ABSTRACT


Mitigation of Carbonation of High Volume Admixture Concrete by Applying Refined Cooking Oil



Choi, Young Doo
Department of Architectural Engineering
Cheongju University
Directed by Professor
Han, Cheon Goo


In recent years, reducing carbon dioxide is regarded as one of the most important action to delay global warming in many countries. It is obvious that manufacturing cement is the main cause of releasing the carbon dioxide in a construction industry. Hence, many researchers have studied to replace cement with mineral admixtures as constituents of concrete, and found that the replacements have many positive effects on the properties of concrete. However, one drawback of the replacements is a carbonation problem, deteriorating the durability of concrete structures.


In previous research work, it was found that the addition of small amounts of waste cooking oil (RCO) in concrete had an effect on filling the capillary pores by chemically reacting with a hydration product, calcium hydroxide. In this current study, RCO is used as the surface-coating material of concrete. By applying RCO to the surface of the concretes with the high volume of fly ash and blast furnace slag, this study mainly investigates its effect on protecting the concretes from carbonation attack. Key findings drawing from this study are as follows.

For the types of surface-coating materials, experimental test results showed that the application of a RCO type was the most effective on delaying the carbonation of concrete, regardless of the contents and types of replacements. In addition, it is important to note that the level of effectiveness of the RCO technique is dependent on the right time of its application. Applying RCO to the concretes after exposing to the accelerated carbonation environment for four weeks have an minor effect on reducing the carbonation depth of 10 to 14%, compared to the control concrete without the application of RCO, whereas applying RCO to the surface of concretes right after de-moulding the concretes have a significant effect on reducing the carbonation depth of 40 to 50%.


It is concluded that the surface-coating method using RCO significantly resists the possible deterioration of concrete attributed to the carbonation process. This RCO technique is good for the concrete with the high volume of mineral admixtures as replacements of cement, and is recommended to be applied right after de-moulding the concrete for the optimum result.