Asphalt concrete can be divided into two categories according to the different binders used: petroleum asphalt and coal tar asphalt; Some countries or regions also use or mix natural asphalt for mixing. Next, let's talk about the classification and properties of Jinan asphalt concrete:
Classification of asphalt concrete:
1. According to the different types of aggregates used, they can be divided into:
Crushed stone, gravel, sandy, and slag are commonly used. According to the different sizes of large particles in the mixture, it can be divided into several categories: coarse particles (less than 35-40 millimeters), medium particles (less than 20-25 millimeters), fine particles (less than 10-15 millimeters), and sand particles (less than 5-7 millimeters).
2. According to the different grading of mineral materials, it can be divided into:
Dense graded, semi open graded, and open graded mixtures are also known as asphalt crushed stones. The dense graded crushed stone mixture of hot mix and hot paving is durable, high in strength, and has good integrity. It is a representative material for building high-grade asphalt pavement and has been widely used.
3. According to the composition of ore, it can be divided into:
Dense suspended structure (such as AC - I), skeleton void structure (such as OGFC), and dense skeleton structure (such as SMA).
4. Different countries have different specifications for asphalt concrete. The technical specifications for hot mix and hot laid asphalt mixtures formulated by China are called asphalt concrete with a porosity of 10% or less, and are further divided into Type I and Type II. Type I has a porosity of 3 (or 2) to 6%, which belongs to the dense grading type; Type II is 6-10%, belonging to the semi open graded type; Those with a porosity of more than 10% are called asphalt crushed stones and belong to the open graded type; The physical and mechanical indicators of the mixture include stability, flow value, and porosity.
Properties of asphalt concrete:
The strength of asphalt mixtures is mainly manifested in two aspects:
One is the bonding force of the binder formed by asphalt and mineral powder;
The other is the internal frictional resistance and locking force between aggregate particles.
The huge surface area of fine particles of mineral powder (mostly less than 0.075 millimeters) forms a thin film of asphalt material, thereby improving the bonding strength and temperature stability of asphalt material; The locking force is mainly generated between the coarse aggregate particles.
When selecting the gradation of asphalt concrete mineral aggregate, both should be taken into account to achieve a dense, stable, moderately rough, and durable road surface after adding an appropriate amount of asphalt.
There are various methods for mixing mineral materials, which can be calculated using formulas or specified based on experience. China adopts the grading range of the experience curve.
The appropriate amount of asphalt in asphalt mixtures should be determined based on laboratory test results and practical conditions on the construction site. Generally, there are reference asphalt dosage ranges listed in relevant specifications as guidance for trial mixing.
When the variety of mineral materials, grading range, asphalt consistency and type, mixing facilities, regional climate, and traffic characteristics are relatively fixed, empirical formulas can also be used for estimation.
That's all for the classification and properties of asphalt concrete. We hope it can be of great help to you. For more information, please come to our website http://www.ycgjglcl.com consulting service