Lecture

Cracking and Sorption

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Description

This lecture delves into the complexity of concrete as a material, focusing on the formation and impact of cracks, particularly microcracks, on its properties and long-term durability. The instructor discusses the various types of cracks in concrete structures, the factors leading to their formation, and their influence on mass transport properties. Additionally, mitigation methods to control crack size and spacing, as well as future research directions, are explored.

In MOOC

Sorption and transport in cementitious materials

In the MOOC: “Cement chemistry and sustainable cementitious materials”; you learned how to create more sustainable cementitious materials. But concrete is not an inert rock. It is a dynamic porous material, which can exchange water, gas and ions with its environment. Through physical and chemical interactions, these exchanges can have dramatic consequences: cracks due to shrinkage, reinforcement bars corrosion, spalling, … For a true sustainability, the durability of cementitious materials should not be f

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Related concepts (14)

Concrete

Concrete is a composite material composed of aggregate bonded together with a fluid cement that cures over time. Concrete is the second-most-used substance in the world after water, and is the most widely used building material. Its usage worldwide, ton for ton, is twice that of steel, wood, plastics, and aluminium combined. When aggregate is mixed with dry Portland cement and water, the mixture forms a fluid slurry that is easily poured and molded into shape.

Reinforced concrete

Reinforced concrete, also called ferroconcrete, is a composite material in which concrete's relatively low tensile strength and ductility are compensated for by the inclusion of reinforcement having higher tensile strength or ductility. The reinforcement is usually, though not necessarily, steel bars (rebar) and is usually embedded passively in the concrete before the concrete sets. However, post-tensioning is also employed as a technique to reinforce the concrete. In terms of volume used annually, it is one of the most common engineering materials.

Prestressed concrete

Prestressed concrete is a form of concrete used in construction. It is substantially "prestressed" (compressed) during production, in a manner that strengthens it against tensile forces which will exist when in service. This compression is produced by the tensioning of high-strength "tendons" located within or adjacent to the concrete and is done to improve the performance of the concrete in service. Tendons may consist of single wires, multi-wire strands or threaded bars that are most commonly made from high-tensile steels, carbon fiber or aramid fiber.

Precast concrete

Precast concrete is a construction product produced by casting concrete in a reusable mold or "form" which is then cured in a controlled environment, transported to the construction site and maneuvered into place; examples include precast beams, and wall panels for tilt up construction. In contrast, cast-in-place concrete is poured into site-specific forms and cured on site. Recently lightweight expanded polystyrene foam is being used as the cores of precast wall panels, saving weight and increasing thermal insulation.

Types of concrete

Concrete is produced in a variety of compositions, finishes and performance characteristics to meet a wide range of needs. Modern concrete mix designs can be complex. The choice of a concrete mix depends on the need of the project both in terms of strength and appearance and in relation to local legislation and building codes. The design begins by determining the requirements of the concrete. These requirements take into consideration the weather conditions that the concrete will be exposed to in service, and the required design strength.

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