Surface Finishability of Concrete According to Degree of Damage and the Number of Uses of the Aluminum Form

As concrete forms, panel forms made of plywood used to be widely used, but recently a system form made of aluminum has been broadly adopted because of the advantages it offers in terms of constructability and economy. However, an aluminum form reacts with concrete, which is alkali, and creates hydrogen gas. As a result, air pockets occur on the concrete’s surface, and its finishability deteriorates. Therefore, this research analyzed the relationship between the distribution of voids and surface roughness and the damage degree and number of uses of the aluminum form. The analysis of the distribution of voids shows that the number of voids of 0.1~1 mm, which are considered to have occurred because of chemical reaction, was 200~500 on the coating plywood, but was 1 500~2 000 on the aluminum form after 3 uses, and impossible to count after a higher number of uses. Surface roughness was 1.7~3.2 ㎛ on the coating plywood form, but was about 2.6 ㎛ after the first use and about 6.8 ㎛ after 10 uses, a 2.6-fold increase. Distribution of voids did not show a particular tendency depending upon the degree of damage to the concrete form, but surface roughness showed an increasing tendency as the degree of damage grows. Therefore, when using aluminum forms, surface maintenance should be carried out completely, such as prevention of damages to the form surface coating materials and spreading of separating materials on forms.