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Falcon Street Overpass
North Sydney, NSW
Reed Civil Contractors
Sydney’s Falcon Street pedestrian overpass spans 220 metres across the Warringah Freeway in North Sydney. The overpass provides a much-needed passage for thousands of pedestrians and cyclists who travel between the congested business centres of Neutral Bay, Crows Nest and North Sydney.
The official opening ceremony, held by the RTA on 17 August 2009, marked the end of a long and challenging project for Hanson's Artarmon concrete plant.
Challenges and Solutions
‘The bridge took fifty weeks to build’, said Petro Flokis, Artarmon Customer Service Manager at the time. ‘During that time, we supplied over 3000 cubic metres of high-strength RTA mixes. From day one there was absolutely no room for error with the column pours, mix quality and most of all, the delivery schedule.’
The RTA required Artarmon to deliver each load for the columns strictly between 7.00 am and
9.30 am each morning.
‘Each truck could take no longer than 45 minutes from the first batch until the final discharge, and they had to arrive within five minute intervals of each other’, Petro added.
‘However, the RTA’s faith in our ability to deliver this high quality customer service was how we originally secured the project.’
The demanding delivery schedule required occasional backup from the nearby Blackwattle Bay plant, and a full-time traffic control program that included highway clearways and restrictions.
One lane of the freeway was blocked off during the critical delivery period.
The Falcon Street Overpass was built by Reed Civil Contractors at a cost of $12.4 million. The project received strong community support as the footway eliminated illegal and dangerous road crossings on Falcon Street.
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Clem 7 Tunnel
Brisbane City Council
The construction of the 4.8 km Clem Jones Tunnel (CLEM7) was part of Brisbane’s Transport Plan to reduce traffic congestion. It was one of Queensland’s largest infrastructure projects and was valued at around $3 billion.
In total, Hanson supplied 249,850 cubic metres of concrete for the CLEM7 project between 2007 and 2009, often as part of a twenty-four hour, seven-day weekly delivery schedule.
Challenges and Solutions
Hanson had to meet rigorous standards for strength, toughness, permeability and fire retardation. They also had to conduct extensive testing to meet the tunnel’s 100-year design life and Main Roads Specifications (MRS).
Hanson’s technical team introduced strict procedures to control the quality of raw materials, the mix design approval process and the water to cement ratio. It was crucial to achieve consistency across all raw materials and field trialling. Extensive testing for slump, shrinkage, compressive strength and concrete temperatures was carried out on each product. A large product development mix and trial mix process was also performed. This resulted in multiple customised mixes for individual sections of the tunnel, including the barrier kerbs, cross passages, road-barriers and smoke duct. All met stringent MRS and LBBJV requirements.
Baulderstone Pty Ltd for Sydney Airport
In 2009, Hanson supplied a self-compacting concrete mix for Sydney Airport and Baulderstone $100 million Runway End Safety Area (RESA) development.
A RESA is a cleared ground area located at the end of each runway and built to Civil Aviation Safety Authority (CASA) requirements. The end of the easy-west runway at Sydney Airport has been an awkward u-shape design, which meant standard compacting and finishing techniques could not be used, and a self-compacting concrete alternative was required.
The project had two objectives. The first was to develop a self-compacting mix that achieved sufficient flowability and strength, with high resistance to segregation. With a fluid flow above 650 mm, the mix avoided the need for internal and external vibration for compaction, without causing segregation or bleeding. The hardened self-compacting concrete was still dense, homogenous and offered the same engineering properties and durability as traditionally vibrated concrete. This meant the concrete achieved the workability and strength required to carry a fully laden Airbus A380 weighing over 600 tonnes.
Self-compacting concrete is rarely used in Australia, so Hanson followed overseas guidelines and standards. A 50 MPa mix design achieved improved workability with the addition of chemical admixtures and by optimising the mix proportions. Numerous trials confirmed the final water/cement ratio and placement properties. By utilising supplementary cementitious materials, the overall heat of hydration was minimised, reducing the likelihood of thermal cracking. The required maximum drying shrinkage was exceeded by selecting aggregates with low shrinkage properties.
A comprehensive testing regime for the product included in-house laboratory trial mixes, trial production mixes at the Blackwattle Bay concrete plant and full-scale on-site tests at Sydney Airport. This allowed Hanson to achieve the specifications developed by Sydney Airport’s consulting engineers, Aurecon, and to meet the three critical performance properties of self-compacting concrete: the ability to flow into and completely fill intricate and complex forms under its own weight; the ability to pass through and bond to congested reinforcement under its own weight; and high resistance to aggregate segregation.
Houghton Highway Bridge
Queensland Main Roads (QMR)
In 2008, Hanson was contracted as the major supplier for the $315 million Houghton Highway Bridge duplication project. The project involved the construction of a 2.7 km bridge, featuring three traffic lanes, a pedestrian/cycle path and a dedicated fishing platform, between Brisbane and Redcliffe. The bridge was to be situated 35 m east of the existing Houghton Highway Bridge. Hanson supplied 35,000 cubic metres between 2008 and 2010 from its Northgate plant.
Challenges and Solutions
Hanson faced a number of challenges, including numerous changes in concrete mix design and issues with thermal cracking in concrete.
Technical priorities included the development and modification of mixes to meet QMR’s and Hull/Albem’s stringent specifications. Hanson was also required to conduct an extensive testing regime, and to reduce concrete temperatures in the bridge’s headstocks to avoid thermal cracking. QMR recorded every mix design, modification, test and temperature control mechanism. This meticulous record keeping resulted in the use of the Houghton Highway Bridge duplication project as a test case for concrete specifications in future bridge construction in Queensland.
Hanson initially submitted mix designs of its standard range of QMR mixes, including a mix at 32, 40
and 50 MPa to meet QMR Specification MRS1170. For the standard QMR mixes, Hull/Albem was supplied with certificates for aggregates, cement/fly-ash and admixtures from Hanson’s previous trial mixes conducted in accordance with QMR Specification 11.70. In this case, the concrete was to be pumped 350 metres across a false work bridge to the new bridge. This meant new mixes were also required. Hanson conducted trials to replicate pumping concrete 350 metres. Concrete was sampled to provide data for QMR, with four different mixes supplied on two separate occasions. The resultant mix included water-reducing admixtures and super-plasticisers. This provided it with sufficient flowability and ensured Hanson achieved both strict water-cement ratios required by Hull/Albem and the higher 150 mm slump requirements of the piling sections. Hull/Albem also trialled other versions of these special mixes to the satisfaction of QMR.
In January 2009, Hull/Albem and QMR noticed excessive bleeding in the piles. Hanson, in conjunction with Hull/Albem, instigated a three-month redevelopment process for the piling mix. Hanson also supplied an agitator truck and trial mix from its Northgate plant so engineers could complete time trials, including slump tests completed at thirty-minute intervals over a four-hour period.
The trials determined the maximum period allowed between loading and placing, while still maintaining the product’s strength and workability requirements. Based on the test results, Hull/Albem gained approval from QMR to extend strict placement times to accommodate the distance between the construction site and Hanson’s Northgate plant.
Hanson’s most significant technical challenge occurred in June 2009, after temperature tests conducted by QMR confirmed issues with cracking in the headstocks. This was caused by excessive concrete temperatures in the headstocks that were reaching up to 90°C during initial curing.
The final mix, supplied by Hanson in November and December 2009, included temperature control methods that ensured Hanson successfully minimised risk of tensile stress and thermal cracking. These measures included substituting ice for water in the mix prior to loading at a 1 to 1 ratio; introducing slag to reduce the heat of hydration as a cement-replacing supplementary cementitious material; using a retarder to decrease setting times and allow mass concrete placing under higher temperatures; and washing down all coarse aggregates used in the production process with water. Concrete temperatures were then carefully monitored by Hull/Albem, with the hardwiring
of temperature probes into the framework of some of the headstocks.
Night pours served as an additional temperature control method. All pours were carried out from the Northgate plant between 1.30 am and 2.00 am. Night pours also allowed Hanson to guarantee the quality and timing of deliveries.
To prepare for these pours, all required aggregates were delivered from Hanson’s Wolffdene quarry during standard trading hours. Six to seven trucks were pre–loaded before delivery. Moisture levels were also set several hours prior to delivery, then checked periodically.
In total, there were three types of pours. These included 76 pours of 170 cubic metres for the bridge’s deck panels; 76 pours of 70 cubic metres for the headstocks and 76 pours of 40 to 50 cubic metres for the piles.
‘Despite the numerous changes in concrete mix designs and the issues that would occasionally arise, they were always dealt with in a professional manner while maintaining a very healthy working relationship.
‘I’d like to thank all of those who were involved in working Friday and Sunday nights throughout the duration of these works. This occurred on numerous occasions over the last 18 months and without the commitment and professionalism of Hanson staff, we would not have completed this component of the project prior to Christmas 2009.’ Paul Fitzgerald, Senior Project Engineer.
BrisConnections was awarded the contract to deliver Australia’s largest road infrastructure project — the $4.8 billion Airport Link, Northern Busway and Airport Roundabout Upgrade. BrisConnections contracted Hanson to supply 2,900 cubic metres of concrete in a continuous pour for the project.
This was the largest single pour ever completed by Hanson in South East Queensland.
Hanson supplied a 40/20/120 special low heat mix developed and trialled specifically for the project. The pour was completed in 10 hours, starting at 3:00 pm and finishing at 1:00 am the following morning.
The scale of the pour required 64 agitators, five concrete plants (decreasing to four) and 31
pre-loaded tippers. Five testers on site cast approximately 149 cylinders and 32 shrinkage bars.
Of the 424 loads batched and delivered to site, not one was rejected, highlighting the professionalism and dedication of all plant staff and agitator drivers involved in the pour.
As most of the concrete was delivered at night, a considerable amount of pre-planning was required, involving all sections of the business, from Production to Transport, Technical Services and the Customer Service Centre.
‘A pour of this size required considerable pre-planning and organisation by both Hanson and the client, particularly due to the short notice of the pour date’, explained Bill Brittain, Hanson Project Manager at the time.
A team effort from Production, Transport, Technical Services and the Customer Service Centre made it all possible.
The ALNB Site Engineer in charge, Bree Johnson, said, ‘I was expecting a long night but it was brilliantly short. It all went smoothly from the concrete point of view and the slumps were spot on.
I will definitely recommend Hanson for any big concrete pours.’
This pour has demonstrated Hanson’s operational strength and technical expertise.
The reliable plants, fleet and equipment ensured the on-time delivery of the project to
an exceptional quality standard.
Fiona Stanley Hospital
D & Z Constructions / G & N Formwork
The $2 billion Fiona Stanley Hospital, equivalent in size to four city blocks, is the largest building infrastructure project ever undertaken by the state. The hospital’s location was chosen for its proximity to a growing south metropolitan population and for its nearby health and learning institutes.
The project required approximately 150,000 cubic metres of concrete. Hanson supplied approximately 60,000 cubic metres of the total amount over the construction period, working closely with clients D & Z Constructions and G & N Formwork to deliver for the project.
The hospital has 150,000 square metres of floor space over five main buildings, with 6300 rooms and 783 beds, including 140 rehabilitation beds. There are also 3600 basement, ground level and multi-storey car parking bays.
The scale and complexity of the project meant a huge effort was required of Hanson. Product quality was paramount, and consistency had to be maintained during the larger pours. Restrictions with site access became an issue as the project progressed, but comprehensive communication with customers on product, delivery and potential hurdles meant issues were addressed quickly and effectively.
Pre-planning, undertaken a day in advance, maintaining a high level of communication between the Hanson team and the customer, and being on site site daily have been the keys to success, according to Customer Service Manager Joe De Lucia.
‘It has been great to be part of and oversee the construction of such a worthwhile facility in our state. With the growing population and increasing need for medical care in Western Australia, this facility is truly a step forward for the WA community. It has been a great challenge but by partnering with our customers we have been able to make it happen’, says Joe.
Tweed Heads, NSW
The $491 million Ballina Bypass development includes a 12.4 kilometre dual carriageway,
11.9 kilometres of local roads, 19 bridges and more than 1.7 million cubic metres of earthworks.
Hanson is supplying 8000 tonnes of sand for the project’s road-paving requirements. This includes a sand supply to several Hanson concrete plants as well as Leighton Contractors’s own wet batch plant.
As part of the project, Hanson designed a simple but effective high-quality drainage system.
Given the high volume of traffic expected on the Ballina Bypass, Leighton Contractors demanded strict adherence to stringent technical standards, with an extensive testing regime conducted on all materials supplied.
This meant Tweed Heads quarry had to guarantee the quality of the sand and avoid allowing water to gravitate to the bottom of a sand pile leaving a saturated band of sand at the bottom. The answer was to design and install a drainage system similar to the one used at the Yannathan Quarry in Victoria.
The Tweed Heads team, led by Quarry Manager Michael Azzopardi and Graduate Management Trainee Cristy Moxly, developed and installed a drainage layer below the wash-plant stockpiles. Several pits were dug in the area where the sand is deposited after washing. The pits were then partially filled with aggregate before being covered in sand. The water in the area drains down to a geo-fab pipe running along the lower side of the site. Once the water is collected, the saturated band of sand is free to drain through the floor of the pit, and the excess moisture is pumped away via a connecting tank, back into the lake.
‘The simplicity of the drainage system has contributed to meeting all of Leighton Contractors’s quality requirements and we’ve been able to avoid any saturation problems’, says Michael.
‘It also means that if the drainage rate ever reduced to a point where it was becoming less effective,
it would be very easy to dig out and rework the system to restore the original drainage capacity.’
‘There were no real problems during the installation process’, adds Cristy. ‘This has had the added benefit of allowing us to meet Leighton Contractors’s stringent time constraints.’
The final word comes from Elizabeth Everett, Senior Project Engineer for Leighton Contractors:
‘The construction of the drainage layer under the sand stockpile at Hanson’s Tweed Quarry has ensured consistent a moisture content of the fine sand supplied to our project. This is critical to the quality of the concrete we produce on a project as large as the Ballina Bypass.’
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