In this study, rubber-sand particle mixtures are investigated to understand their stress-deformation and elastic modulus characteristics. Specimens are prepared with various size ratios, sr ( = Drubber / Dsand ) , between sand and rubber particles, and different volumetric sand fractions, sf ( = Vsand / Vtotal ) . Small strain shear waves are measured under a Ko -loading condition incorporated with the stress-deformation test by using an oedometer cell with bender elements. The stress-deformation and small strain shear-wave characteristics of rigid-soft particle mixtures show the transition from a rigid particle behavior regime to a soft particle behavior regime under a fixed size ratio. A sudden rise of the Λ factor and the maximum value of the ζ exponent in Gmax =Λ ( σo′ /kPa ) ζ is observed at sf≈0.4–0.6 regardless of the size ratio (sr). The transition mixture shows a high sensitivity to the confining stress. The volume fraction for the minimum porosity may depend on the applied stress level in the ri...

The objective of this study is to estimate multiple-cycles of the soil-water characteristic curve (SWCC) using an innovative volumetric pressure plate extractor (VPPE), which is incorporated with a membrane and time domain reflectometry (TDR). The pressure cell includes the membrane to reduce the experimental time and the TDR probe to automatically estimate the volumetric water content. For the estimation of SWCC using the VPPE system, four specimens with different grain size and void ratio are prepared. The volumetric water contents of the specimens according to the matric suction are measured by the burette system and are estimated in the TDR system during five cycles of SWCC tests. The volumetric water contents estimated by the TDR system are almost identical to those determined by the burette system. The experimental time significantly decreases with the new VPPE. The hysteresis in the SWCC is largest in the first cycle and is nearly identical after 1.5 cycles. As the initial void ratio decreases, the air entry value increases. This study suggests that the new VPPE may effectively estimate multiple-cycles of the SWCC of unsaturated soils.

Electrical properties of soils have commonly been used to estimate geotechnical properties. This paper introduces a new device, an electrical resistivity cone probe (ERCP), to determine the electrical resistivity of seashore soft soils and estimate void ratio in the field. The probe consists of inner and outer electrodes with a coaxial structure. The probe tip is conical to minimize disturbance during penetration. A four-terminal pair configuration is used to prevent electrical interference. The electrical resistance is measured during a consolidation test, penetration tests in a large-scale calibration chamber, and at two field sites. With the resistivity of soils and electrical resistivity of pore water extracted from undisturbed soils, the void ratio is estimated using Archie’s law. The void ratio estimated by the ERCP in an oedometer cell is almost the same as the volumetric void ratio of sand determined from consolidation tests. In addition, the void ratio profile obtained by the ERCP agrees well wit...

The objective of this study is to develop and apply reflection methods for guided ultrasonic waves used in evaluating the grout condition of rock bolts installed in a rock mass. Three types of rock bolts with different grouting ratios are prepared. First, piezoelectric disk elements are used as the source of guided ultrasonic waves to investigate grouted nonembedded rock bolts. Second, reflection methods with piezo disk elements and hammer impacts are used with rock bolts embedded in concrete columns. Third, a hammer impact with a center punch is applied for investigating rock bolts embedded in a rock mass in the field. The measured guided waves were analyzed using wavelet transforms. The peak magnitudes of the wavelet transform are used for group velocity calculations. Although piezo disk elements are sufficient as sources for nonembedded rock bolts and rock bolts installed in concrete columns, they do not provide sufficient energy in the field. However, a hammer impact with a center punch can ge...

The purpose of this paper is to evaluate fatigue cracking and rutting performance of two asphalt mixtures with 1) Electric Arc Furnace (EAF) and 2) Basic Oxygen Furnace (BOF) steel slag as 100% recycled aggregate in comparison to hot-mix asphalt concrete mixture (HMA). Fatigue cracking performance was assessed through 3D FEM structural analysis methods of Layered Viscoelastic Continuum Damage (LVECD) based on Viscoelastic Continuum Damage (VECD) material modeling derived through laboratory dynamic modulus and direct tension cyclic fatigue tests. Rutting resistance was evaluated by using laboratory Incremental Repeated Load Performance Deformation (IRLPD) and full-scale Accelerated Pavement Tests (APT). The results of laboratory testing and mechanistic analysis showed better rutting resistance of asphalt pavement with EAF aggregates in comparison to HMA pavement while pavement with BOF aggregates exhibited about the same performance. Additionally, asphalt pavement with BOF aggregates, HMA, and pavement with EAF aggregates manifested fatigue cracking performance in descending order. The findings of this study can be used as a guide for the development of recycled asphalt mixtures containing slag aggregates acquired from steel production.