1) Influence of physical and chemical properties of soil in mixture
It includes the influence of soil composition and variety and the influence of asphalt mixture composition and structure type. According to the different particle size distribution, the mixture can be divided into three physical conditions: suspension dense structure, skeleton open space structure and dense skeleton structure:
The mineral composition and dispersion of cement have a significant impact on the stability effect of cement stabilized soil.
The variety and amount of asphalt have a particularly important impact on the properties of the mixture. Too little amount of asphalt will make the mixture fail to meet the relevant specified specifications. Too much amount will not only make the mixture fail to meet the relevant specifications, but also form waste and uneconomical. The effect of pavement improvement is not very significant.
The water content has a great impact on the asphalt mixture with cement. When the water content is insufficient, the cement can not be fully hydrated and hydrolyzed in the mixing process, which can not play the role of cement in the stability of the mixture and affect the formation of strength. The water content tends to flow out, and the effective components of cement go with the water flow, resulting in the decrease of compressive strength; Excessive water content will also form the problem of dry shrinkage of asphalt mixture mixed with cement.
The strength of asphalt mixture with cement is gradually formed in a series of chaotic physical and chemical reactions, which require certain external conditions. The test shows that a certain temperature and humidity are beneficial to the formation of the strength of the mixture mixed with cement.
General cement stabilized soil has certain requirements for aggregate crushing value. When recycling old asphalt pavement materials with cement and emulsified asphalt, there are certain requirements for the same crushing value of aggregate.
The cost of cold recycled bottom layer (bottom layer and surface layer) on the site of asphalt concrete old road is mainly the cost of machinery and additives, and the labor cost is basically the same as that of other bottom layers. Compared with other semi-rigid bottom layer materials, the on-site cold regeneration process saves the following costs: the cost of milling and outward transportation of the old pavement, the cost of raw materials of the bottom layer (bottom layer, surface layer), the transportation cost of raw materials, the cost of shortening the construction cycle, etc.
Recycled asphalt mixture not only has certain economic benefits, but also indirectly has good social and environmental benefits, which can not be measured by money and silver.
The old asphalt mixture is fully utilized due to the paving of recycled pavement, which solves the problem of environmental pollution caused by many wastes in the renovation of asphalt pavement, protects the environment for human survival, and meets the requirements of waste recycling in China's sustainable development strategy; Because it saves asphalt and gravel materials, reduces the demand for materials, helps to protect natural resources and ease the tension between supply and demand of asphalt materials; Because the investment is saved and the project cost is reduced, some old asphalt pavements that could not be renovated in time can be repaired, so as to improve the road condition, improve the transportation capacity of the road, reduce tire wear, reduce transportation costs, reduce possible traffic accidents and ensure driving comfort and safety.
This paper mainly introduces the aging mechanism of asphalt pavement, the fundamental principle of asphalt pavement cold regeneration technology, influencing factors, economic and environmental benefits, etc. After introducing the basic skill of cold recycling of asphalt mixture, I can have a more comprehensive understanding of the basic characteristics and application advantages of this skill.