The new tech in 3d printed houses promises to revolutionize the way we build things. Using a special 3d printer, companies can quickly make houses in any shape or size. The process of 3d printing can take as little as 24 hours, promising exciting new frontiers in the world of construction. (Source)
But can these houses stand the test of time? Let’s take a moment to examine how durable these concrete-based 3d printed houses really are.
Are 3d Printed Houses Durable / Strong?
3d printed houses are just as durable as any other sort of house. This means that a well-built 3d printed house that’s made with durable materials could have walls that stand for centuries, while one that cuts corners and uses cheaper, less durable materials might not last long at all.
3d printed houses aren’t made exclusively of concrete. The 3d printed part, however, is made of a blend of materials that are exuded from a 3d printer. In a lot of cases, this is concrete, but it can also be mortar, resin, a polymer blend, soil, or even plastic. (Source)
The remainder of the house – including the HVAC, the doors and windows, and sometimes the framework, is made using traditional construction techniques and standard building materials. for more on this, check out our post Could A House Be 3D Print To Include Plumbing and Electrical Components?
Compressive Strength of Different Concrete Blends ( in MPa – Megapascal Pressure Unit)
- Low-Strength Concrete – less than 20 MPa
- Moderate Strength Concrete – 20-50 MPa
- High Strength Concrete – 50-150 MPa
- Ultra-High Strength Concrete – 150+ MPa
As you can see from the table above, there’s a huge difference in the strength of different blends of concrete. 3d printed houses are no different. 3d printed houses are made from complex, customized print material, including cement, sand, and additives to change the properties of the material. (Source)
These additives can make up 10-15% of the mix. Just like with other types of concrete, engineers will vary the mix based on the requirements of the job. This means that a builder can choose exactly how durable they want their 3d printed house to be.
Concrete’s Variable Durability
Humans have been building with concrete for thousands of years. If you travel to Rome, you can see vast, unreinforced structures built thousands of years ago that are still standing today. Despite this, we see sidewalks and walls in our cities crumbling mere decades after they were built.
When engineers select a concrete mix for a job, they often consider factors like cost, drying time, and ease of construction as well as strength and durability. This means that in many cases projects use concrete that’s easier to shape or that dries faster at the expense of durability. If a structure is only supposed to last for a few decades, these tradeoffs are totally acceptable. They help make structures affordable and help ensure that construction progresses rapidly.
For more on this, check out our post on How Long Do 3D Printed Homes Last? Materials Used, Durability & Lifespan
Impact of Weather and Salt on 3d Printed Houses
While concrete’s mix is important, other factors can also have a big role in determining how long it lasts. Salt, for example, can cause concrete to decay much faster than it normally would.
Concrete has calcium hydroxide in it, which reacts with the calcium chloride in salt to form calcium oxychloride. When salt is carried inside concrete’s porous exterior (often by water), expanding calcium oxychloride crystals put stress on concrete from the inside, causing cracks and crumbling. (Source)
Humidity can also have a big impact on how durable concrete is. When concrete is exposed to high relative humidity, it becomes more acidic. This can have a negative impact on sealants and coatings used to keep the concrete dry and safe.
Concrete also grows weaker when it’s exposed to high humidity, meaning its compressive strength goes down. These two factors work in tandem. In a humid climate, acidic concrete can damage sealants and coatings, leading to water, salt, and other unwanted materials getting inside the concrete. Once these impurities infiltrate the concrete, they’ll cause damage more quickly, as the humid environment will reduce the concrete’s strength.
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