Name: concrete fillers that improve performance
Uploaded: 2024-11-07T14:48:38.000Z
Duration: 1 min 29 s
Channel: JoVE

Los rellenos y aditivos son materiales de grano fino con una finura similar al cemento Portland.
Las puzolanas y las escorias de altos hornos, utilizadas como aditivos cementantes, mejoran las cualidades del hormigón, como la trabajabilidad y la densidad, al tiempo que reducen el sangrado y el agrietamiento.
Los rellenos pueden impulsar el proceso de hidratación del cemento Portland al proporcionar puntos de nucleación que forman carbonato de calcio. Estos sitios de nucleación se observan en el hormigón con cenizas volantes y partículas de dióxido de titanio.
El carbonato cálcico se fusiona con la fase hidratada de silicato cálcico, alterando favorablemente la estructura de la pasta de cemento una vez hidratada.
Los rellenos también pueden derivarse de sustancias inorgánicas naturales o procesadas, y ejercen principalmente un efecto físico, como cal hidratada o polvo de agregados.
Por lo general, estos materiales de relleno sirven como mejoradores de la trabajabilidad en lechadas y mortero de mampostería. Los pigmentos de color también se consideran adiciones inertes.
Cuando se introduce zinc o aluminio en polvo en presencia de hidróxido de calcio, produce gas hidrógeno. Estos materiales, conocidos como aditivos formadores de gas, crean hormigón aireado.
El peróxido de hidrógeno, otro ejemplo, libera burbujas de oxígeno retenidas dentro de la mezcla de arena y cemento para producir concreto aireado.

aditivos y rellenos en el hormigón

Los aditivos y rellenos son fundamentales para mejorar las propiedades del hormigón. Las puzolanas y las escorias de alto horno son aditivos o aditivos debido a sus reacciones con el hidróxido de calcio liberado durante la hidratación del hormigón. Los rellenos, que están finamente molidos y tienen una finura similar al cemento Portland, mejoran los atributos del hormigón, como la densidad de trabajabilidad, y reducen el sangrado capilar o el agrietamiento. Algunos rellenos poseen propiedades hidráulicas o participan en reacciones benignas dentro de la pasta de hormigón.

La función de los rellenos es promover la hidratación del hormigón Portland, proporcionando sitios de nucleación, una función que a menudo desempeñan las cenizas volantes y el dióxido de titanio, que contribuyen a la microestructura de la pasta de cemento resultante. Los rellenos pueden ser naturales o procesados, con propiedades consistentes, en particular la finura. No deben aumentar la demanda de agua ni afectar negativamente la durabilidad y la resistencia del hormigón.

Los rellenos y aditivos se mezclan principalmente físicamente con el hormigóny deben ser compatibles. Por ejemplo, algunas partículas de hormigónmuy finas son esenciales para la resistencia inicial. Los materiales inertes como la cal hidratada o los agregados de peso normal se agregan para mejorar la trabajabilidad, no la resistencia. Los aditivos que liberan hidrógeno en presencia de álcalis o hidróxido de calcio se utilizan para hacer hormigón gaseoso o hormigón celular, proporcionando aislamiento térmico. Los aditivos formadores de gas como el peróxido de hidrógeno generan burbujas de oxígeno en las mezclas de hormigón celular.

Aditivos y rellenos en el hormigón

Los rellenos y aditivos son materiales de grano fino con una finura similar al cemento Portland.
Puzolanas y escorias de altos hornos, utilizadas como cemento ...

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JoVE Core

Civil Engineering

Ingeniería Civil

Unit 1

Unidad 1

Admixtures

Aditivos

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

Additives and Fillers in Concrete

concrete fillers that improve performance

Concrete fillers and additives help change how cement paste performs. Pozzolans and blast-furnace slag act as additives or admixtures because they react with calcium hydroxide released during cement hydration. Fine fillers are close in fineness to Portland cement and can improve workability, density, and resistance to capillary bleeding or cracking.

Some fillers are hydraulic, which means they can react with water, while others take part in harmless reactions inside the cement paste. A key role of many fillers is to support Portland cement hydration by giving the paste nucleation sites, or places where new crystals can start forming. Fly ash and titanium dioxide can play this role and help shape the microstructure of the hardened cement paste.

Fillers may be natural or processed, but they should have steady properties, especially fine particle size. They should not raise the water demand of the mix or reduce durability and strength. In concrete, fillers and additives are usually mixed in physically, so they must be compatible with the cement system.

Very fine cement particles can also matter for early strength. Inert materials such as hydrated lime or normal-weight aggregates may be added to improve workability rather than strength. Some additives release hydrogen in the presence of alkalis or calcium hydroxide and are used to make gas concrete, also called aerated concrete, which provides thermal insulation. Gas-forming admixtures such as hydrogen peroxide can create oxygen bubbles in aerated concrete mixes.

Concrete Fillers That Improve Performance

concrete-fillers-that-improve-performance

accelerators

Calcium Chloride in Concrete Mixes

Calcium chloride is a concrete admixture that speeds up hardening and helps concrete gain early strength faster. It does not always change the setting time itself, but it can reduce the time needed in practice. This makes it useful in cold weather and in rapid repair work where quick heat generation after mixing is helpful. A common amount is 1 to 2 percent of the cement mass. Its effect can be compared with raising the concrete temperature by 11 degrees Fahrenheit. To spread it evenly through...

retarders

Retarders in Concrete Pouring

Retarders are chemical admixtures used in concrete to slow the setting time. They are especially helpful when one pour must follow another after a delay. By keeping the concrete workable for longer, they can help prevent cold joints and support a more cohesive structure. Retarders can also improve the look of exposed aggregate finishes when they are used in the right amount. Their effect on setting time can be checked with a penetration test. Common retarding substances include sugar,...

plasticizers

Concrete Workability with Plasticizers

Concrete plasticizers are water-reducing chemical admixtures that improve workability and strength. They help concrete use less water while keeping the same flow, reduce cement content without losing workability, or make mixes easier to place in hard-to-reach areas. Plasticizers work by using surface-active agents. These agents create repulsive electrostatic forces between cement particles. The particles disperse more evenly, and the concrete needs about 5 to 15 percent less mixing water. <br...

superplasticizers

Superplasticizers for Stronger Concrete Mixes

Superplasticizers are concrete admixtures that make mixes flow better while using less water. They are strong water reducers, so concrete can be easier to place without losing strength. This makes them useful when concrete must reach tight spaces or heavily reinforced areas without mechanical vibration. These admixtures work through sulfonated melamine or naphthalene formaldehyde condensates. These chemicals give cement particles a negative charge. The particles repel each other and spread out...

additives and fillers in concrete

Concrete fillers and additives help change how cement paste performs. Pozzolans and blast-furnace slag act as additives or admixtures because they react with calcium hydroxide released during cement hydration. Fine fillers are close in fineness to Portland cement and can improve workability, density, and resistance to capillary bleeding or cracking. Some fillers are hydraulic, which means they can react with water, while others take part in harmless reactions inside the cement paste. A key...

waterproofing and anti-bacterial admixtures in concrete

waterproofing-and-anti-bacterial-admixtures-in-concrete

Concrete Water Resistance and Biological Protection

Concrete can absorb water because of capillary action in the pores of its hydrated cement paste. That movement pulls water into the material. Waterproofing admixtures are added to reduce this penetration and help concrete resist water. The effect of a waterproofing admixture depends on the water pressure acting on the concrete. Rain, capillary rise, and hydrostatic pressure in structures made to hold water can all affect performance. These admixtures make concrete hydrophobic, which means they...

key terms and concepts

Learn how concrete fillers and additives affect workability, density, early strength, cracking, and aerated concrete through simple, science-based examples.

Concrete Fillers That Improve Performance | 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

Concrete Fillers That Improve Performance

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