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Construction Methods

Construction Methods. Lecture 11 Compaction Equipment and Procedures. Compaction Equipment and Procedures. Compaction Operations

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Construction Methods

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  1. Construction Methods Lecture 11 Compaction Equipment and Procedures

  2. Compaction Equipment and Procedures • Compaction Operations • The major variables to be considered include soil moisture content, lift thickness, number of passes used, ground contact pressure, compactor weight, and compactor speed. • Soil Moisture • The optimum water content for compaction varies from about 12 to 25% for fine-grained soils and from 7 to 12% for well-granular soils. • When it is necessary to add water consider the • Amount of water required • Rate of water application • Method of application • Effects of the climate and weather

  3. Compaction Equipment and Procedures • Amount of water required • The amount of water that must added or removed is normally computed in cubic meter per station. • It is good practice to adjust the desired moisture content 2% above optimum, but this depends on the environmental conditions. • Effects of Weather • Weather conditions substantially affect soil moisture content. Cold, rainy, and cloudy weather will allow a soil to retain water. • Hot, dry, sunny and windy weather is conductive to drying the soil. desired WC%  soil WC% water (CM) = desired dry density (t/m3) 100  Compacted vol. of soil (CM) 1 (t/m3)

  4. Compaction Equipment and Procedures • Example • Job specifications require placement of the embankment fill soil in 25cm (compacted). The desired dry unit weight is 1.8t/m3. The laboratory indicates that the optimum moisture content (OMC) of the soil is 12%. Soil tests indicate that the water content of the borrow material is 5%. The roadway lift to be placed is 12m wide. • Compute the amount of water in cubic meter to add on a per station. Solution Take the distance between station is 50m

  5. Compaction Equipment and Procedures • Application Methods • Regardless of which method of application is used, it is important to ensure that the proper application rate is achieved and that the water is uniformly distributed.

  6. Compaction Equipment and Procedures

  7. Compaction Equipment and Procedures • Typical Effect of Number of Passes

  8. Compaction Equipment and Procedures • Mixing and Blending • Whether adding water to a soil to increase the moisture content or adding a drying agent to reduce it, it is essential to mix the water or drying agent thoroughly and uniformly with the soil. • Even if additional water is not needed, mixing may still be necessary to ensure a uniform distribution of existing moisture. • Mixing can be accomplished using motor graders.

  9. Compaction Equipment and Procedures • Grading and Finishing • Grading is the process of bringing earthwork to the desired shape and elevation. • Finish grading, or simply finishing, involves smoothing slopes, shaping ditches, and bringing the earthwork to the elevation required by the plans and specification.

  10. Compaction Equipment and Procedures • Components of Motor Grader • Moldboard (Blade) • Scarifer • Graders may also be equipped with light rear-mounted Rippers

  11. Compaction Equipment and Procedures

  12. Compaction Equipment and Procedures • Moldboard

  13. Compaction Equipment and Procedures • Moldboard

  14. Compaction Equipment and Procedures • Moldboard

  15. Compaction Equipment and Procedures • Trimmers • Trimmers are specialty machines to fine finishing for special jobs. • The result is better accuracy and greater production compared to motor graders. • It is capable of scarifying and removing soil and old asphalt pavement.

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