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Civil Concrete Technology Lectures Notes Download
Concrete in practice
Concrete is a composite with properties that change with time. During service, the quality of concrete provided by initial curing can be improved by subsequent wetting as in the cases of foundations or water retaining structures. However, concrete can also deteriorate with time due to physical and chemical attacks. Structures are often removed when they become unsafe or uneconomical. Lack of durability has become a major concern in construction for the past 20 to 30 years.
In some
developed countries, it is not uncommon to find large amount of resources, such as 30 to 50% of total
infrastructure budget, applied to repair and maintenance of existing structures. As a result, many government
and private developers are looking into lifecycle costs rather than first cost of construction.
Durability of concrete depends on many factors including its physical and chemical properties, the
service environment and design life. As such, durability is not a fundamental property.
One concrete that performs satisfactory in a severe environment may deteriorate prematurely in another situation where it is consider as moderate. This is mainly due to the differences in the failure mechanism from various exposure conditions. Physical properties of concrete are often discussed in term of permeation the movement of aggressive agents into and out of concrete.
Chemical properties refer to the quantity and type of hydration products, mainly calcium silicate hydrate, calcium aluminate hydrate, and calcium hydroxide of the set cement. Reactions of penetrating agents with these hydrates produce products that can be inert, highly soluble, or expansive. It is the nature of these reaction products that control the severity of chemical attack. Physical damage to concrete can occur due to expansion or contraction under loading
Concrete has been the most common building material for many years. It is expected to remain so in the coming decades. Concreting is widely used in domestic, rural, commercial, recreational and educational construction Communities around the world rely on concrete as a safe, strong and simple building material. It is used in all types of construction; from domestic work to multi-storey office blocks and... |
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Concrete is a construction material that consists, cement, aggregate i.e. gravel and sand and... |
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Tests |
Mix design can be defined as the process of selecting suitable ingredients of concrete and determining their relative proportions with the object of producing concrete of certain minimum strength and durability as economically as possible. Design of concrete mix requires...  [Read More] |
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The most important step in placing concrete is planning. Planning means to determine the workability required, the type of concrete to be made, method of placing and mode of transportation, etc. Always plan every step before any concrete is delivered.
Proper planning avoids..... Site preparation is to clear the way for concrete to its place of installment, to identify joints of installment etc. The following steps should be taken before any concrete is placed... |
In concrete a substance other than active and inert matter, added in small amounts to the mix to alter its natural properties to required properties... [Read More]1. Accelerating admixtures 2. Retarding mixtures 3. Fly ash 4. Air entraining admixtures 5. Water reducing admixtures |
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Special Concrete includes hot & cold weather concreting, prestressed concrete, high performance concrete, Polymer modified and self compacting concrete.... |
Civil Engineering Practicals of concrete, Engineering materials and other fields available for a free download here: |
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Workability is one of the physical parameters of concrete which affects the strength and durability as well as the cost of labor and appearance of the finished product. Concrete is said to be workable when it is easily placed and compacted homogeneously i.e without bleeding or Segregation. Unworkable concrete needs more work or effort to be compacted in place, also honeycombs &/or pockets may also be visible in ... |
The type of concrete generally with compressive strength of 6000psi (40MPa) or greater is called as HSC. We need high strength concrete in our modern infrastructures in order to put the concrete into service at much earlier stage, To build up high rise building by reducing column sizes and increasing available space or in case of long span bridges. Now what is mix design?... |
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Strength can be defined as ability to resist change. One of the most valuable properties of the concrete is its strength. Strength is most important parameter that gives the picture of overall quality of concrete. Strength of concrete usually directly related to cement paste. Many factors influence the rate at which the strength of concrete increases after mixing. Before coming toward the factors that influence the strength gain of concrete, it is important to have concept of these terminologies... |
The compressive strength of concrete is calculated by the failure load divided with the cross sectional area resisting the load and reported in pounds per square inch in US customary units and mega pascals (MPa) in SI units. Concrete’s compressive strength requirements can vary from 2500 psi (17 MPa) for residential concrete to 4000psi (28 MPa) and higher in commercial structures. Higher strengths upto and exceeding 10,000 psi (70 MPa) are specified for .... |
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 Applications of Aggregates |
 Advantages of Prestressed Concrete |
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Aggregate can be used in a number of ways in construction. In roads and railway ballast the aggregates are used to resist the overall (static as well as dynamic) load, to distribute the load properly to the supporting ground and to drain the water off the surface. In concrete the aggregate is used for economy, reduce shrinkage and crakes and to strengthen the structure. They are also used in water filtration and sewage treatment processes. The uses of aggregates can be summarized in to the following three categories.... |
The prestressing of concrete has several advantages as compared to traditional reinforced concrete (RC) without prestressing. A fully prestressed concrete member is usually subjected to compression during service life. This rectifies several deficiencies of concrete. The following text broadly mentions the advantages of a pre-stressed concrete member with an equivalent RC member. For each effect, the benefits are listed.... Although prestressing has advantages, some aspects ..... |
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