Date of Graduation

5-2022

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Degree Level

Graduate

Department

Civil Engineering

Advisor/Mentor

Coffman, Richard A.

Committee Member

Barry, Michelle L.

Second Committee Member

Tullis, Jason A.

Keywords

Density; Geotechnology; Non-nuclear; Photogrammetry; Soil

Abstract

Adequate soil compaction is important for the stability and safety of structures and transportation infrastructure. Thus, methods utilized to obtain properties that control the quality of compaction in the field are essential to ensure proper construction. These properties include; total density, dry density, total unit weight and dry unit weight of the compacted soil. The most common method to measure these properties in the field is the Nuclear Density Gauge. Moisture content and density results are obtained using the Nuclear Density Gauge in one to four minutes. However, this method requires specialized training and strict storage requirements in addition to licensing and certification, due to the radioactive nature of the device. Other methods like the Sand Cone Test and the Rubber Balloon Test are tedious, labor intensive and cumbersome. Additionally, the sand cone requires Ottawa Silica Sand, which increases the costs of the method and is heavy to transport to the site if multiple tests are required to be performed.

A photogrammetry-based method to determine total density and total unit weight soil properties by volume estimation combined with separate soil weight measurements is presented herein. This method includes a photogrammetric analysis, using the Photomodeler software, on photographs obtained from an uncalibrated regular mobile phone camera. To validate this method, the images were obtained of a circular excavation dug in compacted soil. The image acquisition process takes less than five minutes. The Photomodeler processing time takes approximately 15 minutes to develop a three-dimensional model and volume of the excavated hole. The results obtained with this analysis method were compared with in-situ results obtained from the Troxler nuclear density gauge, sand cone and from the Humboldt electrical density gauge. Based on the obtained, results the photogrammetric method is capable to provide similar results to the nuclear density gauge and the sand cone (within four pcf for total unit weight).

The soil moisture content is necessary to obtain the dry density and dry unit weight of soils. Laboratory tests to obtain soil moisture content by means of oven drying typically require at least of 24 hours to complete. Also, it is possible to measure soil moisture content by means of evaporation using microwave oven. This method was tested on different soils to determine the feasibility of using this method as an alternative to the density nuclear gauge or laboratory procedures. Modifications to the standard method resulted in positive results at lower power settings of the microwave oven. The ideal amount of time required to obtain results using the microwave oven method was 5 to 20 minutes depending on the soil. An alternative testing method to determine water content was the microwave sensor Hidromix HM-08. This sensor was capable to measure soil moisture content of different types of unsaturated soils including sand, clay and base coarse. This sensor allowed for the instant (within 5 seconds) measurement of soil moisture content of loose and compacted soil.

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