How to design the asphalt concrete mixture, briefly describe the design steps of the target mix rati

Asphalt concrete can be divided into two categories: petroleum asphalt and coal asphalt according to the different binders used; According to the different types of aggregates used, it can be divided into several categories of gravel, gravel, sandy and slag, and crushed stone is the most common. According to the maximum particle size of the mixture, it can be divided into coarse grains (below 35 40 mm), medium grains (below 20 25 mm), fine grains (below 10 15 mm), sand particles (below 5 7 mm) and so on. According to the different degree of compactness of the mixture, it can be divided into several categories, such as dense gradation, semi-open gradation and open grading, and the open gradation mixture is also called asphalt gravel.

Among them, the densely graded gravel mixture of hot mix and hot paving is durable, high strength and good integrity, and is the representative material for building high-grade asphalt pavement and is the most widely used. The principle of combination is that the maximum particle size of asphalt surface course aggregate should gradually increase from the upper layer to the lower layer.

The upper layer should use the medium grain type and the fine grain type, and the maximum particle size of the asphalt mixture aggregate in the upper layer should not exceed the layer thickness 1 2, and the maximum particle size of the middle and lower layer aggregate should not exceed the 2 3 layer thickness. According to the porosity of asphalt mixture after compaction classification 1, type dense graded asphalt concrete: porosity is (3 6) 2, type dense graded asphalt concrete:

The porosity is (4 10) 3, AM type open graded hot mix asphalt gravel: porosity is (greater than 10) at least one layer of asphalt surface layer is dense graded asphalt concrete, in order to prevent water infiltration. If the upper layer adopts type asphalt concrete, the middle surface layer must be made of type asphalt concrete, AM type open graded asphalt gravel should not be used as a surface layer, can only be used as a connecting layer.

Multi-gravel asphalt mixture is a form of asphalt mixture formed by using more coarse gravel to form a skeleton, and asphalt sand glue fills the pores in the skeleton and glues the skeleton together. The specific composition is: coarse aggregate content 69 78, mineral powder 6 10, oil-stone ratio of about 5.

The surface course of multi-gravel asphalt concrete can provide a deeper surface structure, and has the smaller void and small permeability like the traditional asphalt concrete, and has the better deformation resistance (dynamic stability is higher) at the same time.

In general, the amount of asphalt is about right, and the proportion of gradation should be determined according to the actual material, and there is no fixed number!

Generally, modified asphalt is selected as an anti-skid surface, with high viscosity, good high temperature resistance and rutting resistance.

After the asphalt mixture arrives at the site, the temperature should be checked first, and the temperature should meet the requirements, and then the graded oil quantity should be quickly observed when paving, and the gradation and oil quantity and standard density should be sampled and detected at the same time.

Coarse aggregates: Fine aggregates: Fines: Fines: Asphalt (oil-stone ratio) Species ratio: Asphalt 1 cubic meter mixture = 2345 (65 + 30 + parts 82-90kg

Asphalt 1t mixture = 82-90kg

Dear, hello to the asphalt mixture mix design method: one is to determine the mix ratio of the ore, the other is to determine the amount of asphalt. Asphalt mixture mix design is based on the test, inspection, adjustment, improvement of a technical work, only in stages, and combined with the test, construction equipment repeated verification, adjustment, in order to obtain satisfactory mix design results.

1. The target mix ratio target mix design is basically completed in the laboratory, which is the basic work of the mixture composition design, including raw material test, mixture composition design test and verification test, and the proposed mix ratio is called the target mix ratio. Specific design steps: (1) Determination of mixture type and grading range (2) Selection and determination of raw materials (3) Selection of mineral gradation (4) Marshall test (6) Road performance inspection (5) Determination of the best asphalt dosage.

2. Production mix ratio production mix ratio adjustment should be combined with the mixing building, there are two types of mixing buildings used in production at present, one is the continuous mixing building, as long as the flow rate of the cold material bin is adjusted to meet the target mix ratio requirements, the mixing can be heated, and the production mix ratio design is not required; The other type is the batch mixing building, which needs to heat and screen the aggregates, and then weigh and match the hot silos in the hall, and the proportion of the distribution is the production mix ratio. Because the mixing ratio of the ore material of each hot silo will be different from the matching ratio of each ore with the target mixing ratio, it is necessary to determine the matching ratio of the ore material of each hot silo through the test, and the secondary gradation is called on site. The purpose of adjusting the production mix ratio is to adjust the flow rate of each cold silo to meet the requirements of the design synthesis gradation on the basis of the target mix ratio, and to determine the mix ratio of the ore in each hot silo for the batch mixing building.

Specific design steps: (1) Adjustment of the flow rate of the cold silo (2) Determine the mixing ratio of ore in each hot silo (3) Determine the amount of asphalt. 3. Production mix verification The target mix ratio is completed in the laboratory, although the production mix has started the mixing building, but there is no formal mixing, and the production standard mix design stage needs to be formally mixed and paved with test roads.

At the same time, the mix ratio is further adjusted, and finally the mix ratio is determined as the basis for production control and quality inspection, which is called the production standard mix ratio. The production standard mix ratio is mainly to solve two problems: to determine the mixing temperature and to carry out the mixture material and performance analysis.

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Asphalt mixture with key ratio design:

Abstract:With the rapid development of China's economy, the transportation lines are also under construction at an unimaginable speed every year, and asphalt is used as a highway.

Construction is an important material, so it occupies a very important position. The main factor affecting the performance of asphalt is the mix ratio of slow and slow mixture, so the mix ratio of asphalt mixture has more practical significance for the construction quality of the highway.

1. Asphalt mixture mix ratio design.

Production mix design. Before designing the asphalt mixture mix, the size comparison can be selected according to the gradation type of the pavement structure.

Suitable vibrating screen, vibrating screen should also follow the following three principles when choosing: first, the vibrating bin of the vibrating screen should be made in the hot silo.

The material is maintained in equilibrium, which can also effectively improve the production efficiency.

Second, the selection of raw materials.

1. Under normal circumstances, asphalt concrete is composed of the following raw materials: fine aggregates, coarse aggregates of different specifications, filling materials and asphalt, etc. The principles to be followed in the selection of raw materials include good economy, high technology and relative environmental protection.

2. Selection of fine aggregates. Generally speaking, fine aggregates mainly include artificial sand, natural sand and stone chips and other materials, which are in asphalt mixtures.

The main function is to make the void between the coarse aggregate smaller, so that the stability of the asphalt mixture is higher. In the actual selection, not only its technical indicators should be considered, but also its wear resistance and adhesion to asphalt.

The method is as follows: the maximum particle size of asphalt concrete mix ratio should not exceed 1 2 of this layer thickness, and the maximum particle size of aggregate of asphalt mixture in the middle surface layer should not exceed 2 3 of this layer thickness;The maximum nominal size of aggregate of asphalt pavement structural layer mixture should not exceed 1 3 of the thickness of this layer, and for the coarse mixture, this proportion should also be reduced.

The design process of asphalt concrete mix is divided into three stages: target mix design, production mix design, and production mix verification.

Although the work content of each stage is different, the final problem to be solved in each stage is the same: one is to determine the gradation ratio of the ore, and the other is to determine the optimal amount of asphalt.

The purpose of this design method is to make the design gradually deepened, the design results are more in line with the actual production, and the indoor test is really linked with the construction production, so as to fully guide the role of construction.

If the grading type is selected according to the minimum requirements of the "highway asphalt pavement construction technical specification", the particle size of asphalt mixture aggregate is generally large, not to mention that there is also the particle size of rock 0 5% more than the maximum particle size, so that the rough rise is bound to bring the construction difficulty that is difficult to solve to the asphalt concrete pavement.