Australia Post Granville

  • Client: Australia Post
  • Principa: ISIS
  • Contract Superintendant: James Fitzgerald

Project Description

Northern Group was engaged by ISIS to undertake the demolition of an existing internal courtyard and construction of a 1000m2 concrete slab at the Australia Post Mail Sorting Facility in Granville. This was only a small portion of the overall renovation and fitout being undertaken by ISIS

Northern Group’s works packages involved demolition, bulk excavation, importation of compactable fill (sandstone), construction of reinforced concrete piers, preparation of DGB20 subbase, edge thickenings, jointing, concreting, saw (soff) cutting, joint sealing and spray on curing.

The demolition works consisted of excavating an access ramp in the existing staff carpark and cutting a hole 4m x 4m in the side of the building to allow truck movements through the existing warehouse to the internal courtyard. The courtyard was previously used as a lunch / common area with native trees and palms up to 7m high, several raised brick planter beds, brick paving and 2 concrete and timber pergolas. This was all demolished, separated and disposed of at a recycling facility.

Bulk excavation was required to approximately 800mm depth over the 1000m2 area to remove all of the planting soil and uncontrolled fill to ensure the subgrade was consistent and compacted to 95% standard density. This guaranteed suitable founding for the imported subgrade material. The excavated subgrade material was screened, sorted and loaded into bogie trucks and disposed of at a licensed facility.

Replacement subgrade material consisting of 1200 tonnes of -150mm sandstone was imported, compacted in layers and compaction tested up to 290mm below the proposed finished floor level of the warehouse floor. A combination of bogie trucks and truck and trailers, 2 x 12t excavators, a Kubota track loader and a 13t smoothdrum roller were used for the portion of the works.

This area will eventually have a roof constructed over therefore Synergy was required to construct 4 x 3m depth 600mm diameter reinforced concrete piers. These will be used to found the roof support structures. Engineers inspections were required to ensure suitable founding and depth of the piers along with the reinforcing cages.

DGB20 subbase material was imported and compacted to 100% standard compaction over the sandstone subgrade. Detailed excavation based on the engineers drawings for thickened edges, construction and expansion joints was undertaken. A 20mm thick sand leveling layer was installed over the works footprint with use of a Kubota track loader and leveled manually with a laser level to ensure minimal wastage of concrete was achieved.

Prior to the installation of the steel reinforcement a orange polythene vapor layer was installed with all joints sealed with waterproof tape. Steel reinforcement including 1 layer of SL82 mesh, trenchmesh and cages to the perimeter thickenings and joints was installed with the addition of a Tera joint construction / key joint to allow for slab movement. All works pre concrete were signed off by the client supplied engineer prior to each of the 500m2 pours.

The warehouse slab consisted of 170mm thick 40 Mpa concrete mix which was pumped with a line pump through approximately 100mm of line. A combined total of 210m3 of concrete was used over 2 consecutive days pouring. As specified by the engineer the slab surface finish was achieved by way of a ride on helicopter float with soff cutting (dry saw cutting) and concrete curing compound sprayed on prior to complete curing on to ensure no cracking.

Due to part of the facility being in use while the construction and renovation works were being undertaken in stages there was a detailed construction program that all contractors had adhere to. This was to ensure a continuity of works between all trades. Synergy satisfied the clients programming requirements and have been recommended for further stages.