estimates and Budgets From there, you want to establish the Budget of the project from the design stage through the construction stage. The DBC team will start with square foot estimates. As more detailed drawings are completed by the  D BC, they will develop a more detailed construction estimate.   Incorporate Value Engineering into your  project. At this point, the DBC will develop some Value engineering suggestions and Options for the building. The Value Engineering suggestions would look at alternate materials, methods, and components in the design that can ad...
Read more

Beyond the Dig: A Quality Control Checklist for Site Excavation

By -
Image
Quality Control Checklist for Site Excavation   1. Review your job survey information, monuments, and property corner stakes. Check to see if your property corners are set by your survey crew. Identify where your survey crew established a Benchmark with an identifying  elevation.                   Your survey crew may need to bring in an elevation mark from an offsite benchmark. They then can set a benchmark stake in a power pole or tree.  All your excavation elevations will then be determined from the benchmark.  Existing Underground and Overhead Utilities 2. Verify the existing utility lines are located, staked, and protected, and observe conditions of the uncovered lines.  3. Verify that the utility companies have been notified.  4. Verify that all underground lines have been identified. Have you called Miss Utility or 811 in Texas? Contact them at least 48 hours before you begin any excavation. Have...
Read more