Transcription of Student Manual Lesson 3- Moisture Density Relationship
1 Student Manual Lesson 3- Moisture Density Relationship Version 3/09 3-1. Student Manual Lesson 3- Moisture Density Relationship Version 3/09 3- 2. Student Manual Lesson 3- Moisture Density Relationship Version 3/09 3-3. Student Manual Lesson 3- Moisture Density Relationship Invented byy Mr. Proctor in the earlyy 1930's. In his honor, the Standard Laboratoryy Test that he developed is called the Proctor Test. The contractor uses compaction, a process, to achieve Density , a product. Version 3/09 3- 4. Student Manual Lesson 3- Moisture Density Relationship Compactive effort is a measure of the mechanical energy applied to a soil mass. In the field, compactive effort is the number of passes or coverages of compaction equipment of a certain type and weight on a given volume of soil . Version 3/09 3- 5. Student Manual Lesson 3- Moisture Density Relationship The project and/or design specifications and standards will set forth a certain percentage of Density value the contractor must achieve of the laboratory Proctor test performed for that particular material.
2 Greater control of compaction effort is obtained in the laboratory. Field Density is usually expressed as a percentage of lab maximum Density ( 100% of AASHTO T 99 or 98% of FM 1 T-180). Version 3/09 3- 6. Student Manual Lesson 3- Moisture Density Relationship In the lab, lab 4-5 material samples are prepared with a different known amount of water to each, thereby creating 4-5 samples with different water content. The samples are placed in pre-weighed molds in lifts which are compacted by a rammer. The Dry Unit Weight and Moisture contents are then determined for each sample. Proctor Machines Proctor octo Mold old Version 3/09 3- 7. Student Manual Lesson 3- Moisture Density Relationship In these figures, figures A . A and B . B represent: A = Optimum Moisture Content B = Maximum Density 100% or the maximum that can be expected to be achieved. Typically the test involves running a minimum of 4 to 5 points, each at a different Moisture content. Hence, we are able to draw a curve, the Proctor Curve, reflecting the maximum Density at a given Moisture content.
3 Content Typically, Typically specifications will require achieving either 100% or 98% of a Proctor value, therefore, as shown, we have also plotted the 98% data. Moisture contents falling less than the Targeted Area will typically be too dry to achieve maximum Density . Those greater, will typically produce mud . Remember building sand castles on the beach? Dry beach sand just wouldn't mold and the real wet sand, at the waterline or wave line was too soupy. But the damp sand in between these two was perfect, although sometimes you had to add some water from your beach bucket. Version 3/09 3- 8. Student Manual Lesson 3- Moisture Density Relationship The FDOT uses two types of Moisture Density Relations tests: Standard - AASHTO T-99, which employs the use of a rammer dropped from a height of 12 inches. Specimens are prepared in 4 inch molds. Modified - FM 1 T-180, which employs a 10-lb. rammer dropped from a height of 18. inches. Specimens are prepared in 6 inch molds and a spacer disk used in the bottom of the mold.
4 As road construction equipment and methods improved, it became apparent that construction methods were outdistancing testing methods. In an effort to have Proctor testing be more representative of what was being done in the field, the Modified Proctor was adopted by the FDOT. The Modified Proctor requires substantially more effort in the compaction process than the Standard method. Version 3/09 3- 9. Student Manual Lesson 3- Moisture Density Relationship In the laboratory, the technician will then plot the measured unit weight of the 4 or 5. samples (% in our example above) that were prepared at the different Moisture contents. As shown above, the 10% Moisture sample plotted at pcf and so on, finishing with pcf at 14% Moisture . This data, when plotted, represents a curvilinear Relationship known as the Compaction C. Curve or more commonly,l the th Proctor P t Curve. C. The high point of the curve, which does not have to be at a data point, is selected as the Maximum Dry Density at the corresponding Moisture content.
5 As shown above,, this is calculated in the laboratoryy to the nearest whole p percent in p pcf and Moisture to the nearest tenth of a percent. Please note, that the report from the laboratory to the field reports both Dry Density and Moisture to the nearest whole number. Version 3/09 3- 10. Student Manual Lesson 3- Moisture Density Relationship Version 3/09 3 - 11. Student Manual Lesson 3- Moisture Density Relationship Version 3/09 3 - 12. Student Manual Lesson 3- Moisture Density Relationship Version 3/09 3- 13. Student Manual Lesson 3- Moisture Density Relationship Version 3/09 3- 14.
