Precast Concrete Shell Formwork for Thermal Bridge-Free Walls
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Solution Overview
Problem
Existing concrete formworks face challenges in maintaining quality and precision due to varying environmental conditions, are costly and time-consuming to assemble and disassemble, and create thermal discontinuities at joints.
Innovation Solution
A building system using precast inner and outer concrete shells with embedded stiffeners, mechanically coupled to form a mold cavity, allowing for precise manufacturing, reduced transportation and installation costs, and integration of insulation to eliminate thermal bridges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional concrete formworks are assembled at the building site, then flexibility in construction is maintained, but quality and precision deteriorate due to varying environmental factors
Solution Approach 1:
The system divides the construction process into two segments: precision manufacturing of formwork shells in a controlled plant environment, and flexible assembly at the building site. The precast concrete shells are manufactured with high precision in the factory, then transported and assembled on-site, combining the benefits of both controlled manufacturing and construction flexibility.
2Manufacturing precision
If precast concrete wall panels are manufactured in a facility, then manufacturing precision is improved, but weight increases requiring costly transportation and erection
Solution Approach 1:
The wall structure is segmented into three components: two precast concrete shells (inner and outer) and the poured concrete core. The shells serve as lightweight formwork that can be precisely manufactured and transported, while the heavy concrete is poured in-place, avoiding the need to transport entire wall panels.
Solution Approach 2:
The precast concrete shells act as intermediary formwork elements that enable precise manufacturing without requiring transportation of heavy finished wall panels. The shells are the lightweight carriers that facilitate the transfer of precision manufacturing benefits to the final structure.
3Strength
If precast concrete members are joined using welded connections, then structural strength is achieved, but thermal insulation deteriorates due to cold bridges
Solution Approach 1:
The structural connection and thermal insulation functions are merged into a single integrated solution. The poured concrete core simultaneously provides structural bonding between shells and serves as thermal insulation, eliminating the need for separate metal connections that would create thermal bridges.
Solution Approach 2:
The system uses homogeneous concrete material throughout the wall assembly - in the shells, the core, and the bonding zones. This eliminates material interfaces (particularly metal-concrete interfaces) that would create thermal bridges, maintaining uniform thermal insulation properties throughout the structure.
4Device complexity
If traditional formwork is used, then construction simplicity is maintained, but time and cost increase due to assembly and disassembly
Solution Approach 1:
The formwork shells are prepared in advance in a controlled factory environment, with all necessary reinforcement, insulation, and surface treatments completed beforehand. This preliminary preparation eliminates on-site assembly complexity and reduces construction time, as the shells arrive ready-to-install.
Solution Approach 2:
The precast shells function as disposable formwork - they are manufactured, installed, filled with concrete, and then removed. This eliminates the need for complex reusable formwork systems and their associated assembly/disassembly processes, reducing both time and long-term costs.
Data Source
AI summary
A wall assembly for a building structure, uses (i) an inner shell cast in a first mold to define a first panel of concrete having a plurality of stiffener members embedded in the concrete so as to be at least partly exposed at the inner side of the panel, and (ii) an outer shell cast in a second mold to define a second panel of concrete having a plurality of stiffener members embedded in the concrete so as to be at least partly exposed at the inner side of the panel. The inner shell and the outer shell are mechanically coupled after casting to define a mold cavity between the inner sides of the panels. Field concrete can be cast into the mold cavity between the inner and outer shells once the wall assembly is mounted on site into position within the building structure.