Investigations have shown that the principal cause of the deterioration was corrosion of reinforcing steel due to the presence of chlorides, with marine salts being the main source. But material limitations, design and construction practices, and severe exposure conditions can cause concrete to deteriorate, which may result in aesthetic. Pdf a study on deterioration of reinforced cement concrete. Deterioration of reinforced concrete in sewer environments article pdf available in municipal engineer 1591.
The deterioration of reinforced concrete structures is a major problem. Guide for concrete floor and slab construction, aci 302. Introduction this chapter presents information on how to conduct an evaluation of the concrete in a concrete structure. The hypothesis that is followed during the design and the structural analysis of reinforced concrete structure is that the concrete will crack in the tension zone before the reinforcement bars will take the tension. Deterioration and nondestructive evaluation nde of concrete structures 22 earthquake resistant design. Mk685gb0711 headquarters mapei spa via cafiero, 22 20158 milan italy tel. Relative size will affect strength and detailing for practical reasons. Failure, distress and repair of concrete structures 1st. Topics define environmental concrete structure pictorial examples historical stroll down memory lane nrcs based wsdasd flexural model usdlrfd flexural model the new millennium aci 318, aci 350, and nrcs concrete design criteria sidebyside ncsea september, 2012 environmental concrete structures 2. Effects of concrete deterioration on safety of dams. Pdf the deterioration of reinforced concrete structures not only depends on the. The performance of concrete structures depends upon the quality of construction and the environment. With the data generated using fly ash concrete and portland cement concrete see fly ash reference data sheet no.
Deterioration and condition assessment of concrete structures. Chloride ingress is a common cause of deterioration of reinforced concrete bridges. Durability of reinforced concrete structures,theory vs practice. Pdf case studies of concrete deterioration in a marine. If a repair is to be successful it must address the cause, seek to repair. Bhattacharjee focuses on issues related to service life of concrete structures. An appendix for the structural design of foundations using limit state philosophy as foreseen by envec7, has also been included. Aalborg universitet deterioration of concrete structures. Manual for assessing corrosionaffected concrete structures. Deterioration mechanisms of reinforced concrete structures. Pdf deterioration of concrete structures semantic scholar. He includes mistakes discovered at the design stage, ones that.
Materials and methods for corrosion control of reinforced. Development of strategic maintenance is the highest priority under the background of aging of huge amount of stock of concrete structures and restrained budget. This paper presents probabilistic and sensitivity analysis of service life or time to repairs for attaining corrosionfree condition of concrete structures under chloride attack. Concrete can deteriorate for a variety of reasons, and concrete damage is often the result of a combination of factors. Therefore, an inhouse local concrete mix is proposed combining high strength and dense internal structure as summarized in table 2 below. Concrete basicsaddresses the needs of unskilled and semiskilled persons undertaking general concreting projects including home and handyman projects. Structural performance deterioration of reinforced concrete structures has been extensively investigated, but very limited studies have been carried out to investigate the effect of reinforcement corrosion on timedependent reliability with consideration of the influence of mechanical characteristics of the bond interface due to corrosion. Deterioration of concrete structures thoftchristensen, palle publication date. Evaluation of the concrete in concrete structures 21. A reinforced concrete structure may deteriorate because of deterioration of the.
Repair and seismic retrofit of concrete structures pdf. A level 3 inspection to assess the cause, extent and rate of deterioration where possible is preferable before repair work is undertaken on structures. Several researchers have performed studies to indentify the causes of deterioration of rc structures, wang and liu 2010 identified change in bond strength, loss of concrete cover in tensile zone andor reduction of concrete cover in compressive zone as the major cause of deterioration of rc structures. The material reported here is drawn from many sources, which have, it is hoped, been adequately. Many concrete structures have been constructed in japan. However, concrete structures are vulnerable to a number of factors that can cause deterioration. Corrosion of reinforcing steel is the most common cause of concrete. This international standard treats design for environmental actions leading to deterioration of concrete and embedded steel. Deterioration of concrete takes place due to many reasons such as poor quality materials, degradation due to environmental effects, design and constructional errors or an adverse combination of these factors.
Four groups of probabilistic parameters are determined, i. Full bond strength needs to be developed to transfer shear forces into the concrete core. Concrete basicsaims to provide a clear, concise explanation of all aspects of making quality concrete. Errors in the design assumptions or the design process. Combining these factors results in another source of differential. Deterioration and condition assessment of concrete structures page 3 of 4 course convenor prof. Case studies of concrete deterioration in a marine environment in portugal article pdf available in cement and concrete composites 241. Protective coatings to prevent deterioration of concrete by deicing chemicals, national cooperative highway research program report no. A dditionally, the installation of wire mesh and rebar will significantly increase the durability of the concrete and provide greater structural strength and support to the slab. Proper concrete placement is essential not only to satisfy the design and service requirements of the structure, but also to decrease the potential for premature deterioration and reduced lifespan. Hans beushausen is a researcher and lecturer in the fields of structural engineering, construction material technology, structural condition assessment, and concrete repair technology at the university of cape town. Protection and repair of reinforced concrete structures by means of mciinhibitors and corrosion protective materials 555 h2o to the do reinforcing steel, and in this way they protect it against the oxidation processes, in distinction from anode inhibitors on the nitrites andor chromates basis, which. If the acid is able to reach the rein forcing steel through cracks or pores in the concrete, corrosion of the reinforcing steel will result and will cause further deterioration of the concrete aci 201.
Chapter 2 evaluation of the concrete in concrete structures. Effects of concrete deterioration on safety of dams 2 conclusions and recommendations 2. To evaluate the concrete for deterioration, a fairly level mat of steel is chosen within the concrete as the base reflection. In30902i contecvet a validated users manual for assessing the. Construction defects and durability of concrete structures. Baiant, elsevier applied science, london, 1140 reprinting of s25. Concrete may be exposed to chloride by seawater or deicing salts. Assessment of concrete damage and strength degradation. When concrete structures deteriorate, it is extremely costly to repair or replace them. Case studies in reinforced and prestressed concrete presents a selection of the authors firsthand experience with incidents related to reinforced and prestressed concrete structures. Concrete came into existence in last 200 years or so and it was expected that concrete should behave like stone structures.
The rate of carbonation in concrete is influenced by both its physical properties and exposure conditions. Deterioration can result in loss of strength and unsafe conditions. Aci 56216 code requirements for assessment, repair and rehabilitation of existing concrete structures was developed to provide design professionals involved in the assessment of existing concrete structures a code for the assessment of the damage and deterioration, and the design of appropriate repair and rehabilitation strategies. This paper describes the deterioration of reinforced concrete structures at a liquefied gassulfur plant that occurred shortly after completion of the construction. Environmental engineering concrete structures introduction. Deterioration of concrete structures fprimec solutions inc. Chapter 5 environmental deterioration of concrete wit press. It provides an overview of deterioration and damage mechanisms but. However many structures world over have shown deterioration during the last 6070. Concrete is usually a durable material whose usefulness equals or exceeds its intended service life. But with the introduction of steel reinforcement in concrete, its structural utility has been enhanced for taking tensile loads. Deterioration mechanisms and diagnostics of concrete structures 3.
Identifying defects in the assessment stage of an rps project is important in developing the proper repair plan to address the specific cause of the. Properly designed concrete structures are both strong and durable. Pdf some issues related to service life of concrete structures. Types and causes of concrete deterioration the exceptional durability of portland cement concrete is a major reason why it is the worlds most widely used construction material. Detailed nondestructive bridge inspection guidelines. The amount of reinforcement is limited to 6 c y f f 4. Corrosioninduced deterioration of steel rebar in concrete structures often demands costly repair and maintenance, where the steel rebar swells and increases the tensile load in concrete resulting in cracks, spallings and openings that increase its susceptibility to corrosion. Deterioration of concrete structures can become a challenge for the owners of these structures. Structural concrete structures reinforced concrete construction. Some concrete structures show severe deterioration and need repair or strengthening to keep their serviceability.
The following summary discusses potential causes of concrete deterioration and the factors that influence them. The flowchart in figure 1 illustrates the flow of decisions and the design activities needed in a rational service life design process with a chosen level of reliability. Manual for the design of reinforced concrete building. Mechanism of deterioration and penetration of aggressives. Causes for accelerated structural deterioration of. If we observe a concrete construction which is in a condition similar to the one illustrated in photo 4, it is now possible to carry out an initial hypothesis regarding the cause of deterioration. An aci provisional standard american concrete institute. Areas of the concrete deck that reflect weaker amplitude values tend to indicate deteriorated concrete. Deterioration is the result of exposed concrete on balconies, improper detailing of the base plates of balcony railings, and a lack of waterproofing. The paper is aimed at the investigation of the concrete deterioration using various analytical methods.
Since many of the symptoms may be caused by more than one mechanism acting upon the concrete, it is necessary to have an understanding of the basic underlying causes of. Concrete deterioration reinforced concrete is a very versatile construction material. Rebar corrodes when carbonation reaches to a depth of concrete cover provided. It is important to identify these defects on time, and plan appropriate repair strategies. The deterioration of concrete thedeteriorationofconcrete c. Types and causes of concrete deterioration portland cement. The corrosion process ultimately causes concrete deterioration and loss of serviceability. Using a lowslump, low water content concrete with a high coarse aggregate content will minimize shrinkage and reduce cracking. In the present work, various concrete structures with different life periods and exposed to different weather conditions have been considered to study the. As was described in chapter 1, a thorough and logical evaluation of the current condition of the concrete in a structure is the first step of any repair or rehabilitation. Material and methods concrete samples were investigated in terms of the concrete deterioration influenced by both biogenic sulphate attack in situ experiments and 0.
Durability problems of 20 century reinforced concrete. Taketo uomoto professor emeritus, the university of tokyo chief executive, public works research institute when i was a student, i learned that if concrete with proper materials and proportions is sufficiently mixed and. Durability of concrete water both creates and destructs many natural materials pious q and poison q in porous solids physical process of deterioration vehicle for transportation of aggressive ions source of chemical degradation physicochemical phenomenon surface and internal deteriorations rate of deterioration affected by concentration. Although much research is focused on the development of knowledge in the field of concrete deterioration processes and on the improvement of nondestructive evaluation techniques ndt, a huge gap exists between what is known and what is put into practice. Premature deterioration of a concrete building or its components can occur, however, if the concrete is not of adequate quality, the building and the concrete were not properly designed for the service environment, or the environment was not as anticipated or changed during the. Repair and retrofitting of deteriorated reinforced concrete structures. Study of the deterioration of concrete influenced by. Maintenance of prestressed concrete structures from. Once the evaluation phase has been completed for a structure, the next step is to establish the cause or causes for the damage that has been detected.