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Concrete in practice

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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.

A Lecture on Concrete Basics			Types of Concrete
Concrete has been the most common building material for many years. It is expected to remain so in the coming decades. Concrete 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... [Read More]			Normal concrete High-Strength Concrete High Performance Concrete Air Entrained Concrete Light Weight Concrete Self Compacting Concrete Shotcrete Pervious Concrete
Properties of Concrete			Batching, Mixing, Placing & Compaction of Concrete
Setting Workability Bleeding and Segregation Bleeding Segregation Hydration Air Entrainment			Concrete is a construction material that consists, cement, aggregate i.e. gravel and sand and... [Read More] Batching of Concrete Mixing of Concrete ingredients Placing of Concrete Compaction of Concrete
Tests on Concrete			Concrete Mix Design
Tests Slump Test Compression Test Test for Poisson's ratio of concrete Test for Mod. of Elasticity of concrete... [Read More]			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]
Planning and site preparation			Concrete Admixtures
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..... [Concrete Planning Read More] 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... [Read More]			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
Applications of special concrete			Lab work & Practicals
Special Concrete includes hot & cold weather concreting, prestressed concrete, high performance concrete, Polymer modified and self compacting concrete.... [Read More] Cold Weather Concreting Hot weather Concreting			Civil Engineering Practicals of concrete, Engineering materials and other fields available for a free download here: Civil Engineering Practical Notebooks

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