What happens if rebar is missing at an apartment construction site? It can lead to shoddy work and possibly cause a collapse. The problem is that it's not easy for people to detect 100% of the missing rebar at a construction site.
There is a company that solves this problem with artificial intelligence (AI). This is the story of Double S NDT, a smart supervision technology company. Chief Executive Choi Hajin said, "We can strengthen safety by meticulously managing construction sites with AI."
◇ "The rebar spacing looks different"… found by AI
Double S NDT has technology to supervise rebar structures with AI. Structural supervision of rebar is performed by a structural engineer. They check whether construction follows the design, and if not, they request corrections or a work stoppage.
Choi said, "There aren't many structural engineers nationwide, so it's hard for them to visit every construction site," adding, "Even when they go on site, the land area is large and there are often holes in the floor due to construction, so only limited parts get inspected."
This is where AI can be used. Video shot with a helmet-mounted camera or a smartphone at the site is sent to a web platform and analyzed by AI.
Choi said, "Like Google or Naver Maps, the space is recreated on the web and AI automatically recognizes rebar placement, spacing, length, and more." Choi added, "In the past, when building, a person would inspect just one place among three to five floors, but AI can scrutinize every floor," and "because it can remotely and automatically identify even what people might miss, precise supervision is possible."
This helps prevent safety accidents. When constructing a building, rebar is sometimes lapped at 200–300 mm intervals or bent at 130–160 degrees. After confirming the rebar matches the design, concrete is poured and work continues.
Choi said, "If the rebar spacing should be 200 mm but is 400 mm, there is a high possibility rebar is missing," adding, "By detecting this, AI can improve construction quality and prevent safety accidents." The explanation is that this technology can be applied at apartment or officetel construction sites.
◇ "Finding voids in concrete with ultrasound"
The company also has technology to examine the inside of concrete using ultrasound and ground-penetrating radar. Even when concrete is poured, if voids (holes caused by poor placement, etc.) form, the rebar can corrode.
Choi said, "Due to issues such as noise between floors, slab (concrete ceiling) thickness is becoming more important," adding, "As with reading medical images with ultrasound during a health checkup, we can manage quality by examining whether there are internal defects in concrete."
The company not only measures the inside of concrete but also provides analysis services. When poor concrete compaction is found, it produces a quality report that the client, supervisor, and builder can use in decision-making. The goal is to create a safe and sustainable construction environment.
Choi founded Double S NDT in Aug. this year. Choi said, "We are conducting on-site demonstrations and research in collaboration with universities, research institutes, and construction companies," adding, "We plan to transfer the research results to industrial sites."
Double S NDT moved into Soongsil University Campus Town as part of the Seoul city Campus Town program. The Soongsil University Campus Town Promotion Group selects promising startups, provides office space, and supports practical training, business advancement, and expert consulting.