Dimitrios K. Atmatzidis

LABORATORY TESTING OF CHEMICALLY GROUTED SAND

The effect of 14 parameters, associated with specimen preparation, handling, and testing, and with soil characteristics, was evaluated experimentally for laboratory prepared specimens of chemically grounted sands. Over 200 unconfined compression tests were conducted, and results are presented and comparisons are made in terms of unconfined compressive strength and tangent modulus at 50% of maximum stress. Curing environment, curing time, specimen size, grain size, and grain size distribution are the parameters that affect significantly the observed mechanical behavior of grouted sands. The results of this study were used in the development of ASTM Laboratory Preparation of Chemically Grouted Soil Specimens for Obtaining Design Strength Parameters (D 4320).

A general procedure for simulating EPR spectra of partially oriented paramagnetic centers

Abstract A general procedure for simulating EPR spectra of partially oriented paramagnetic centers is presented. The procedure is applied to the systems of [Ni(maleonitriledithiolato) 2 ] − in oriented nematic N -(4′-methoxybenzylidene)4- n -butylaniline liquid crystal and to consolidated clays. The Ni(mnt) 2 − case is unusual in that the long, in-plane molecular axis tends to align with the liquid crystal, while for the clay, no g -tensor axis is colinear with the axis of orientation. With the present development, the degree of orientation in a wide range of partially ordered systems can now be quantitatively analyzed.

Mechanical Behavior of a Pulverized Fly Ash Grouted Sand

A laboratory investigation was conducted in order to develop a new grout based on pulverized fly ash. Pulverization of a selected Greek fly ash yielded a gradation with D15 = 1.3 µm, D50 = 6 µm, and D85 = 20 µm and Blaine specific surface approximately equal to 8300 cm2/g. Suspensions of this pulverized fly ash, improved with additives, have comparable properties to ordinary and microfine cement suspensions. Suspensions were injected into clean sands. Permeability, UU, and CU-PP triaxial compression tests were conducted on the grouted specimens. The coefficient of permeability of the sands is reduced by 4 to 7 orders of magnitude. Grouting increases the stiffness and reduces the deformability of the sands. The Mohr-Coulomb failure criterion represents adequately the behavior of the grouted sands, yielding cohesion values ranging from 290 to 450 kPa and angle of internal friction values up to 5° higher than those of the clean sands. The shear strength parameters vary with axial strain, attaining their final values well before failure.