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Pre & Post Pour Inspection
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Check your product. Pic from NY precaster who should have done pre/post pour inspections.
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Overview Documentation Pre-Pour Inspection Post-Pour Inspection
Equipment Reinforcement Post-Pour Inspection Stripping & Handling Visual & Dimensional
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Why Document? Not just for posterity Documentation is a legal record
Quality Control means nothing without it Allows others to: Duplicate our successes Analyze our failures Prove our compliance Benefits our company & industry There is a mindset to keeping documentation. If someone is signing off on something, he will think twice about what he’s doing.
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Sample Documentation Forms
Q-Cast Appendix A Joint forming equipment Pipe, manhole and pre-cast reinforcing Pipe, manhole and pre-cast post-pour Box culvert equipment set-up Box culvert reinforcing Box culvert post-pour Recommend an initai on the bottom of docs for added accountability Show students where to find notes pages above
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DOCUMENTATION Documentation for Qcast program
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Other Required Documentation
Initial shop drawings for pre-cast structures Document sanitary sewer pipe and manhole spigot gasket-sealing surface measurements (go/no-go)
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PRE-POUR INSPECTION
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Pre-pour Inspection Measure incoming equipment
Form equipment Joint forming equipment Proper storage/maintenance Store headers/pallets flat Cover/coat during storage Sandblast/prime/re-paint Clean after each use Suggest not storing Headers or Pallets on end as they will end up out of tolerance Sandblast should not be used on concrete forming surfaces
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Where to get gauges? Hamilton Kent and Hawkeye
Sanitary should be checked as incoming and annually…Storm as incoming only.
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How not to store equipment
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Pre-pour Inspection Inspect equipment prior to each use for:
Cleanliness Excess build-up, rust, other impurities Condition Chips, cracks, damage Dimensions Roundness Vibrator mounts, Seams, Gates, Lifting lugs, Latching devices, Bolts and welds
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This form was in use and heavily sledge hammered…Get rid of the sledge hammer
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This is what happens with dirty forms are used
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Note: build up on the forms
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Pre-pour Inspection Additional inspection for box culvert equipment
Thickness of top, bottom and side walls Core rise & span Both core diagonal measurements Document measurements Qcast requirements
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Pre-pour Inspection Inspect Reinforcement for:
Style, steel area, dimensions Cage diameter, length, location Lap, welds/ties Bell reinforcing Spacers Shear steel Document one cage at the start of production and after each shift change
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Mid: inspect spacers for quantity, location and size
Top: inspect lifting device to make sure it is placed correctly. If additional steel is required, make sure it is there. Note: the circumferentials that have been cut away. Check your specifications! Mid: inspect spacers for quantity, location and size Bottom: inspect cover when the cage is properly centered 2 2
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Note not only the weld, but scaling rust on right
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Pre-pour Inspection Additional inspection for each box culvert produced Cage orientation Form release (correct, good coverage) Embedded items Cleanliness Reinforcing cover, spacers, chairs Document inspection
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Pre-pour Inspection Additional inspection for Manhole and Pre-cast structures Location of embedded items Location of blockouts Document by initialing the shop drawing
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Pre-pour Inspection Blockouts Must be properly designed and secured to
Withstand placement stresses Achieve design location of the hole Achieve adequate concrete cover for all reinforcement Suggest non-corrosive material to attach blockouts
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Made at 2-contour. Straps are hanging from the top
Made at 2-contour. Straps are hanging from the top. They can be screwed at different lengths for various pours
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If in a plant where knockout attached to cage, pre-pour should be done just before pour in case of shifting of the cage. Suggest attaching to form or using magnets
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Pre-pour Inspection Form Release Purpose is to
Prevent hardened concrete from adhering to the form Provide form protection Improve product appearance
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Categories of Release Agents
Barrier (non-reactive) Chemically Active Combination of above
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Barrier (non-reactive)
Examples Petroleum-based diesel, heating oils, used crankcase oil Advantages Creates a physical barrier between form and fresh concrete Disadvantages Need heavy application for easy release ( ft2/gal) Can cause staining and bugholes May not meet VOC requirements Can cause buildup on forms
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Chemically Reactive Examples
Fatty acids (vegetable and mineral oils) are chemically reactive agents that combine with calcium in fresh cement paste to produce a soap-like film between the concrete and the form Advantages Prevents bonding of concrete to form Ultra-thin Layer (0.005”) Reduce bugholes, stains, dusting Typically meets VOC requirements (verify) Disadvantages Typically more costly per gallon
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Seasoning Remove protective coating to prevent staining, sticking, poor finish Wear off during production Solvents Grind Blast Apply high fatty acid concentrate release agent; Let it react (forms metallic soap barrier). If using a barrier agent, use it for seasoning. Ideally allow 24-hr sit-time Apply release agent Put into use When using chemically reactive release agents, it is critical that the form be properly seasoned
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Pre-pour Inspection Form Release Application methods
Brush, spray How much is enough?? Too Little Concrete sticks, patching/repairs, form damage Too Much Affects concrete finish, may affect curing Generally, thinner is better
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Illustrates the result of not enough release agent
This picture shows the end of a bell where concrete stuck to the pallet and pulled from the pipe.
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POST-POUR INSPECTION
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Post-pour Inspection Stripping & Handling
Minimum strength Form disassembly Proper rigging Product identification and documentation Goal is to minimize damage to the product, and therefore the above are important checks. Products should be identified in the kiln or when forms are removed prior to further handling
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Post-pour Inspection Pipe, manhole and pre-cast inspection Cracks
Slumping, segregation Voids, bleeding, excessive bugholes Exposed steel Cage twist Joint smoothness Swedging, slabbing, flashing Size & location of embedded items, blockouts Review pages in Qcast with students
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Post-pour Inspection Box culvert inspection: Appearance Cracks
Voids/bleeding Flashing Slumping Exposed steel Bug holes
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Poor forms creating poor product
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Use to be the only precaster in the area, and now there is another…could be due to this poor quality
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Post-pour Inspection Pipe and manhole joint inspection
Before patching - inspect for cracks, smoothness of bell and spigot, snap ring positioning After patching - inspect patching technique and quality, smoothness of bell and spigot, uniform snap ring width and depth, no concrete ridges in the recess Go/no-go or similar required for sanitary There is initial post –pour and an final post-pour if repairs were made
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Great for adjustment, but this one should be checked everyday if they have changed
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Post-pour Inspection Pipe and manhole dimensional check
One for each size per shift Measure and record pipe and manhole length, diameter, wall thickness Calculate and record minimum difference in length of two opposite sides Maintain dimensional reports for each pipe section on which a 3-edge-bearing test has been performed Qcast requirements and sheets can be found in the appendix
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Post-pour Inspection Record for 20% of all boxes produced each day, for each form used that day – minimum of one per form per day Dimensional record for: Thickness of top and bottom slab Thickness of both side walls on both ends Inside rise on both ends Inside span on both ends Inside length: top, bottom, both side walls
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QUESTIONS?
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