Isolated Urease Cementation for Fine Sand and Silt
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Solution Overview
Problem
Current methods for soil improvement through mineral precipitation are limited to medium or coarser sands and face challenges such as microbial growth requirements and pore plugging, restricting their application to finer permeable materials like fine sands and silts.
Innovation Solution
Combining isolated urease, urea, a source of divalent cations, and an organic additive with permeable or fractured starting materials to induce carbonate precipitation and cementation, allowing for effective treatment of a broader range of soils, including fine sands and silts, while avoiding plugging issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If microbial-based carbonate precipitation methods are used for soil improvement, then treatment effectiveness on medium or coarser sands is improved, but application to finer permeable materials like fine sands and silts is restricted due to pore plugging
Solution Approach 1:
The patent extracts the harmful microbial components from the system and replaces them with isolated urease enzyme. This eliminates the pore plugging issue caused by microbial growth while retaining the beneficial carbonate precipitation function. The enzyme can be applied to finer soils without the risk of biological plugging that limits microbial-based methods.
Solution Approach 2:
The patent introduces an organic additive as an intermediary substance that facilitates carbonate precipitation without causing plugging. This intermediary enables the process to work effectively in finer permeable materials by providing a different mechanism for crystal formation that doesn't block pores.
2Reliability
If microbial growth is required for carbonate precipitation, then effective treatment can be achieved in medium or coarser sands, but the complexity of the process increases and finer materials cannot be treated
Solution Approach 1:
The patent removes the complex microbial growth requirement from the process by using isolated urease enzyme directly. This simplifies the treatment protocol while maintaining reliability, as the enzyme can be applied without needing to establish and maintain microbial populations, making the process more controllable and less complex.
Solution Approach 2:
The isolated urease enzyme performs the carbonate precipitation function independently without requiring microbial hosts. The enzyme self-catalyzes the urea hydrolysis reaction to produce carbonate ions, eliminating the need for complex microbial culture and growth conditions.
3Strength
If multiple treatment cycles are used to improve soil properties, then bearing capacity and strength can be enhanced, but the time and cost of treatment increase
Solution Approach 1:
The isolated urease enzyme provides continuous carbonate production as long as urea and divalent cations are present, allowing sustained precipitation without interruption for microbial growth cycles. This continuous action achieves the required strength enhancement in fewer application cycles compared to microbial methods.
Solution Approach 2:
The patent changes the kinetic parameters of carbonate production by using isolated enzyme instead of microbial systems. The enzyme reacts more rapidly and predictably, allowing the treatment to reach effective strength levels in less time with fewer cycles.
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
This method enhances the stiffness, strength, and liquefaction resistance of soils, enabling significant improvements in bearing capacity, settlement reduction, and lateral resistance, with the ability to treat finer materials and reduce the need for multiple treatment cycles.
Implementation Method 1
combining a column of a permeable starting material or a column of a non-porous but fractured starting material with a mixture comprising (a) isolated urease; (b) urea
Implementation Method 2
combining a column of a permeable starting material or a column of a non-porous but fractured starting material with a mixture comprising (a) isolated urease; (b) urea
Implementation Method 3
the combining is carried out under conditions suitable to cause carbonate precipitation and/or cementation of the starting material within the column
Data Source
AI summary
The present invention provides methods for mineral precipitation and/or cementation of permeable or fractured non-porous materials using isolated urease.