How Hempcrete can Relieve the Portland Cement Shortages

Have you heard? There’s a shortage of Portland cement that (almost) no one is talking about. It’s gotten bad enough that contractors are delaying jobs and weighing lay-offs.

The good news, is that hempcrete (or hemp-lime) construction is a highly sustainable alternative that can help relieve the shortages.

Portland cement: always there… until it’s not

There are certain things I’ve grown accustomed to while living in our modern age. Flip a switch and the lights come on. Go to the grocery store, see shelves full of food. Go to the [Big Box Home Improvement Store] and see dozens of bags of Portland cement.

As you may already know, Portland cement is the gray powder that when mixed with water, becomes the pasty glue of modern concrete. The other key ingredients are sand and gravel.

And as long as I’ve walked this great plane, Portland cement is always available at the store.

But what happens when it’s just not there…?

As you and I experienced during the Covid pandemic, it is entirely possible for the supply chain to stall or outright collapse. This was demonstrated by the widely reported, barren grocery shelves. Who expects that grocery stores just won’t have food? Or what they have is so tightly rationed…

As I write this in September of 2022, I can say that by late spring/early summer, I noticed that my local Home Improvement store seemed to be running awfully low on Portland cement.

First, the big 92.6 lb. bags were gone. And there were only a handful of the 47 lb. bags left. (The big bags cost lest, per lb.)

Next time I happened to be in the store, I checked out of curiosity and there was no Portland cement at all! This continued for several months.

And then a good friend of mine, who uses a lot of Portland cement for building and heavy duty drilling, said he’s been backordered with [The Popular Brand of Bagged Cements You Always See at the Depot] for weeks and weeks. He needs multiple pallets at a time, he’s paid for it, but can’t get it. He’s had to put jobs on hold and finally had to drive the next state over to pick it up from the cement plant.

I wondered if this was just an issue in my rural Colorado town, or something bigger? Here’s what I found…

Labor and cement shortage causing ‘perfect storm,’ industry expert warns

Demand for construction is ‘crazy,’ Metrocon, Inc. president said

Concrete company president on how labor, cement shortage impacts industry

Metrocon, Inc. President Dan Crosby warns that the labor and cement shortage is causing the ‘perfect storm’ in the industry.

Metrocon, Inc., is based in South Carolina and prides itself on premier ready-mix concrete. Crosby stressed that his business is only taking on 60% of the work that it can normally handle amid the labor and supply shortage.

The few other articles I found had more of the same story. Surprisingly, the Portland cement shortages extend all the way into Canada!

Cement shortages are putting pressure on Canada’s construction industry

Uncertain supply means hard choices for builders, even as the sector enjoys a boom year. Emad Sleiman, the owner of Apex Concrete, says the cement shortage has his business scrambling to schedule concrete for their contracts. (Justin Pennell/CBC News)

Apex used to schedule concrete trucks based on the projects they had coming up. Now, they’re booking any available concrete and trying to squeeze clients into those days. Some jobs are being pushed back weeks as they wait for materials and other Calgary companies, like Omega 2000 Cribbing Inc., are turning clients away. 

“I don’t know how other contractors are going to survive. I don’t know how the suppliers [are] going to keep providing,” said Sleiman.

The construction sector is having a boom year, as consumers and companies pour more dollars into building infrastructure. But cement, a key ingredient in making concrete, has become scarce, and the shortage — caused by a confluence of increased demand, labour shortages, inflation and issues at major plants — is creating serious problems for the construction industry across the country. […]

I then called up the big name-brand cement company who supplies the stores and normally sells Portland in bulk. They literally told me that they can’t even take my order!

The cement shortage is so bad, they’ve had customers who are on “allocation” for a certain volume are having trouble getting all their material on time.

After a bit digging on the internet, I found several cement plants and terminals within my state. They were having the same troubles, although one offered bulk tanker orders (I’d need a large cement silo on-site to receive the delivery). Basically, bagged Portland cement was a no-go except for what you could scavenge (fight for?) at the store.

Portland cement gets a lot of heat for its environmental footprint, as global production is responsible for at least 8% of total global CO2 emissions. Last I’ve heard, to alleviate shortages in the US, Portland cement is being imported by truck and freighter ship. What’s the footprint on that?

How Hempcrete can help relieve Portland cement shortages, globally

Hempcrete, a form of hemp-lime construction, offers a sustainable alternative to Portland cement-based concrete.

In a broader scope, hemp-lime involves any use of hemp and a lime-based binder or mortar for building. It is masonry in the vintage and historic sense, as an extension of the lime (limestone, quicklime, slaked… etc.) construction methods dating back to the Romans and ancient Greeks.

The definition of hempcrete emphasizes use as a self-insulating, non-structural, thermal mass for walls, floors and more. Hempcrete is being recognized and celebrated for being resistant to fire, mold, pests, it “breathes” to improve air quality and reduce dampness buildup within walls and homes, gives acoustic benefits to walls, has autogenous healing properties and more. There’s also a great deal of exciting research about the performance benefits of “fiber reinforced concrete,” to which hempcrete shares.

Although Portland cement-based concrete is more appropriate for below grade applications such as foundations, hemp-lime methods have great use above ground level. And while “hempcrete” is most often designed to be light and insulating, I’ve mixed and cast hemp-lime masonry products that are hard as stone.

This includes blocks, pavers and garden benches that I weathered outside 24/7 uncovered, unfinished (no lime render etc.), through Colorado rain, snow and sunshine for 3 years before ever discussing them with the public.

Depending on project goals and preferences, hempcrete can be made with more or less Portland cement. Or no Portland cement at all. Portland gives a strong and fast hydraulic set to concrete or hempcrete, meaning it cures through hydration and can even cure under water. However, those benefits come with drawbacks, including Portland cement creating masonry that can be brittle, inflexible, overly reactive with chemical salts and even steel rebar causing early failure… and then there are the environmental concerns.

Lime-based binders and mortars typically take longer to set, cure and gain compressive strength, but carry long term benefits of strength and longevity. See, Roman Concrete and The Pantheon. The world’s largest unreinforced concrete dome, still standing after approximately 2,000 years! They accomplished that without Portland cement or steel rebar.

The lime-based binder is what allows hempcrete walls to breathe, self heal, and more. Although Portland cement could be used (and from what I’ve seen, often is used) for hempcrete, it can impede the benefits of using lime, creating a less flexible, less breathable, perhaps shorter lived building or home. Using a small amount in the binder may give the benefit of quicker and more hydraulic sets, but that is up to the builder, contractor or homeowner and their preferences.

So whether someone uses some Portland or no Portland in their hempcrete project, there is a lot of value in at least replacing a portion of Portland cement with more sustainable and more readily available alternative materials. Each ton of Portland cement that is not used can prevent 1 ton of CO2 being released.

Certain types of lime are more hydraulic than others. And then there is the topic of pozzolans. Such as volcanic ash, that when in small, divided form and mixed with hydrated lime and water forms cementitious compounds . I was truly fascinated to discover the accomplishments of Roman engineers and masons, who built massive structures that were beautiful, functional and withstood the sands of time.

I carried that wisdom forward when formulating the proprietary and exclusive mix designs for Hemp and Block, LLC. By utilizing lime and pozzolanic materials, you can build as needed without being so reliant on a single product such as Portland cement, which may or may not be available when you actually need it. The raw materials are available in abundance, so I acquire those in bulk and cast hempcrete as needed.

Pre-cast hempcrete blocks for building walls also offer you convenience on bigger jobs. Rather than having to rely on Portland-cement based concrete the day of the job, you can have cured hempcrete blocks delivered to the job-site and build as fast as you want.

Portland cement definitely has its purpose, but the Portland Cement shortage of 2022 is another great example of why we constantly explore and develop sensible and sustainable natural building methods. Hemp-lime and hempcrete have a bright future in this space.

Derek Wolf, CEO, Hemp and Block, LLC.

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