The construction industry in Hong Kong is the backbone of continued development in one of Asia’s most dynamic cities. Established in 1993, Hong Kong Concrete Repair Association (HKCRA) is the key industry body promoting and developing the practice of good concrete repair, advancing education and technical training, and representing members in matters of common interest.
On 27 May 2011, the HKCRA Annual Dinner and presentation of 5th Awards for Excellence was held at Happy Valley racecourse. Always a popular and fun event attended by a wide cross-section of industry members, guest attendance grows year on year and also presents an excellent opportunity for attendees to network and catch up with former colleagues. 
This year HKCRA was also honoured to host keynote speaker, Ir Dr. Pang Hon Wah, Chief Manager of Estate Management Division of Hong Kong Housing Department. Other Housing Authority guests included, Ir. Au Lap-kei, Bosco, Senior Structural Engineer, Ir. Lau Kwok-chu, Structural Engineer, Ir. Kwan Kwong-chit, Alfred, Structural Engineer, and Ir. IP Wing-sang, Thomas, Structural Engineer.
Additional guests included Ir C K Cheung, Vice-President of Hong Kong Concrete Institute (HKCI), Dr. Y L Wong, Executive Board Member of HKCI, and Dr Tommy Lo, Executive Board Member of HKCI.
Hong Kong’s aging buildings
In his keynote presentation, Dr Pang addressed the issue of sustaining aging buildings and the future challenges this brings to the industry as a whole.
“As you are all aware, the Mandatory Building Inspection Scheme (MBIS) would be enforced following the Legco’s scrutiny, which is now in the pipeline,” said Dr Pang. “I understand that under the proposed scheme about 2,000 buildings aged over 30 years would be selected for inspection and repairs if found needed each year.”
“The scheme is set to turn a new page of the building maintenance industry by creating a promising market. However, success will hinge on the repair work being suitably selected and properly done. To meet the challenge, I wish, and I surely believe the HKCRA would step up its leading role in developing and promoting the best practices and solutions for the repair and protection of concrete, which is crucial to sustaining our huge stock of aging buildings.”
Elaborating, Dr Pang stated that The Hong Kong Housing Authority is now maintaining some 700,000 rental flats in over 1,000 buildings, with the oldest approaching 60 years of age. The current policy is to sustain buildings unless they are no longer safe or economically viable to maintain.
Driven by this policy, the comprehensive structural investigation programme was launched in 2005 to probe into the structural condition of buildings aged around or over 40 years old and to determine what needs to be done to further sustain them. To date some 15 estates have been investigated.
HKCRA Awards for Excellence
Addressing attendees, HKCRA Chairman, Brian Clements, presented details of HKCRA Awards for Excellence recipients.
“The Award for Excellence in concrete repair 2011 flooring repairs goes to Marvel Harvest for repairs and resurfacing to car park bays at Worldwide Gardens,” stated Clements. “The judges found this to be a clean presentation and while the repairs were quite straight forward, they were well implemented resulting in great visual improvement of the car park areas.”
“The Award for Excellence in innovative repairs goes to The Housing Department for the installation of Hydrotech’s MPS system at Oi Man Estate,” announced Clements. “This is a very innovative approach in a pulsed osmosis system for use in concrete repairs and in the judges opinion this is a glimpse of the future.”
“The Award for the best in innovative repairs is awarded to the Housing Department for work applied at Oi Man Estate, the Award for Management of Repairs & Safety” is awarded to Nga Luen Construction & Engineering Co Ltd for KMB Bus Depot 82 in Tuen Mun, and the Award for Excellence in Sustainable Repairs is awarded The Hong Kong Housing Authority for works as applied at Wo Lok Estate.”
“The standard of entries submitted in relation to this year’s Awards was extremely high,” continued Clements. “We were also delighted at the number of awards submitted this year, which also indicates the growing prestige of these awards across the industry.”
The Hong Kong Housing Authority at Wo Lok Estate
In relation to The Hong Kong Housing Authority’s repairs as applied at Wo Lok Estate, this is one of the oldest public rental housing estates maintained by the Hong Kong Housing Authority (HKHA).
Built in 1963, the Estate comprises three buildings of 14 to 16-storeys and one building of 7-storeys. An investigation in 2007 revealed that bathroom slabs in the 7-storey buildings were highly contaminated with chloride ions and reinforcing steel bars seriously corroded, attributed to the toilet-cum-bathroom design and the subsequent conversion of the toilets from squat type to pedestal type and resulting in prolonged soaking of the concrete slab by the trapped water. This situation was aggravated by the use of sea water for toilet flushing.
The repair involved remedying the concrete defects and corroded steel reinforcing bars; replacing the loose cement/sand infill inside the toilet gullies with high performance concrete; laying waterproofing; and installing galvanic sacrificial anodes, with improved geometry and with RFID. Repair to 326 defective bathrooms together with other repair to other structural elements in the buildings were substantially completed in 2010.
To ensure the quality of repairs, technical staff supervised the whole process of work and certified and recorded each satisfactory critical activity on inspection forms with recorded photos. Moreover, a concrete specialist also monitored the whole process of the HPC laying. Two permanent stations, where the bathrooms at the above flats have been repaired, are monitored at regular intervals to measure the corrosion current and voltage to validate the effectiveness of the sacrificial anodes.
The work was completed within the shortest time in the least disturbing way and the bathrooms were re-opened on the day of the repair. The project also included long-term monitoring of the performance of the repairs.
The Housing Department at Oi Man Estate
Oi Man Estate is a public housing estate in Ho Man Tìn, Kowloon City District, Kowloon. It is the largest public housing estate in Kowloon City District with a total of 72 residential blocks completed in 1974 and 1975. Public housing is mainly built by the Hong Kong Housing Authority and the Hong Kong Housing Society.
Preserving a 36-year old structure using innovative technology, Hydrotech Asia Ltd was commissioned by the Hong Kong Housing Authority in-cooperation with the local term contractor to install the MPS System at Tun Man House in Oi Man Estate.
Hydrotech’s MPS System is a proprietary active electro osmosis treatment that dries out concrete and other masonry structures and maintains them in a permanently dry state. Sheet membranes and other traditional water proofing systems are not compatible with the design life of the structure.
Early failures of membranes and bitumen coatings had resulted in water penetrating through the exterior walls of three underground lower levels and causing serious damage to steel reinforcement and caused the concrete ceiling to crumble.
MPS System was installed on three units located at three underground lower levels of Oi Man Estate and was fairly simple for public housing type of construction. Anode circuits were constructed on walls of each unit and were independently connected to a junction box and a control unit.
Two cathodes were installed at the lower level of the building. The MPS System was activated two weeks after completion of grouting works.
The MPS system hose dried out the saturated exterior concrete wall at Oi Mon Estate and stopped further progress of water. The drying out process significantly enhances the durability of the structure by reducing the rote of corrosion of the steel reinforcements. By maintaining the structure in a dry condition, health issues such as the growth of fungal bacteria on the concrete is virtually eliminated and long-term maintenance costs are dramatically reduced.
Nga Luen Construction & Engineering Co Ltd and KMB Bus Depot
Nga Luen Construction & Engineering Co Ltd words as applied at KMB Bus Depot in Tuen Mun, involved exterior wall repairs, painting and window repairs at 82 Depot. Phase I commenced August 2009. Phase II commenced December 2010. Phase I was completed in December 2009 and Phase II in March 2011.
To fulfill the client’s high demand of quality and safety requirement and since no architect or consultant was employed to monitor the project, work was under the direct and close supervision of KMB.
Materials used on this project included Fosroc Nitobond SBR, Nitoprime Zincrich WB (waterbase), Fosroc Renderoc HB25, SKK PC paint (waterbase).
Nga Luen workers had attained the related qualifications of construction craftsmanship in different trades, such as concrete repairer (spalling concrete), bamboo scaffolder, painter & decorator. Approximately 30 workmen were involved in the project. The company provided a safety environment to pedestrians around the premises and also gave a new look to the premises. Workmen also demonstrated their professionalism in the building maintenance field.
Nga Luen is a fully registered contractor under the new Minor Works Control System of Building Departments. Its scope of works includes building maintenance including concrete repairs and waterproofing treatments, interior decorations, heat insulations treatments.
Marvel Harvest Ltd. and Worldwide Gardens
Marvel Harvest Ltd. was contracted by ISS Eastpoint Facility Services for the resurfacing of existing parking spaces at Worldwide Gardens between October 2010 and October 2011 to protect the existing concrete slab, improve the problem of water ponds, and refurbish the flooring of parking spaces.
Methods applied in resolving the existing problem included hammer tapping tests, saw-cutting debonded concrete, removal of loose concrete, removing loose rusts on re-bars, applying epoxy primer as anti-corrosive coating, applying one epoxy primer to concrete substrate and back-filling the repaired area, grinding the floor to remove oil, grease and dust on concrete substrata, applying epoxy primer as bonding agent, laying epoxy silica to the floor, and applying waterproofing coating to the floor.
The HKCRA was delighted and impressed with the high standard of entries submitted for consideration for this year’s Awards for Excellence and we congratulate the winners. We also look forward to viewing entries next year and look forward to another successful annual dinner and once again welcoming our many friend and colleagues from across the construction industry.
HKCRA also hosts regular technical evenings addressing crucial construction issues and methodologies. Future 2011 technical evenings will include presentations on “repairs to fire damaged concrete”, “repairs to precast concrete” addressing the types of defects that can occur during casting and damage that may occur during transportation and handling and “fixings for concrete and render” covering the various options for fixings and which of those fixings should be used in which circumstances.
Attendance at HKCRA technical evenings is always popular and bookings are advised. More information at www.hkcra.com.hk
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