Deviser: Dr. Chan -Moon Chung

Address: South Korea Yonsei University

 The new material being capable of self-repair at small cracks and holes now becomes not strange for the expert of construction .

Concrete is the most useful material in the construction, but it has some disadvantages compared with other material , especially the resilience to weather, compared with rock. Salt and ice are often to be the cause of small cracks and holes, making concrete structures becoming vulnerable to penetration by water. So the consequences is expense and labor cost for repairing and upgrading concrete structures .

The self- healing concrete is not a new idea . Since 2009 , the research group of Delft University of Technology , The Netherlands showed the feasibility of incorporating some special bacteria having the ability to secrete chemicals to mend the cracks in the concrete before pouring . The bacteria that keeps the concrete structure stronger, but they only take effect when alive . But the tests at also showed that bacteria exist only within not more than one year .

 Dr. Chan -Moon Chung , Yonsei University, South Korea is one of the scientists hoping to create a self-healing material . Instead of access to biological research , Dr. Chung studied using chemical methods .

 He and his colleagues found that , when two substances called methacryloxypropyl -terminated polydemetylsiloxan and benzoin isobutyl be mixed together , along with the sunlight , they will transform into a waterproof polymer , easily bonding with concrete . Difficult problem is how to preserve until needing time to release these chemicals .The solution was placed in a healding plastic in the microcapsules made ​​with urea and formaldehyde . We keep a safe chemical mixture and break up when the concrete cracked , releasing chemical mixture.

For capsules , the researchers mixed and stirred  water , urea , ammonium chloride and benzene are called resorcinol . Then the researchers team mixed methacryloxypropyl -terminated polydemetylsiloxan , benzoin isobutyl ether and formaldehyde , and then cooked mixture at a temperature of 55 ° C for four and a half hours . If this process is successful, will create capsule containing two concrete healing chemicals as desired .

 To deploy using the capsule , Dr. Chung mixed with thin polymer , spray this mixture on some concrete block samples and harden membranes . Then he turns smashing each concrete block and leave them in the sun conditions in four hours , with the hope that the cracks in the concrete will break polymer capsules containing the liberation of substance inside . After exposure to the sun , concrete creates a waterproof layer . He then soak them in water for concrete block , and reality has proven chemical processes occur successfully .

24 hours later , he brought Chung measure and weigh the amount of water in hydrated concrete blocks . Results are average size concrete containing 11.3 g of water ; concrete capsules 3.9 g water entrapment , but the impression is more concrete coated capsules containing polymer layer absorbs only 0.4 g water . So the aspirations and efforts of Dr. Chung is paid off , the block has self-healing concrete cracks .

Sources: NASATI (According to techmartvietnam.vn,)