Does Concrete Have a Shelf Life? (Does It Really Expire?)

Concrete is an essential component of any building project, helpful in making durable structures. But often, while using concrete, a question arises: does concrete have a shelf-life?

Concrete has a shelf life and does not last indefinitely. A bagged concrete mix can be kept for 3 months to a year, depending on how it has been stored. Because it hydrates when exposed to moisture and can suffer compaction in storage, concrete can lose integrity if not stored properly.

So, always use the concrete within the time period stipulated on the bag.

In this guide, you’ll learn the various factors that influence the sell-by date of concrete. Plus, you’ll know how long you can store concrete and how to ensure it stays fresh for as long as possible. 

The Shelf Life Of Concrete Mix

The concrete mix consists of a mixture of cement and aggregates such as sand and stone. Sand and stone are inert materials that do not influence the aging of concrete mix. However, cement is much less stable.

Concrete is usually made with Portland cement, which takes its name from its Portland grey color and is derived from chalk and clay.

The chemistry of Portland cement is triggered by a chemical reaction called hydration, whereby the cement paste hardens and gains strength. 

Portland cement can last a long time if you keep it dry. Still, even the moisture present in the atmosphere is enough to cause the cement to harden. So, it must be kept in an airtight environment. Remember, once the moisture content exceeds five percent, cement cannot be used in construction (source).

Compaction issues occur when you bag and stack the Portland cement and allow the content to settle over a period of time. This is referred to as “warehouse pack,” resulting in the cement becoming hard, even though it has remained dry.

Most of the time, you can still use the concrete after you roll the bag on the floor to loosen the lumps. 

If a packaged concrete mix is less than six months old, has no lumps, and is a completely free-flowing powder, you can use it for non-structural purposes. However, the concrete used in all structural jobs with high strength requirements must be made from a fresh concrete mix.

What Happens When Concrete Expires?

While many users may be tempted to use the concrete after its sell-by date, a few things have already happened to the concrete that may render it useless.

Firstly, it may have formed lumps or hardened completely through hydration. Secondly, the strength of concrete reduces proportionally over time until it is ineffective.

Image by Jarrod Erbe via Pexels

You can clean (using a cleaning agent) and dispose of the packaging that is soiled in accordance with local, state, and federal regulations.

For further information on other options, read “What Can I Do with a Hardened Bag of Concrete?”

How Do You Store Bags of Concrete?

There are a few practices that help maintain the freshness and strength of a concrete mix. While the product is stable in dry conditions, it must be transported from the factory to the customer. Once it leaves the factory, procedures must be followed to ensure optimum shelf life.

Bags of mixed concrete should be stored on raised surfaces in a dry place. Ensure it is inside a dry building or shed, away from rain, moisture, sunlight, and wind.

By following these general guidelines, the integrity of the product should be assured. Below are pointers for the ideal storage and transportation of bags of concrete mix.

Speaking of concrete, have you ever wondered if you can pour concrete directly on dirt? Check out the guide to learn more about the correct concrete pouring technique.

Avoid Dampness and Moisture

The cement changes from a powder when water is added, becoming a paste.

When the paste combines with the aggregate, it forms a binding mix. The effect of water on the cement is called hydration. This results in the cement paste hardening and strengthening.

As cement hardens when it comes into contact with any form of dampness, it must be protected from atmospheric moisture or water. Storage must be in dry conditions, in a closed structure, properly stacked, and covered. 

Even if the concrete mix has been kept in dry conditions, it still tends to react to humidity and moisture in the air — not just water and dampness — and, over time, it loses its strength.

Pro-Tip: Avoid storing concrete bags directly on concrete or wood floors. As moisture can permeate from the ground upwards, a bagged concrete mix should never be laid directly on a floor. Rather, raise it off the ground with a waterproof sheet underneath the stack. 

Store indoors in a well-ventilated building to prevent moist air accumulation. The storage unit must be dry and safe from any possibility of exposure to water. 

If bags need to be offloaded and are in transit to a storage area, this should be as brief a period as possible, secure from water exposure. To learn more about this, read “Can Bags of Concrete Be Stored Outside?”

How Concrete Packaging Affects Shelf Life

Concrete mix and cement are mostly packed in environmentally friendly, durable paper bags. Because these bags are not airtight, moisture can enter, even if unopened. Therefore, they must be used within three months.

Trials of concrete mix or cement stored in airtight containers and controlled environments of constant temperature and humidity have successfully lengthened the shelf life of the concrete.

Other trials using plastic bags monitored the aging behavior of calcium aluminate cement in normal warehouse storage conditions for a period of 40 months. These trials revealed that plastic packaging protecting concrete from moisture greatly improved the product’s shelf life, and a one-year shelf life guarantee could be given (source).

Minimize Warehouse-Pack

Efficient warehouse packing limits any damage to the item once it has moved into the warehouse. The packaging is designed to protect the concrete mix inside. But also has to be efficient in terms of moving and stacking the material. 

However, if the bags are piled too heavily, this could result in warehouse-pack and compaction of the lower layers. To prevent this, stacks should be kept to less than 12 bags in height.

Also, the first-in-first-out rotation method should be stringently applied to a concrete mix and cement products. This ensures that bags in storage are rotated accordingly.

Pro-Tip: Avoid storing a concrete mix with any other products, as this could affect the strength and performance of the product.

Handle with Care

By following the handling procedures below, damage to the concrete mix will be minimized:

• Never use hooks to load concrete mix.
• Don’t throw or drop a bag, as the packaging could split or weaken.
• Roll bags before lifting to help loosen the contents and reduce the risk of splitting. 
• Carry the bag in your arms like a baby, supporting the underside.
• Lay cement bags flat when storing, broadside down.

Bags should be loaded with care, avoiding sharp protrusions that could pierce them. Ensure there is thorough waterproofing to prevent the bags from getting wet during transport.

Did you know that by sealing it, you can make it last longer? Check out this guide to learn more: Is Sealing Concrete Really Necessary?

How Long Will a Bag of Concrete Last Once Opened?

This depends on the conditions of humidity and temperature under which it has been stored. Frequently, partially used bags are leftover from a project, and the paper is torn, leaving the concrete mix exposed to the air.

This will result in product degradation. To avoid this, the contents should be re-bagged in tightly sealed impervious plastic bags and stored in a dry place. This may help it last a few more weeks.

While there may be a temptation to use an old concrete mix, you will ultimately regret it. The product will cause quality problems and will require repairing or replacement down the line, jeopardizing your relationship with your customer and damaging your reputation. 

To avoid leftover concrete, calculators provided by manufacturers are great tools to help you calculate accurate quantities needed for the job at hand. If you are unsure, professionals can help, too.

Either way, our advice is to try to avoid having a leftover concrete mix, as you cannot be assured of retaining its integrity for any length of time.

Now that you know about concrete’s shelf life, it’s also good to know how to make a concrete surface smooth and shiny. Check out the article to explore an in-depth guide on the topic.

Image by Matthew Bowden via FreeImages

Final Thoughts

The cement in a concrete mix displays hygroscopic tendencies. This means that any water it comes into contact with will change its character. This is good if you will use the concrete immediately as water acts as the binding agent to strengthen the concrete. However, as concrete mix ages, it becomes less effective until it reaches its sell-by date.

Typically, concrete has a sell-by date that is three months from its manufacture date, and this should be displayed on the packaging. If you store concrete mix responsibly, you could extend the product’s life, but it could also be shorter if stored badly. We hope this article has helped you understand the shelf life implications of concrete.

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