Cement Mortar for Offshore Grouting
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Solution Overview
Problem
Current high-viscosity polymer concretes used for subsea grouting in offshore structures are expensive and require pure, temperature-controlled water, leading to thermal stresses due to temperature gradients between the grout and seawater, which can cause damage such as cracks in the foundation.
Innovation Solution
A cement mortar composed of Portland cement, seawater, and a silicon-containing aggregate like rice hull ash, which reduces exothermic reactions and thermal stresses, allowing for stable grouting without the need for expensive polymer concretes or temperature-controlled water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Portland cement is used instead of polymer cement, then cost is reduced, but thermal stresses increase due to exothermic reaction with salt water
Solution Approach 1:
The patent changes the chemical composition parameters of the cement mortar by incorporating specific admixtures (polycarboxylate-based superplasticizer, lithium nitrate, and naphthalene formaldehyde sulfonate) to modify the exothermic reaction characteristics. These parameter changes reduce the peak temperature and thermal gradient while maintaining the cost advantage of using Portland cement instead of polymer cement.
Solution Approach 2:
The patent introduces chemical admixtures as intermediary substances that mediate between the Portland cement and salt water interaction. These admixtures control the hydration process, reducing the intensity of the exothermic reaction and thereby reducing thermal stresses without requiring expensive polymer cement.
2Reliability
If pure water at specified temperature is used for mixing, then grout performance is improved, but equipment complexity and cost increase due to temperature control requirements
Solution Approach 1:
The patent enables the cement mortar to self-regulate its mixing water requirements through the use of chemical admixtures. The superplasticizer and other additives allow the use of seawater at ambient temperatures without requiring external temperature control equipment, while still achieving adequate grout performance and reduced thermal stresses.
Solution Approach 2:
The patent changes the water quality parameters from requiring pure water at controlled temperatures to accepting seawater at ambient temperatures. This parameter change is enabled by chemical admixtures that compensate for the lower quality of seawater while eliminating the need for complex temperature control equipment.
3Strength
If high-viscosity polymer concrete is used, then force transmission is improved, but cost increases and pure water with temperature control is required
Solution Approach 1:
The patent creates a composite cement mortar material combining Portland cement with specific chemical admixtures (polycarboxylate superplasticizer, lithium nitrate, naphthalene formaldehyde sulfonate) and controlled water-cement ratio. This composite material achieves adequate force transmission capability while avoiding the high cost and strict water requirements of polymer concrete.
Solution Approach 2:
The patent modifies the rheological and mechanical parameters of the cement mortar through chemical admixtures, achieving sufficient strength and force transmission properties that replace the need for expensive polymer concrete while maintaining workability with seawater.
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 cement mortar provides a cost-effective, bubble-free grouting solution with improved flow properties and thermal insulation, reducing thermal stresses and ensuring the stability of offshore structures without the need for expensive polymer concretes or temperature-controlled water.
Implementation Method 1
the strong exothermic reaction, further intensified by the penetration of or reaction with salt water, generates high temperatures of 150–180 °C
Implementation Method 2
The cement mortar according to the invention exhibits significantly reduced blistering during mixing and hardening... the maximum temperature during the mixing of the cement mortar according to the invention can be reduced, which advantageously improves its pumpability
Data Source
AI summary
The present invention discloses a cement mortar for filling cavities located below the water surface. The cement mortar comprises cement, mixing water with a salinity of at least 0.1%, and a silicon-containing aggregate. Further aspects of the present invention relate to the use of the cement mortar according to the invention for filling cavities located below the water surface or for thermal insulation, as well as methods for filling cavities located below the water surface or for thermal insulation of building components using the cement mortar according to the invention.