Prestressed Concrete Fencing Posts

 

Our prestressed concrete fencing posts are the product of over 40 years of experience, and have been used all over Southern Africa, being specified by consulting engineers for some of the highest level security installations in the sub-continent.

 

These posts are designed by a professional engineer, and manufactured in a production facility designed to ensure adherence to the specification and quality standards.

 

Cavcon pre-stressed fencing posts are an excellent choice for your wire mesh fence. Some notably important features are:

• They have little intrinsic value, unlike timber or steel posts, and therefore are ideal for areas where there is high risk of theft.
• In a field test they were shown to be very much stronger than 50mm x 2mm tubular steel posts.
• They are extremely long lasting and manufactured for maximum corrosion resistance.
• They are much more competitively priced than galvanized tubular steel posts.
• They are aesthetically pleasing and have a beautiful finish.

 

You can have complete confidence in specifying and using fencing posts from Cavcon.

 

 

Features

 

Cavcon prestressed fencing posts are manufactured to comply in all respects with SABS specifications CKS 451 of 1976 and BS 2691.

 

 

Corrosion Resistance

 

Ability to withstand highly corrosive atmospheric conditions in coastal areas (salt penetration) and highly corrosive soil conditions in industrial areas (precipitation of acidic gas, effluent) achieved through:

 

 

Adequate concrete cover of prestressing wires (20 mm)

 

    Densely vibrated concrete in individual moulds

    Alkali-reaction-free concrete

    Smooth surface on all faces with rounded corners

 

 

Bending Resitance

 

Bending moment values far in excess of requirements of CKS 451 of 1976 achieved through:

• Concrete compressive strength of 50 MPa at 28 days
• Unique stressing of wires using fixed anchorage
• Good engineering design maximises strength to mass ratio

 

 

Quality and Durability

 

• This prime Cavcon objective is achieved through:
• Superiority in all essential technical characteristics
• Unique patented production and design features
• Strict adherence to product specifications and quality standards
• Alkali-reaction-free concrete
• 50 years experience in producing quality concrete products
• Production facility designed by professional engineer
• Backed by Cavcon lifetime guarantee

 

 

Availability

 

The following products are available ex-stock and delivered to site:

• Fencing Posts: 1,80m, 2,10m, 2,40m, 2,70m, 3,00m, 3,60m (straining, stay and intermediate posts)
• Overhangs: single and double (easily attached, bolted on)

 

 

 

 

 

 

 

Specifications

 

 

Concrete

 

The concrete shall consist of 13mm quartzitic stone, Swartkops River sand and Portland Cement, weigh-batched to produce a mix which has an average compressive strength of 50Mpa at 28 days for 150mm test cubes.

 

The mix shall be compacted by vibration in steel moulds, to produce dense concrete.

 

 

Prestressing Wire

 

Posts are to be prestressed with four crimped prestressing wires accurately positioned in the four corners of the moulds to give a concrete cover of 20 mm. Major posts shall be prestressed with four 5.0mm dia crimped prestressing wires, and intermediate and stay posts with 4.25mm dia crimped prestressing wire.

 

The prestressing wire shall comply with B.S. 2691 having a yield stress of approximately 1500MN and Young’s Modulus of approximately 200GPa.

 

The prestressing wires shall be equally tensioned in the moulds by a force producing an initial stress of not more than 70% of the 0,2% proof stress.

 

No prestressing wires shall be exposed when the posts are erected in concrete.

 

 

Fittings

 

The stay connectors and bolts shall be of hot dipped galvanised mild steel or as specified.

 

 

Spacing of Posts

 

Major post spacing shall be between 30m to 60m maximum on a straight run and fitted with 1 or 2 stay posts each. Major posts fitted with 2 stay posts shall be erected wherever there is a change of direction in the line of the fence.

 

Intermediate post spacing shall be 3m to 4m.

 

Standard footing sizes for posts are as below (see Dimensions). All footing sizes are dependent on ground conditions and mesh type.

 

 

Bending Moments

 

The major posts, intermediate posts and stay posts are to resist a minimum bending moment of 2.7kN.m, 1.3kN.m and 1.3kN.m respectively, in any position before initial failure occurs.

 

 (Note: The force required to break a post, so that it does not fully recover, is considerably greater than the above specification.)