AS 4198:2022 pdf – Precast concrete access and maintenance chambers for sewerage applications.
3.4.6 Slab thickness
The thickness of a concrete cover, concrete surround precast base unit (slab portion) or conversion slab component shall be determined by direct measurement at three equidistant points on the perimeter and taking the mean of the three values.
The variation between the measured thickness and the manufacturers nominated design thickness shall not vary by more than ± 5mm and no individual measurement shall vary by more than 10 mm than the nominated design thickness.
NOTE For base units without an anti-floation ring measurement can be via indirect measurement and calculation.
3.5 Workmanship and finish
3.5.1 General
Concrete cover requirements shall not apply to reinforcement spacer stud ends, radial nibs, end spacers or longitudinal reinforcement ends. Where steel spacer studs (or nibs) are used to maintain circumferential reinforcement cages at an appropriate depth of concrete cover, stud caps made o(brass or other metallic material shall not be used.
3.5.2 Joints
The ends olcomponents shall be formed so that, when components of the same diameter are assembled.
the diameters of jointed components are concentric in the plane of each component joint.
3.5.3 ReinForcement General
At the time of placing the concrete, the reinforcement shall be free of materials or coatings likely to impair its bond with the concrete. Fabrication
Reinforcement shall be fabricated so that it can be easily placed and accurately held In the required position during the manufacture of the access or maintenance chamber component. Mild steel nibs/spacers can be used to locate cages in position for mild and moderate external environments. Stainless steel spacers shall be used for severe external environments.
NOTE Cover requirements do not apply to steel spacers. Splicing
Where it is necessary to splice the reinforcement, this shall be done by lapping the reinforcement not less than 50 diameters of the bar or wire, or by welding In accordance with AS 1554.3. For lap splicing of welded wire fabric, the length of the lap shall be not less than the spacing of the transverse bars.
3.5.4 Cover
When determined in accordance with Appendix 0. the clear cover to the reinforcement for all components shall be not less than the values given in Clause 2.4. The tolerance on the cover shall be -O/.+1Omm. Unreinforced components
Cracks in unreinlorced components shall not exceed 0.05 mm in width and neither extend through the component wall nor extend for more than one-half the component length. Classification and acceptance of defects 1pes 4 to 7 in unreinforced components shall be as specified in iauesIL&2 and i5.5.3. Finishing and repairs
Finishing and repairs to components shall be carried out using cement mortar, epoxy mortar, or other similar material. Materials used for repairs shall have a tensile and bond strength not less than that of the concrete in the component.
3.6 Marking
Each component shall be legibly and permanently marked In a prominent easily visible location with the following information:
(a) The manufacturer’s name or registered mark, or both.
(b) For access covers and frames, the applicable test verified type or class B, C or D load classifications, and the mass of the separable components In kilograms. visible from above.
(c) For unreinforced components, iJ. For reinforced components, R.
(d) The month and year of manufacture, the place of manufacture, or the manufacturer’s traceability code.
(e) Maximum mass of each separable component in kilograms.
(1) For base components that are custornised with holes and benching to purchasers’ specific requirements, a unique reference number shall be branded on the base component with traceability to match the purchasers’ pit number.
NOTE 1 Indenting and engraving are two methods of marking which are considered permanent or indelible.