Self Healing Concrete Skip to main content

Self Healing Concrete

Self Healing Concrete 

Cracks in concrete are a common phenomenon due to the relatively low tensile strength. Durability of concrete is impaired by these cracks since they provide an easy path for the transportation of liquids and gasses that potentially contain harmful substances. If micro-cracks grow and reach the reinforcement, not only the concrete itself may be attached, but also the reinforcement will be corroded. Therefore, it is important to control the crack width and to heal he cracks as soon as possible.
Since the cost involved for maintenance and repair of concrete structure are usually high, this research focuses on the development of self-healing concrete. 

There are different investigation done and the following were concluded:

1) Concrete has an Autogenous healing capacity as unhydrated cement is present in the matrix. When Water contacts the unhydrated cement, further hydration occurs. Furthermore, dissolved CO2 reacts with Ca2+ to form CaCO3 crystal. These two mechanisms, however, may only heal small cracks.
So to enhance and to make use of this mechanism, microfibers are added to the mixture. By mixing microfibers in the concrete, multiple cracking occurs. So not one wide crack, but several small cracks are formed, which close more easily due to autogenous healing.
Self healing concrete and its properties

2) Super-absorbent Polymer SAP, or hydro-gels, are able to take up a large amount of fluid and to retain it in their structure without dissolving. When cracks occur, SAP are exposed to the humid environment and the swell. This swelling partly fills the cracks and the fluid absorbed by the particle is then available to the cement particle to form CaCO3 and fill cracks.

3) Cracks can be healed by using calcium carbonate precipitation micro-organisms. These organisms are embedded in the concrete matrix after immobilization on diatomaceous earth in mirocapsules or in SAP, and will start the precipitation of CaCO3 once a crack occurs. Through this process the bacterial cell will be coated with a layer of calcium carbonate, resulting in crack filling. 
Self healing concrete and its properties and details
4) One of the research programs considers the use of encapsulated polymer in order to obtain self healing concrete crack. When a crack appears, the capsules is braked and the content is released. Due to capillary action, the agent will flow into the crack. After reaction, the crack face are bounded together and the crack is thus healed.

5) While Fly Ash and blast furnace slag concrete seem to be inferior with regard to early age micro-structure and strength development, their self healing capacity can be much higher, precisely because  of the low hydration degree of the slag and fly ash particles. Upon cracking the unreacted particles can be activated again in order to close the crack and to regain the water impermeability and strength. 

Besides this all methods the concrete is treated in extreme environment and high sulphate and chloride concentrations or in the case of carbonation.


Comments

  1. Thanks for sharing such a valuable information. Excellent post.
    Whether you require repairs for your potholes or advice on achieving better drainage on your driveway, our staff can help improve the safety and value of your property.
    Construction Companies Winnipeg
    Concrete Paver Winnipeg

    ReplyDelete

Post a comment

Thank You for visiting, if you have any questions please feel free to ask:

Popular posts from this blog

Great Man-Made River (GMR)

Libya's Great Man Made River: The Great Man-Made River in Libya is one of the most ambitious Civil Engineering Project in history of mankind.  In the year 1953, the Libya Government found out not only vast oil reserves but also vast quantity of fresh water locked under the strata, most of the water was trapped around 7000-30000 years ago which is divided in 4 different basins. The first basin is named Kufra basin which is neat Egypt Border which covers almost 35000 sq kilometer which is quite deep around 2000 m deep. The other basin is in Sirte Basin which cover 10000 sq kilometer, third in Murzuk Basin and the last in Jabal Fezzan Basin covering 4800 sq kilometers area.  The GMR project will be used to transfer water to North of the country to provide water for irrigation purpose for more than 6 million  people. This will be a changing point  for Libya and the Colonel Muammar Gaddafi called it the Eighth Wonder of World. The work started in 1984 of the project and estimated to be

Timber Buildings !?

 Why do we need a timber building? Yes, timber buildings. As on earth human population is on an exponential rise, many and many people are trying to get home in a city where they have easy excess for the workplace for their own living. In the near future, as the population gets more concentrated in cities more and more structures I mean Tall Structures need to be built. Loading Bearing and Comparison So now architects and builders have opted for the old Technic of using timber as a building material eliminating concrete and steel. Yes, it is very hard to find this amount of trees but not impossible. It can be grown and regrown as needed. Many projects have been in progress of this idea and it reduces about 75% of carbon emission as compared to concrete and steel structure. Using timber coming directly from the forest doesn't have the appropriate strength required for a high-rise building. So designers came up with the new idea of CLT i.e. Cross Laminate Tim

DDSS - Roof Truss

Design Of Roof Truss: If load from purlin, false ceiling etc are applied in between the nodes, then principal rafters or main ties are designed for combined stresses from bending and axial loads. IS 800 - 2007 provides general design procedure for the angle Purlins conforming to steel grade of Fe 410 of O, S, W  and not exceeding slope more than 30 degree based on live load of 750 N/m2. Loads on Trusses: Dead Load, Live Load, Wind Load and Snow Load are types of loads on the truss. The main in Design of Truss in small truss and some Industrial Truss. Dead Load (DL): If spacing of Truss is 4 m and pitch of truss is 1:4 then self weight of the truss is taken as, w = (l/3+6) of plan area .... in kN/m2. Then add all the dead loads with this such as GI sheet, AC sheet and Purlins weight. Then multiply with the plan area to get the actual DL. Live Load(LL): If the angle is less than 10 degree, then the LL will be directly taken as 750 N/m2. If slope of truss is more than 10 degree, live load