Manufacture Information

Manhole Rings

Acheson & Glover products offer a complete range of precast concrete manhole units from DN 675mm to DN 4000mm in various depths with tongue and groove, and ogee joints manufactured in:

1). Ordinary Portland cement
To comply with exposure classes set out in Table 1, EN 206-1: 2000 (AMD 1-3).

2). Sulphate resisting Portland cement
To meet with recommendation of Table 1, EN 206-1 :2000 (AMD 1-3).

All as set out in BS 5911-3: 2002 Table 2.

All units are manufactured and tested in accordance with BS EN 1917 : 2002 and BS 5911-3: 2002 and Kitemarked. Acheson & Glover operates a Quality Assurance Scheme to these standards to cover all aspects of production.

All units are supplied with suitable lifting points. A precast concrete manhole is a strong, durable structure with its own inherent strength and does not require a concrete surround at standard depths.

Materials

High quality aggregates are used in the manufacture of products, supplies of which are constantly monitored to ensure compliance with the relevant British Standard.

The process of producing a dense high strength concrete involves electronic monitoring to control content and batch weighing and mixing of premium ingredients.

Methods

Acheson & Glover manufactures units by two main methods both of which utilise a low water / cement ratio producing a dense homogeneous concrete of high strength and durability, which complies with all aspects of the relevant BS requirements.

1) High frequency vibration
Semi-dry concrete is fed into a vertical sheet mould and a very high pressure is exerted resulting in a unit of very high density coupled with very low water / cement ration, which is capable of standing upright moments after pressing.

Steel reinforcement

Steel is purchased only from CARES approved suppliers that meet the new CE requirements to EN10080 in conjunction with the relevant national standards. BS 4449: 2005 (yield strength 460 MPa) for cover slabs and BS 4482: 1985 for rings.

Reinforcement wires for ring manufacture are produced from cold reduced steel wire on automatic welding machines. As the steel wire is wound in a spiral it is automatically welded at each contact point.