ERI: Dielectric Mixing Models for Coarse Aggregate

该工程研究启动奖(ERI)支持的研究将侧重于改进用于估计粗集料混合物的相对介电常数的介电混合模型。介质混合模型将土壤或团聚体(水、空气和固体颗粒)的物理特性与探地雷达(GPR)捕获的体介电常数(体电材料特性)联系起来。这些介电混合模型反过来又允许工程师从探地雷达数据中估计属性，如含水率、饱和度、密度或目标深度。这项研究将通过创建高质量的相对介电常数测量的开放数据集来研究粒子分级对相对介电常数测量的影响，该数据集涵盖了从较小粒子到较大粒子的分级，这将填补现有文献中的空白。根据这些数据，建立了适用于粗骨料的新的介电混合模型。此外，这笔资金将允许史密斯学院的学生与Girls Inc Eureka合作！该计划将具有协同效益，使史密斯学院的学生在工程和STEM方面担任初中和高中女生的导师角色。同时，期待的是尤里卡！该项目的学生将受到工程专业的大学年龄女性的启发。为了达到改进粗骨料介电混合模型的目的，将进行大尺寸(约1立方米)的盒子测试，以产生数据集来开发新的介电混合模型。这些盒子测试将考虑各种颗粒大小不等的材料，从沙子-粉砂混合物(现有模型应该能很好地模拟)到卵石-砾石混合物(现有模型预计模拟效果不佳)。样品将在干燥、饱和和部分饱和的条件下进行测试。这项工作有三个主要目标。第一个目标是确定标本制备的常见做法和产生最高质量标本的方法的可重复性。第二个目标是创建相对介电数值的数据集，涵盖广泛的集合级配、密度和水分含量。第三个目标是创建和验证适用于粗集料的介电混合模型。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This Engineering Research Initiation (ERI) award supports research that will focus on improving dielectric mixing models used to estimate the relative permittivity of coarse aggregate mixes. Dielectric mixing models relate the physical characteristics of soil or aggregate (the water, air, and solid particles) to the bulk relative permittivity (bulk electrical material property) captured by ground penetrating radar (GPR). These dielectric mixing models in turn are what allow engineers to estimate properties such as water content, saturation, density, or object depth from GPR data. The research will investigate the effect of particle gradation on relative permittivity measurements by creating a high-quality open data set of relative permittivity measurements on gradations ranging from smaller particles to larger particles which will close an existing gap in the literature. From these data a new dielectric mixing model suitable for coarse aggregate will be created. In addition, the funding will allow for Smith College students to work with the Girls Inc Eureka! program which will have the synergistic benefit of putting Smith College students in a mentoring role to middle school and high school girls in engineering and STEM. Simultaneously, it is anticipated that the Eureka! program students will be inspired by the college-aged women in engineering. In order to achieve the goal of producing an improved dielectric mixing model for coarse aggregates, large box tests (approximately 1 cubic meter in scale) will be conducted to produce a data set to develop a new dielectric mixing model. These box tests will consider a variety of materials with particle sizes ranging from sand-silt mixtures (which existing models should model well) up to cobble-gravel mixtures (which existing models are anticipated to model poorly). Specimens will be tested under dry, saturated, and partially saturated conditions. The work has three main objectives. The first objective is to establish the repeatability of common practices for specimen preparation and methods that produce the highest quality specimens. The second objective will be to create the data set of relative permittivity values covering a wide range of aggregate gradations, density, and water content. The third objective is to create and verify the dielectric mixing model suitable for coarse aggregates.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.