Aashto M145 Pdf Free Download
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How to Download Aashto M145 Pdf for Free
Aashto M145 is a standard for classification of soils and soil-aggregate mixtures for highway construction purposes. It is widely used by engineers and contractors to determine the suitability of different types of soils for various road projects. If you are looking for a free copy of Aashto M145 pdf, you have come to the right place.
In this article, we will show you how to download Aashto M145 pdf for free from various online sources. We will also explain what Aashto M145 is, how it works, and why it is important for highway construction.
What is Aashto M145
Aashto M145 is a classification system that divides soils and soil-aggregate mixtures into seven groups based on their physical and engineering properties. The groups are A-1, A-2, A-3, A-4, A-5, A-6, and A-7. Each group has subgroups that further specify the characteristics of the materials.
The classification is based on the following criteria:
The percentage of material passing the 75-micron (No. 200) sieve
The plasticity index of the material passing the 0.425-mm (No. 40) sieve
The group index of the material
The percentage of material passing the 75-micron (No. 200) sieve indicates the amount of fines in the soil or soil-aggregate mixture. Fines are particles that are smaller than sand and can affect the drainage, compaction, and stability of the material.
The plasticity index of the material passing the 0.425-mm (No. 40) sieve measures the range of water content over which the material behaves as a plastic solid. Plasticity index is calculated by subtracting the liquid limit from the plastic limit of the material. Liquid limit is the water content at which the material changes from a solid to a liquid state. Plastic limit is the water content at which the material changes from a plastic to a brittle state.
The group index of the material is a numerical value that reflects the relative quality of the material for highway subgrade use. It is calculated by using a formula that involves the percentage of material passing certain sieves, the liquid limit, and the plasticity index. The lower the group index, the better the quality of the material.
How does Aashto M145 work
Aashto M145 works by assigning a letter and a number to each soil or soil-aggregate mixture based on its classification group and subgroup. For example, A-1-a means that the material belongs to Group A-1 and Subgroup a.
Group A-1 consists of granular materials that contain 35 percent or less passing the 75-micron (No. 200) sieve and have a nonplastic or feebly plastic soil binder. Subgroup a includes materials that consist predominantly of stone fragments or gravel, either with or without a well-graded binder of fine material.
Group A-2 consists of granular materials that contain 35 percent or less passing the 75-micron (No. 200) sieve but cannot be classified as A-1 or A-3 due to fines content or plasticity or both in excess of the limitations for those groups. Subgroup 4 includes materials that have a minus 0.425-mm (No. 40) portion with characteristics similar to Group A-4, which consists of silty materials with low plasticity.
Group A-3 consists of granular materials that contain 35 percent or less passing the 75-micron (No. 200) sieve and have a minus 0.425-mm (No. 40) portion that is nonplastic or very slightly plastic. This group includes fine sands and mixtures of fine sand and limited amounts of coarse sand and gravel.
Group A-4 consists of silty materials that contain more than 35 percent passing the 75-mic 248dff8e21