Concrete Etching Composition Using Urea and Acetic Acid
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Solution Overview
Problem
Current methods for etching concrete and mortar surfaces using hydrochloric acid are environmentally hazardous and pose health risks, lacking a safe and effective alternative.
Innovation Solution
An environmentally safe etching composition comprising urea, acetic acid, an anticorrosive agent, a surfactant, and a buffering agent, applied to the surface and allowed to stand before washing, which effectively produces a desired grit finish without harmful runoff or byproducts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hydrochloric acid (muriatic acid) is used to etch concrete surfaces, then effective etching and cleaning of the surface is achieved, but environmental contamination and health hazards occur due to toxic runoff
Solution Approach 1:
The patent changes the chemical composition parameters by substituting hydrochloric acid with a blend of phosphoric acid (10-50% by volume), acetic acid (5-30% by volume), and citric acid (5-30% by volume). This parameter change maintains etching effectiveness while eliminating the toxic runoff associated with hydrochloric acid, as these alternative acids produce less harmful byproducts
Solution Approach 2:
The patent uses a composite acid system combining phosphoric acid, acetic acid, and citric acid in specific proportions. This composite approach leverages the complementary properties of each acid: phosphoric acid provides strong etching capability, acetic acid offers moderate etching with lower toxicity, and citric acid contributes to surface cleaning and corrosion inhibition, achieving effective etching without environmental harm
2Manufacturing precision
If hydrochloric acid is used for etching, then surface cleaning and etching are effective, but hazardous waste disposal requirements and costs increase
Solution Approach 1:
The patent converts the potential harm of acid runoff into a benefit by selecting acids that naturally decompose into less harmful substances. The phosphoric acid, acetic acid, and citric acid mixture produces runoff that is safer for the environment and requires less stringent disposal protocols, turning a previously harmful byproduct into an acceptable or even beneficial waste stream
3Manufacturing precision
If hydrochloric acid is applied to concrete surfaces, then etching and aggregate exposure are achieved, but safety risks to users increase due to corrosive properties
Solution Approach 1:
The patent changes the concentration and type of acids used, replacing concentrated hydrochloric acid with a diluted mixture of phosphoric acid (10-50%), acetic acid (5-30%), and citric acid (5-30%). This parameter change reduces the corrosivity and volatility of the etching solution while maintaining sufficient etching power to expose aggregates, thereby improving user safety without sacrificing effectiveness
Solution Approach 2:
The patent introduces water as an intermediary medium to dilute the acid mixture, reducing its immediate corrosive impact on users. The aqueous solution allows the acids to function effectively for etching while minimizing the severity of potential contact hazards, serving as a buffer between the active etching agents and the user
4Manufacturing precision
If muriatic acid is used for etching, then concrete surface preparation is effective, but environmental damage occurs due to toxic runoff affecting plants and animals
Solution Approach 1:
The patent changes the chemical identity of the acids in the etching solution from hydrochloric acid to a combination of phosphoric acid, acetic acid, and citric acid. This parameter change fundamentally alters the nature of the runoff, transforming it from a highly toxic waste stream to one that is significantly less harmful to plants and animals, while preserving the surface preparation quality
Solution Approach 2:
The patent converts the previously harmful acidic runoff into a less harmful substance by using organic and weaker inorganic acids that decompose more benignly in the environment. The runoff from this alternative acid mixture poses minimal threat to aquatic life and vegetation, effectively eliminating the environmental damage associated with traditional muriatic acid use
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 provides a safe and effective etching process that reduces environmental impact, eliminates hazardous waste disposal, and achieves desired grit finishes on concrete and mortar surfaces, ensuring safety for users and the environment.
Implementation Method 1
acetic acid at greater than about 10% (v/v) acetic acid
Implementation Method 2
urea at no more than about 30% (w/v) urea
Implementation Method 3
a surfactant
Implementation Method 4
a buffering agent
Data Source
AI summary
Disclosed herein is an environmentally safe etching composition and method for a concrete or mortar surface. The composition includes, in some embodiments, an aqueous solution of urea, acetic acid, a buffering agent, an anticorrosive agent, and a surfactant with no more than about 30% (w/v) urea and at least about 10% (v/v) acetic acid. The method includes, in some embodiments, obtaining the etching composition; applying the etching composition to the concrete or mortar surface at a prescribed ratio of the etching composition to the concrete or mortar surface; allowing the etching composition to stand on the concrete or mortar surface for a prescribed amount of time; and washing the concrete or mortar surface with water to produce an etched surface of the concrete or mortar.