Reduce, reuse, and recycle. Most people are aware of these three environmentally conscious 'R' words and more often than not associate them with items like plastic, glass, and paper. But what about more substantial materials like concrete?
Concrete reclaiming is a process that allows manufacturers of concrete, along with construction and other types of companies to get the most out of their supplies, or their 'leftovers,' without having a negative impact on the environment!
Mid Atlantic Concrete Equipment, INC., headquartered in Lititz, PA is a Lancaster County business that has made great strides towards greener and more sustainable ways of reducing waste, reusing aggregates, and recycling water from unused concrete. Read on or skip forward to your area of interest to learn way more than you thought you knew about concrete!
What is Concrete?
Concrete is a building material that is made from water, sand, stone, and cement. People often use concrete and cement synonymously, but that's incorrect. Cement is an ingredient in concrete and is what essentially binds everything together. The following analogy was offered to clarify the relationship:
- "Cement is to concrete as flour is to cake."
Process of Using Concrete
When a business or an individual needs concrete for a project, regardless of size, it's customary to order more than needed. This will prevent having to order more concrete, which would involve additional charges for extra concrete, truck usage, labor, and the time needed to wait for the next delivery.
There are several variables that go into estimating the approximate amount of concrete needed for the desired project:
- Concrete shrinks as it dries,
- Measurements could be off,
- Concrete can remain trapped in the mixer truck,
- And so on.
The Problem – Returned Concrete
In purposely ordering more concrete, the mixing trucks end up bringing "returned concrete" back to the concrete manufacturer. There are a few methods used to effectively handle returned concrete. The method(s) used are determined by whether or not the concrete manufacturer has a concrete reclaimer.
Without a concrete reclaimer, the following methods can be used to prevent returned concrete from going to waste.
Methods Used Without Concrete Reclaimer
There are two types of concrete blocks that can be made from returned concrete:
Each of these blocks is one cubic yard and weighs approximately 4,000lbs.
When a mixing truck comes back with returned concrete, a steel form must be prepared for the returned concrete. Preparation of the form involves cleaning the concrete flooring (base for the form) and steel form with scraping tools and water. Once everything is cleaned and moved to the proper location, the form is sprayed with a form-release liquid agent (the Pam non-stick spray of the concrete business). This release agent is environmentally friendly and biodegradable.
The forms are now ready to be filled with returned concrete! After the concrete dries, the blocks need to be stripped, or removed, from the forms. The steel forms consist of two separate pieces to remove the blocks from the forms. The blocks are moved twice by a tow-motor to be stored and then to be sold.
The Cons Associated with Concrete Blocks
25% of all blocks that are made are considered waste according to the NRMCA (National Ready Mix Concrete Association). These "waste" blocks could have cracks, defective corners, or are not fully formed. Factors that lead to "waste" blocks include:
- Extreme temperatures,
- Returned concrete has exceeded its working time,
- Form filled by two separate batches of returned concrete, which forms a separation layer.
There is a lot of time, man-labor, and machinery that goes into creating these blocks. The raw product (returned concrete) has been paid for by the customer, but the amount of labor required translates into a large cost. The basic and architectural blocks are priced accordingly.
These 4,000lb, 1 cubic yard concrete blocks could be used for any number of things, such as: retaining walls, bases for construction projects, at garden centers/plant nurseries, and other business/household building projects.
This method, however, does not effectively handle the truck washout and consequent gray/processed/slurry water. In this situation, a retention pond would most likely be used for the slurry water, increasing the amount of waste produced by the business. Retention ponds full of slurry water generally create an unusable muck or sludge that must be disposed of; generally at a landfill.
Another method for reusing returned concrete without a concrete reclaimer involves the windrow method. When a mixing truck returns to the concrete manufacturer, the truck needs to be cleaned. The truck operator would discharge the "returned concrete" onto a flat surface, and windrow the concrete to allow it to dry.
The barrel of the truck would then be filled with water and essentially rinsed out at a different location. The water used could be fresh water or gray, previously used, water. The truck operator would then discharge this water containing cement, sand, stone, and aggregate into a retention pond.
This water could make its way towards ground water, but not before filtering through limestone, other minerals, and the earth. It could also evaporate or sublimate. Sublimation is the process of a solid being converted to a gas form. As previously mentioned, this process produces a "muck" or "sludge" that cannot be reused in any way and must be gotten rid of.
Windrow Method "Moves"
Move #1: After the returned concrete has dried, it will then be moved via loader bucket to an area for storage.
Move #2: A contractor is typically hired to use a large hydraulic hammer on a track hoe to break up the windrowed concrete into more manageable pieces.
Move #3: A loader bucket is then used to move the stockpile of smaller chunks of concrete into a higher pile that takes up less ground area.
Move #4: Once the stockpile has reached a certain size, the concrete producer will hire a contractor to crush the concrete chunks into smaller bits. This occurs approximately every 6 months to a year. The crushing conveyor goes through thousands of tons of concrete in one crushing session.
Move #5: The now finely crushed concrete needs to be moved again via loader bucket to be stored.
Move #6: The last time the crushed returned concrete is moved at the facility would be to sell it or to use it on site. It can be used as a sub-base (to raise elevation), for roadways, or as a compactable fill.
This process involves a lot of transportation of the concrete, which is no easy task. It requires extensive time, money, and labor to complete the windrow process. It costs more to process the concrete into a crushed state in some areas than the business would receive in the sale of the recycled product.
Clean Water Act (CWA)
The Clean Water Act was established in 1948 and was originally named the Federal Water Pollution Control Act; the act was reorganized, amended, and renamed in 1972. The main functions of the CWA are (1) to regulate the discharge of pollutants into the surface and ground water of the United States, and (2) to regulate the quality of the surface water in the U.S.
Under the Clean Water Act it is unlawful without a permit to discharge pollutants into "navigable" water from a point source. The EPA defines point sources as, "discrete conveyances such as pipes or man-made ditches," (EPA, 2011). The EPA has also implemented restrictions on industries regarding wastewater standards and water quality standards for contaminants in surface water.
The Clean Water Act directly affects the concrete industry because gray/processed/slurry waters cannot simply be 'discharged'. This is why those that do not use concrete reclaimers are forced to used retention pits and/or ponds, which have their own associated problems and challenges. Some of these issues include possible overflow due to precipitation, the unusable muck/sludge, and the inevitable lack of space.
Types of Concrete Reclaiming
There are two more common methods for reclaiming concrete and gray water; open loop, or weir, system and the closed loop system.
- Open Loop/Weir System
The first method is the open loop, or weir, system. This process involves the use of several retention tanks or ponds. The wash-out from the mixing trucks is sent through these multiple tanks or ponds. The aggregates that settle in each pond need to be removed to be dried and reused in future production. The final tank or pond that the water reaches is the most clarified form of water that can be used for future production or truck washout. This method can be hard on the equipment used to clean out the tanks/ponds because "concrete sludge" or "muck" is a byproduct, which ends up at a landfill.
- Closed Loop System
The closed loop system is the method used by BIBKO for their reclaimers. This method is discussed in Methods Used After Installation of Concrete Reclaimer.
Mid Atlantic Concrete Equipment
Mid Atlantic Concrete Equipment was originally founded in 1986 by Jay Robinson under the name Jay Robinson and Associates. Due to Robinson's reputation in the concrete manufacturing industry, Jay Robinson and Associates flourished.
The organization changed its name to Mid Atlantic Concrete Equipment in 2005 after Robinson partnered with Owen Blevins. They service and sell automatic controls, concrete plants, concrete reclaimers, dust control systems, as well as water heating/cooling equipment. In addition, Mid Atlantic Concrete Equipment is a dealer for BIBKO products.
Mid Atlantic Concrete Equipment is headquartered in Lititz, PA, but serves businesses in Maine, Vermont, Massachusetts, New Hampshire, Rhode Island, Connecticut, New York, New Jersey, Delaware, Maryland, Virginia, West Virginia, Washington D.C., and of course, Pennsylvania.
BIBKO North America
BIBKO North America is the organization that Mid Atlantic Concrete Equipment represents. Simply, they service and sell BIBKO products. BIBKO North America is the import manufacturer for BIBKO products; BIBKO is a located in Germany.
BIBKO products are unique because they allow for a complete reclaim/recycle process. The concrete reclaimers allow for the separation and re-use of stone, sand, and slurry/gray water from returned concrete and truck washout. Those within the concrete industry have the ability to recycle 100% of their returned concrete with the use of BIBKO products.
Mid Atlantic Concrete Equipment and BIBKO North America offer ROI calculators on their websites to illustrate that their concrete reclaimers have a positive impact on businesses. These impacts are not just environmental, but they're economical as well.
BIBKO North America's website heralds themselves as, "the leader in Concrete Reclaim Systems, with over 1300 Concrete Recycle Systems installed," (www.bibko.us).
Concrete Reclaiming in Lancaster County
Rohrer's Quarry, located in Lititz, PA, is a family-owned business that sells ready-mix concrete, lime, and stone products throughout central PA and beyond. Limestone has been quarried and processed from this site since 1886, and concrete production was added to the Rohrer Quarry agenda in 1962.
In 2010, with the assistance of Mid Atlantic Concrete Equipment and BIBKO North America, Rohrer's Quarry installed a BIBKO Model 4000 concrete reclaimer. The information presented in this article regarding concrete reclaiming was gathered on site at Rohrer's Quarry. The decision to purchase and use the BIBKO concrete reclaimer illustrates the dedication those at Rohrer's Quarry have to the environment, the Lancaster County community, and their business conduct.
For more information about Rohrer's Quarry or to set up an educational tour of the quarry, visit their website at www.rohrersquarry.com.
Question & Answer with Owen Blevins of Mid Atlantic Concrete Equipment
Project Green Lancaster: How long have you been working for Mid Atlantic Concrete Equipment?
Owen Blevins: Mid Atlantic Concrete Equipment has been in business for about 30 years. I came onboard in September of 2005 after selling my interest in a retail automobile dealership.
PGL: What is your role in the organization?
Mr. Blevins: As one of two partners in my company, my role is to ensure that we have a robust sales and marketing arm in our 13 state territory.
PGL: How did you come to be involved in the concrete manufacturing business?
Mr. Blevins: As I mentioned, my partner and friend of 25 years, Jay Robinson, made it easy for me to get involved in the business. We have known each other for quite some time and when I sold my dealership, he asked if I would be interested in coming onboard with him. While not knowing much about the concrete industry at the time, I did know that Jay and I would get along fabulously. I was definitely right.
PGL: When did you first become aware of concrete reclaiming?
Mr. Blevins: My partner has a relationship with a company called BIBKO. This German company has over 1,400 installations throughout the world. They do one thing – make concrete reclaimers. They do it well so well in fact that we decided to represent the line in our territory. After several years, BIBKO came to us and asked if we would be interested in important and distributing the product throughout North America. We teamed up with two other dealers and formed BIBKO North America. It has been a whirlwind of a year for us with our new company.
PGL: What are some other ways that Mid Atlantic Concrete Equipment may "go green" in the future?
Mr. Blevins: We've taken a very active interest in becoming known as a sustainable company. There are several products on our radar. One is a product that reduces the amount of water needed to rinse out the barrel [of a mixing truck] when a company uses colored concrete. This would save hundreds of gallons [of water] on every truck, which would amount to several hundred million gallons of water saved each year. Another product would be jobsite wash out devices that are attached to trucks. These devices would allow the [truck] operator to rinse the truck off and bring cementitious product back to their 'yard' to be disposed of in a more sustainable manner. Another product is a line of chemicals that are acid-free and much more Earth-friendly used to clean the trucks when any concrete adheres to them.
PGL: What does the green/sustainability movement mean to you and/or your organization?
Mr. Blevins: Sustainable means being able to use our resources but ensure that they are available and plentiful for future generations. Our industry has taken great strides in the last few years to ensure that we do as much as possible to live by that definition.
PGL: Has the green/sustainability movement had an impact on other areas of your life besides work?
Mr. Blevins: I have two children ages eleven and eight that are both very passionate about recycling and green initiatives. Our family likes the outdoors and tries to walk places or ride our bikes when it makes sense. My kids are involved in my business and understand what daddy is doing to recycle resources in the concrete industry.
PGL: What are some "green resolutions" you may have for yourself, your family, or your neighborhood?
Mr. Blevins: Thanks to my kids we have a compost pile at our house where we deposit our scrap fruits and vegetables. We plant lots of trees each year in our yard and exist well with nature.
PGL: What are your hopes for the future of concrete reclaiming in Lancaster County and/or the state of Pennsylvania?
Mr. Blevins: My ultimate goal would be to have all producers recognize that it is not just the right thing to do, but that is actually profitable to be sustainable. One can talk until they're blue in the face, but you can't show a businessperson the benefits of being sustainable without the financial benefits; you won't keep their attention. Fortunately, reclaiming concrete is a no-brainer when it comes to saving money. It requires everyone from the top down to buy into it and understand their role in the process.
PGL: What is one thing you want the residents of Lancaster County to be aware of regarding your industry?
Mr. Blevins: Our industry is one of many that is getting on the bandwagon and beginning to practice sustainable initiatives. We can't live without concrete. We build with it, we drive on it to work and play, we use it every day. Designers and engineers have embraced it as a multifaceted sustainable product. Making sure others know that we use it wisely and responsibly is a great goal. Concrete is extremely sustainable product that lasts for hundreds of years with minimal maintenance.
Methods Used After Installation of Concrete Reclaimer
The process of reclaiming concrete has multiple steps, but all steps occur in sequence. All the machinery that is involved in the process is interconnected and stored within a moderately sized building; approximately 40'x 60'. There is outside access to the concrete reclaimer so concrete trucks can park right in front of the building housing the reclaimer.
The reclaimer is essentially a one stop station for the mixing or pumper (different types of concrete trucks) truck operators to clean their trucks and "dispose" of the returned concrete. This cuts down on required time, machinery, and manpower needed for methods of handling returned concrete that do not involve the reclaiming process.
Step 1: Trucks Return to Manufacturer/Quarry
At the end of the day, when a truck operator comes back to the quarry or manufacturer with "returned concrete" the truck is positioned outside of the building housing the reclaimer. A pipe extending from the 'reclaimer building' fills the barrel of the truck with gray water – water previously used to clean the barrels of mixing trucks.
The barrel of the truck is filled with gray water for approximately two minutes. The truck operator then 'charges' the barrel of the truck; simply, the barrel of the truck rotates in a certain direction.
Step 2: Discharging Returned Concrete & Gray Water
After the barrel or drum has rotated for a certain amount of time, the returned concrete (cement, stone, water, and sand) and washout water are discharged into a trough. The trough is the portion of the reclaimer with access to the outside of the structure.
Step 3: Separation into Buffer & Wash Chambers
The BIBKO reclaimer then separates all of the stone and sand from the water and cement. The water from the process is stored in concrete pits with large paddles to prevent materials from settling in the water. The aggregates (stone, sand, etc) that were separated from the water are dried, separated and stored in specific stockpiles for future use in the production of concrete.
There are two pits located inside the structure housing the reclaimer; one is a 30,000 gallon pit, while the other is 20,000 gallons. These pits are used to house the gray water and are equipped with paddles to ensure the suspension of the aggregates in the water. These pits are heated in the winter and cooled during the summer with waste oil.
Step 4: Recycling Gray Water
Due to the location of the steel building housing the reclaimer, a 400ft, 4-inch diameter pipe is used to transport the gray water to the batch plant, where concrete is produced.
Keep in mind that this water is not potable water. It also contains cementitious material suspended in the water; thanks to the paddles in the gray water holding tanks.
To make a batch of concrete, a certain amount of water is needed. Think about baking a cake; if you add to much milk, water, or oil to the batter, the cake won't rise when you bake it.
To always ensure a quality batch of concrete, the plant uses automation software to determine the specific gravity of the gray water. The software determines the specific gravity, if fresh water will be needed to regulate the specific gravity to the desired level, and if so, how much fresh water.
Specific gravity is the relationship between the density of a substance and the density of a reference substance. In this circumstance, the reference substance is water. Specific gravity of the gray water is so important to the manufacturing of concrete because one gallon of gray water isn't equivalent to one gallon of fresh water. In the same way that those aggregates displace the water they are in, it also impacts the amount of gray water required.
Zero Discharge, Zero Waste
The use of a closed loop system reclaimer allows for all materials (gray water, sand, stone, aggregates) to be reused. This eliminates the need for retention ponds (that ultimately turn into unsightly pits of muck and sludge), reduces the amount of fresh water used, eliminates waste and discharge, and saves money among other things.
Ancient Usage of Concrete – Where It Began
Concrete is a building material used in many ways that we see every day, but do not necessarily acknowledge. But where exactly did concrete come from? Who first started using concrete and for what?
Amazingly, the first form of concrete was created by mixing straw and mud; upon drying it became relatively strong and sturdy. Egyptians used this method of concrete production over 5,000 years ago to build pyramids. They also used gypsum and lime mortars in their construction efforts. I actually made bricks from mud and straw when I was a child; thanks for the history lesson Mom!
The Romans also used a form of concrete, called pozzolana, to build marvels such as the Colosseum and the Pantheon. This ancient form of concrete is apparently quite similar to modern day concrete. The Romans also incorporated animal fat, blood and milk into their concrete to increase the properties.
During ancient times, concrete was an important building material and its importance has remained steadfast. The structures that were constructed with concrete throughout time that are still standing are testaments to the strength and versatility of concrete.
Some of "The Firsts" for Concrete
- In 1889, the first fully concrete reinforced bridge was constructed in San Francisco, California where it still stands today.
- In 1891, the first concrete street was built in Bellefontaine, Ohio.
- In 1903, the first concrete skyscraper was constructed in Cincinnati, Ohio where it still stands today. The Ingalls Building consists of sixteen floors.
- In 1908, Thomas Edison designed and constructed the first fully concrete homes in Union, New Jersey. These homes still exist today.
- In 1913, the first delivery of ready-mix concrete took place in Baltimore, Maryland.
- In 1936, the first major concrete dams, the Hoover and Grand Coulee, were constructed.
- In 1992, the tallest reinforced concrete building was constructed in Chicago, Illinois. This building is most commonly known by its address; 311 S. Wacker Drive.
An interactive timeline regarding concrete can be found at http://www.concretenetwork.com/concrete-history/.
Frequently Asked Questions
How is concrete made?
Concrete is a specific combination of sand, aggregates/stone, cement, and water. At Rohrer's Quarry concrete is manufactured with reclaimed aggregates, stone, sand, and gray/slurry water.
What is 'concrete reclaiming'?
Concrete reclaiming is essentially the recycling of unused or returned concrete that is often seen as a problem to those within the concrete industry. The reclaiming of returned concrete also allows businesses to save money because they are using what would be considered waste to make new concrete.
Why is concrete reclaiming important?
Concrete reclaiming is so important to the concrete industry because it reduces the amount of waste and discharge. Finding solutions to effectively handle returned concrete has been a pertinent issue for decades, until now! Recycling 100% of returned concrete is now a possibility for businesses that choose to solve problems regarding waste/discharge, helping the environment, and saving their business money.
What makes BIBKO concrete reclaimers different than other reclaimers?
BIBKO concrete reclaimers are unique because they allow for concrete manufacturers and similar industries to recycle and reuse 100% of returned or unused concrete for future production of new concrete. BIBKO concrete reclaimers are characterized by 'zero waste, zero discharge.'
[Photographs taken by Martha Swanson at Rohrer's Quarry, Lititz, PA.]