When it comes to the use of Mainmark’s technologies, a common question we encounter is “how do you validate your work?”. As ground engineering solutions do not always have visible results, validation testing is an integral part of any project.

Geophysical testing provides a suite of tools used in geotechnical engineering to identify the soil types present and to analyse their expected behaviour. Mainmark utilises these tests to determine project suitability and design. By comparing the ground investigation results before and after the completion of a project, we can determine if the targets set out in the design were met.

Re-levelling is a Mainmark solution that uses cementitious grout or an expanding resin to accurately lift and re-level a structure. A positive side-effect of these re-levelling approaches is ground improvement of the soils near the injection locations. While other mechanical lifting techniques can sometimes create voids beneath the foundation, our methods have a densification effect on the surrounding soil, which in turn can increase the strength of the bearing soils.

The primary measure of validation for a re-level project is before and after floor level surveys. However, a ground investigation tool called a Dynamic Cone Penetration (DCP) test is also conducted to demonstrate that the re-level process has not had a negative impact and has subsequently increased the strength of the bearing layer. Like a floor level survey, DCP tests are conducted before and after the re-level of the structure. A comparison of the before and after results from this test allow us to measure and define the increase in the bearing capacity of the soil as a result of the injection works.

Mainmark also offers shallow bearing capacity improvement as a stand-alone solution for structures with weak bearing soils. These projects specifically target the densification mechanism to achieve the increase in bearing capacity for depths less than 3 m. DCP tests are used prior to the initiation of a project to provide the pre-improvement bearing capacity (kPa) of the soil along with the target level of improvement required for the project. Post-improvement DCP tests validate if the target increase in bearing capacity was reached.

Another Mainmark solution that requires the use of geophysical testing is Terefirm® ground improvement. Terefirm is a technique used for bearing capacity increase (depths more than 3 m) and liquefaction mitigation. Ground improvement projects completed to date have treated soils as deep as 12 m below ground level, and therefore required geophysical testing tools that can be completed to greater depths. These projects also require an extensive understanding of the soil types present at the site and the expected behaviour of the soils during a seismic event.

Initial geophysical tests are required to determine if Mainmark’s ground improvement technique is a viable solution for the soil conditions present. Following this initial assessment, target design strengths and the parameters that will be used to measure improvement are set. There are many possible parameters than can be used to measure improvement and these need to be outlined prior to the commencement of a project, as these will determine the geophysical testing requirements. However, two ground investigations techniques are consistent.

On every Terefirm ground improvement project, Cone Penetrometer Tests (CPT) are conducted. This test can determine the soil type, soil strength, liquefaction triggering potential, and predicted settlement for a design earthquake. The targets for improvement are given as a percentage increase or set target values for these parameters. The injection design is then based on the targets, and post-injection CPT results are compared with the initial tests to determine if the targets were met.

Another test used on liquefaction mitigation projects is Direct-Push Cross-Hole (DPCH). This test determines the shear wave velocity of the soil which is used to determine the soil stiffness. It is similar to carrying out a CPT, with results compared before and after injection to determine the level of improvement.

All post-improvement tests are also analysed together to compare the overall performance of a structure before and after Terefirm ground improvement has been implemented.

By Georgia Crosby

Georgia Crosby is Mainmark NZ’s Technical Manager. During her studies at the University of Canterbury she took an interest in Geotechnical Engineering and spent two summers interning at Mainmark before joining full time as a Graduate Engineer. Georgia’s current areas of focus are in the research and development of Mainmark’s solutions and internal systems, as well as, providing technical support for commercial projects.

Conventional underpinning using steel and concrete has long been the go-to solution for supporting or strengthening the foundation of an existing house, building or structure for engineering and construction professionals. However, alternative more innovative solutions are challenging the status quo.

These methods of stabilising and lifting structures have been in use for more than a decade and are gaining favour because they eliminate the invasive and disruptive side effects of conventional underpinning. This raises the question: Is conventional underpinning still the best solution or can we confidently shift to more innovative alternatives, particularly when it comes to larger buildings and assets?

Understanding underpinning

Underpinning involves installing an additional structural support system to the foundation of a structure. The most common approach to underpinning involves extending the depth of the foundation into firmer soil. This requires invasive digging of holes for access and the installation of a new underpin beneath the foundations. The underpin is constructed of steel or concrete and steel, to ultimately create a new foundation beneath the existing one. Once these new foundations are installed the structure can be lifted using mechanical jacking and packing.

While traditional underpinning delivers effective results, which is why it still exists today, it is a rudimentary remedy that is slow to install, very invasive and can also cause more damage to already fragile buildings.

One of the key drawbacks with traditional underpinning is logistics. Often due to high costs and the size of installation equipment, new foundations are typically only installed three metres apart. This leads to fewer footings being installed which can cause a point load to the bottom of the foundations during the mechanical jacking process. Point loads can cause damage to the building, especially if its foundations are inadequate or if the building is a rigid structure built from stone or brick.

The underpinning process normally involves jacking one underpin position at a time, which can place undue stress on other parts of the building and cause serious aesthetic and structural issues.

Traditional underpinning can be an incredibly invasive process as it requires access for excavation works to be carried out. The excavation works often damage footpaths, services and gardens that require costly reinstatement or repairs, and forces building occupants to deal with disruptive elements, like large excavations with all the associated mess, noise, and the impact of transporting, delivering, and storing steel and other underpinning materials.

The solution is already available

Technology already exists to replace invasive and costly underpinning techniques. Mainmark’s JOG Computer Controlled Grouting (JOG), for example, has proven to be a superior approach to underpinning and lifting with the ability to relevel very large structures and buildings up to ten storeys high.

JOG is a unique cementitious grout mix that sets in less than a minute and develops compressive strengths that are far higher than most foundation soils. The JOG grout is mixed in a central, computer controlled, mixing plant on site. Once mixed, the grout is circulated through high pressure hoses to 40mm injection holes that are drilled to the required location and depth under the structure’s foundations. The number of injection points needed varies from dozens to many hundreds. Small quantities of the grout are injected into the ground where it quickly sets and creates a stable layer. The process is repeated hundreds of times over several days, creating a solid foundation that eventually provides a lifting force that slowly, gently and evenly raises the structure or building.

The whole process is carefully monitored with accurate survey equipment and the amount of grout directed into any of the injectors can be controlled from a central computer. This level of control allows technicians to send more grout to areas that need additional material. The outcome is a uniform lift that does not damage the structure. Compared to traditional underpinning, JOG injection grout points are spaced more tightly at 1.0 to 1.2m, allowing for a more even injection process that minimises structural stress.

Due to JOG’s ability to be delivered through 40mm holes, injection points can be easily repaired. Ultimately, the whole JOG process is surgical with only minimal disruption to the structure and its occupants.

Comparing JOG with traditional underpinning

There are many factors that determine if traditional underpinning is a suitable solution, but the cost, invasive process and the ground’s long-term bearing capacity often mean it is not viable for many projects. New technology, like JOG, is not only easily delivered and non-invasive; it has a lifting capacity of 25 tonnes per injector. This makes it suitable for:

• Larger footprint and multi-level buildings
• Brittle and ageing structures, including churches and heritage buildings
• High traffic infrastructure that needs to minimise downtime, e.g., train stations, bridges, retail complexes
• Unlevel gravity sewer or gravity water pipelines
• High value, critical infrastructure, including industrial facilities, mining processing plants, and
• Public buildings such as like museums and galleries.

Mainmark has used JOG to successfully repair hundreds of structures across Australia and New Zealand, including an earthquake damaged heritage church, the award-winning Christchurch Art Gallery liquefaction remediation project, an unlevel multi-storey apartment building and a two-storey waterfront brick home suffering from adverse soil conditions.

With techniques like JOG already available, the future of structural remediation is no longer speculative. Mainmark is constantly researching and developing new ways to improve the cementitious grout mix and its delivery. However, even in its current form, JOG is the next evolution in engineered building stabilisation and lifting solutions. Perhaps it’s time to respectfully leave traditional underpinning in the past and look ahead to new alternatives to the conventional method.

By Steve Piscetek

Steve Piscetek is Mainmark’s Divisional Manager, MCM (Mainmark Civil and Mining). Steve has extensive experience working in construction, road and water infrastructure, the mining and resources sector and offshore construction. At Mainmark, his technical acumen and pragmatic approach to safety and quality assurance has seen him successfully tackle many challenging and complex ground remediation projects.

Climate change is often associated with cataclysmic weather events and temperature changes but it can also have more subtle, long-term effects on our homes.

Scientific research over the decades has revealed that the earth’s average temperature has gradually increased due to the greenhouse gases that are trapped in the atmosphere. This is particularly noticeable in warmer environments, like Australia, where an unnaturally altered climate is resulting in drier conditions for longer periods of time combined with sudden and heavy bouts of extreme wet weather. For the majority of Australia’s housing stock, which is built on moderately to highly reactive clays, this is especially challenging.

Reactive clays are prone to seasonal ground movement due to changes in the soil’s moisture levels which swell in winter as they absorb excess moisture and shrink in summer when conditions are usually drier. While the constant movement caused by expansion and contraction in the ground can contribute to foundational shifts and slab movement, the reaction is exacerbated by the prolonged drier conditions and heavy wet weather events which can be attributed to climate change.

The truth about wet conditions

Flooding caused by intense storm activity can have a direct impact on a property’s foundations or concrete slabs, resulting in damage. While water that moves slowly through clay during a single heavy storm is unlikely to have an adverse effect on a building, ongoing wet weather can accelerate the movement of water through the clay which is more likely to create drainage issues. These extended periods of rain cause the clay beneath the ground’s surface to become oversaturated and therefore too fluid and weak to provide consistent support to the building’s footings.

In addition to residential homes, it is not uncommon after periods of heavy rain for commercial warehouses and transport yards to notice concrete slab movement when the ground begins to dry out.

To prevent damage to a building, it is important to consider the relationship between weather events and climate change, being aware of the current conditions and paying closer attention to general home maintenance.

The effects of dry conditions

 Similar to heavy storms, droughts can also cause problems when excessive moisture in the oversaturated ground dries up. This can lead to soils shrinking, resulting in foundation movement and slab lifting due to the new conditions. Foundations that have been damaged due to settlement can cause cracks in walls, uneven floors, jammed or misaligned windows and doors, and skirting boards separating from walls. Puddles around the exterior of the building and leaking gutters can also result in saturation of the soil around the foundations, contributing to subsidence while slab lifting may result in cracked driveways and unlevel or sunken concrete floors

Remediating damaged foundations

Foundations and concrete slabs that have been affected by extreme weather and changing ground conditions can be repaired in many instances. However, it is essential to first identify the cause of the damage. A broken pipe or a blocked drainage system will require the appropriate tradesperson to fix the leaking prior to addressing the underlying weak foundation ground.

After assessing the extent of the problem and determining the area to be treated, Mainmark’s Teretek® resin injection technology can be applied to help re-level and re-support structures impacted by subsidence. When injected into the affected ground, the solution also increases ground bearing capacity and fills voids at a fraction of the cost and without the disruption of traditional underpinning.

With the impact of climate change increasingly noticeable in the region, property owners will need to be more vigilant about ground movement and know how to identify the signs of subsidence early to ensure professionals such as Mainmark are able to remediate the issue before the damage becomes too severe and too costly to address.

By James O’Grady

James O’Grady is a Sales and Business Development Manager at Mainmark. He is a civil engineer with 25 years’ experience in structural engineering, construction materials and ground treatment.

Culverts are the hidden heroes of the infrastructure sector and while they are often not as prominent as bridges, tunnels and road networks, they are an essential asset that protects, roads, rail and other buildings and structures. Unfortunately, culvert maintenance and repairs are not always prioritised appropriately.

Typically, culverts are concrete box sections, corrugated steel or concrete pipes, designed to ‘impound, accommodate, convey or control the flow of water’[1]. Essentially, they are responsible for managing stormwater runoff, allowing water to flow freely under road and rail corridors. In many cases culverts also provide fauna with safe access. Their construction and maintenance need to adhere to standards that protect waterways, the community and other infrastructure like roads, pathways, and rail lines.

Culverts are designed with a hydraulic capacity capable of handling runoff water with AEPs (annual exceedance probability) up to two per cent, or ARIs (average recurrence intervals) up to 50 or 100 years. The ‘1 in 100 year’ rule is commonly referred to by engineers, and it defines significant flood incidents that have a one per cent chance of occurring in any given year. Unfortunately, as we learn more about weather events, it has become clear that heavy floods can occur more frequently than we originally estimated which increases the strain on a culvert’s passable hydraulic capacity. As a result, many culverts are now considered undersized which increases the risk of damage to roads, rail, and other critical infrastructure.

The challenge of building and maintaining effective culverts

Culverts are susceptible to deterioration over time that can diminish performance and structural integrity, including clogging with debris, scouring at outlets, and abrasion and corrosion. The main challenge with maintaining culverts is that they are invariably located underground, often under critical infrastructure. As a result, replacing the culverts can be very expensive and disruptive. Therefore, asset owners have sought innovative ways of monitoring the condition of and repairing and refurbishing their culvert assets

Maintaining healthy and effective culverts

Mainmark recommends proactive culvert damage mitigation which includes performing regular inspections to ensure all blockages are removed. Monitoring to consistent standards by checking for corrosion, settlement, joint or compression failures, water ingress and fire damage should be carried out. Any potential hazards affecting a culvert’s structural integrity should be dealt with immediately.

The conventional approach to remediating and maintaining culverts is to patch or line the culverts with new materials. Often cementitious materials are applied as a shotcrete or gunite solution to remediate damaged or deteriorated areas. Unfortunately, this approach can compromise culvert effectiveness over time. For example, if a 2m diameter damaged culvert is remediated using a 100mm repair layer of cementitious material, its diameter is reduced to 1.8m. This significantly reduces the overall hydraulic capacity of the culvert making it less effective.

Alternatively, ‘re-sleeving’ – which involves inserting a smaller diameter pipe into a culvert and grouting the space between them – is another widely accepted option. However, while these methods are effective, they can also contribute to the capacity dilemma.

New Innovations

Mainmark has developed new solutions that are more cost-effective and time-efficient than conventional methods which do not significantly reduce culvert hydraulic capacity. For example, relining culverts with vinyl ester structural coatings can replace the strength of the culvert without the added thickness of conventional cementitious material. The thin 12-15mm coating minimises the loss of hydraulic capacity.

Teretek® engineered resin has also been used to increase ground bearing capacity and to realign culverts that have moved due to settlement. When all else fails and a culvert needs to be abandoned, Mainmark’s Terefil® is a lightweight cementitious-based flowable filler that is an ideal solution for decommissioning ageing and redundant culverts and pipes.

Mainmark has remediated hundreds of culverts over the years using these techniques, including relining seven major culverts in the Toowoomba Bypass with Terefil® cementitious void fill.

While culverts may not always be highly visible, they contribute significantly to our everyday lives and our communities rely on their ability to perform correctly.  It’s therefore important that they are taken care of, and remediation is prioritised accordingly.

[1] https://austroads.com.au/publications/bridges/agbt08-18/media/AGBT08-18_Guide_to_Bridge_Technology_Part_8_Hydraulic_Design_of_Waterway_Structures.pdf

By Steve Piscetek

Steve Piscetek is Mainmark’s Divisional Manager, MCM (Mainmark Civil and Mining). Steve has extensive experience working in construction, road and water infrastructure, the mining and resources sector and offshore construction. At Mainmark, his technical acumen and pragmatic approach to safety and quality assurance has seen him successfully tackle many challenging and complex ground remediation projects.

As our population increases, so does the demand for infrastructure. However, an influx of residents, new development and increased traffic can put a significant strain on infrastructure, particularly in older suburbs surrounding large metropolitan cities such as Sydney, Melbourne and Brisbane.

Replacing ageing or damaged assets, such as underground pipes and culverts, is an expensive process that often requires ground excavation works that could take weeks or even years to complete. It can also have a significant impact on the environment and cause major disruption to roads and facilities that the community relies on.

Yet, we cannot simply leave ageing infrastructure to deteriorate. Old or abandoned stormwater, sewer, gas, water and fuel pipelines degrade over time, resulting in cracking and leaking that can cause numerous other issues such as soil destabilisation, erosion, subsidence, underground voids and ground collapse. In areas with a low water table, groundwater can build up and cause sinkholes which may damage homes and public areas.

Furthermore, as populations grow the demand on underground utility networks increases, resulting in older pipelines no longer being fit for purpose as they can’t keep up with demand. When new pipelines are then commissioned, the old pipelines are often decommissioned and left in the ground. These abandoned pipelines may need to be filled with specialty grouts to mitigate risks, such as ground subsidence, that can occur as the pipes deteriorate over time. This is especially serious if you consider the pace of ongoing development and the growing focus on new projects, such as the Queensland Government’s commitment to a $52.2 billion infrastructure pipeline[1] and $2.9 billion in local housing[2]  projects over the next four years.

What’s the answer?

For ageing infrastructure, particularly assets affected by erosion or water ingress that cannot be removed from the ground and easily replaced when they become obsolete, often the best solution is to explore remedial solutions that can future-proof and, where necessary, extend the life of the asset. An effective example of this is the work that Mainmark undertook repairing damaged steel corrugated culverts beneath an access road in Far North Queensland. Likewise, often the most fit for purpose approach is to decommission the asset outright, as was the case when Mainmark decommissioned an underground gas main at a busy intersection in Melbourne.

When remediating ageing civil infrastructure, we need to consider the following:

• Remediation is often more cost effective. Replacing ageing pipes and drainage usually requires large local disruptions around the asset, heavy machinery, excavation works and longer timelines, leading to greater expense. Alternative solutions, such as Teretek® resin injection and Terefil® lightweight cementitious fill, provide ground strengthening and stabilisation, and can fill voids following a partial collapse. Likewise, Mainmark’s specialist waterproof resins and coatings are highly durable and provide a viable long-term solution for water and gas ingress control. These solutions often prove to be more affordable compared to asset replacement or traditional remediation methods. Advanced specialty grouts such as Mainmark’s Terefil are purpose used and superior to conventional fills for complex pipe utility abandonment. It is highly flowable, easily placed, and does not require pre-loading or compaction for settlement mitigation. It will flow into spaces to fill voids and exhibits shrinkage of less than 0.1%, making it very well suited for assets that need to be completely filled.
• Remediation works are less invasive than alternative solutions that require excavation work and additional time to complete. Depending on the scale of the project, removing ageing or damaged pipelines often limits or completely cuts off traffic access. By using Mainmark’s innovative solutions, projects can be completed more quickly and with less disruption, including below ground infrastructure, and at sites that are difficult to access.
• Modern remediation solutions provide superior effectiveness for utilities management. One of the biggest challenges when remediating or decommissioning old pipes is managing the flow of utilities, like water and gas, to prevent build up and leaks. Mainmark’s engineered coatings and linings are high performance control treatments that can stop flowing water or gas quickly and effectively, providing an excellent waterproofing solution to seal and stabilise water ingress.

Often infrastructure deteriorates due to a lack of investment in public works programs and failure to recognise cost effective solutions that can affect an asset’s longevity. For more information about Mainmark’s civil infrastructure remediation capabilities, or to seek advice regarding the best solution for an upcoming project, contact our customer service team on 1800 623 312 (AU) or 0800 873 835 (NZ) and they will forward your details to one of our expert team.

[1]  https://www.statedevelopment.qld.gov.au/__data/assets/pdf_file/0028/57655/queensland-government-infrastructure-pipeline.pdf

[2] https://statements.qld.gov.au/statements/93633

By Max Kudrenko – Regional Manager (Vic, Tas, SA, WA)

Max Kudrenko is the regional manager (Vic, Tas, SA, WA) for Mainmark’s civil and mining division. Max is a civil engineer who has experience working with different grout, resin and other cementitious geotechnical and ground improvement technologies in the residential, commercial, gas/oil and civil sectors. He has successfully project managed works throughout Australia, New Zealand and Japan.

As part of our regional series, we take a closer look at the Australian Capital Territory (ACT) and how its ground conditions can impact the area’s built environment.

Like in most regions, Mainmark’s operations in Australia’s capital city span residential, commercial and civil infrastructure. While several public infrastructure sites have benefited from Mainmark’s ground remediation expertise, including Lake Burley Griffin and Federation Mall, homeowners in the territory and surrounding areas also keep our team busy.

Understanding the ACT’s ground conditions

The topography surrounding Canberra consists of forested hills and alluvial flats, with much of the urban areas built on gently undulating terrain that features gravelly and sandy soils. However, the broader soil profile in the ACT is primarily clay, ranging from low, medium and high plasticity, and is classified as moderately reactive in accordance with AS2870 “Residential slabs and footings” standard.

The weather also plays a big part in the region’s ground conditions. Depending on the time of year, the ACT can experience temperatures ranging from -8 to 45 degrees, with cyclical weather patterns such as La Nina and El Nino leading to both saturation and dehydration of the ground. This causes reactive clay to shrink and swell much like in many other parts of Australia, creating structural challenges for homeowners.

A typical home in the ACT

While the ACT residential market has become more diverse in styles and architecture over time, it is best known for the colloquial ‘Govie’ style house. Govies are homes that were built quickly and in large volumes to meet high demand. The population growth from politicians and their families moving to the ACT resulted in greater investment and liveability. Govies therefore needed to cater for the influx of residents, built with the most affordable and readily available materials to ensure quick turnarounds.

From the 1920s to 1950s, most houses were built with double brick exterior and a single brick interior, on narrow and shallow concrete strip footings, with little or no articulation in the walls to allow for movement. In the 1960s and 1970s, the government oversaw a large expansion of Canberra, creating the ‘Govie’ design with simple rectangular layouts and wet areas on concrete floors above narrow strip footings. Many of these houses remain standing today and are regularly renovated and extended.

While Govies have always been compliant, they were often constructed quickly, not allowing builders to consider the relationship between the foundations and the reactive clay. During cyclical weather changes, the clay would shrink and swell, affecting the footing and creating a loss in soil volume, resulting in foundational settlement. In many cases, old Govie footings have not been maintained and over the decades, this has resulted in settlement-related damage such as sunken floors and cracks in the interior and exterior walls.

Overcoming the challenges

Fortunately, building codes have improved over the years. They now better consider the ACT’s ground conditions and its impact on residential construction. However, regardless of the age of a building, footings require monitoring over their lifespan and at times, property owners may need to take action to manage ground moisture levels, which may include removing trees or addressing leaking pipes.

While the ACT’s ground engineering sector has historically relied on conventional remediation methods like traditional underpinning, Mainmark’s Teretek® resin injection solution has become a popular alternative as more homeowners recognise the benefits of using a modern technology that is easier to apply, cost effective and less invasive.

In addition to working directly with local homeowners, Mainmark has also formed relationships with local builders and engineers regarding ground remediation solutions for local infrastructure. For example, the Australian Government’s National Capital Authority (NCA) engaged Mainmark to re-support the Lake Burley Griffin foreshore wall by injecting more than 40 tonnes of Teretek into a 4km section of the lake’s concrete and stone wall. The solution successfully filled voids, increased ground bearing capacity and agglomerated the loose soil to mitigate fines being lost into the lake through cracks in the ageing walls.

Mainmark was also engaged by the NCA to address settlement issues affecting the Federation Mall bridge using Teretek to fill underground voids beneath the bridge’s approach slabs and roadway to rectify ‘dishing’ and minimise the risk of ongoing settlement.

Over the years, Mainmark has established a strong presence in the ACT and is looking forward to continuing to support the region using its innovative range of ground and asset remediation solutions in the residential, commercial and infrastructure sectors.

By Alan Reid

Alan Reid is a Territory Manager at Mainmark Ground Engineering that services the ACT region. Holding a degree in Civil Engineering from University of Sydney he has years of experience in project management and customer acquisition in several industries including construction.

As 2021 draws to a close and we reflect on the year that has been, I think our biggest achievement this year is that we managed to successfully complete well over 1,800 projects across Australia and New Zealand despite extended lockdowns and border restrictions, which impacted our business in every region.

The Australian and New Zealand economies remained remarkably strong this year, buoyed by record levels of government infrastructure investment. This has had a positive impact on our business, with civil infrastructure and remediation now a huge focus for Mainmark. The increased demand for our specialised products and services is the driving force behind the evolution of Mainmark’s civil and mining division, which offers a unique range of solutions to re-level, repair and rehabilitate assets in the civil infrastructure, mining and seismic environment sectors.

This year, Mainmark had the opportunity to demonstrate its breadth of capabilities by completing a number of significant projects. In Australia we are currently undertaking a major culvert rehabilitation project in South East Queensland involving a wide range of complex remediation solutions, including Terefil^®, our flowable lightweight polymer modified cementitious grout which is part of the solution being used to fill significant voiding behind the steel culverts. Terefil was also used as an innovative alternate structural solution for the change of use of an Olympic swimming pool in Sydney. In New Zealand, we also used Terefirm^® to strengthen the ground beneath O’Connells, an iconic retail, dining and office complex in Queenstown, to increase liquefaction resistance and increase its NBS (New Building Standard) rating.

We were also honoured to receive a Good Design Award in the engineering category for our Toowoomba Bypass project in Queensland. While Mainmark doesn’t embark on projects to win awards, we were extremely proud to be acknowledged for successfully completing this unique and complex Queensland project which involved upgrades and repair work to culverts along the $1.6 billion bypass. The sheer level of on-site research and development that was required to overcome the design constraints was a significant factor in the successful outcome of this project and the judges summed up our work nicely.

“Clearly innovative, the design was clever and had benefits for the project in terms of cost, schedule and quality. This is really impressive design and engineering, and a standout example of good design in this category that deserves to be recognised.”

Mainmark is constantly pushing geotechnical boundaries through research, development and trials. It’s this dedication to innovation that also led us to develop Terefil as a proven alternate solution for gravel raft slab replacement in several building projects, having recently successfully completed the first stage of a large project at Wainuiomata, Wellington.

These projects are just a few examples of why Mainmark is becoming renowned for its innovative approach to solving complex remediation projects and we are well placed to leverage further opportunities as further projects are rolled out under the Australian Government’s $110 billion rolling infrastructure pipeline.

As we enter 2022 filled with optimism, we have significant growth aspirations for all operating divisions. We also look forward to continuing to demonstrate our breadth of applications, which include evolving our specialised resins, gels and coatings for reinforcing ageing or damaged buildings and assets, and water mitigation and control in more infrastructure and tunnelling projects.

I would like to thank all of our clients, industry partners and staff for being flexible, adapting to change, and working collaboratively over the last 12 months. We have achieved great things and are looking forward to an even more productive year ahead.

By Joe Glanville

Joe Glanville is Mainmark’s ANZ General Manager. He has over 15 years’ experience in the Construction Industry, acquiring broad commercial, construction and project management skills.

With increasing urban population density and traffic loads, tunnel infrastructure is often the difference between commuters reaching their destination and transportation grinding to a halt. Tunnels help to alleviate congestion, promote healthier traffic flow, and minimise disruption in suburban areas making them increasingly important for metropolitan growth areas.

For example, in Greater Sydney, New South Wales, hundreds of thousands of vehicles travel through the city every day. According to the latest motor vehicle census, there were 5,892,206 motor vehicle registrations in New South Wales in 2020[1], suggesting that roads will continue to feel the strain of heavy traffic.

With infrastructure projects currently booming across Australia, there are a number of large-scale tunnels that will commence in the coming months, such as the new Sydney Harbour tunnel in New South Wales and the North East Link project in Victoria. However, while the infrastructure boom is great for the economy, keeping these projects on track and within budget will be critical.

There are several challenges and considerations that make the development and ongoing maintenance of tunnel infrastructure incredibly complex. From Mainmark’s perspective, as a ground engineering industry leader consulting on a number of large-scale tunnel projects, our technicians have seen firsthand what is needed to ensure the safety, quality and longevity of Australia’s most utilised transport corridors.

Considerations for tunnel infrastructure

On the surface (or rather below the surface), tunnels appear sturdy and reliable. However, they are like any piece of infrastructure and require maintenance and repair over time. Tunnels are particularly susceptible to degradation when surrounding ground conditions have not been fully considered during construction. For example, unconsolidated soil can result in a soft and often precarious envelope for tunnels that is prone to shifting.

This can be problematic for Sydney, given the area’s geological profile which consists of weak and unconsolidated sandstone. Water tables, where groundwater saturates spaces between sediments and cracks in rock, are another major consideration for tunnel construction, as well as palaeochannels, which are inactive water channels that have been filled or buried by younger sediment. These geological occurrences, if not identified and planned for in advance, can significantly affect a tunnel’s structural integrity and exposed surface over time either through ground movement and cracking, or significant water ingress that can slowly degrade the structure.

A lack of planning and proactive mitigation of waterproofing and ground reinforcement, are common in tunnel construction. However, this is not always a sign of negligence; tunnels often take decades to deteriorate and the immediate demand, or available funds, can sometimes influence the cost-to-benefit decisions for long term planning and maintenance. In other words, a tunnel’s construction is often planned around the urgency to help keep traffic moving, rather than addressing an unforeseen issue that may arise several decades down the track.

Remediating problems before they occur

With increasing pressure on roads in our expanding urban centres, the need for tunnel infrastructure is always growing. Unfortunately, there is no magic spell to completely alter the existing geological landscape. Instead, successful tunnel construction hinges on a combination of careful pre-construction planning, ground and risk analysis, and the ability to use effective remediation solutions if needed.

While ongoing maintenance is important, the quality and longevity of our tunnels should not be compromised. Fixing problems that have already emerged can be incredibly costly. Instead, detailed planning, site surveying and a thorough geotechnical analysis of the surrounding ground conditions should take place well before construction begins, with tailored solutions introduced before and during the construction phase.

Understanding what solutions and application techniques to use for different tunnel systems and ground conditions is vital to mitigating potential issues. It is why Mainmark is continually developing and trialling new applications and solutions for long term performance.

Mainmark’s specialised resins, gels and coatings can help engineers minimise the risk of issues, such as water ingress, by forming impenetrable barriers tailored to specific substrates. Our range of proven, hard-wearing water stop solutions are non-invasive, easy to apply and cost effective to help to meet project timelines and objectives.

Using the latest technology, Mainmark can tailor the strength, viscosity and flowability of its solutions to help reinforce tunnel substrates and address surrounding weak ground using solutions such as permeation grouting. Our fast-acting water stop solutions are also ideal for urgent emergency works, stopping leaks within minutes, which is a superior outcome for high-risk projects.

Ultimately, Mainmark’s technologies and capabilities challenge traditional standards and approaches to tunnel construction and remediation. By utilising the right solutions, we can ensure the quality and longevity of Australia’s existing and future tunnel infrastructure for decades to come.

[1] https://www.abs.gov.au/statistics/industry/tourism-and-transport/motor-vehicle-census-australia/latest-release

By Matt Mclean

Matt McLean is the Operations Manager for specialised resins and coatings at Mainmark. He is a concrete remediation, coatings, resins and waterstop injection specialist with a long history of working with ground stabilisation and grouting technologies.

As part of our regional series, where we discuss Mainmark’s operations in different areas across Australia and New Zealand, we turn our attention to Victoria and Tasmania. While Mainmark’s residential division has thrived in these regions for many years, more recently there has been a major focus on infrastructure remediation due to a record level of Government investment, which has resulted in rapid growth for Mainmark.

The geographical area in Victoria and Tasmania includes thriving cities, sprawling low density suburban areas and vast rural farmland, with geotechnical challenges spanning residential and commercial development to major civil infrastructure projects. Our team specialises in identifying and solving a wide range of ground engineering and remediation issues, such as ground re-levelling and soil strengthening, concrete repair and specialist grouting, as well as specialised resin coatings and waterproofing solutions.

The soil composition in Victoria and Tasmania also varies from reactive clay, common in urban areas including metropolitan Melbourne, to sandy and loam soils which are found throughout the state. In contrast, Tasmania contains a more diverse range of soils due to the state’s landscape and geology.

Maintaining assets and critical infrastructure

Infrastructure, civil remediation and concrete repair have become a growing area of focus for our business, perhaps more so here than in any other region in Australia after the Victorian Government announced a $90.2 billion investment into local infrastructure projects over the next four years[1]. Mainmark has consistently demonstrated how our products and expertise are more efficient and cost effective when addressing geotechnical and asset remediation challenges for these sectors.

Commercial remediation projects that require ground improvement works are an important part of Mainmark’s operation, such as this multi-storey business complex in Victoria which was saved from subsidence using our proprietary JOG Computer-Controlled Grouting and Teretek^®. The geotechnical site survey revealed that the complex was built on a combination of fill material and highly reactive clay. Water ingress had caused the clay to heave, resulting in building movement and damage to the buildings.

Many single and multi-storey developments experience subsidence due to water ingress, as excessive water can oversaturate and soften the soil underneath foundations. Reactive clay is particularly susceptible to subsidence as the soil swells and shrinks in response to changing moisture levels, which reduces ground bearing capacity and exacerbates the risk of differential soil settlement.

Decommissioning old or damaged pipe infrastructure, including redundant gas, water and sewer pipes, can also be problematic, particularly in inner city areas and older suburbs where ageing infrastructure has started to crack and leak, releasing water into the ground. These pipes cannot be easily removed without impacting the surrounding environment. This is particularly challenging if the pipes are located below roads and rail tracks as the disruption would not only result in the lengthy closure of essential transport corridors but would also be cost prohibitive. For this reason, they usually remain in the ground.

However, abandoned pipes cannot simply be left to deteriorate underground without being filled with an appropriate inert solution. If the pipe was to collapse or if water leaked into the surrounding ground, subsidence and erosion could lead to dangerous voids and sinkholes. Filling redundant pipes with a highly flowable structural fill material, such as Mainmark’s Terefil®, which is designed to be pumped further and faster than traditional concrete fill solutions, is providing a new way to solve the problems associated with pipe abandonments. Projects like the abandoned cast-iron gas main in Brunswick and the ground stabilisation and void fill at a stormwater deck replacement in Fitzroy, particularly benefited from our specialist solutions.

How the pandemic has impacted operations

While COVID-19 has impacted many businesses across the country, including Victoria which experienced numerous hard lockdowns and ongoing restrictions, Mainmark’s civil infrastructure division continued to experience high demand due to our range of specialised applications that are used for projects classified as critical infrastructure.

Mainmark’s reputation as a civil remediation expert has helped maintain the pace for the business, following the completion of a variety of successful projects across Victoria and Tasmania. Back in 2019, Mainmark stabilised the heritage listed Kimberley Rail Bridge in Tasmania by using Teretek to fill underwater voids. This work forged strong relationships with infrastructure maintenance contractors, leading to our range of bespoke solutions being specified for recent major capital works projects such as The West Gate Tunnel, Western Roads Upgrades and the North East Link.

Research and innovation keep Mainmark at the forefront of ground engineering

Mainmark’s innovative products like Terefil, Teretek, JOG and specialised engineered coatings and waterproofing solutions have consistently proven over time to be more cost-effective and time-efficient compared to more traditional remediation alternatives. This has resulted in Mainmark fast becoming recognised as the region’s ‘go-to’ contractor for complex problems.

Research and development have become a crucial reason why Mainmark delivers, and exceeds, customer expectations. Products and advanced delivery methods are continually being developed and tested to ensure the applications are tailored to Australia’s ground and civil remedial challenges. This involves quality assurance and stress tests that push the product’s individual capabilities.

The expertise and tailored solutions-focused approach from Mainmark helps project managers and asset owners across the wider region realise the deeper value and insight that ground engineering specialists can provide. This has steadily strengthened Mainmark’s following and increased our reputation as a reliable problem solver throughout the industry and the local community.

[1] https://infrastructure.org.au/wp-content/uploads/2021/05/MEDIA-RELEASE-PALLAS-DELIVERS-HIGHEST-INFRASTRUCTURE-SPEND-ON-RECORD-SETTING-THE-STATE-ON-STABLE-PATH-TO-RECOVERY.pdf

By Max Kudrenko – Technical Manager

Max Kudrenko is the Technical Manager(Vic/Tas) at Mainmark Ground Engineering. Max is a civil engineer who has experience working with different grout, resin and other cementitious geotechnical and ground improvement technologies in the residential, commercial, gas/oil and civil sectors. He has successfully project managed works throughout Australia, New Zealand and Japan.

Due to the disruption caused by restrictions that Australia and New Zealand have experienced as a result of COVID-19, many trades and businesses including ground engineering specialists, have been unable to visit homes in some regions to conduct on-site inspections.

Without visiting a customer’s home, it is difficult to assess structural issues like wall cracks and sinking foundations that may be caused by subsidence. However, rather than leaving homeowners to worry about the issues, and their potential to worsen, Mainmark has harnessed digital tools and Apps to continue offering expert ground remediation advice virtually. This enables clients to safely receive professional support and guidance regardless of their circumstances.

Traditionally, the site inspection process has involved visiting the customer’s home face-to-face and conducting a detailed on-site analysis of the issue. Once the problems are identified, Mainmark determines the best solution, process and timeline, before carrying out the work. A virtual site inspection, ideally via video call, can help to pre-qualify work, identifying any significant issues that might need to be addressed urgently and enable Mainmark to provide the homeowner a budget price. It also gives peace of mind to those with a more minor problem that may not need to act immediately. Customers are also encouraged to share videos of their problem areas, like this example from the owner of an ACT residence who shared this video with our local engineer, Alan Reid:

Here is Mainmark’s simple three-step virtual site inspection process which is proving to be extremely valuable for worried homeowners, utilising a combination of enhanced customer service and technology.

Step one: Connecting with the homeowner

The process begins as soon as a customer reaches out to Mainmark. Once their site’s issue and symptoms have been established, Mainmark’s team arrange a convenient time for an expert ground remediation representative to “e-meet” the customer.

Everyone has their preferred online or visual method and Mainmark connects with people in ways that make them feel comfortable. Video calls via phone, tablet or laptop are popular using platforms such as FaceTime, WhatsApp, Zoom and Skype. Others may choose to capture a video of their issue and send it to their Mainmark representative for assessment and further discussion via a phone call. Further supporting documentation such as site plans and photographs, and a builder’s or structural engineer’s report can also be sent to the Mainmark team to help with diagnosis and assessment.

Step two: Virtual assessment

Mainmark will then visually assess the customer’s home to better understand the issue. The Mainmark representative will ask the homeowner a series of questions to obtain a detailed understanding of the type of home, the condition of the foundations, the type of soil and ground conditions the home sits on, and any other factors that may be causing the damage, such as a leaking pipe. A walk through of the indoor and outdoor areas may be requested, including close ups of any cracking or other symptoms.

Step three: Solution

Once the home and surrounds have been viewed and remotely examined, the Mainmark representative will analyse the situation and discuss what could be causing the issue. While the virtual diagnosis cannot be confirmed until a physical inspection can take place, Mainmark can provide preliminary advice, explain remediation options and discuss the non-invasive solutions to fix the underlying subsidence problem, including providing budget costs.

When restrictions allow, further onsite assessment can be carried out and the actual remediation works scheduled. Depending on the nature and scope of work required, it can sometimes be possible to accomplish this without Mainmark’s team stepping inside the home.

Despite the challenges presented by the global pandemic, the current landscape has allowed us to adapt in ways that can be beneficial into the future, even after the current restrictions have been removed. Virtual site inspections can provide a starting point for homeowners needing advice, particularly those in more remote locations. The service can also support homeowners impacted by further lockdowns in the future, or residents who are simply more comfortable with an initial virtual assessment.

By Lincoln Grody

Lincoln Grody is Regional Sales Manager (NSW & ACT) at Mainmark Ground Engineering. Lincoln has a Bachelor of Applied Science in Civil Engineering from University of Colorado and holds a Master’s Degree in Construction Management from The University of Texas. Originally from Colorado, USA, Lincoln began his career in the construction industry as a structural engineer, researching building information modelling and data analysis techniques in the commercial sector. Subsequently, he has spent the last 10 years working in various roles in engineering, project management and sales management for leading global firms in the United States, Europe, South America and Australia.

In 2019 Mainmark embarked on a project in Toowoomba, Queensland, playing an important role in one of the largest infrastructure projects in the state’s history.

The project was the $1.6 billion Toowoomba Bypass, a 41km long dual carriageway and ring road that was designed to improve freight connections to major ports and markets and reduce the number of trucks on Toowoomba’s local roads.

This week, our work on the Toowoomba Bypass received a prestigious Good Design Award Winner accolade in the Engineering Design category, in recognition of outstanding design and innovation.

Our role in the project was to help reline, repair and future-proof seven concrete drainage culverts which were damaged and threatened the structural integrity of the bypass.

Needless to say, it is thrilling to be acknowledged for our contributions to the ground engineering and asset preservation sector. This important project for Queensland challenged our team to think outside the box and deliver an alternative solution to a complex problem. Being recognised for that effort is a great reward for all involved.

This year, the Australian Good Design Awards attracted 933 submissions, which were evaluated by more than 70 Australian and international jurors, including designers, engineers, architects and thought leaders. Each entry was assessed according to a strict set of design evaluation criteria which includes good design, design innovation and design impact. According to Good Design Australia CEO, Dr Brandon Gien, the standard of design excellence represented in this year’s entries were the best he’d seen in 25 years of running the Awards; an encouraging sign that the design sector is flourishing.

The Good Design Awards Jury said, “Mainmark’s solution was a wonderful example of optimising on a range of parameters within constraints. Clearly innovative, this design was clever and had benefits for the project in terms of cost, schedule and quality. This is really impressive design and engineering, and a standout example of good design in this category that deserves to be recognised.”

About the project

During construction of the Toowoomba Bypass, it was discovered that seven reinforced concrete pipe culverts contained at least one damaged barrel while several were compromised in up to five separate remote and isolated locations. These culverts provided drainage from the invert of a valley beneath the fill under the road alignment. Without these culverts, rainwater and other natural events could potentially degrade the valley and the road, making a vital transport route unsafe and unusable.

Mainmark was contracted to repair and reline the damaged culverts, ensuring that they would last for years to come.

Working closely with Nexus Delivery and Roundel Civil Projects Pty Ltd, Mainmark developed an engineered solution using a multi-faceted approach to relining the RCP culverts which involved the insertion of site based custom manufactured corrugated metal pipes (CMPs) inside the damaged RCP concrete culverts and then filling the void (or annulus) between the CMP and the original RCP concrete culverts with Terefil^®.

Terefil®, is our proprietary lightweight cementitious grout containing a uniformly distributed matrix of air bubbles generated by mixing cement slurry with stable, pre-formed hydrocarbon foam. This produces a lightweight concrete mix that provides the most suitable fill which does not require maintenance with additional supporting material, energy or resources. Terefil was instrumental in remediating the compromised culverts underneath the bypass, restoring their structural integrity and ensuring suitable drainage for the bypass upgrade.

Terefil is also highly flowable, making its delivery to the project site simple and stress free. This, as well as its high setting strength, allowed the team to complete the work on time and within budget in compliance with specific project requirements set by the Queensland Department of Transport and Main Roads (DTMR).

Since completion in 2019, the bypass has been able to reduce travel time across the Toowoomba Range by up to 40 minutes for heavy commercial vehicles, improve freight connections and redirect trucks away from Toowoomba’s CBD, which enhances liveability in the Toowoomba and Lockyer Valley areas.

Mainmark is proud to win the Good Design Award in the Engineering Design category, in recognition of outstanding design and innovation for this project. Read the case study here.

By Joe Glanville

Joe Glanville is Mainmark’s ANZ General Manager. He has over 15 years’ experience in the Construction Industry, acquiring broad commercial, construction and project management skills.

There is no denying that trees are a beneficial asset to the environment, our lifestyle and a symbol of a healthy landscape. They create shade and privacy, contribute to better air quality, provide habitats for native birds and animals, and help to reduce salinity and soil erosion.

However, without proper consideration and monitoring, trees can also impact our built environment by causing damage to buildings, paths, driveways, and underground infrastructure.

A tree’s influence starts, literally, at the roots; they are responsible for keeping the tree alive by drawing essential nutrients and water from its surroundings. The roots will continue to grow as a tree matures and during this growth, the roots will extend towards anything that will maintain the tree’s life. Roots typically seek out moist soil and will often find entry into old or damaged pipes including stormwater drains, sewage pipes and water mains.

Seasonal change also influences how trees interact with the built environment. During the warmer months of spring and summer, soils can dry out with the lack of moisture causing reactive clays to shrink. In extreme cases, shrinking soil can lead to significant ground movement, subsidence and foundation settlement across the home. Unfortunately, trees can exacerbate this process. In their hunt for moisture, root systems will extend through dried soil, desiccating the ground and absorbing remaining water from the already dry earth.

The combination of dry soil and thirsty tree roots is the perfect recipe for ground movement, and the appearance of worrying subsidence symptoms, including cracks in brick walls, distorted timber frames, and doors and windows that jam. Examples of different causes of subsidence around the home, including those triggered by tree roots, can be viewed on Mainmark’s interactive house: www.mainmark.com/subsidence-problems-around-homes. Understanding the cause of problems is essential before a viable solution can be found.

Assessing the influence of trees

There are several factors to consider when determining whether trees could be the ‘root cause’ of damage to a home. These include:

Groupings

When trees are planted closely together, they are forced to compete for moisture and nutrients in the same area of soil. The larger the group of trees, the greater the impact on soil drying out in the surrounding area. It is therefore more likely for homes or buildings located near large groups of trees to experience effects of adverse ground conditions as the trees absorb more moisture which can contribute to greater ground movement.

Tree types

Tree activity varies across the year depending on its type, so it’s important to identify the trees that are growing near your home. Deciduous trees, for example, hibernate in winter and re-grow in spring. This lifecycle means their water demand is often highest during drier months, which has the effect of increasing the magnitude of soil shrinkage.

Characteristics

A tree’s physical characteristics can determine how much moisture its root system is likely to absorb, but it’s not always just in relation to its overall size. Research into a tree’s influence on ground conditions has indicated that it is the leaf area of the tree rather than its height that ultimately determines its moisture demand[1]. Therefore, thick or tall trees aren’t always the culprit for dry soil; it’s the amount of foliage that can indicate how much water a tree needs to sustain itself.

Surrounding environment

Roads, footpaths, and larger scale developments with limited green space can also prevent moisture from reaching the soil underneath. This lack of permeability can cause dry soil conditions and may force tree roots to draw on the limited moisture available, intensifying soil shrinkage and ground movement. This is common in urban areas where trees are planted for aesthetic or ‘greenscaping’ purposes, without considering the degree of exposed soil and abundance of moisture.

The risk of roots affecting the structural integrity of your property should not be a barrier to planting trees or moving to an area where trees are in abundance. Understanding tree behaviours and their relationship with the surrounding environment can help to manage their influence and reduce the likelihood of damage to the home or a commercial premises.

[1] https://treenet.org/wp-content/uploads/2020/01/A-Geotechnical-Engineer%E2%80%99s-Approach-Towards-Trees.pdf

By James O’Grady

James O’Grady is a Sales and Business Development Manager at Mainmark. He is a civil engineer with 25 years’ experience in structural engineering, construction materials and ground treatment.