Particulate Wetting Agent for Dry-Mix Building Materials
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Solution Overview
Problem
Building materials like cements and mortars face challenges in achieving effective hydrophobicity without compromising wettability, as existing hydrophobic additives often result in poor mixing and reduced performance due to their hydrophobic nature, and available surfactants have limitations in pH stability and efflorescence issues.
Innovation Solution
A particulate wetting and hydrophobing additive comprising a disiloxane with specific structural components and a carrier, which functions as both a wetting agent and hydrophobing agent, improving wettability and hydrophobicity without affecting the hydrophobic properties of the additives, and degrading to enhance hydrophobicity in the hardened state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrophobic additives (metal soaps, silicon-based materials) are added to building materials, then hydrophobic performance is improved, but wettability of dry-mix deteriorates
Solution Approach 1:
The hydrophobic additive is segmented into two functional components: a hydrophilic wetting agent (surfactant) that enables water absorption and mixing, and a hydrophobic agent (metal soap or silicon-based material) that provides water repellency. This segmentation allows each component to perform its specific function without interfering with the other, resolving the contradiction between wettability and hydrophobic performance
Solution Approach 2:
The patent changes the parameters of the hydrophobic additive by controlling the hydrophobe/surfactant ratio (typically 90:10 to 70:30), particle size distribution (0.1-2.0 mm), and moisture content (0.5-5.0%). These parameter adjustments optimize both the initial wettability during mixing and the final hydrophobic performance in the hardened state
2Ease of operation
If water-soluble surfactants are used to improve wettability, then wettability is improved, but efflorescence increases and shelf-life decreases
Solution Approach 1:
The patent creates a composite material system combining surfactants (for wettability) with metal soaps or silicon-based materials (to suppress efflorescence). The metal soaps act as efflorescence suppressants by forming a protective layer that prevents salt crystallization, while the surfactant ensures proper water absorption and mixing. This composite approach eliminates the harmful effects of using surfactants alone
3Ease of operation
If trisiloxane compounds are used as wetting agents, then wettability is improved, but stability deteriorates outside narrow pH range
Solution Approach 1:
The patent introduces alkali earth metal soaps (calcium, magnesium) or transition metal soaps (zinc, aluminum) as intermediary substances that stabilize the pH environment. These metal soaps act as buffers that maintain pH within the stable range for trisiloxane compounds, preventing hydrolysis and decomposition while allowing the surfactant to perform its wetting function effectively
4Reliability
If hydrophobic additives are added to dry-mix, then hydrophobic performance is improved, but mixing homogeneity deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-coating the hydrophobic particles with surfactant before incorporation into the dry-mix. This pre-coating ensures that the hydrophobic particles are already wettable when water is added during mixing, promoting uniform distribution and homogeneous mixing throughout the building material matrix
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 additive enhances wettability and hydrophobicity of building materials, ensuring better mixing and performance while maintaining the hydrophobic properties, and its degradation products improve the hydrophobic nature of the materials, addressing the limitations of existing surfactants and additives.
Implementation Method 1
the trisiloxane compounds may only be used in a narrow pH range, ranging from a slightly acidic pH of 6 to a very mildly basic pH of 7.5. Outside this narrow pH range the trisiloxane compounds are not stable to hydrolysis and undergo a rapid decomposition
Implementation Method 2
Surfactants do not only induce a positive impact on properties of fresh concrete but also on a long term basis when concrete has hardened by reducing for example shrinkage through decrease of tap water surface tension
Implementation Method 3
the presence of such materials can have detrimental effects. Their hydrophobic nature results in poor wettability of the dry-mortar when water is added to the dry-mix
Data Source
AI summary
A particulate wetting and hydrophobing additive comprising components a) and b), where: component a) is a disiloxane having structure (I) Where R2 is selected from a branched or linear hydrocarbon group of 2 to 10 carbons, a substituted branched or substituted linear hydrocarbon group of 2 to 10 carbons, an aryl group, a substituted aryl group and an optionally substituted alkyl hydrocarbon group of 4 to 9 carbons containing aryl substituents of 6 to 20 carbons; R1, R3, R4 and R5 are each independently selected from the monovalent hydrocarbon groups of 1 to 4 carbons, substituted monovalent hydrocarbon groups of 1 to 4 carbon atoms, aryl, and a hydrocarbon group of 6 to 20 carbons containing an aryl group; Z is a linear or branched divalent hydrocarbon radical of 1 to 10 carbon atoms and R8 is selected from OH, H, monovalent hydrocarbon groups of 1 to 6 carbons and acetyl, each of the subscripts a, b and c are zero or positive provided that a+b+c≧1; and component b) is a carrier.