Vertical Feed Store Panel Specifications

1. Description: Precast concrete walls panels designed provide structural walls to bulk grain stores and silos both above and below ground


2. Materials: All materials are sourced in accordance with the appropriate British Standard and in accordance with the ACP performance specifications.
Concrete typical 28 days strengths are 60N/mm²
Concrete strength at transfer 30 N/mm²
Water cement ratio 0.45 Maximum
Reinforcement typically 9.3mm dia prestressing strand

3. Design: All units are designed in accordance with BS8110 and BS 5502. Unit design is typically to Class 3 with a limiting crack width of 0.1mm unless otherwise stated. It is the clients responsibility to provide loading data including bulk material density, angle of internal shear resistance and load condition. Any surcharge, grain stirring or impact loadings must be provided.


4. Manufacture: ACP wall panels are manufactured in the long line prestressed method. Units are wet cast into steel moulds with under plate heating to assist in accelerated curing.  Standard unit sizes are as follows:
      Thickness          Standard Widths                                     Length
      145mm                 0.5m 0.6m 0.7m 1.0m 1.2m 1.5m           up to 7.0m
      180mm                 1.0m 1.2m 1.5m                                     up to 7.0m
      280mm                 1.2m                                                      up tp 8.0m


5. Tolerances: Cross-sectional tolerances are within limits set out in clause 6.2.8.3 of BS8110:1997. ACP acceptable tolerances for standard prestressed units are as follows
            Length -5mm to +10mm 
            Width -0mm to +5mm
            Thickness -2mm to +6mm 
            Squareness 12mm difference between diagonals
            Socket positions -/+ 10mm
            Lifter position -/+ 100mm
 Special cast units will be to tolerances laid down in BS8110 where casting techniques permit.


6. Mould Finishes: All faces with the exception of the trowel face will be cast from steel shutter moulds. Surface finish is listed in BS8110 6.2.7.3 and is to conform to Type A.
Small blemishes caused by entrapped air, excess mold release agent, marks on the casting surface and mould release agent staining can be expected.
The surface will be free from voids and honeycombing.
Surface marks from stacking timbers, strand runs and fork truck tine marks can be expected. Surface marks of stacking timber, strand run and mold release agent will fade out over time and use.
Where a blemish free surface is required, masonry paint application is recommended.

7. Trowel Finishes: The trowel face of units will comply with a U1 type finish.
Finish will be uniform and provide full grout cover to aggregates.
Some trowel marks will be visible
Some colour and texture variation may be expected.
Stacking timber marks and cement blooming may be expected.
Colour variation, trowel pattern and cement blooming will fade over time and weathering. Where uniform colour is required, masonry paint or mineral staining is recommended.

8. Camber: Units will have a little or no prestressing camber.


Site Works

9. Site Access: Full site access free of any obstructions or trenches to all site areas is assumed unless otherwise agreed.
Access is required to both sides of wall construction unless previously arranged at pricing
stage.
Delivery vehicles are to unload inside the building to minimise on site handling.
A suitable hardstanding surface must be provided to enable safe lifting operations for a 15
tonne telehandler lifting a 5 tonne load.
The hardstanding is to extend a minimum of 2m beyond the edge of the building area.
Any doubt over the suitability of the hardstanding will result in halted operations whilst
investigations take place. Any delay and disruption costs due to inadequate hardstanding will be borne by the employer.
An uninterrupted wall line must be provided, any excavations required to install units must be
carried out prior to delivery and must be graded and battered to a safe working angle.
A minimum of 3m clear headroom is required for all installation.
It is assumed precast installation will be the sole site activity at the time of construction.


10. Panel Support: A minimum blinding support strip of 550mm wide must be provided, typically 100mm thick but designed to suit the wall line load.
The support area must be designed to carry the full line load of the wall panels without settlement and must be a smooth flat surface.
A propping support strip must be provided to secure suitable push pull props.


11. Vertical Joints: Panel edges are cast with a tongue and groove edge detail designed to lock together. Tolerance in the erection of the structure and the cross section of the precast units will result in a joint varying from 0mm to 15mm.
This variation may occur joint to joint or within any individual vertical joint.
Mastic sealant applied to the joint is designed to accommodate these variations.


12. Top Line of wall: Variation in panel lengths and in finished level of blinding strip will produce a variable top line to the wall. Where a consistent top line of panels is required, we recommend a capping channel be applied to the wall after installation.


13. Erection Systems: Panels are erected using either D-shackles located in cast holes or clutches located in cast inserts.
Formed holes may contain a thin grout skin to the mold face that should be tapped out prior to fitting lifting shackles.
Erection inserts may require cleaning prior to attaching lifting clutches.


14. Vertical Internal Joint Sealant: Internal joint seal is provided with a one part polyurethane mastic sealant.
Sealant is gunned to vertical joints and tooled into recessed “V” shaped joint.
Sealant is supplied to provide a moisture and dust barrier and is not designed to produce an aesthetic jointing detail.
Some curling of sealant edges may be expected during curing.
The “V” joint is not designed to be full filled with sealant


15. External Joint Sealant: Where selected external joint sealant is provided with a one part polyurethane mastic sealant.
Sealant is applied and treated exactly as internal joints


16. Supporting Floor Slab: It is usual for foundation concrete to be placed in 2 separate pours. Initial concrete placement and compaction should be designed to allow temporary prop removal. Final floor slab placement and finish is to be designed to suit site conditions and loadings but is generally 150mm RC35 mass pour slab contain 1 layer reinforcing fabric (A193 minimum) placed onto blinding layer containing suitable DPM over compacted hardcore typically 150mm thick. Concrete finish is typically rough tamp or easy float trowel.

17. Strand Ends: Prestressing tendons or strands are visible at the unit ends. The density of the concrete means that no further treatment of the strand ends is required to ensure the serviceability and durability of the units.


18. Damage: It is highly likely that precast units will suffer small chips and superficial damage to unit surface. This damage should not compromise the units structural integrity.
Any areas should be repaired with a high strength mortar.
Colour matching of suitable repair mortar and the precast unit is not possible due to high strength requirements of the repair.
Once the repair is fully cured, panel joint should be cut and mastic applied as above.


19. Floor Joint: Attention should be paid to the design to the floor to wall joint detail. Prestressed wall panels are designed to flex under load and the joint sealant detail must accommodate this movement.

 
 

Enquiries

Floors / Stairs:

01900 814659

Walls, Agriculture and Bespoke:

01889 598660
 
 
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