Defects in Concrete - Report Example

CONCRETE DEFECTS By Name: Course: Tutor: Institution: Date: Defects in Concrete Concrete structures should be carefully constructed and properly monitored during constructions and are regularly and according to the regulations constructed without any type of complications. However, in the course of preparation of the materials a defect can occur either due to negligence or materials defects. This can be traced to very many factors and especially problems that relates to environmental conditions at the time of concrete preparation as well as during construction period. It can also be rooted from the procedures used to concrete preparation. In order to come up with the best repair method, it is crucial for one to identify properly the causes of the defects. This type of evaluation is necessary as it ensures that the repairs that are conducted are as effective as the repairer would wish and that the defect does not affect the concrete that surrounds it (Koren & Hall 2012). Identifying Concrete Defects At times it takes a long period of time to detect a certain defect on concrete since it is difficult for unskilled persons to identify the defects. However, many concrete defects can easily and immediately be recognized while others are difficult to. It is crucial to correctly identify the defects as doing so will aid the proper identification of the defect and it will help to choose the appropriate way of evaluation as well as the best method that can be used to repair the concrete defect. The different concrete defects are easily categorized into four groups that are wide and are based on the visual observation of the defect. The categories may include; surface deformation, surface cracks, surface disintegration, other defects that are visual. Surface Deformation This type of defect is where by it is visible from the surface either of the wall or the floor that has been built using the particular concrete. There three defects that are known to cause concrete surface deformation. However, they may not be able to show other symptoms. The first of the defects is warping of the concrete or curling. This type of defect is characterized by the deformation and dilapidating of the corners and the edges of a slab-on-ground without any loads or even any pressure being applied. This type of defect can be caused by a lot of moisture and it is at this time that it is called warping. However, the defect can also be caused by extreme temperatures and at that time it is known as curling. The other type of defect is the failure mechanism of surface mortar. It is especially noted from the underlying concrete and is also known as delamination. It is very hard for the unskilled persons to visually and clearly see delamination before the defect is clearly dislodged against the surface of the mortar. However, this defect can also be noted through another characteristic of rising in some discrete locations that are very small. The rise from the other mortar and this is called blistering which is clearly seen when one is keen in examining the defects of the concrete. In most cases he blisters are sparsely located but in other times depending on the degree of defect the blisters may be in close range which at times may come close enough to form one big blister that creates delamination. The third type of defect is when isolated and few low spots that are on the surface of the concrete collect and store water on them since there is no means of drainage of the water. The water on the surface forms small pools that are called the “birdbaths.” (Llewellyn 2002). Surface Cracks Cracks on the surface of the concrete can appear for very different and distinct reasons. The cracks may appear due to other defects that may be on the concrete and hence it becomes just a secondary symptom due to the other defects. The defects that mostly cause cracks as secondary symptoms are a structural failure from a warped slab. This may cause a very large crack that can be dangerous to the users. However still, there cracks that are primary symptoms and that may cause other defects. These are the types of cracks that will be discussed here. Shrinkage cracks are very crucial to understand as they are very in nature and portray different shapes and looks and therefore become difficult to identify them and differentiate from the cracks that are caused by other defects. These types of cracks are discreet and are parallel which look like a tearing that was formed while the concrete had not dried off. This is known as the plastic shrinkage (American Concrete Institute 1967). There are also some very small and fine cracks found on the surface. The fissures can only be seen as the concrete is in the process of drying up and it is moistened. The fissures are known as crazing. This type of defect also at times becomes evident when a coating that is translucent is applied on the surface of the concrete when it is clearly visible. “Cracking that occurs in a three-point pattern is generally caused by drying shrinkage. Large pattern cracking, called map-cracking, can be caused by alkali-silica reaction within the concrete. Structural failure cracking may look like many other types of cracking; however, in slabs they are often associated with subsequent elevation changes, where one side of the crack is be lower than the other” (American Concrete Institute 1979). Surface Disintegration This is a type of defect that is also very dangerous when noted on concrete as it may have some serious defects that it causes to the concrete leading to its weakening and later fall out. It is caused by distress of the concrete, heat difference in chemical combination as well as too much moisture on the concrete. “Disintegration of the surface is generally caused by three types of distress. When laitance forms on the surface, it is called dusting. This can be caused by a number of reasons, which include carbonation of the surface by unventilated heaters or by applying water during finishing. Ravelling or spelling at joints occurs when aggregates or pieces of concrete from the joint edges are dislodged. The last form of disintegration is the breaking of pieces from the surface of the concrete generally caused by delaminations and blistering. Pop outs are conical fragments that come off the surface, typically leaving a broken aggregate at the bottom of the hole. Pop offs, or mortar flaking, is similar to pop outs, except that the aggregate is not broken and the broken piece is generally smaller. Flaking of the concrete surface over a widespread area is called scaling.” (Reynolds 1967). Below is an image of disintegration defect. By the look of the image one can clearly see by touching the surface of the concrete one is left with sand and cement on the hands, a clear indication of the defect in picture. Evaluation of Concrete Defects It is critical to properly examine the possible defects on concrete to avoid any major risks in future. This is because; visual examination does not give enough information about the defects, their causes, as well as the remedy to avoid major effect to the surrounding. In checking of the defects the most important factor of the defect is the cause. This is because it provides enough information to cure the defect. Visual examinations do not provide the necessary evidence of a defect to both the skilled and the unskilled personnel at all. So as to narrow down the scope of investigation and at the end get reliable information and a proper and suitable method of dealing with the defects it is necessary to gather the information skilfully and in a professional manner. This helps identify the proper methods to repair and eliminate the defects (Concrete construction 1999). Conclusion In conclusion, it is necessary to have proper evaluation and it does not have to be visual examination. A professional way of examination is necessary so that it can lead proper information for the elimination of the defects. There are several methods that are different and they provide the exact information that is necessary and that can be relied on and which can be used in identification or aid to identify the different causes that cause a given specific defect. It is also necessary to use the professional ways of evaluation so that one can avoid making a mistake in the process of trying to find out the causal agent of the defect. This will reduce making of mistakes that may lead to excessive destruction (Concrete construction 1956). Reference list American Concrete Institute. 1967. Concrete construction. Detroit. American Concrete Institute. 1979. Concrete international: Design & construction. Detroit, MI: The Institute. Concrete construction. 1956. Addison, Ill., etc.: Concrete Construction Publications. Concrete construction. 1999. Addison, IL: Aberdeen Group. Koren, L., & Hall, W. 2012. Concrete. London: Phaidon. Llewellyn, C. 2002. Concrete. New York: Franklin Watts Reynolds, C. E. 1967. Concrete construction. London: Concrete Publication. Read More