Cold-Mix Modulus-Adjustable Pavement Material
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Solution Overview
Problem
Current bituminous pavements in China face early damage due to inadequate high-temperature stability of the bituminous surface layer and excessive rigidity of the semi-rigid base layer, leading to mismatched modulus between layers, increased tensile stress, and subsequent shear damage.
Innovation Solution
A cold mixing type modulus-adjustable pavement material composed of specific mass ratios of coarse and fine aggregates, fillers, cement, and waterborne epoxy emulsified bitumen, which undergoes a preparation process involving the synergistic effects of waterborne epoxy resin curing, cement hydration, and demulsification reactions to create a material with adjustable modulus and enhanced high and low-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the modulus of the semi-rigid base layer is increased to satisfy deflection design requirements, then the pavement bearing capability is improved, but the tensile stress between bituminous pavement layers increases causing early shear damage
Solution Approach 1:
The patent applies parameter changes by developing a cold mixing material with adjustable modulus through varying cement content (4-8% by mass). This allows the base layer modulus to be optimized to match the bituminous surface layer, reducing tensile stress and preventing shear damage while still satisfying deflection design requirements. The adjustable modulus range enables precise matching between layers to eliminate the contradiction between bearing capability and service life.
Solution Approach 2:
The patent uses composite materials by combining waterborne epoxy emulsified bitumen, cement, aggregates, and fillers to create a cold mixing material with tailored mechanical properties. This composite structure allows the base layer to achieve both adequate bearing capability and compatibility with the bituminous surface layer, resolving the modulus mismatch problem that causes early shear damage.
2Temperature
If high-performance SBS modified bituminous mixture is used to improve high temperature stability, then the high temperature performance is enhanced, but the early damage from modulus mismatch and shear stress still occurs
Solution Approach 1:
The patent changes the fundamental approach by adjusting the base layer modulus parameter rather than continuously enhancing surface layer temperature performance. The cold mixing material's modulus can be tuned to match the bituminous surface layer, addressing the root cause of shear damage while maintaining adequate high temperature stability through the epoxy-modified bitumen binder.
Solution Approach 2:
The cold mixing material acts as an intermediary between the subgrade and the bituminous surface layer. By positioning this material with adjustable modulus in the base layer, it mediates the stress distribution and prevents direct transmission of tensile stresses from the surface layer to the subgrade, thereby preventing shear damage while maintaining overall system performance.
3Productivity
If conventional hot mixing methods are used for pavement construction, then construction efficiency is maintained, but environmental pollution from VOC emissions and high energy consumption occurs
Solution Approach 1:
The patent replaces the thermal field (heat) used in conventional hot mixing with a chemical field approach using waterborne epoxy emulsified bitumen. This substitution eliminates the need for high-temperature heating, thereby preventing VOC emissions and reducing energy consumption while maintaining construction efficiency through the cold mixing process that allows immediate placement and compaction.
Solution Approach 2:
The patent changes the temperature parameter from high-temperature hot mixing to ambient temperature cold mixing. The waterborne epoxy emulsified bitumen remains stable and workable at low temperatures, enabling construction without thermal heating equipment and eliminating the harmful emissions associated with traditional hot mixing operations.
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 material reduces modulus differences between layers, alleviates crack reflection, and improves high-temperature stability, while being environmentally friendly and suitable for flexible base and bituminous surface layers, with the added benefits of low VOC emissions and ease of industrial production.
Implementation Method 1
the waterborne epoxy resin and the waterborne curing agent are simultaneously added in a container, and manually stirred continuously for 2 to 4 min to obtain the waterborne epoxy resin mixture
Implementation Method 2
the emulsified bitumen is first added in the container, and the pH is regulated with hydrochloric acid to be 5.0 to 6.5; and the waterborne epoxy resin mixture, the emulsifying agent, the defoaming agent and the stabilizing agent are mutually stirred and added simultaneously, and continuously mutually stirred for 1 to 3 min until the mixed liquid is uniform
Implementation Method 3
A stator of a high-speed shearing machine is put into the mixed liquid, and the rotational speed is set as 350 to 500 rpm; and a switch is enabled to perform shearing for about 20 to 40 min to obtain waterborne epoxy emulsified bituminous emulsion
Data Source
AI summary
An environmental protection cold mixing type modulus-adjustable pavement material and preparation method thereof. Equal components of waterborne epoxy resin and waterborne curing agent are added in a container to obtain a waterborne epoxy resin mixture. Emulsified bitumen, the waterborne epoxy resin mixture, an emulsifying agent, a defoaming agent and a stabilizing agent are prepared according to a certain mass ratio; the emulsified bitumen is first added in the container, and the pH is regulated with hydrochloric acid to be 5.0 to 6.5; the above-mentioned other materials are added and stirred to make mixed liquid; a stator of a high-speed shearing machine is put into the mixed liquid, and the rotational speed is set as 350 to 500 rpm for about 20 to 40 min to obtain waterborne epoxy emulsified bituminous emulsion. B. Coarse aggregate, fine aggregate, fillers, cement and the waterborne epoxy emulsified bitumen obtained from the above-mentioned preparation are selected in proportion; and after the coarse aggregate, the fine aggregate and rubber powder are added in a stirring machine of asphalt mixture and stirred and the waterborne epoxy emulsified bitumen is added and stirred, the cement is added and stirred.