Controllable High Flow Concrete Mix Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing concrete mix designs face challenges with high fluidity leading to instability and segregation, particularly in self-consolidating concrete (SCC), which requires high cement content and fine aggregate, resulting in excessive heat generation, shrinkage, and difficulty in maintaining consistency and flow control.
Innovation Solution
A concrete composition with a high stone content and low cement content, utilizing two polycarboxylate comb polymers and specific viscosity modifying agents to achieve controlled slump flow and reduce segregation risk, similar to ready-mix concrete (RMC) characteristics, while maintaining high fluidity and flowability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the dosage of dispersant is increased to achieve longer slump life, then slump retention is improved, but initial fluidity increases to the point where concrete mix becomes unstable and severe segregation occurs
Solution Approach 1:
The invention changes the chemical parameters of the dispersant by using polycarboxylate comb polymers with specific molecular structures (comb-shaped architecture with pendant side chains) rather than conventional linear polymers. This structural parameter change allows achieving longer slump life without excessive dosage, thereby maintaining mix stability while avoiding severe segregation.
Solution Approach 2:
The invention uses composite admixture systems combining polycarboxylate comb polymers with specific viscosity modifying agents (such as cellulose ethers or starch derivatives). This composite approach allows the dispersant to provide effective dispersion at lower dosages while the VMA maintains viscosity and prevents segregation, thus resolving the contradiction between slump retention and stability.
2Duration of action of stationary object
If excessive dosage of dispersant is used to achieve longer slump life, then slump retention is improved, but setting time is extended undesirably
Solution Approach 1:
The polycarboxylate comb polymer structure changes the dosage parameter required for effective dispersion. The comb-shaped molecular architecture provides more efficient cement particle coverage per unit mass, allowing lower dosages that do not excessively interfere with cement hydration, thus avoiding extended setting times while still achieving desired slump retention.
3Stability of the object's composition
If SCC contains high content of fine material to produce stable mixture, then segregation resistance is improved, but cement content and pozzolan content must be increased leading to excessive heat generation and shrinkage
Solution Approach 1:
The invention extracts the fine material requirement from the SCC system by using polycarboxylate comb polymers that provide effective dispersion and stability without needing excessive fine particles. The comb polymer structure creates a protective layer around aggregates, allowing coarser aggregate gradations and lower cement contents while maintaining segregation resistance.
Solution Approach 2:
The invention changes the aggregate size distribution parameter by allowing coarser maximum aggregate sizes and adjusting the gradation curve to reduce fine material content. Combined with the specialized dispersant, this parameter change reduces cement content requirements while maintaining mix stability and segregation resistance.
4Ease of operation
If SCC flows like water to achieve self-consolidation, then ease of placement is improved, but formwork requirements become more robust and water-tight increasing complexity
Solution Approach 1:
The invention changes the rheological parameters of the concrete by using polycarboxylate comb polymers that provide controlled flow characteristics. The dispersant creates a balance between yield stress and plastic viscosity, allowing the concrete to flow adequately for placement while maintaining enough body to not require perfectly level forms or excessively robust water-tight formwork systems.
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 solution provides a concrete with enhanced consistency and flow that is controllable, reduces cement requirements, decreases shrinkage and heat generation, and lowers the carbon footprint, while maintaining stability and minimizing segregation risks.
Implementation Method 1
at least two cement dispersant polycarboxylate comb polymers
Implementation Method 2
polycarboxylate comb polymer cement dispersants
Implementation Method 3
particular viscosity modifying agents
Implementation Method 4
viscosity modifying agents
Implementation Method 5
aggregate particles will tend to sink and water and cement will float to the surface
Data Source
AI summary
The present invention relates to very high workable yet controllable concrete mix design, admixture composition, and process for placing concrete. The mix design relates to particular aggregate/cement ratios and types which are characteristic of ready mix concrete (RMC), which provide high fluidity reminiscent of self-consolidating concrete (SCC), and which provides advantages over both RMC and SCC in terms of ease and speed in placement and finishability at the construction site placement zone, regardless of whether into a horizontal formwork (e.g., for slabs, floors) or into vertical formwork (e.g., for blocks, walls, columns, etc.), without loss of control and without generating high risks of segregation even when small amounts of water are added at the size to facilitate finishing of the concrete surface. An inventive admixture combination which enables this unique design involves two different polycarboxylate comb polymers in combination with two specific viscosity modifying agents, and this combination provides highly workable concrete to be placed in a controlled, efficient manner.