16 - CIVE 2700 Civil Engineering Materials, Winter 2007...

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CIVE 2700 – Civil Engineering Materials, Winter 2007 1 Concrete Professor George Hadjisophocleous, Ph.D., P.Eng. Carleton University Department of Civil and Environmental Engineering Ottawa, Ontario CIVE 2700 – Civil Engineering materials, Winter 2007, 16.2 Outline • Portland cement • Cementitious phase • Properties of concrete • Testing • Admixtures
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CIVE 2700 – Civil Engineering Materials, Winter 2007 2 CIVE 2700 – Civil Engineering materials, Winter 2007, 16.3 Introduction Concrete is one of the most common construction material: piles, multistory buildings, foundations, pavements, moldings. It is one of the most economical material of construction Important properties of concrete include: – Compressive strength – Durability and freeze and thaw resistance – Wear resistance – Impermeability – Abrasion resistance – Resistance to environmental attacks (sea water, soil, sulfates etc) – Fire resistance – Excellent resistance to water CIVE 2700 – Civil Engineering materials, Winter 2007, 16.4 Introduction Portland cement concrete consists of 1. Continuous binder phase – cementitious matrix . 2. Dispersed particulate phase – aggregates. Aggregates size varies from fine material smaller than 5mm to coarse aggregates with size usually in the range of 20 – 40mm. In most concretes aggregates are much stronger than the cementitious matrix and therefore most of the mechanical properties of the concrete are controlled by the continuous cementitious matrix. Presence of aggregates is important because: 1. It is an inexpensive filler 2. reduces deformation of concrete (creep and shrinkage).
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CIVE 2700 – Civil Engineering Materials, Winter 2007 3 CIVE 2700 – Civil Engineering materials, Winter 2007, 16.5 Cementitious Phase • Mixture of cement and water is known as cement paste. • Initially fluid – with time it becomes hard and strong due to chemical reaction between cement grains and water referred to as hydration reaction. – Paste is fluid as long as the individual grains are separated from are another. – Hydration products occupy a greater volume than the original cement grain (pore filling effect). – During the early stages of hydration sufficient contact has formed between hydration products so it partially looses its fluidity – referred to as setting. – Continuation of hydration process after setting results in the generation of strength due to bonding interactions between the hydration products (paste already a solid – strength is very low). – Progress of hydration from final setting time is accompanied by measurable strength increase (hardening stage). CIVE 2700 – Civil Engineering materials, Winter 2007, 16.6 Cementitious Phase Types of cement – There are two types of cements: hydraulic and non-hydraulic. – Hydraulic: any cement that turns into a solid product in the
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This note was uploaded on 11/13/2011 for the course CIVE 2*** taught by Professor - during the Spring '11 term at Carleton CA.

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16 - CIVE 2700 Civil Engineering Materials, Winter 2007...

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