Describe the advantages and disadvantages of prestressed concrete compared to normal reinforced concrete
Category : Construction Essays
As a person with knowledge of Materials Technology, the author has always brought up to his superiors the viability of strategy formation regarding the analysis of concrete technologies and at times fails to understand the reasons or logic behind certain strategic implementations imposed on its distribution .
By delving into this project paper, the author intends to have better insights into how concrete technologies are thought up, formulated and then integrated down into the framework of buildings and establishments. The author hopes to have an in-depth understanding as to how the utilization of concrete technologies enable the rise of buildings and establishments that are safe and secured enough to compete effectively and profitably in this era of internationalization where competition is extremely intense.
In order to reinforce the learning objectives, two key focal issues were focused upon, i.e. innovation and diversity. Innovation was discussed with regard to concrete technologies where they were renowned for their development and manufacturing capabilities to constantly innovate. Diversity came under strategic thinking and formation as the author considered the diverse culture, political climate, economic surroundings, social environment, technological settings, government policies and legal systems in order to better understand the issues being discussed.
Reinforced concrete is concrete that cannot stand alone. It has to be supported by rebars or fibers to make it firm and tough enough to hold. Nowadays, almost all building constructions use reinforced concrete, especially the skyscrapers and highly significant establishments.
Concrete is usually reinforced with steel. The resulting material is string and durable enough to withstand shaking, bending, and weathering. To achieve the best results, it also takes the right type of concrete and steel. If successfully achieved, establishments with reinforced concrete as their major foundations can support up to an amazing 500 times their combined weight and yet still maintain its durability as a strong, solitary building ( 1989).
Advantages of Reinforced Concrete
First, the coefficient of thermal expansion of concrete is as tough and strong as steel. This eliminates the possibility of the occurrence of internal breakdown even after long periods of time. Second, the bond that forms between the cement and the concrete is also hard and durable enough to prevent any breakdowns of the steel supports. Although of course steel bars are also corrugated to enable the smooth process of bonding with the concrete to materialize. Lastly, the lime mixture found on the concrete mixture creates protective shield on the surface of the steel foundations, enabling it to endure even the hottest or moist conditions.
Disadvantages of Reinforced Concrete
Buildings and establishments made under the foundations of poorly constructed reinforced concrete are susceptible to damages brought about by rusting. When the steel foundations are exposed to rust, the concrete becomes unattached from the steel, causing the total structural breakdown if not detected early. Poorly constructed reinforced concrete is also susceptible to damages that can be brought about by hot and cold water. Whenever water is able to enter the reinforce concrete, it will start to wreak havoc by creating cracks, and eventually holes on the affected structure. The end result of this is also structural failure.
In areas where weather conditions are unpredictable, buildings and establishments made under the foundations of poorly constructed reinforced concrete are susceptible to damages that can be brought about by carbonation, as well as chloride and silica reactions. As a preventive measure, epoxy is being used to repair the cracks, holes and other damages that reinforced concrete foundations have undergone (1995).
Prestressed concrete incorporates a technique in order to compensate for the concrete's immediate susceptibility in terms of handling tension. When properly done, prestressed concrete is strong and durable enough to sustain floors and major roads longer than what a reinforced concrete can give. The process of prestressing a concrete is normally done in three ways:
a) Pre-tensioned concrete is bonded around tensioned tendons. This technique creates a strong and tough combination of tendon and concrete. The concrete is able to secure the tendon from unnecessary damage and tension is safely handled by the tendons.
b) Bonded post-tensioned concrete uses the technique of the integration of the process of compression after the concrete is placed. The concrete is bonded with steel, and the tendons are tensioned by hydraulic jacks that react against the concrete member itself.
c) Unbonded post-tensioned concrete undergoes a unique process where each tendon is able to move in accordance to the shape or structure of the concrete. For this to happen, each tendon is applied with a specialized grease and protected by a sheathing formed in an extrusion process.
Advantages of Prestressed Concrete
First, the usage of prestressed concrete translates to minimal construction costs as compared to the usage of reinforced concrete. Second, since prestressed concrete makes use of thinner slabs, then the floor thickness savings can be transformed into additional floors. Third, the usage of prestressed concrete often translates to an increased floor space in establishments. Fourth, since the usage of prestressed concrete significantly reduces the number of joints, this translates to the reduction in maintenance costs over the design life of an establishment ( 1997).
Disadvantages of Prestressed Concrete
Buildings and establishments made under the foundations of poorly constructed prestressed concrete are susceptible to damages. Poorly constructed prestressed concrete dries faster than usual. This leads to the possibility that the concrete may shrink due to evaporation. When this happens, the foundations of the establishment are put under tremendous stress, resulting in the formation of cracks within the tendons leading to its collapse.
Prestressed Concrete vs. Reinforced Concrete
Head to head, prestressed concrete offers more advantages and lesser disadvantages than reinforced concrete especially in the following aspects:
Prestressed concrete is able to take the shape of the mold easily without any significant effects on its consistency as compared to reinforced concrete. On the other hand, reinforced concrete normally uses a significant level of water to take the shape of its mold. Add the fact that it is often very hard to measure the appropriate amount of water that will make the reinforced concrete bond with the steel reinforcement.
B) Overall Strength and Durability
The overall strength of concrete is determined through its water-cement ratio. Since prestressed concrete has a lower water-cement ratio than reinforced concrete, the former makes a stronger concrete than the latter.
Due to the reduction of its tensile stress, prestressed concrete is more elastic than reinforced concrete.
The results of the analysis carried out on both the prestressed and reinforced concrete indicated very significant benefits for the prestressed concrete, even amidst the threats of environmental factors. Therefore, we could conclude that the utilization of prestressed concrete is much better than reinforced concrete, but it could still depend on the demands of the situation.
The review of the capabilities and strengths of prestressed concrete revealed very little inconsistencies as compared to the reinforced concrete. This is coherent with its traditional inside-out strengths. However, the need to reconcile both the inside-out and outside-in strengths becomes imperative now for the engineers and project management group.
The analysis among the capabilities of both the prestressed concrete and the reinforced concrete revealed certain gaps, most of which are biased towards the environmental factors. However, these gaps paved the way towards determining a number of recommended strategic options to secure the competitiveness of both concretes.
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