Fillers for concrete and mortars: what is it, the main types (large and small)

Fillers are vital ingredients in mortar and concrete because they give different types of construction projects the structure and bulk they require. They affect the material’s workability, durability, and strength in addition to aiding in the mixture’s binding.

Large and small fillers are the two primary types of fillers used in mortars and concrete. The foundational support is provided by large fillers like crushed stone and gravel, which also lower the amount of cement needed. By filling in the spaces left by the larger particles, small fillers—like sand—make the mixture smoother and more cohesive.

Selecting the appropriate materials for your project can be aided by having a thorough understanding of the various fillers and their functions. To get the desired results in your construction work, choosing the right fillers is essential. Each type has distinct properties that influence the finished product.

Concrete categories

Concrete is a dense, carefully blended material that solidifies over time. Water and cement are its primary ingredients, and they are mixed in exact amounts.

1. Inorganic:

• cement with fillers made of Portland cement, slag or pozzolanic Portland cement;
• silicate with the addition of lime;
• gypsum with a gypsum additive;
• slag-alkaline using slag and an alkaline solution;
• special with the use of specific additives.

1. Organic – polymer concretes (polymer cement, plastic concrete, concrete polymer), in which mineral components are replaced by polyester or epoxy resins.

• especially lightweight (less than 500 kg/m³);
• light (from 500 to 1800 kg/m³);
• heavy (from 1800 to 2500 kg/m³);
• super heavy (more than 2500 kg/m³).

Selecting the right concrete will increase the structure’s resistance to outside forces, prevent future deformation, and ensure reliability.

Fillers have a major impact on the strength, durability, and workability of concrete and mortar, making them indispensable components. They can be roughly divided into two categories based on their size: large and small. While small fillers, like sand and fine aggregates, ensure a smooth mix and fill spaces between larger particles, large fillers, like crushed stone and gravel, provide structural integrity. Comprehending the function and varieties of fillers facilitates the selection of appropriate materials for particular construction requirements, guaranteeing maximum efficiency and durability of the final product.

Types of fillers

The mixture contains 80% of its total mass in other substances.

• size of the material fraction;
• purpose of the additive.

• natural substances;
• artificial (heat-treated) raw materials;
• industrial waste;
• recycled waste.

Concrete’s properties are essentially unaffected by natural elements or production waste. Conversely, artificially made ones have an impact on its properties such as hardness, plasticity, hardening rate, and others.

Requirements for fillers for concrete mix

The type of object being constructed dictates the requirements for concrete. For instance, clean filler is needed for heavy concrete structures. Frost-resistant materials are necessary in areas with harsh weather, and hardening-accelerating additives are needed in areas with mild weather.

Large

The most common aggregate, gravel works well in a variety of concrete mixes. It is a loosely structured rock sediment that contains fragments of other minerals. Its granules vary in size from 5 to 70 mm. The average bulk density, strength grade, and frost resistance are 1200, 1400, and F-350, respectively.

Among the larger aggregates, granite is the most resilient. High density indicators—up to 1700 kg/m³—are present. It is produced as small, medium, and large granules (5-70 mm), just like gravel. Because of its low moisture absorption, the material resists frost. There is a little dust in it. It is employed in the building of bridges, retaining walls, roads, and foundations.

Rocks and inferior waste from mining and construction companies (brick, slag, ash) are crushed to create crushed stone. There are no impurities in it. Crushed stone granules are cube-shaped and come in a variety of colors. Crushed stone has a rougher surface than granite and gravel, which makes it more abrasive and strengthens concrete.

The construction market offers large concrete aggregates in a range of fractions (1-200 mm) with varying bulk densities.

Small

It is possible to make fine-grained mixtures without big aggregates. On the other hand, a dense stone cannot be produced in concrete without the presence of tiny additives.

The GOST states that sand grains in cement or cement-lime mortars cannot be larger than 2 mm. Granules up to 1 mm must be present in small aggregate in gypsum or gypsum-lime concrete. Mixtures shouldn’t contain any 10 mm granules.

There are very few impurities, such as pyrite, gypsum, and clay, in any kind of sand. Use only natural and artificial sands for mortars, with a maximum 3% dusty-clay particle content.

Finer sand lowers expenses by 12%, while coarse sand (1.5-2 mm) can increase cement consumption by 5%.

The end properties of concrete—strength, resistance to shrinkage, and resistance to frost—are impacted by the addition of fine particles.

Classification by purpose

To improve the cement dough’s composition and boost the materials’ resistance, additives are added to the mixture.

Special

Special concrete is designed to support heavy loads under adverse circumstances.

Magnetite, boron carbides, barite, calcium lime, lead chips, etc. are additional special additives.

Porous

Light concrete requires these kinds of additives.

• Natural aggregates (pumice, volcanic ashes, crushed tuff, porous limestone, shell riches, diatomite, etc.);
• industrial production waste (slag and ash);
• artificial additives (expanded clay, aggloparrite, slag pumice, perlite, burned vermiculite, etc.).

Lightweight concretes are classified into vermiculite concrete, expanded clay concrete, perlite concrete, tuff concrete, foam concrete, etc. based on the base aggregate that is present in the mixture.

Thermal insulation

Increased porosity additives are the foundation for the creation of structural thermal insulation materials, such as foam concrete, aerated concrete, expanded clay concrete, and polystyrene concrete. They are less likely to shrink and have greater strength than cellular products.

Azerite, diolite, foam glass granulate, barothelite, foam glass, tuff argellites, vitrosites, and vitrophyres are examples of gravel-like additives in an amorphized glassy state that are used as heat-insulating fillers for concrete and mortars.

They are employed in the building of warm screeds, roofing, external walls, facades, and structures with a moderate bearing capacity.

Other additives

Concrete is treated with bleaching, modifying, and plasticizing additives in addition to multicolored cement and crushed granular fillers for architectural uses.

• fire retardants that increase fire resistance;
• hardening accelerators of the mixture;
• fillers that increase moisture resistance and strength;
• polymer mixtures (epoxy resins, polyester and furan);
• plasticizers that enhance moisture resistance.

Certain unique fillers are made of boron carbide or contain light elements like lithium, cadmium, or hydrogen.

Main Types	Examples
Large Fillers	Crushed Stone, Gravel
Small Fillers	Sand, Fine Gravel

Any construction project requires an understanding of the various kinds of mortar and concrete fillers. Regardless of size, these components are essential to the finished product’s performance, robustness, and longevity.

To ensure that the concrete can withstand heavy loads and withstand deterioration, large fillers such as crushed stone and gravel give the material the required bulk and stability. However, tiny fillers like sand and fine aggregates contribute to a smoother mixture, which enhances workability and finish.

You can customize concrete or mortar to meet specific requirements, such as a strong foundation or a polished interior floor, by selecting the appropriate mix of fillers. The strength, density, and surface quality of the mixture are affected by the ratio of large to small fillers.

Ultimately, how well you comprehend these materials and their interactions will determine how well your concrete project turns out. By becoming proficient with fillers, you can make the most of the available resources while ensuring your construction is sturdy and functional.

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