Civil Engineering: definition of kerb | Type of kerbs | desgin of kerbs

KERBING

1). Different type of kerbs and dimension

2). Desgin of Kerbs

DEFINITIONS:

1. Filler - Elastic, tight fitting, non-rotting, non-absorbent material used to provide firm backing, against which the sealant can be tooled off. Filler shall also prevent the sealant from adhering to the bottom of the joint and cause the sealant to fail during the expansion of joints.

2. Sealants - Material used to seal expansion joints to prevent penetration of destructive materials.

TEMPORARY KERBING

1. Temporary kerbing shall be installed where shown on the Drawings in accordance with the requirements for permanent kerbing. Temporary kerbing shall be laid on a bond breaker membrane between the kerbing and the surface to prevent adhesion to the surface and to assist future removal.

2. When the concrete has set, a suitable fill material shall be placed between the permanent kerbing and the temporary kerbing, and left flush with the top of the kerbing.

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JOINT FILLERS AND SEALANTS

1.Filler

Joint fillers shall comprise either a closed cell polyethylene rod of 10 mm diameter, or a strip of poly urethane foam 12mm wide.

2. Sealer

Joint sealing compound for surface sealing shall be a grey butyl mastic sealant.

CURING COMPOUNDS

Concrete curing compounds shall be based on an aliphatic alcohol for application in spray form.

CONSTRUCTION

GENERAL

1. Kerbs on straight alignments exceeding 10m and on curves of radii exceeding 3m shall be placed by an extrusion machine.

2. Where the kerb is on a straight line of 10m or less, or on a radius of 3m or less, or where the lack of clearance prevents the kerb being placed by an extrusion machine, the section of kerb may be hand placed. Hand placed kerb shall be rodded and shaped, to give a finished kerb meeting the requirements of this Specification.

3. The shape and dimensions of the kerb shall be in accordance with the Drawings.

SETTING OUT:

Setting out of the kerb shape, profile and alignment shall be carried out on the rear of the kerb. Spikes and nails shall not be driven into the pavement surface.

SURFACE PREPARATION

The surface to receive kerbing shall normally be a bituminous aggregate seal.

The Contractor shall clean the area between the receiving surface and the new kerb of all loose sand, stones, dust and other foreign matter and shall wet the surface with water immediately prior to placement of the new kerbing.

EXTRUDED KERBS:

1. Extruded kerbs shall be laid by a suitable extrusion machine. No dowels are required.

2. Extruded kerbs shall be dense with regular sides, edges and chamfers finished to a fine surface free from blow holes and dragging and shall be impervious.

KERB OPENINGS:

Kerb openings shall be located and installed in accordance with the Drawings.

CURING:

All exposed faces of the completed kerb shall be kept permanently wet for the curing period of a minimum 72 hours after placing. Concrete maybe cured by spraying with approved curing compounds.

1 Any water applied shall not cause erosion of the concrete surface.

2 The concrete shall be protected within 15 minutes after completion of casting the kerb.

3 The kerb shall be protected from rain for at least twenty four (24) hours following placement.

4 The kerb shall be protected from traffic for a period of twelve (12) hours following placement.

JOINTS

1). Contraction

Immediately after placing the kerbing, contraction joints shall be formed by grooving the exposed faces of the kerbs. Contraction joints shall be formed at spacings not exceeding 4m.

2). Expansion Joint

Not less than 24 hours nor more than 72 hours after placing of concrete, expansion joints shall be constructed at the midpoint between contraction joints by sawing a 6 mm wide gap through the full cross section of the kerb. Kerb cutting shall be carried out with water to minimise dust in the sawing process.

3). Fillers & Sealants

3. An approved joint filler shall then be forced into the sawn joint such that a 12 mm deep space remains to the concrete surface. This space shall be completely filled with an approved joint sealant such as Sikaflex construction polyurethane joint sealant or equivalent approved by the Superintendent and used as per manufacturer’s instructions.

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1). Different type of kerbs and dimension

2). Desgin of Kerbs