Concrete is strong inside and beautiful outside. Concrete is a composite building material made by combining cement (usually Portland cement), water, coarse aggregates, and fine aggregates.
From airport runways and bridges to patios and roadways, concrete is an essential component of residential and commercial construction across the world.
Concrete is cast in many forms and is suitable for a broad range of uses.
Different construction needs demand a variety of concrete types, such as plain concrete, precast concrete, prestressed concrete, ready mix concrete, air-entrained concrete, high-density concrete, lightweight concrete, reinforced concrete, stamped concrete, self-consolidating concrete, and shotcrete. How many types of concrete are in use?
This post will help you choose the type of concrete that is right for your construction project.
What is Concrete? What is a Concrete Mix Ratio?
The history of concrete goes back to 6500 BC when the Nabataea traders in the regions of Syria and Jordan built the first concrete-like structures. Concrete has evolved over the centuries to become a widely used customizable and versatile building material.
In civil engineering, the use of concrete as a structural material is widespread and well known for the value provided by concrete and its versatility of applications. A standard (normal concrete) concrete mix ratio is 1:2:4:
- 1 part – cement
- 2 parts – sand
- 4 parts – aggregates
The above materials are mixed to form a stone-like paste that hardens over time and is ready for use in different structures. The ratio of components in a concrete mix changes based on the construction requirements.
Sometimes, supplementary cementitious materials (SCMs) are added to concrete mixes for key benefits like decreased permeability and the overall hardening of concrete. For example, fly ash concrete is known to be a stronger concrete with improved durability.
Let’s get started with the most common types of concrete used in construction:
Common Types of Concrete Used in Construction
Also known as “ordinary concrete,” plain concrete is used with a mix ratio of 1:2:4 of cement, sand, and aggregates. As plain concrete cannot stand up well to wind loading or vibrations, it is used for construction projects that do not require high-tensile strength.
Normal Strength Concrete
Normal strength concrete is a fast-setting compound of aggregates, cement, and water. Lack of tensile strength makes normal strength concrete suitable for buildings or pavements that do not require high tensile strength. Like plain concrete, normal strength concrete contains similar ingredients but differs in strength with 10-40 MPa.
Casting concrete into a reusable mold or form creates precast concrete that is cured in a controlled environment to gain the desired strength. Concrete grade is a key manufacturing component of precast concrete products because it helps increase concrete strength to avoid future collapse.
Another critical factor is the proportioning of the main ingredients so that the concrete holds other members in place. Cured precast concrete is transported to construction sites for forming complete precast structures, such as floors and walls.
Precast concrete structures are erected using cranes and special hooks are provided to lift them as well.
Applications of precast concrete include:
- Box culverts
- Bridge decks
- Concrete blocks
- High-rise buildings
- Railroad ties
- Retaining walls
- Sound walls
- Staircase units
Furthermore, precast concrete is used for building decorative and protective fencing in private residential properties.
Prestressed concrete is industrially built concrete that involves placing bars or tendons at the ends of a structural unit before the application of concrete. The unit is subject to compression stresses during production to achieve a higher structural load capacity and increased durability and tensile strength.
Prestressed concrete units provide faster construction and are commonly used for heavily loaded structures, such as bridges and roofs.
Ready Mix Concrete
Also known as “ready-mixed concrete,” ready mix concrete (ready-mix concrete or RMC) is manufactured in factories under controlled operations and transported to construction sites via trucks with in-transit mixers. When already produced specialty concrete mixtures are available, they just have to be poured at construction sites.
Contrary to on-site concrete mixing, ready mix concrete offers high precision and reduces worksite confusion.
However, admixtures like retarders are necessary to preserve ready mix concrete for use at construction sites too far from the factories that produce and mix the concrete.
The leading ready mix concrete variations include:
High-strength concrete: The elasticity and resilience of this mix make it a great choice for footers, foundations, and heavy equipment bases or heavy industrial loads.
Fast-setting concrete: As the mix sets in 20-40 minutes, it works well for projects like a fence, mailbox post, a small concrete slab, or any other construction project that needs rapid-setting concrete.
Fiber-reinforced concrete: Fiber-reinforced concrete is infused with macrofibers or microfibers to make it last longer in harsh weather conditions like extremely cold winters.
Self-leveling concrete: This mix has high flow properties that allow the concrete to level on its own without the need for extra water or hand-leveling. Self-leveling concrete is suitable for projects that require flat, smooth surfaces.
Reinforced concrete is a composite building material reinforced with steel bars placed in the formwork during construction. Examples of such bars include prefabricated steel cages and steel rebars.
After the forms are ready, concrete is poured and vibrated to ensure both materials blend well. Buildings, bridges, culverts, retaining walls, and roadways typically use reinforced concrete.
Alternatively known as “cellular concrete” and “flowable concrete,” lightweight concrete is made from various aggregates, such as clays, pumice, shales, and scoria.
This easy-to-pour, self-leveling concrete with low thermal conductivity is used for fabricating structures, such as floor slabs, long-spanning bridge decks, and window panels.
Lightweight concrete is also used for protecting steel structures and is made using light aggregates, including:
Processed natural light aggregates: Expanded clay, expanded shale, and synthetic shale.
Unprocessed natural light aggregates: Lapilli, Pozzolan, and Travertines.
Processed light industrial aggregates: Expanded ashes, expanded slag, and synthetic ashes.
Unprocessed light industrial aggregates: Blast furnace slag and pulverized fuel ash.
Also known as “permeable concrete,” pervious concrete’s design allows for 15% to 20% voids of the volume of concrete. As pervious concrete is ideal for the passage of water, it is used in the construction of driveways and pavements to recharge groundwater and solve drainage issues. For example, storm water can pass through a pervious concrete pavement and reach groundwater without causing a drainage issue.
Stamped concrete derives its name from stamping or placing a kind of mold on top of the hardening concrete to achieve a decorative concrete finish. The surface finish mimics the look and feel of natural brick, tile, and stone surfaces, among others.
Once the floor has hardened, it is usually sealed to increase the longevity of the concrete mixture. Stamped concrete is commonly used for concrete driveways, parking lots, pool decks, sidewalks, walkways and other high-traffic areas.
Air-entrained concrete is concrete in which air is entrained (infused) with the addition of a foaming agent such as foam or gas. The result is concrete with billions of microscopic air cells per cubic foot, with the entrained air constituting 3% to 6% of the concrete.
This method provides greater resistance to concrete against abrasion, deterioration due to freezing and thawing, and scaling. In addition, it increases the workability of concrete without adding water. Common air-entraining agents include fatty alcohols, fatty acids, and resins.
Asphalt is a dark mineral that consists of a mixture of hydrocarbons called “bitumens.” Alternatively known as “asphalt” or “blacktop,” asphalt concrete is the concrete of choice for pavement work and projects, such as airport runways, highways, parking lots, roads, and sidewalks.
The preference for asphalt is due to its various attributes, including:
- Fatigue resistance
- Skid resistance
Shotcrete concrete involves pumping “shots” of concrete using the dry-mix or wet-mix method. In 1907, Carl Akeley invented the dry-mix shotcrete method that uses a compressed air nozzle and injects water to shoot dry mix toward the wall.
In contrast, the wet-mix shotcrete uses premixed concrete to place a larger quantity in less time without creating more waste or rebound off the wall.
Also known as “limecrete,” lime concrete uses lime and a lightweight aggregate such as glass fiber or sharp sand. Lime concrete is used to construct domes, floors, and vaults.
Limecrete is environmentally friendly as it is renewable, easily cleanable, and an absorber of carbon dioxide (as the concrete sets).
Moreover, the ability of limecrete to control moisture makes it possible to use natural products like hemp, wood, or straw without any risk of composting or deterioration.
Polymer Impregnated Concrete
In polymer concrete, aggregates are bound with a polymer instead of cement. Commonly used polymers include acrylics, epoxies, and urethanes. Polymer cement concrete, partially impregnated, and polymer impregnated concrete (PIC) are popular types of polymer concrete.
In polymer impregnated concrete, water-filled voids or water-filled pores account for a large amount of the total volume after the normal curing of the hardened concrete.
Once the curing is complete, monomers like acrylonitrile and styrene are injected into the voids at high temperatures and the voids are then packed through polymerization.
Glass concrete is made from recycled glass and increases the aesthetic appeal of a construction structure while providing higher thermal insulation and strength.
Glass powder increases the workability of concrete and improves its hardened properties. As a result, it is easier to save cost, energy, and time for placing and consolidating glass concrete.
Adding glass aggregate can produce visually appealing effects that range from concrete that sparkles and shines to concrete with a granite- or marble-like finish.
Also known as “self-consolidating concrete” and “zero-slump concrete,” self-compacting concrete (SCC) consists of cement, coarse aggregates, and fine aggregates. In addition, SCC has mineral admixtures to modify viscosity and chemical admixtures to improve flowability and workability.
The applications of self-consolidating concrete extend to deep beams, heavy reinforcements, and congested reinforcements like beam-column junctions. As SCC does not require any extra compaction, it is used in places where compaction is not possible or it is quite difficult to achieve full compaction.
High-density concrete (HDC) is made of coarse aggregate and crushed rocks and possesses exceptional strength. The heavy aggregate uses iron or barytes. The radiation-shielding ability of high-density concrete makes it a preferred choice of construction engineers for use in concrete structures that need to be extra secured such as power plants.
Vacuum concrete is made by pouring more water than required into the formwork. When a vacuum pump removes excess water before the concrete sets, it creates vacuum concrete that is ready for use earlier compared to the regular construction technique. This means that the concrete attains compressive strength within 10 days rather than 28 days.
In addition, vacuum concrete has 25% greater crushing strength compared to conventional concrete.
Volumetric concrete is created by mixing water and concrete ingredients transported by volumetric mobile mixers to construction sites. Volumetric concrete is particularly useful for large project sites in need of several types of concrete.
Other significant types of concrete include bacterial concrete, ferro cement concrete, pumped concrete, roller-compacted concrete, smart concrete, and smog-eating concrete.
How to Choose a Concrete Type?
Choosing the correct concrete type makes a difference in any construction project.
The first step is to determine the temperature and surface area of the space for the application of concrete. For example, air-entrained concrete would be a good choice for areas subject to an unpredictable climate and a variety of temperatures.
Similarly, ready mix concrete offers a perfectly proportioned premixed combination of cement, sand, and gravel for convenient use.
The second step is to consider the concrete mix design based on durability, strength, and workability as economically as possible.
Lastly, it is important to finalize the quantity and mix number/type of concrete apart from making estimates based on on-site measurements and allowances for on-site wastage.
Some ready mix concrete companies accept a short load concrete delivery for projects that require small quantities of concrete. It is recommended to consider your construction project needs fully before placing and confirming an order for concrete.
Safety Tips for Concrete Work
Whether you are working at a small or large construction site, here are some key tips to follow when doing concrete work:
- Wear a hard hat to prevent head injuries
- Wear a mask to avoid concrete dust
- Wear waterproof boots and gloves to protect your feet and hands
- Wear knee pads for long periods of work
- Use protective eyewear to protect your eyes
- Use reliable and safe equipment to lift heavy concrete
- Take safety precautions to reduce back strain
Many construction projects use concrete for durability, resilience, stability, strength, and an aesthetic appeal. In today’s world, concrete exists in several forms and serves multiple uses.
Whether your construction project needs high-performance concrete or decorative concrete, you can choose from the various types of concrete used in the construction industry.
Now that you know the concrete types available for construction, you can opt for the type of concrete that matches the budget, scope, and style of your construction project.
If you are looking for residential or commercial construction projects, check out the Global Project Tracker for the most up-to-date listings of construction projects worldwide.