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POSCO’s PosMAC Barrier Saves the Trees


In the middle of a bleak city street, trees deliver a fresh breather for the pedestrians. These street trees are typically managed by the local governments as part of the “Urban Forest Landscape” project under the auspices of the Korea Forest Service. Not only do they create a pleasant ambiance for pedestrians, but they also provide many practical benefits, such as absorbing fine dust and mitigating urban heat island effect.

Around these roadside trees, however, sidewalk blocks are often found to be misplaced or even broken. The recent typhoon Lingling turned so many street trees in Korea, upside down inside out.

Korea’s epic poem Yongbieocheonga features trees with deep roots that never sway, even in the face of the strongest winds. But outside the poem, keeping the trees steady and strong requires an actual solution. In POSCO’s partnership with its customer, MYSTECH Co., LTD., there might be an answer the industry has been looking for. Meet PosMAC Barrier, the result two companies’ latest collaboration, at POSCO Newsroom.

▲ The aftermath of the recent typhoon Lingling

l Water Supply: the Key to Urban Forest Maintenance

From 1988, Korea carried out extensive afforestation policy, especially for roadside trees — and since 2000, the country has been planting 600,000 roadside trees every year, accelerating the progress of the country’s urban forest landscape project. However, planting trees is one thing, maintaining is another. In 2017, Korea Land & Housing Corporation released a new study on the reasons behind roadside trees defect in Gyeonggi Province. The study revealed over 35% of trees defects were due to water shortage.

Underground water shortage causes abnormal growth in roots as they outstretch themselves for an alternative water source. These roots soar above the ground, breaking down the sidewalk blocks. Or, these roots overgrow underground, making the ground uneven.

With sufficient water supply, a tree grows countless fine roots. These fine roots firmly ground the tree. Otherwise, a tree solely relies on the main root with no firm grip. A strong typhoon like Lingling could topple over such trees.

When tree roots are not kept under control, they can damage underground utilities like sewer pipes. Worse, it could cause dangerous sinkholes. Maintaining roadside trees require a huge financial commitment in the form of taxes — proper water supply can help deal with many problems in maintaining roadside trees.

l PosMAC Barrier, a Sustainable Solution Recycles Rainwater

So, how to keep the trees hydrated? POSCO, together with its client company MYSTECH CO., LTD., is providing an innovative solution with the PosMAC Barrier, a tree barrier made of POSCO’s high-strength and corrosion-resistant PosMAC. PosMAC Barrier protects rainwater storage and water tank.

Under the leadership of CEO Jin-Hwan Kim, MYSTECH CO., LTD. was founded in 2002. The company produces specialized products for roadside facilities such as sewer covers and protection plates for trees. POSCO’s relationship with the company dates back to 15 years ago when the two companies’ R&D endeavors led to the creation of sewer coverage that prevents odor — across the globe, the first of its kind. After the years of focused work on developing an eco-friendly technology for tree growth, MYSTECH reached out to POSCO in 2017.

POSCO’s collaboration in MYSTECH’s research can be attributed to the high bar set for the material. Since MYSTECH’s rainwater storage tank stays underground, it must withstand the underground pressure and resist corrosion. An ordinary steel plate would require much thicker coating, making it difficult to manufacture. Stainless steel could have been the alternative material if it weren’t for its high cost.

Enter PosMAC, rust-free and one of POSCO’s WTP (World Top Premium) products which provided just the right solution for MYSTECH’s dilemma.
*PosMAC: POSCO Magnesium Aluminum Alloy Coating

PosMAC is a ternary alloy coated steel composed of zinc, magnesium, and aluminum. When exposed, the coating forms a highly stable and dense film layer called “Simonkolleite.” This means the product creates an extra protective layer, a ternary alloy layer whose density much higher than that of conventional galvanized steel sheet. PosMAC is 10 times more corrosion-resistant than conventional steel.

The high-strength PosMAC’s tensile strength is 400Mpa or up. Because of this, PosMAC can hold rainwater for a long time even in the corrosive environment such as soil or chloride-rich roads. It is also strong enough to withstand root pressure. To ensure optimal design and development of the product, POSCO provided full support to the R&D endeavor by forming a research team with MYSTECH and the RIST (Research Institute of Industrial Science and Technology).

Gwang-Ho Ko of POSCO Construction Steel Solution Group summarized the strength of the PosMAC Barrier: “It is a strong and eco-friendly steel product that addresses the fundamentals of urban forestation. The Barrier controls the uplifting of tree roots and recycles stored rainwater to provide water to the roots when needed.

l Two Years of Testing Proves, “PosMAC Barrier Saves Trees”

Above the ground, the only visible part of the PosMAC is its main body and the cover, but underneath the ground, there is a water tank.

When it rains, rain accumulates in the tank, and a water discharge pipe located towards the direction of root discharges rainwater, providing much-needed water to the roots during the periods of water shortage. The filter located in the upper body guards off foreign substances, and a water inlet allows in additional water supply when necessary. The water tank can hold 45 liters of water per unit and can be selectively installed from one side to four sides. One set of the water tank can hold up to 180 liters of water.

POSCO and MYSTECH completed the commercialization and the patent registration (patent 10-2108-0162207) for PosMAC Barrier. Over the past two years, the product received rigorous testings to help verify how much it contributes to tree growth. PosMAC was installed for the tree on the verge of perishing, and the trees with too many roots also received the Barrier treatment.

The result was incredible. After two years of installation, it was clear PosMAC Barrier made huge difference. PosMAC Barrier even revived dying trees, sprouting green leaves shortly after the installation.

PosMAC Barriers to Go Nationwide

Last April, a policy seminar at Korea’s National Assembly introduced PosMAC Barrier as an ideal steel solution to address climate change. The seminar generated momentum in raising awareness on how water shortage could trigger damages to urban forestation. It also created opportunities for PosMAC Barriers — numerous local governments are turning to the product as a solution to deal with damaged roadside trees.

Since then, the PosMAC Barrier has been installed for 255 trees across Korea. POSCO and MYSTECH are currently conducting pilot projects in collaboration with Seoul, Jeonju, Suwon and Korea Forest Service. Local governments are currently undertaking urban forestation projects and POSCO is proactively supporting its client companies to meet the growing demands across the country.

A local government official said, “Conventional tree barriers merely set boundaries for the tree protecting them from the footsteps of pedestrians or vice versa. As the need for proper management and tree growth escalate, we’re realizing that PosMAC Barrier is providing an excellent solution.”

He added, “Urban forestation can truly benefit from this kind of innovative brand-new technologies. Not only does PosMAC provide sufficient hydration to the trees, but it’s also extremely cost-efficient. Compared to conventional tree barriers, the cost difference is minimal.”

In collaboration with MYSTECH, POSCO is putting forward eco-friendly marketing to expand the application of POSCO’s LID (Low Impact Development) steel products. As part of the plan, the company is carrying out a marketing strategy to install POSCO Barrier in the landscaping businesses of large construction companies as well as for public roadsides facilities.

MYSTECH CEO Jin-Hwan Kim said, “The roots of roadside trees trapped underneath concrete pavement suffocate and perish. Every year, precious resources are being wasted just to remove these dead roots.”

He continued, “Time and again, our collaborative research demonstrated that PosMAC provides a nip-it-in-the-bud solution to this problem. Now, it is time for us to see beyond the domestic market and head to the global stage. We are set to establish PosMAC as the go-to steel product when it comes to environmental sustainability.

Right next to POSCO Center at the heart of Seoul’s Gangnam district, PosMAC is protecting trees. With deep faith and confidence in the product, the company installed PosMAC for dying trees. Needless to say, PosMAC saved the dying trees!

Roadside trees are essential elements of urban living. Unlike other urban facilities, it breathes and brings life to cities, so it requires more sustainable and long-term management. PosMAC Barrier, POSCO’s sustainable steel solution, is bringing life and vitality to roadside trees and thus, urban life.

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