Concrete Fastener Installation With Low-Viscosity Adhesive
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Solution Overview
Problem
Thread-tapping concrete screws generate stone powder during installation, leading to potential cracks and reduced fastener stability over time, and existing adhesives do not effectively address these issues.
Innovation Solution
A method involving the use of a low-viscosity adhesive with a viscosity of 150 cP or less is injected into a pre-drilled hole using an injection gun, followed by rotating a fastener with a thread that removes base material portions, ensuring the adhesive is forced into the concrete adjacent to the shank and thread.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thread-tapping concrete screw is screwed into a drilled hole, then the screw cuts a mating thread into the construction material, but stone powder is formed and can result in cracks developing over time
Solution Approach 1:
The patent converts the harmful stone powder byproduct into a beneficial filling material. The adhesive composition is designed to fill the voids and cracks created by stone powder during thread-tapping, transforming the harmful effect into a strengthening mechanism that improves bond strength and prevents crack propagation
Solution Approach 2:
The patent uses a composite adhesive system combining a polyol component and an isocyanate component that react to form a flexible polyurethane adhesive. This composite material provides both structural strength and flexibility to accommodate the stone powder particles while maintaining bond integrity
2Reliability
If adhesive is used to repair cracks in fastener installations, then crack propagation is prevented, but the adhesive must have low viscosity to penetrate into the concrete pores and cracks
Solution Approach 1:
The patent controls the viscosity parameter of the adhesive by adjusting the molecular weight and chemical structure of the polyol component. The adhesive is formulated to have a specific viscosity range that allows penetration into concrete pores while maintaining adequate bond strength, achieving the right balance between flowability and structural performance
3Strength
If the fastener thread removes portions of the base material during insertion, then a mating thread is created for positive fit, but voids and cracks are formed around the thread
Solution Approach 1:
The adhesive acts as an intermediary material between the fastener thread and the concrete substrate. It fills the voids and cracks created during thread-tapping, bonding the thread to the surrounding concrete and distributing stresses uniformly, thereby preventing crack propagation and maintaining concrete integrity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method enhances fastener resistance to pull-out forces and reduces crack development by reinforcing the concrete surface where the thread engages, resulting in improved performance and stability over time.
Implementation Method 1
The hole is then filled with an adhesive having a viscosity of 150 cP or less using an injection gun
Implementation Method 2
The fastener is rotated into the hole such that the adhesive is forced into portions of the base material adjacent to the shank and thread
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A method for installing fastener in a base material. The fastener has a shank having a first end and a second end defining a length, a head provided at the second end, and a thread provided on the shank which includes a leading edge and a trailing edge adapted remove portions of the base material when inserted into the base material. The method includes forming a hole having a diameter which is a nominal shank diameter of the fastener to be installed in the base material. The hole is then filled with an adhesive having a viscosity of 350 cP or less. Finally, the fastener is rotated into the hole such that the adhesive is forced into portions of the base material adjacent to the shank and thread when the thread is fully inserted into the hole.