A team of NUS Engineering researchers has discovered that grains of sand have the unique ability to potentially resist impact better than steel. While sand has been often used in military fortifications, little is known about its energy absorption capabilities.
Led by Assistant Professor Darren Chian Siau Chen from NUS Civil & Environmental Engineering (CEE), the researchers made the novel discovery after conducting tests where projectiles of various shapes and masses were fired against a silica sand block. Silica sand is one of the world’s most common variety of sand.
The team, which includes Associate Professor Vincent Tan (Department of Mechanical Engineering) and Adjunct Assistant Professor Anand Sarma (CEE), found that sand can absorb more than 85 per cent of the energy exerted against it. “Our findings show that sand holds a strong potential as a receiving layer of a composite material subjected to impact,” said Asst Prof Chian.
The NUS Engineering researchers also found that resistance offered by the sand block increases with the speed at which projectile travels. Different nose shapes and masses of projectiles were fired at a wide range of velocities. The impact also results in an extreme frictional force that could cause the projectile to break into pieces.
They also believe that the findings of their study may expand the applications of sand, which is presently used extensively in areas such as glass making, building construction and land reclamation. “These unique characteristics of sand may open up exciting new applications in areas that impact our daily lives, as well as in defence. For instance, steel, which is one of the key materials used in the construction of armour systems, can be partially replaced with sand as a costeffective, environmentally friendly, and lightweight sacrificial layer, given its superior energy absorption performance. Given the possibility of hostile threats, sand could also be used as a complementary building material to steel to enhance protection of critical infrastructures and household shelters, given its projectileresisting function,” added Asst Prof Chian.
The NUS Engineering team will be conducting larger scale trials to further study the ability of sand to resist impact, as well as starting research into the energy absorption capabilities of similar materials, such as rock rubble.