reinforced concrete fence posts
1984 Edition

As per the standard, the minimum concrete cover for reinforcement must be at least 15 mm or twice the diameter of the main longitudinal bar, whichever is greater. This cover should be maintained at the bottom of corrugations, holes, and at both ends of the posts. In environments prone to corrosion, such as coastal regions, the minimum cover is increased to 25 mm to enhance durability and protect the reinforcement from deterioration.

The standard permits use of mild steel bars, medium tensile steel bars, hard-drawn steel wires, hot rolled mild steel bars, hot rolled medium tensile steel bars, high yield strength hot rolled deformed bars, and cold-worked high strength deformed bars. These conform to the Indian Standards IS 432 (Parts 1 & 2), IS 1139, and IS 1786, ensuring compatibility and adequate strength for reinforced concrete fence posts.

Fencing wires are attached using either cast-in metal clips or galvanized wire tying methods. Metal clips, made of galvanized or corrosion-resistant steel, are embedded perpendicular to the post face with bent ends to prevent wire pull-out, though they are not recommended for coastal areas due to corrosion risks. Alternatively, galvanized wires are twisted around the fencing wire and the post’s back surface, often aided by chamfered or notched post edges and corrugations to secure the wire firmly. For barbed wire, special larger holes and hairpin-shaped wire ties are used for secure fixing.

The standard requires initial sampling of fence posts for strength evaluation. If any post fails, a doubled sample size is tested. Acceptance is granted if no failures occur in the retest. Static load tests involve applying load until the first visible crack appears, with minimum load thresholds established for line, strainer, and strut posts. Additionally, dimensional and uprightness criteria must be met. Failure beyond allowable limits necessitates full lot testing and rejection of non-conforming units.

Line posts are generally spaced at intervals of 3 meters, while strainer posts are positioned approximately every 30 meters. Fence wire spacing varies depending on application, with recommended distances provided in the appendices. Installation requires posts to be set plumb at specified depths, using flat iron clamps or other fixtures for wire attachment. Specific methods for fixing plain and barbed wires are outlined, ensuring structural stability and long-term durability in various environments.