A versatile and indispensable material used in many different construction projects is concrete. It is a well-liked material for a variety of applications, including buildings, bridges, roads, and ornamental elements due to its strength, resilience, and versatility.
Knowing the fundamental characteristics of concrete will make it easier for you to understand why it’s so popular and how it functions under various circumstances. These characteristics include workability, which impacts how simple it is to form and pour, and compressive strength, which establishes how much weight it can support.
Other crucial qualities are its setting time, which affects how quickly it hardens, and durability, which refers to its resistance to environmental elements like moisture and temperature fluctuations. Every one of these characteristics is essential to the longevity and functionality of concrete constructions.
| Property | Description |
| Compressive Strength | The ability of concrete to withstand axial loads without failure. It is a key measure of how much pressure concrete can handle. |
| Durability | How well concrete resists weathering, chemicals, and physical wear over time. Durable concrete lasts longer and performs better in harsh conditions. |
| Workability | How easy it is to mix, place, and finish concrete. Good workability ensures that concrete can be properly molded and set without excessive effort. |
| Setting Time | The time it takes for concrete to start hardening after mixing. This includes the initial setting time and final setting time. |
| Shrinkage | The reduction in volume of concrete as it dries and hardens. Minimizing shrinkage helps prevent cracks and structural issues. |
| Thermal Conductivity | How well concrete transfers heat. Concrete"s thermal conductivity affects its use in insulating and energy-efficient buildings. |
- Compressive strength
- Deformation properties
- Flowability
- Shrinkage and swelling
- Frost resistance
- Durability and resistance to chemical influences
- Density of concrete building materials
- Fire resistance
- Heat release during hardening
- Water resistance
- Workability of concrete mixture
- Video on the topic
- Lecture 2 The main properties of concrete aggregate and test methods
- What kind of concrete brand is used for hi-tech houses? #concrete
Compressive strength
This is one of the primary characteristics of concrete mortar, which is expressed in megapascals and indicates the highest gravity resistance this construction material can withstand. Concrete’s strength can rise as a result of interactions between the ingredients that make up cement and water. We refer to this process as hydration.
Strength factors are unique to each concrete and are listed in the purchase declaration. However, this property doesn’t show up for four weeks. Concrete strength gain is dependent on a number of factors. First of all, the season and air temperature have an impact on this process.
Concrete freezes in the winter, which halts strength growth. The concrete is heated in order to continue this process. Because of the special additives, some builders prefer to use mixtures that are frost-resistant right away.
It so happens that concrete that is poured during the winter months thaws and gains strength with the arrival of spring. Building mixtures lose ground, though, in other operational properties.
Ordinarily, the first week following laying is when concrete actively gains strength. The strength level reaches as high as 70% of production standards on the seventh day. The concrete mixture no longer requires formwork, but it is still too early to load it. By the end of the month, only then is the maximum strength coefficient attained.
Concrete mixtures harden more quickly as air temperature rises. Here, keeping an eye on the material’s moisture content is crucial. The solution will stop strengthening if it dries out too quickly. In this sense, freshly constructed concrete structures are covered with damp burlap or PVC film, or they are sprayed with hot steam. A technique used by some artisans is adding water to the mixture.
Deformation properties
Concrete building mixture behaves entirely differently from other materials when subjected to gravity. The way concrete mortar behaves under pressure is determined by how compacted it is.
Concrete exhibits slight deformation similar to that of a spring when it is subjected to light, transient loads. Along with its increased strength, the building mixture’s elasticity also increases. Additionally, the springiness of the solution is influenced by its pore count. The degree of elasticity decreases with the number.
Concretes with cells have the least amount of elasticity. Lightweight porous concretes have slightly higher indicators. The heaviest building materials have the highest springiness. The solution’s structure can be readily changed by adjusting the concrete’s springy qualities.
Flowability
Spreadability, also known as creep, is the gradual deterioration of a concrete structure caused by constant static load impact over time.
Many factors influence a building solution’s spreadability, including the list of ingredients, the kind of cement and other additives, the age of the concrete mix, the humidity level, and the hardening conditions.
Crushed stone or other dense fillers reduce the spreading of concrete solutions. Increased porosity light mixtures flow significantly more. When concrete building mixes dry out too quickly, it increases their spreadability and negatively affects the structure.
Shrinkage and swelling
A concrete mix’s characteristics include swelling and shrinking. When concrete is allowed to harden outdoors, it will eventually sink. This causes shrinkage stress, which in turn causes cracks in concrete structures. Therefore, shrinkage joints divide massive structures apart.
Craftsmen attempt to stop the building material from shrinking in order to lessen the stress caused by shrinkage and shield the finished structure from cracks. This is accomplished by accurately calculating the shrinkage coefficient prior to the start of construction and by adding special fillers to the solution.
Because of their forced, sporadic contact with water, cement-concrete roads and hydraulic structures are always prone to shrinking or swelling. Concrete is destroyed and developed microcracks as a result of these alternating processes.
Frost resistance
To determine this property, the concrete material is alternately frozen at 15 to 20 degrees in the freezer and thawed in water at the same temperatures—minus the "plus" sign. The concrete sample is allowed to harden for four weeks under normal conditions, or one week after heat drying, before the test is conducted.
The degree of porosity and the quality attributes of the ingredients used to make the solution have an impact on how resistant concrete structures are to frost. The resistance to below-freezing temperatures rises if it falls below 7%.
Durability and resistance to chemical influences
The building mixture’s resilience to chemical reactions and durability are dependent on numerous variables. Here, the material’s low porosity and high density are crucial.
Density of concrete building materials
The solution’s structure has an impact on the concrete structure’s density. The specific gravity of different grades of cement varies. This also holds true for crushed stone, whose density is determined by the kind of material and the size of the grains. Concrete’s strength is directly correlated with its density. The final product is stronger the higher the density property.
If the right fillers are added to the solution at the same time as it is being made, the density of the mixture will rise. This property can also be enhanced by vibrating the solution while it is being poured.
Because high porosity concrete materials don’t have a normal density, they are less durable due to their decreased resistance to moisture and dampness, temperature fluctuations, and chemical reactions. However, compared to building mixtures with higher densities, these concretes have excellent thermal insulation qualities.
Concrete’s strength, workability, and durability make it a highly versatile and long-lasting material for construction. Its workability makes it simple to mold into a variety of shapes and sizes, and its strength enables it to support heavy loads. In addition, concrete’s resilience makes it a dependable material for a variety of applications, including roads, sidewalks, bridges, and buildings.
Fire resistance
Concrete’s ability to withstand fires is referred to as fire resistance. This attribute is fairly high for mixtures used in cement construction. After all, when a concrete structure is heated, the crystalline hydrates in the cement stone break down and release a chemically bound liquid through adsorption, which evaporates to remove nearly all of the heat. This procedure lessens the impact of high temperatures on concrete.
Simultaneously, as concrete structures undergo intense heating, the filler and cement mixture particles expand. Strong stress is created inside the building material as a result, which lowers the material’s strength and adhesion between its constituent parts.
Heat release during hardening
As a result of the water’s reciprocal interaction with the clinker processing minerals, heat is released, heating the solution as it solidifies. The type of cement used and how much of it is used per m3 of concrete affect how much the temperature of the mortar rises. Concrete that is hardening can heat up to 50 degrees under specific circumstances, which causes the concrete to expand and prevent the structure from shrinking.
Expansive thermal stresses result from temperature increases in the building material of large concrete structures; these stresses can reach levels greater than the tensile strength of concrete. Concrete buildings break and become less durable as a result.
Unequal heating of the concrete material results in thermal stress. In this instance, the interior levels of the concrete blocks stay hot for an extended period of time while the surface layers cool down too quickly. A large concrete structure will require more than a month to reach a constant temperature throughout. The size of the crushed cement crystals, how much of it is used per cubic meter of concrete structure, and other factors all affect the amount of heat released during the compaction of the concrete mix.
During hardening, aluminous cement-concrete mortars release the most heat. Concretes that contain slag release the least amount of heat. Portland cement that contains a large percentage of slag. Reducing heat release during solution hardening is facilitated by the addition of finely ground materials to the concrete mix.
Water resistance
The quantity of pores in the mixture determines how water resistant the building mixture is. It is more moisture-resistant the lower its porosity. If improving this aspect of the building mixture is required, incorporate water-repellent additives and sodium aluminate compactor into the mixture during preparation.
Petroleum products can easily seep through regular concrete because they have a lower surface tension than water. Ferric chloride and other comparable materials are added to the mixture to slow down this process.
By substituting expanding cement for regular Portland cement, it is possible to quickly increase the building mixture’s water resistance and decrease the permeability of petroleum products into concrete.
Workability of concrete mixture
The workability of a solution is influenced by the amount of water needed to achieve the desired consistency. The filler and the cement paste each receive a portion of this liquid. The maximum shear stress, buoyancy, stiffness, and viscosity of the mixture all affect how much of it is contained in the cement paste. When the aggregate’s grain surface area grows, so does the amount of water that the aggregate needs. Smaller sand varieties will therefore need a larger quantity of liquids.
The ratios of interacting cement and water in the solution should never change to ensure that the concrete is strong enough. In this sense, as water demands rise, so do the cement and sand expenses. 15–25% of the material is wasted when using small varieties of cement. As a result, small sands are added to the primary mixture, which is made up of large or crushed sand and plasticizers that lessen the requirement for fluid.
For those working on building or remodeling projects, it is imperative to comprehend the fundamental characteristics of concrete. Concrete is a popular material for a variety of applications, from decorative elements to foundations, due to its strength, durability, and adaptability. You can use concrete more effectively if you are aware of how these properties operate.
Concrete constructions are guaranteed to be sturdy and long-lasting due to its resistance to fluctuating weather and heavy loads. Achieving the best results in your projects and optimizing these properties requires careful mixing, curing, and upkeep.
All things considered, having a solid understanding of the primary characteristics of concrete will help you select the best kind for your requirements and guarantee that your constructions will endure. Armed with this knowledge, you can use concrete with confidence in your next building or renovation project.
