Gypsum Composite With Porous Calcium Silicates for Fire Stability
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Solution Overview
Problem
Gypsum-based building materials face issues with mechanical instability, high density, and thermal shrinkage during fires, which compromise their fire resistance and structural integrity.
Innovation Solution
A gypsum-based composition incorporating porous, approximately spherical hydrated calcium silicate aggregates, produced via a hydrothermal synthesis using a lime and silica suspension with sulfate and alkali hydroxides, enhances mechanical strength and reduces thermal shrinkage while maintaining fire resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gypsum is used as a base material for fire-resistant building elements, then fire resistance is improved due to incombustibility and endothermic effect, but mechanical stability is lost on heating causing shrinkage and cracks
Solution Approach 1:
The patent combines gypsum with specific additives including hydrated calcium silicates (xonotlite, tobermorite), fibrous materials (cellulose, glass fibers), and binding agents to create a composite material that maintains the fire resistance of gypsum while compensating for its mechanical instability through the reinforcing properties of the other components
Solution Approach 2:
The patent modifies the chemical composition and physical structure of the gypsum matrix by controlling the hydration degree, particle size distribution, and chemical additives to achieve optimal balance between fire resistance and mechanical stability at elevated temperatures
2Reliability
If gypsum matrix is used, then fire resistance is achieved, but high density (1000 to 1350 kg/m³) is obtained which is undesirable
Solution Approach 1:
The patent incorporates porous hydrated calcium silicate aggregates and creates a porous structure within the gypsum matrix through controlled voids and air pockets, reducing the overall density while maintaining fire resistance through the endothermic decomposition of gypsum and the protective char formation from organic additives
Solution Approach 2:
The patent divides the dense gypsum matrix into a composite structure with dispersed lightweight aggregates (hydrated calcium silicates, perlite, vermiculite) and fibrous reinforcement, creating a segmented architecture that reduces density while preserving structural integrity and fire protective functions
3Use of energy by stationary object
If gypsum dehydrates during heating, then endothermic effect provides fire protection, but mechanical strength is lost and cracks appear creating heat and smoke transfer paths
Solution Approach 1:
The patent incorporates fibrous reinforcement materials and flexible binding agents into the gypsum matrix beforehand to cushion and compensate for the volumetric shrinkage and cracking that occurs during dehydration, maintaining structural continuity and preventing crack formation that would otherwise accelerate heat and smoke transfer
Solution Approach 2:
The patent uses fibrous materials (cellulose fibers, glass fibers) and polymer binders as intermediary elements that bridge the gypsum crystals during dehydration, maintaining the structural integrity of the matrix and preventing the formation of continuous crack pathways while allowing the endothermic reaction to proceed
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 composition achieves improved mechanical properties, reduced thermal shrinkage, and lower density, enabling the production of fire-resistant building materials with enhanced thermal stability and reduced weight.
Implementation Method 1
Particular hydrated calcium silicates are xonotlite and tobermorite, which can be obtained by the hydrothermal synthesis of an aqueous suspension of lime and silica
Implementation Method 2
the heating of a gypsum containing construction element when exposed to a fire is remarkably slowed down thanks to the considerable endothermic effect that takes place when this material is subjected to heat. When heating the gypsum (or calcium sulfate dihydrate (CaS0 4 .2H 2 O)), it first loses the water present in its pores, and gradually dehydrates to turn into plaster (or calcium sulfate hemihydrate (CaSO 4 .1⁄2 2 H 2 0)) and later to anhydrite (CaSO 4 )
Data Source
Figure 1A~1B
Figure 2A~2B
AI summary
A material composition and a manufacturing process wherein porous crystalline aggregates of hydrated calcium silicates are homogeneously distributed in a matrix containing gypsum and optionally hydrated cement. The structure of the aggregates of calcium silicates is such that it enables to produce fire resistant building elements with improved mechanical properties and improved thermal stability at high temperatures.