Name: special portland cements for durability
Uploaded: 2024-09-12T16:16:36.000Z
Duration: 1 min 22 s
Channel: JoVE

L’interbroyage du clinker de ciment Portland avec du laitier de haut fourneau granulé, un sous-produit du processus de fabrication du fer, produit du ciment de laitier.
Il peut être utilisé pour construire de grandes structures conçues pour résister à l’attaque des chlorures et des sulfates.
Le ciment blanc, fabriqué à partir de craie et de kalin, contenant moins de quantités d’oxydes de fer et de manganèse, a une couleur blanche distinctive et peut être utilisé pour créer des façades d’excellente esthétique.
L’ajout de pigments colorés qui ne nuisent pas au béton avec du ciment blanc produit du ciment coloré.
Les ciments expansifs, tels que les types K, M et S, sont produits en combinant du ciment Portland avec un agent expansif et un stabilisant. Cela permet d’éviter la fissuration par retrait grâce à une dilatation contrôlée due à la formation précoce d’ettringite pendant le durcissement.
Le ciment Portland entraîné par l’air utilise de plus petites quantités de matériaux entraîneurs d’air pour former des millions de bulles d’air microscopiques dans la matrice de ciment.
Cela fournit des espaces dans lesquels l’eau peut se dilater lorsqu’elle gèle, empêchant ainsi les fissures causées par les cycles de gel-dégel. 
Le ciment Portland imperméable incorpore des substances hydrofuges, garantissant que les structures exposées à l’humidité sont protégées contre les infiltrations d’eau.

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types de ciment ii

Types of Cement II

Le ciment Portland de haut fourneau est fabriqué en mélangeant du clinker de ciment Portland avec du laitier granulé de haut fourneau, qui représente 25 à 65 % du poids du ciment. Malgré ses similitudes avec le ciment Portland ordinaire (type I) en termes de finesse et de temps de prise, sa résistance initiale est inférieure, bien qu'il atteigne une résistance comparable par la suite. Il est particulièrement adapté aux structures en béton massif et aux environnements marins en raison de sa chaleur d'hydratation plus faible et de sa résistance supérieure aux sulfates.

Les ciments Portland blancs et colorés sont principalement utilisés lorsque les considérations esthétiques sont primordiales, comme les panneaux de murs-rideaux préfabriqués, les panneaux de parement, les sols en terrazzo, le stuc, le plâtre de finition et le coulis de carrelage. Ces ciments sont plus chers en raison des exigences de production strictes pour éviter les impuretés et obtenir une uniformité de couleur.

Le ciment expansif se dilate pendant la période de durcissement précoce pour compenser le retrait de séchage. Il existe trois types disponibles : K, M et S, qui diffèrent principalement par leur composition chimique. Le type K est conçu pour le contrôle général du retrait, le type M pour la résistance aux sulfates et le type S pour une exposition élevée aux sulfates. Chaque type est conçu pour minimiser les fissures en contrant les effets du retrait. Ce ciment convient aux situations nécessitant un changement de volume minimal pour éviter les fissures.

Le ciment Portland imperméable comprend des additifs comme le stéarate de calcium ou le stéarate d'aluminium mélangés au clinker de ciment Portland pendant le broyage, améliorant la résistance du ciment à la pénétration de l'humidité.

Types de ciment II

L’interbroyage du clinker de ciment Portland avec du laitier de haut fourneau granulé, un sous-produit du processus de fabrication du fer, produit du ciment de laitier.
Il peut être utilisé pour...

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special portland cements for durability

Special Portland cements are made for specific building needs, such as added durability, color, or lower cracking risk. One major example is Portland blast-furnace cement. It is made by blending Portland cement clinker with granulated blast-furnace slag, which makes up about 25 to 65 percent of the cement by weight.

Portland blast-furnace cement sets at about the same rate and has about the same fineness as ordinary Portland cement, which is Type I cement. Its early strength is lower, but it reaches similar strength later on. It is useful for mass concrete structures and marine environments because it gives off less heat during hydration and resists sulfate better.

White and colored Portland cements are used when appearance matters most. They are common in precast curtain-wall panels, facing panels, terrazzo floors, stucco, finish-coat plaster, and tile grout. These cements cost more because they must be made with careful control to avoid impurities and keep the color uniform.

Expansive cement is made to expand during early hardening so it can offset drying shrinkage. This helps reduce cracking when minimal volume change is important. Three types are available: K, M, and S. Type K is used for general shrinkage control, Type M is made for sulfate resistance, and Type S is for high sulfate exposure.

Waterproof Portland cement is another special type. It includes additives such as calcium stearate or aluminum stearate mixed into the Portland cement clinker during grinding. These additives improve the cement’s resistance to moisture penetration.

Special Portland Cements for Durability

concrete

Concrete Materials and Reinforcement

Concrete is a major construction material used in buildings, bridges, airfields, highways, dams, and silos. It is valued for strength, durability, and versatility in many structural designs. A concrete mix usually includes Portland cement, coarse gravel, fine sand, and water. Concrete can be mixed by hand or made at industrial plants with computer control. The mix has aggregates and a paste made from water and Portland cement. This paste coats the aggregates. Through hydration, a chemical...

portland cement

How Portland Cement Is Made

Portland cement is the main binding material in concrete. It is made from finely ground ingredients that include lime, iron, silica, and alumina. These materials give cement the properties it needs to hold concrete together. The raw ingredients come from several common natural sources. Lime is obtained mainly from limestone, marble, marl, seashells, and clays. Those same clays can also supply iron and alumina. Silica is sourced from sand, chalk, and bauxite. Making Portland cement starts by...

hydration of cement

Cement Setting and Strength Formation

Cement setting and strength formation begin when water is added to cement particles. The main reaction is called hydration. During hydration, the anhydrous cement compounds react with water and form new solids that help harden the material. Hydration can happen by two main paths: through-solution and topochemical. In through-solution, anhydrous compounds dissolve into their parts, hydrates form in the liquid, and then they come out of a supersaturated solution. In topochemical hydration,...

strength and heat of hydration

Cement Hydration Heat and Strength Gain

Cement hydration produces heat and builds strength at the same time. Hydration is an exothermic reaction, which means it releases heat as cement reacts with water. That heat of hydration is a key part of how cement develops strength. Most of the heat is released early in the process. About half is given off in the first three days, and about 75% is released in the first week. The rate of heat release also affects how much the temperature rises during hydration. Some cement compounds...

fineness of cement

How Cement Particle Size Changes Behavior

Cement particle size changes how cement behaves in concrete. Finer cement has more surface area, so hydration starts faster at the particle surface. This affects the rate of hardening and also influences workability, gypsum requirement, and long-term behavior. Cement fineness is usually described by its specific surface area. This is the total surface area of cement particles per unit mass, and it is often measured in square meters per kilogram. Several methods can be used to determine it,...

setting time of cement

Cement Initial and Final Set

Cement setting time describes how cement paste changes from a plastic state to a solid state. This change matters in construction because it sets the window for placing, compacting, and finishing concrete. The first stage is called the initial set. At that point, the paste becomes unworkable. The next stage is the final set. By then, the paste has solidified completely, and further handling can no longer change its shape. Cement strength is still very low at this stage because hydration of...

soundness of cement

Cement Expansion Tests for Soundness

Cement soundness is the ability of cement paste to keep its volume after it sets. If cement is unsound, it can expand later and damage a structure. This problem can come from free lime, magnesia, and calcium sulfate in the cement. Free lime hydrates very slowly. As it reacts, it can expand and cause unsoundness. It is also hard to detect because it intercrystallizes with other compounds in the cement structure. Magnesia can also react with water. It forms crystals that may disrupt the cement...

strength of cement

Cement Strength Tests and Standards

Cement strength is measured with standard tests that use mortar, not neat cement paste. Cement paste alone is hard to shape into specimens that give consistent and reliable results. For that reason, the test samples are usually made with cement and sand. For compressive strength, ASTM C 109-05 uses a cement-sand mix ratio of 1:2.75 and a water/cement ratio of 0.485. The mixture is cast into 2-inch cubes and cured in saturated lime water at 23°C until testing. This method measures how well the...

types of cement i

Portland Cement Grades and Uses

Portland cement comes in several grades with different properties and uses. Its chemical composition and hydration behavior help determine how it performs in concrete. These differences matter in general construction, fast repairs, large structures, and places where sulfate exposure is a concern. Type I, or Ordinary Portland Cement, is the common choice for general construction. It is used when special properties are not required. This type has moderate sulfate resistance and moderate heat of...

types of cement ii

Special Portland cements are made for specific building needs, such as added durability, color, or lower cracking risk. One major example is Portland blast-furnace cement. It is made by blending Portland cement clinker with granulated blast-furnace slag, which makes up about 25 to 65 percent of the cement by weight. Portland blast-furnace cement sets at about the same rate and has about the same fineness as ordinary Portland cement, which is Type I cement. Its early strength is lower, but it...

pozzolans

Pozzolans in Stronger Concrete Mixes

Pozzolans are siliceous or aluminous materials used with Portland cement to improve concrete performance. They react with the calcium hydroxide formed during cement hydration. This reaction helps increase strength and durability. The usefulness of a pozzolan is measured by its pozzolanic activity. One common test is the strength activity index from ASTM C 618-93. It compares the compressive strength of cement mixtures made with and without pozzolan. Fly ash is a common artificial pozzolan. It...

key terms and concepts

Explore Portland blast-furnace, white and colored, expansive, and waterproof cements, and see how each type supports strength, appearance, and moisture resistance.

Special Portland Cements for Durability | JoVE K12

JoVE Core Civil Engineering provides a foundational exploration of essential construction materials in civil engineering, focusing on bricks, stones, steel, wood, and concrete through easy-to-understand animated videos. This collection covers the properties, manufacturing processes, and practical applications of these materials. Additionally, the accompanied science-in-action videos demonstrate the research experiments performed in laboratories.

civil engineering

Special Portland Cements for Durability

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