Published Date: Issue Sep/ Oct 2019
To advance its goal of building well-designed, quality homes, HDB has been on a continual quest to deepen its expertise in construction technology. More recently, new partnerships and research projects have broadened the horizons to keep HDB towns future-ready.
West Terra @ Bukit Batok is the first public housing project to be built with Pre-fabricated Volumetric Construction (PVC) technology. The PVC construction method increases construction productivity and safety on work sites, while helping to reduce labour needs, as well as noise and dust generated from building works.
Singapore’s urban landscape can be described as a vibrant tapestry of building forms in myriad colours and shapes. Even so, in every HDB town, neatly arranged blocks of public housing exude a certain visual consistency — an outcome of HDB’s intensive construction productivity efforts to build better homes safer, faster. HDB has made big strides in construction innovation over the years, from embracing prefabrication technology to developing its own Precast Building System, and in recent years, implementing wider adoption of Prefabricated Prefinished Volumetric Construction (PPVC) as part of a national effort to increase construction productivity.
As the largest housing developer in Singapore, HDB plays an important role in leading the industry’s technological development and growth. To better meet the growing demand for well-designed, quality homes, HDB has taken an integrated approach across the construction value chain — from upstream designing and planning, and construction, to downstream building and facilities maintenance. Working behind the scenes, engineers and architects from HDB’s Building Groups have been driving innovations and research endeavours to further enhance HDB’s construction capability and capacity through innovative technologies.
Venturing into 3D Printing
Additive manufacturing, or 3D printing, has ushered in a new era of mass customisation, offering the ability to create 3-dimensional objects with intricate details or geometric forms that would be near impossible to create with traditional methods. Its applications are almost limitless and could offer a revolutionary leap, changing the way homes are designed and built.
In 2018, HDB embarked on a research project to explore the potential adoption of 3D concrete printing. Working with Robin Village Development, Witteveen+Bos, and Nanyang Technological University, the research collaboration looked into developing digital fabrication technologies through 3D concrete printing and other supporting systems to boost construction productivity and sustainability.
1. 3D concrete printing material is prepared by mixing a customised cement blend with water.
2. Design plans for the concrete component are loaded into the 3D printer control panel to control the print path of the nozzle.
3. Like squeezing toothpaste out of a tube, the concrete component is additively manufactured – one layer after another.
HDB’s 3D Concrete Printer
Installed at the HDB Centre of Building Research (CBR), the 3D concrete printer is currently the largest of its kind in Southeast Asia. It is capable of printing components up to 9m long, 3.5m wide and 3.8m tall, and successful printing trials have since produced a room-sized 3D-printed volumetric component with reinforcements, a first of its kind in the world of 3D concrete printing, right here in Singapore.
Building on these efforts, the research will expand to other areas to enhance the printer’s capabilities, such as using multiple nozzles to increase printing productivity, and the development of a robotic system to place steel reinforcements into the concrete during the printing process. Software will also be developed to seamlessly integrate the 3D concrete printer with HDB’s Building Information Modelling system, allowing the direct flow of data from design to production, and minimising the need to create another set of workshop drawings for the production of volumetric components.
The customisability of 3D-printed concrete opens up more possibilities in producing more varied and inviting features with an organic and free-form design. Think curvilinear benches, meandering planter boxes and distinctive sculptural forms — these features, not common in today’s
housing projects, could well become a reality in future HDB projects.
3D concrete printing will enable more creative design features to be built at HDB estates, which would be challenging to create using conventional construction techniques. These features could include customised sun shades, 3D artwork, organic landscape features and precinct furniture.
Advancing Concrete Performance
However, 3D concrete printing is not without its challenges. Engineers at HDB’s Building and Research Institute (BRI) discovered that getting the right concrete mixtures is essential to printing objects successfully. Mixtures that were proven to work overseas would need to be reworked to suit Singapore’s humid and tropical climate.
Leveraging private expertise in material science, HDB has inked a Memorandum of Understanding (MOU) to collaborate with Evonik (SEA) Pte Ltd on a study to improve the workability and strength of concrete material used in advanced manufacturing methods such as 3D printing. By using silica as additives to the concrete premix, the early strength, homogeneity and flowability of concrete can be enhanced, allowing the smooth laying of concrete layers and ensuring that the layers are well-bonded after the 3D printing process.
Upon successful trials, new standards could be developed for materials used for 3D-printed concrete components in the construction of HDB buildings.
Smart Building Inspection
Another research study in the works is the use of unmanned aerial vehicles or drones for facade inspection. HDB blocks are regularly inspected to ensure that they remain in good condition for residents. Manual methods, such as using suspended gondolas, are currently deployed to perform building facade inspection.
Recognising the benefits drones can offer, in March 2018, HDB embarked on a research collaboration with HUS Unmanned Systems to explore the adoption of drones and visual analytics technology to help automate the building inspection process, with the goal of improving productivity, safety and inspection accuracy.
HDB’s future drone inspection system taps into a cloud software platform to conduct a visual scan of building facades captured during inspection. Leveraging artificial intelligence (AI), the system processes thousands of photos and identifies building defects in the cloud. It can detect and categorise the types of defects, and tag them to a drawing or visual of the building. The platform would then deliver a report to highlight the severity of the defects detected and recommend possible remedies.
A small-scale trial was conducted in July 2018. Anticipating concerns that could arise from flying the drones around homes, residents were notified in advance on the use of drones, with the area below the flight path cordoned off for safety during the inspection process. Any images of residents captured during the scanning process will be masked out, before the captured data could be used for analysis. Future research will also look into the possibility of developing a feature to automate masking, ensuring that the privacy of residents is protected even as the inspection is taking place.
The use of drones offers multiple advantages. Apart from providing greater visibility to areas that would be challenging for workers to access, eliminating the use of gondolas also reduces potential hazards that could happen during inspection, such as falls from height. The inspection process would be less laborious, and the documentation and reporting of defects more precise.
Keeping Construction Sites Safe with Video Analytics
Construction sites depend on manual supervision to ensure safety requirements are met, and that the works are progressing as planned. With many concurrent activities happening at these sites, maintaining our high standards of safety and supervision is a resource-intensive endeavour as multiple workplace, safety and health officers, as well as site supervisors are deployed to worksites.
HDB is collaborating with the National University of Singapore and AI Singapore to study ways to automate safety inspections. The research project aims to enable continuous and real-time monitoring of hazards through live CCTV footage by integrating video analytics and AI technology.
To augment manual supervision, tower cranes at HDB construction sites have CCTV cameras installed to record construction activity. Trials are underway to use the footage to run video analytics to identify safety lapses, or even detect potentially unsafe behaviours and conditions.
Concurrently, the research data and models developed in the study will broaden the application of video analytics in the field of construction management and supervision for HDB worksites and the construction industry as a whole. HDB is currently test-bedding the system at a BTO project and exploring wider application at other sites.
Live video feeds from construction sites are retrieved and ingested into the system. The AI engine, pre-trained using deep neural networks, will perform real-time video analytics to detect workers and potential hazards. If the AI engine detects danger, it will immediately trigger a text alert to the safety officer-in-charge. A management dashboard will allow users to view results of the video analytics and alerts that were triggered by the system.