Imagine a concrete so light and soft it can gently stop a speeding airplane without causing damage. That’s exactly what researchers from the China Building Materials Academy (CBMA) Co., Ltd. have achieved with their groundbreaking “marshmallow” concrete.
Developed in collaboration with the China Academy of Civil Aviation Science and Technology and a Beijing-based tech firm, this ultra-lightweight foam concrete is set to transform runway safety. Recently awarded second prize for innovation by the China Building Materials Federation, this invention promises a safer future for air travel.
A Gentle Barrier
The “marshmallow” concrete looks like ordinary concrete but holds a secret: it’s over 80% porous and weighs just 200 kilograms per cubic meter—a mere tenth of the weight of standard concrete. This unique composition creates a “soft barrier” that absorbs the kinetic energy of an aircraft through controlled crushing.
“It looks solid, but crumbles upon impact, decelerating planes smoothly,” explained Fang Jun, a research and development engineer at CBMA.
Addressing Critical Safety Phases
Takeoffs and landings are the most critical phases of flight, accounting for a significant proportion of aviation accidents. To enhance safety, the International Civil Aviation Organization (ICAO) requires runway end safety areas (RESAs) that extend at least 90 meters beyond the runway.
Traditional RESAs have used water pools, grass areas, soil, or sand. However, these materials come with drawbacks. “Water pools can freeze in winter and attract wildlife, while soil surfaces are sensitive to environmental conditions, leading to unstable mechanical properties,” Fang noted.
Innovative Engineering
Creating a material that can absorb the immense energy of a landing aircraft required precise engineering. For instance, the foam concrete’s strength must be meticulously controlled within a range of 0.30 to 0.35 megapascals. “Unlike ordinary foam concrete, where higher strength is better, our material operates optimally at lower strengths with a very narrow fluctuation range,” Fang explained.
International solutions often use calcium sulfoaluminate cement, which, while effective, is expensive and can degrade over time. Seeking a more affordable and durable alternative, the Chinese team developed a formula using ordinary cement.
Blowing Bubbles into Concrete
The key to their success lies in the foaming process—essentially “blowing bubbles” into the concrete mixture. To strengthen these bubbles, the team introduced a maleated rosin-based twin-chain air-entraining agent. This innovative agent forms a strong “armor” around the bubbles, preventing the material from collapsing under stress.
Additionally, they developed a dual-stage strength-regulation technology that precisely controls the material’s strength development. This ensures the “marshmallow” concrete maintains its performance over time, even when exposed to environmental factors.
A Safer Future for Aviation
With this revolutionary material, airports, especially smaller ones, can enhance safety without incurring prohibitive costs. The “marshmallow” concrete stands as a testament to innovative engineering and its potential to make air travel safer for everyone.
