The Bone Test: Pushing the Limits of Material Strength

What is the Bone Test?

The bone test is a specialized experiment designed to evaluate cracking and shrinkage behavior in 3D-printed concrete under varying environmental conditions. The name comes from the geometry of the test sample, which resembles a bone with two anchor points on either end and a deliberate weak point in the middle. This setup ensures that cracks consistently form in a predictable location, allowing us to study their behavior under controlled conditions.

The geometry’s middle discontinuity acts as a stress concentrator, making it an ideal weak point for cracks to initiate. By deliberately designing this flaw, we can simulate real-world conditions where unexpected forces or material inconsistencies might cause structural weaknesses. This gives us valuable insights into how materials perform under pressure and helps refine the mix designs for greater strength and durability.

Why Conduct Destructive Testing?

Destructive testing may sound counterintuitive, but it’s one of the most effective ways to understand material limits and improve them. By intentionally breaking samples under controlled conditions, we can:

• Pinpoint Weaknesses: Identify exactly where and why cracks occur.
• Test Material Variants: Compare different mixes and suppliers to find the most robust formulations.
• Optimize Conditions: Adjust environmental factors like humidity to reduce shrinkage and improve print longevity.

The Role of Moisture in 3D Concrete Printing

Shrinkage cracking is one of the most common issues in 3D concrete printing. As the concrete cures, water evaporates, causing the material to shrink. If this process happens unevenly, it can result in cracks that weaken the structure.

To combat this, we created a controlled environment that surrounds the print with water vapor, forming a fog-like effect. This high-humidity setup slows evaporation and keeps the surface moist during curing. By preventing rapid moisture loss, the cracks are significantly reduced, and the overall durability of the printed object is improved.

This technique isn’t just functional—it’s visually striking. The fog surrounding the print creates an almost ethereal atmosphere, perfectly blending science and artistry.

Comparing Materials and Suppliers

The bone test has been a game-changer in evaluating materials. By applying the same conditions across various concrete mixes from different suppliers, we can directly compare their performance. Key insights include:

• Shrinkage Behavior: Which mixes are more prone to cracking during the curing process.
• Durability: How different material formulations withstand stress over time.
• Consistency: Identifying suppliers that consistently meet our high standards for 3D printing.

This level of analysis ensures that we always work with the best materials available and continue pushing the boundaries of what’s possible in 3D concrete printing.

The Bigger Picture

The bone test is more than just a fascinating experiment—it’s a critical step in Vertico’s mission to create stronger, more sustainable structures. By understanding and optimizing the curing process, we’re not only improving individual prints but also advancing the entire field of 3D concrete printing.

Our collaboration with partners like Sika has been instrumental in this journey. Their insights, coupled with our cutting-edge technology, allow us to refine our methods and materials continuously. Together, we’re shaping a future where 3D printing isn’t just innovative but reliable and durable.

See the Bone Test in Action

Check out the video to see the bone test in real-time. Witness the fog-like humidity environment and how it plays a vital role in preventing shrinkage cracks. This simple yet effective approach showcases our commitment to precision and innovation.