Concrete

“The imperial vastness of late Roman architecture was made possible by the invention of concrete.” – Iain McGilchrist (author)

The Romans understood and valued concrete’s strength and durability and used it to build out their vast empire. Roman builders worked with concrete and understood the physical challenges and demands of working with this versatile but rough building material. Yes, concrete's density and strength have made it a go-to material for centuries. It is the essential ingredient that makes our modern world possible. Without concrete, the world would look unimaginably different. Concrete is everywhere!

Prepare to explore the art of concrete!  We're about to highlight everything you could want to know about concrete, cement, and those who work with these essential materials.

Industry Overview

As mentioned earlier, concrete's history dates back to ancient Roman times, with evidence of concrete mortar being used in 200 B.C. to attach stones. Unfortunately, the secrets of concrete were lost when Rome fell in 476 A.D. to Germanic tribes. Concrete was not rediscovered as a building material until 1824, when English cement manufacturer Joseph Aspdin developed Portland cement. This product would go on to form the modern concrete industry and completely change the construction world.

Today's businesses that pour, build, and finish concrete foundations are classified under NAICS code 23811. This coded number allows the government to classify all the business activities within this sector, helping workers and suppliers better understand the industry.

According to IBISWorld, the concrete industry produces over $57 billion in economic activity each year, with over 53,000 concrete businesses operating in the U.S. Here are some of the industry's top segments:

• Ready-mix contractors
• Concrete block manufacturers
• Stucco contractors
• Demolition / Repair
• Concrete pumping services

Concrete vs. Cement

What is the difference between concrete and cement? While they are often used synonymously, they are actually different products. Cement, as shown above, is a crushed powder made of limestone and clay. Cement is an ingredient of concrete, making up roughly 10 to 15 percent of concrete mix. The amount of cement used in the mix will impact the final concrete structure's strength and durability. 

In addition to cement, concrete is also made up of other materials, including a fine aggregate, typically sand, or a coarse aggregate, typically rock or gravel. These materials are then mixed with water and chemical additives to begin the hydration process. Once the water is mixed in, the clock starts ticking, and a worker has approximately two hours to form the final look of the concrete before it is set!

Concrete Uses

Looking around, you are likely to spot concrete somewhere in your daily life. This is because concrete is essentially everywhere and found in bridges, walls, car garages, and warehouse floors. Its applications are endless, as it can be poured to create all types of shapes.

Here are some of the most common uses for concrete:

• Curbs and Parking Lots that utilize concrete have a long lifespan and require less maintenance.
• Dams made of concrete are strong enough to hold back millions of gallons of water and make for impressive feats of engineering, like Hoover Dam.
• Driveways are often made of concrete for long-lasting durability.
• Fireplaces made of concrete are resistant to fires and earthquakes. Plus, they can be formed into all types of shapes and sizes.
• Floors made of concrete are one of the most basic and inexpensive forms of flooring; often used in industrial buildings, concrete floors are starting to become popular in other commercial spaces and even in residential homes.
• Furniture in the form of benches, tables, and bookshelves can all be made from concrete; it's a cheap material and looks great in homes!
• Home Foundations make up one of The Three Fs in construction and are a part of every building. 
• Patios featuring concrete are one way to upgrade your backyard living space.
• Piers use concrete columns to support structures, primarily in coastal areas.
• Retaining Walls resist the pressure of soil because of concrete’s strength and help hold the earth back.
• Roof Tiles made from concrete are fire-resistant and can resist harsh weather better than asphalt.
• Sidewalks provide curb attraction to buildings and walkways for people.
• Streets and Roads often utilize concrete since it’s more durable than asphalt; you will also find concrete used in highways and airport runways, which must endure heavy equipment and high-volume use.
• Swimming Pools made from either gunite or shotcrete (types of concrete) are considered the best due to their long-lasting performance.

 
Sidewalk Pool

Parking Lot

  
 Furniture Roof Curb

  
Furniture Foundation     Dam

Types of Concrete

Each of the structures mentioned above is built in different environments, which means not one form of concrete will suffice for all. Also, some final products require different shapes or finishes, each requiring different grades of concrete.

Here are the different types of concrete used across the industry:

• Air-Entrained – mixed on the job, this concrete contains air pockets that allow water to expand during freezes without causing cracking.
• Asphalt – a mixture of aggregates, asphalt binder, and additives, asphalt is a popular concrete for roads, parking lots, and other paving projects.
• Glass Cement – a binding blend used to affix glass to metal; this lightweight cement acts as a glue.
• High-Density – using heavyweight aggregates, this concrete, as its name suggests, has a higher than average density, which comes in handy for stabilization.
• High-Performance – offering low shrinkage, minimal permeability, and high modulus elasticity, this concrete resists loads that your everyday concrete can't withstand.
• Permeable – for use in rainy or wet environments, this pervious concrete allows water to pass directly through it.
• Precast – cast before arriving at its final destination, this concrete comes ready to install on the job site.
• Prestressed – applying predetermined compression during production, this concrete’s overall tensile strength is enhanced.
• Self-Consolidating – when surface smoothness is required, this fluid mixture is used because of its flow and consolidation properties.
• Stamped – patterned to resemble common textures, such as brick, this concrete is often used for patios, driveways, and sidewalks.
• Ultra-High Performance – the most recent concrete innovation, this concrete is used primarily in bridge construction, precast piles, and blast applications.

Stamped

 
Precast         Air Entrained

Concrete Block Types

Concrete blocks, also referred to as cement or cinder blocks, are manufactured using cement, aggregate, and water. They are made into all types of shapes, sizes, and weights, making them indispensable for workers forming a structure. They can be joined together using mortar, making them a preferred material across the construction industry.

Depending on the structure being built, different types of concrete blocks are used. Here is a breakdown of the different types:

• Solid - immensely strong and durable, these blocks are used primarily to build columns, piers, beam foundations, and retaining walls.

• Hollow - made with a hollow core area, these blocks are advantageous to builders because of their reduced weight, lower cost, and better insulation properties. They are primarily used in building non-load bearing walls. Here are all the variations of hollow blocks.
• Corner –blocks join the ends of structures, typically at windows or door openings
• Bullnose – a type of corner block made with a rounded edge
• Lintel – made with deep grooves running across its length that can be manipulated effortlessly and provides a worker increased flexibility when constructing
• Partition – used primarily to construct partition walls; its hollow area is split into two or three parts
• Pillar – used when a structure’s ends are noticeable to provide a clean look
• Stretcher – another type of corner block, these are set with their length parallel to wall's face and are one of the most commonly used blocks in construction

Common Questions from DIYers

Concrete is one of the handiest and most versatile building and construction materials available, making it widely used by DIYers. Those looking to resurface their driveway, or construct a brand new patio, will most likely select concrete. However, there is a reason why professional concrete companies exist: the work can be challenging. Yet, that doesn’t deter many DIYers from trying their hand at it.

One of the best websites for DIYers looking for help with a concrete project is www.bobvila.com. Here are some of their articles around concrete:

• Curing Concrete
• 9 Easy Concrete Projects
• Preventing Concrete Cracks
• Renewing Concrete Patios
• Resurfacing Concrete Driveways

There are tons of other articles on the subject in their How-To Center. In addition to the resources they provide, here are some common questions we know many DIYers have when using concrete:

How to drill into concrete?

• You will need a special drill, especially if the concrete foundation has been around for decades.  Home Depot has prepared a video that shows you how to drill into concrete safely. Don't forget to wear your safety goggles, as the dust and material will be flying!

How long does concrete take to dry?

• Concrete sets hard enough for people to begin walking on it within 24 to 48 hours of the concrete being poured. Vehicles can start traveling over it within about seven days. Drying and curing times will vary depending on the mix of concrete and environmental factors, like weather.

What is concrete made of?

• Concrete is made of cement, aggregate (e.g., sand or pounded stone), and Portland cement.  Water is then added to start the chemical reaction of curing.

How to mix concrete?

• It's not the most complicated process; it just requires some water, aggregate, and cement.  However, you'll need to follow a process, as identified by the familyhandyman.

How to repair concrete cracks?

• Since concrete is rigid, it can crack when under intense loads or as the ground below it shifts. Repairing those cracks quickly is essential, as water can cause even more cracks to occur. To fix a minor crack in the concrete, you'll need a chisel and a hammer to prepare the surface. Then, a flexible sealant and caulk are often used to fill in these cracks. We recommend watching this video to help aid your efforts.

How to get oil stains out of concrete?

• You've probably encountered an oil stain in your garage or someone else's garage. One of the top-rated items for helping to eliminate those pesky, unsightly stains is Oil Eater. Don't forget to wear your goggles and gloves during application and clean-up!

How to build wood concrete forms?

• To contain and form the concrete into the desired shape, wooden forms are often used. To determine the best way to erect the form, identify whether you're building forms for slabs or walls. For walls, we recommend reading the 6-step quick guide from wikiHow.

How to cure concrete?

• Curing is the process of maintaining moisture in the concrete during the early stages of installation to gain the best results in terms of strength and performance. There are two primary ways to cure concrete, either by wet-curing or by applying a curing compound. Wet-curing is more time-consuming, but it produces the best results. Wikihow has a multi-step article on both processes, and Civil Mentors has an entire video explaining the process.

How to lay concrete?

• Pouring a concrete slab is not all that difficult, but it does require specific steps, similar to mixing concrete. You'll need build the correct form, insert rebar, and smooth the finish out. With over 8 million views, you can't go wrong watching this video to help you lay a strong foundation for your project.

How much does a yard of concrete weigh?

• The average concrete structure weights 4,050 lbs per cubic yard.  If you know the volume, online concrete calculators will help you compute the weight.

How long does it take for concrete to cure?

• It takes about 28 days for concrete to cure fully. However, forms can be removed after 48 hours, and vehicles can begin using new concrete in roughly seven days.

Cost of Concrete

How much does concrete cost? Pricing depends on the size of what is being built, its thickness, and whether it will be reinforced. You're going to pay a lot more for a 20x30 slab than a 12X12 one. On average, most concretes cost anywhere from $4 to $8 a square foot.

When you examine HomeGuide’s concrete pricing guide, you can quickly see how costs can increase. A standard 4” slab costs a little over $5 per square foot. However, when you start adding in thick edges, reinforcement, or barriers, costs can quickly ascend to the $8 to $10 per square foot range.  Keep in mind; pricing may fluctuate when a professional concrete contractor performs the work.

Concrete Calculator

How much concrete do I need? It's an important question asked by anyone who wants to control costs and make sure enough material is purchased. The formula for understanding how much concrete is needed depends on the type of concrete used and the project's scope. To calculate costs, you will need to know the following measurements for these types of concrete projects:

• Slabs - thickness, width, and length
• Footings - depth, width, and length
• Columns - diameter and height

Once you have the measurements, you can use the Concrete Network's handy calculator. It will tell you precisely how many bags of concrete will be needed for the construction project.

Slabs

 
Columns Footings

Associations and Trade Shows

Most industries typically have associations and establishments that promote all companies' general welfare and support workers operating in the industry. Established in 1904, the American Concrete Institute (ACI) is considered one of the leading associations for concrete workers. ACI represents over 30,000 members, across 120 countries, by providing educational resources, certifications, and industry-accepted standards.

Here are three additional recognized associations for concrete workers: 

• Associated General Contractors of America
• American Society of Concrete Contractors
• American Concrete Pipe Association

The Portland Cement Association, one of the most trusted in the industry, has produced an informative video about safety around concrete. You'll want to check it out to make sure the highest safety standards are being observed on your jobsite.

All concrete associations have one thing in common: keeping concrete workers armed with the most relevant, up-to-date information possible to help them best perform their job. Many construction workers look to the above professional associations for answers.

In addition to associations, trade shows such World of Concrete (WOC) provide valuable insight into the industry. In 2019, over 60,500 people attended WOC’s show from a wide range of concrete-related activities. The concrete industry knows how to put on a show!  

Employment and Occupations

According to the Bureau of Labor Statistics (BLS), there are 216,910 workers finding employment in the Poured Concrete and Structure industry. However, the concrete sector covers a broad range of people. Cement masons are the primary workers operating in this industry segment, though there are numerous trades finding employment in this specific construction sub-industry. Here are the top ones:

• Cement Masons and Concrete Finishers - 74,110
• Laborers - 54,000
• Carpenters - 20,860
• Reinforcing Iron and Rebar Workers - 1,850
• Paving and Surfacing Operators - 1,260

Here is a look at the various types of workers operating in this industry and identified by the BLS:

• Cement Mason and Concrete Finishers - perform a vast amount of work with concrete, from pouring it to finishing it.

• Carpenters - construct forms for pouring concrete.

• Iron and Rebar Workers - position steel bars or steel mesh into concrete forms to reinforce the concrete once it’s poured.

• Construction Laborers - smooth poured concrete and disassemble forms once the concrete is set.

Laborers also cast and shape molds, as well as pour and spread concrete into molds.

• Terrazzo Workers - Spread pigment, sand, or marble mixtures over finished concrete for a decorative surface appearance.

• Shotcrete Contractors - Spray concrete through a hose.

• Mud-Jacking Contractors - repair concrete foundations by drilling holes and injecting a mixture of cement to help stabilize the slab.

• Paving and Surfacing Operators - Use machines that spread out concrete onto roads and curbs.

Each of these workers fulfills an essential role within a project. Since concrete work involves multiple types of workers, there are various types of work activities performed.

Work Activities

Concrete work comes in all shapes and forms, and each concrete worker performs a wide range of activities. These activities include carrying heavy tools and equipment and handling abrasive material, all of which can injure hands. We highlight this fact because many work-related injuries are caused by the tools workers use on the job.

Here are some of the activities performed by individuals working around concrete:

• Applying sealant to floors
• Constructing forms that hold concrete
• Coring into concrete structures by drilling and removing areas
• Cutting out damaged areas of concrete
• Decorating using different patterns and textures pressed into the surface
• Demolition and removal of older structures
• Fabricating concrete beams and columns 
• Finishing concrete by smoothing the surface out, most often with a trowel
• Grinding surfaces with handheld devices to remove imperfections
• Installing precast concrete
• Leveling uneven surfaces
• Mixing sand, cement, and water to produce concrete
• Operating robust vibrating equipment to compact concrete
• Painting decorative effects into concrete to produce a stunning and unique design
• Polishing concrete floors with heavy-duty polishing machines
• Pouring concrete over steel reinforcements
• Repairing damaged concrete
• Resurfacing concrete by applying a new concrete coating over older surfaces to refresh the color and texture 
• Spreading concrete using a rake, shovel, or trowel
• Staining concrete to add color at an affordable price
• Stamping to create patterns and textures in the concrete
• Using a broom to produce a rough finish 
• Waterproofing concrete surfaces using specific mixtures

Polishing

  
        Repairing Sealing Spreading Concrete

  
Waterproofing Installing Grinding

 
Cutting Demolishing

Resurfacing

As you can see from the images and descriptions above, a lot goes into making concrete objects come to life. No matter what task a concrete worker performs, you can be sure they are exposed to various hazards. We understand this, which is why we highlight some of the dangers concrete workers face and suggest the PPE to keep them protected. Before we explore PPE options, here is an overview of the tools commonly used by workers handling cement and concrete.

Tools and Trucks

Before any concrete foundation is set, workers handle a wide range of tools to complete the project. We highlight the most common tools workers use because many work injuries are caused by the tools used on the job.

Here is a look at some of the most common tools used by concrete workers:

• Anchor Bolts – secure steel to concrete
• Bristle Brush – to clean up concrete projects
• Buckets – containers with moveable gates that transport concrete material  
• Caulk and Caulk Gun – used to repair cracks 
• Cement Mixer Truck – as we highlight in our Construction Equipment article, they mix and churn cement, aggregate, and water 
• Compactors – help compact surfaces into dense surfaces
• Core Drill – removes cylindrical concrete cores
• Crusher – breaks down large concrete blocks into smaller pieces
• Curing Compounds – lock moisture into concrete during curing 
• Drill Bit - designed to penetrate hard surfaces 
• Fabric and Plastic Sheets – keep concrete moist during the curing process
• Floor Scrubber – used to aggressively clean concrete floors
• Grinder – for removing concrete toppings
• Groover – creates joints on walkways and slabs; helps make concrete finishing jobs much quicker
• Hammer – demolition hammers, rotary hammers, and standard heavy-duty hammers are all used by concrete workers
• Hoe – used to mix smaller batches of cement
• Leveler – used to produce an even, flat surface
• Mixer – combines aggregate, water, and cement to create concrete
• Paint Roller – for staining concrete
• Polisher and Pads – to grind and smooth concrete surfaces to desired appearance 
• Portable Mixer – to produce concrete directly at construction sites
• Pump Truck – transfers mixed cement to precise locations
• Rake – to push and pull the concrete
• Saws – power tools made to cut through solid concrete
• Screeds – long tubing used to smooth freshly poured concrete
• Shovel – for spreading concrete
• Sprayer – applies concrete onto surfaces at high velocity
• Trowel – smooths the surface of the concrete
• Wheelbarrow – helps carry and deposit concrete across job sites

Leveler

 
Paint Roller Mixer

  
Hammer Anchor Bolts Sprayer

 
Grinder Rake

Trowel

Materials

A tool is pointless if it has no materials to shape or mold.  Here are some of the common materials used in concrete construction:

• Accelerators – help quickly set concrete
• Acid Wash – helps prepare surfaces to receive a sealer by removing heavy grime
• Aggregate – reduces cement requirements and occupies most of the volume
• Blankets – protect concrete from moisture loss
• Blocks – commonly found in constructing walls
• Caulking Gun – used to spread caulk across cracked concrete
• Epoxy  - used to smooth concrete surfaces, making them more durable; also used for binding concrete, making repairs, and applying over floors to make the surface more durable and smoother
• Gap Fillers – a type of concrete caulk used to patch cracks
• Glue – binds concrete to other surfaces
• Nails – made with heavy-duty steel and thick shanks
• Paint – extends the life of the concrete and provides an even color
• Pavers – small slabs of concrete
• Ready-Mix– made up with the aggregates specifically formulated for building and repairing foundations
• Rebar – iron bars used to strengthen and reinforce concrete foundations
• Retarder – extends the time a worker has to set concrete
• Sand – is blended with cement and water to produce concrete
• Sealants – help waterproof and protect surfaces from corrosion and damage 
• Sealer – provides a water-repellant barrier in areas subjected to moisture
• Stain – protects and customizes interior and exterior concrete
• Wire Mesh – steel mesh material that reinforces and supports concrete
• Wood – used to create concrete forms that keep concrete in place while it’s curing

In 2019, the BLS reported 890 injuries caused by all the different parts and materials handled in the Poured Concrete industry. The safety gear workers wear must address the different materials they will be handling and the variety of activities they will perform. If you’re handling sharp steel wires, the last thing you want is to be wearing disposable gloves.

 
Paint Epoxy

  
Rebar             Sand       Wire Mesh

 
Sealant Wood

Safety

Accidents and injuries are common across the construction industry, especially those responsible for pouring concrete, so keeping a watchful eye on the work environment is crucial. The Poured Concrete sub-industry industry ranks #5 out of 21 total construction sub-industries for injury incidents.  For every 100 people finding employment in this industry, there is an injury experienced by 3.8 workers.

Here are some other stats the BLS provides that concrete workers should consider:

• The industry ranks in the top five for eye injuries, with 170 reported.
• Concrete workers experience the fourth-highest number of hand injuries, with 710 reported.
• There were 210 foot injuries, the fifth-highest number of all construction sub-industries.
• 470 injuries were reported from hand tools, the fourth-highest number.

Out of all potential concrete hazards, wet cement causes the most hand injuries across the industry. This is because concrete is highly caustic and highly abrasive. As we mentioned above, you’re going to need some nice waterproof gloves.  Skin exposed to wet concrete can receive 2nd-degree burns. Also, wet concrete can easily splash into one's eye. With these hazards, you can understand why workers want safety gear they can trust. Here are some examples of the hazards faced by those working around concrete:

• Splashing curing compound
• Splattering concrete
• Falling objects landing on a worker's foot
• Sparks from welding operations 
• Working in dusty areas
• Handling abrasive sand
• Lifting heavy material

Lastly, before we move on to highlight different types of PPE, here are some other articles and guides we've written on safety when working around concrete:

PPE Solutions

As mentioned above, ready-mix contractors, concrete block manufacturers, stucco contractors, demolition/repair, and concrete pumping services are the specialized segments of the concrete industry. They all have one thing in common: each requires PPE to protect their workers.

Protecting one's skin is probably the top reason workers wear PPE. Without gloves, shirts, and boots, caustic chemicals will quickly cause skin irritation and chemical burns. To combat potential injuries concrete workers may suffer, they look to MCR Safety to protect them with high-quality PPE.

Here is a broad list of various PPE that MCR Safety supplies to help concrete workers avoid injury:

• Disposable gloves
• Face shields
• Goggles
• Work gloves – cut, chemical, impact, etc.
• Steel toe boots
• Safety glasses
• Hi-vis clothing 
• Safety shirts
• Insulated clothing
• Long-sleeve shirts
• Waterproof lined gloves

As always, our goal is to get you into the best PPE for the hazards you face. Below, we highlight some of the most common concrete hazards, along with safety product recommendations. In the event we do not cover your unique hazard, let us know. Feel free to contact us using the link at the bottom of this page. If you wish to have direct consultation, we can assist there too! All you have to do is contact us, and we will have a trained 360° Safety Specialist get in touch with you.

You might be interested in checking out our other dedicated construction sub-industry pages.  Our entire construction industry home page can be found by clicking the below image.