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

La molienda de clínker de cemento Portland con escoria granulada de alto horno, un subproducto del proceso de fabricación de hierro, produce cemento de escoria.
Se puede utilizar para construir grandes estructuras diseñadas para resistir el ataque de cloruros y sulfatos.
El cemento blanco, hecho de tiza y arcilla china que contiene menos cantidades de óxidos de hierro y manganeso, tiene un color blanco distintivo y se puede utilizar para crear fachadas con una excelente estética.
La adición de pigmentos coloreados que no son perjudiciales para el concreto con cemento blanco produce cemento coloreado.
Los cementos expansivos, como los tipos K, M y S, se producen combinando cemento Portland con un agente expansivo y un estabilizador. Esto evita el agrietamiento por contracción a través de una expansión controlada debido a la formación temprana de ettringita durante el endurecimiento.
El cemento Portland incorporado por aire utiliza cantidades más pequeñas de materiales incorporadores de aire para formar millones de burbujas de aire microscópicas dentro de la matriz de cemento.
Esto proporciona espacios para que el agua se expanda cuando se congela, evitando el agrietamiento causado por los ciclos de congelación y descongelación. 
El cemento Portland impermeable incorpora sustancias repelentes al agua, lo que garantiza que las estructuras expuestas a la humedad estén protegidas contra la infiltración de agua.

No se han declarado conflictos de interés.

tipos de cemento ii

Types of Cement II

El cemento Portland de alto horno se fabrica mezclando clínker de cemento Portland con escoria granulada de alto horno, que representa entre el 25 y el 65 por ciento del peso del cemento. A pesar de sus similitudes con el cemento Portland común (Tipo I) en términos de finura y tiempos de fraguado, su resistencia inicial es menor, aunque alcanza una resistencia comparable más adelante. Es particularmente adecuado para estructuras de hormigón en masa y entornos marinos debido a su menor calor de hidratación y resistencia superior a los sulfatos.

Los cementos Portland blancos y coloreados se utilizan principalmente donde las consideraciones estéticas son primordiales, como paneles de muro cortina prefabricados, paneles de revestimiento, pisos de terrazo, estuco, yeso de acabado y lechada de baldosas. Estos cementos son más caros debido a los estrictos requisitos de producción para evitar impurezas y lograr uniformidad de color.

El cemento expansivo se expande durante el período de endurecimiento inicial para compensar la contracción por secado. Hay tres tipos disponibles: K, M y S, que difieren principalmente en su composición química. El tipo K está diseñado para el control general de la contracción, el tipo M es para la resistencia a los sulfatos y el tipo S es para una alta exposición a los sulfatos. Cada tipo está diseñado para minimizar el agrietamiento al contrarrestar los efectos de la contracción. Este tipo es adecuado para situaciones que requieren un cambio mínimo de volumen para evitar el agrietamiento.

El cemento Portland impermeable incluye aditivos como estearato de calcio o estearato de aluminio mezclados con el clínker de cemento Portland durante la molienda, lo que mejora la resistencia del cemento a la penetración de la humedad.

Tipos de Cemento II

La molienda de clínker de cemento Portland con escoria granulada de alto horno, un subproducto del proceso de fabricación de hierro, produce cemento de escoria.
Se puede utilizar para ...

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Introduction to Concrete

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KEY TERMS AND CONCEPTS

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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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