M. A. Taylor

Bio: M. A. Taylor is an academic researcher from University of California, Davis. The author has contributed to research in topics: Aluminate & Wave propagation. The author has an hindex of 2, co-authored 2 publications receiving 8 citations.

An investigation of the hydration of calcium aluminate through ultrasonic wave propagation

Abstract: The hydration process of a high alumina cement was investigated through ultrasonic wave propagation techniques A correlation between wave amplitude and velocity and breaking strength of the cement is demonstrated The wave behaviour through hydrating cements was found to be a function of the cement-to-water ratio between values of 2 and 4 Changes in the temperature of the hydrating samples were found to exhibit a similar dependence

Correlation of the phase transformation accompanying the hydration of calcium aluminate with ultrasonic wave behaviour

Abstract: Observations of changes in the amplitude and velocity of the ultrasonic wave transmitted through a hydrating high alumina cement were found to have no corresponding changes in X-ray phase analyses A continuous X-ray scan of an hydrating sample showed no evidence for the completion of hydration X-ray patterns from a sample aged for two months and from one aged for 24 hours were basically identical

Ultrasonic measurements on hydrating cement slurries: Onset of shear wave propagation

Abstract: The ultrasonic properties of three oil field cement slurries are studied during the early stages of the hydration process. As a percolating solid framework is established, the slurries develop mechanical integrity and shear waves begin to propagate. This transition is also apparent in the behavior of the compressional wave, but is considerably more clear-cut in the shear signals. For the three samples examined here, the ratios of the shear wave onset times are in good agreement with the corresponding ratios of the American Petroleum Institute (API) thickening times.

Thermal analysis of hydrated calcium aluminates

Abstract: Differential scanning calorimeter (DSC) has been used to study the dehydration characteristics of hydrated calcium aluminates such as CA, CA2 and C12A7 where C and A stand for CaO and Al2O3 respectively. Dehydration of CAH10 and C2AH8 (whereH=H2O) occur ∼ at 160–180°C and 200–280°C respectively. These two phases are unstable and ultimately get transformed to AH3 and C3AH6. Dehydration of AH3 and C3AH6 occur between 290 and 350°C and overlap at lower scanning rate. The activation energy for dehydration of the stable AH3 and C2AH6 phases has been found to be 107.16 and 35.58 kJ mol−1 respectively. The compressive strength of the hydrated calcium aluminates has been determined. The result shows that in the case of CA, almost 90% of ultimate strength has been attained in 1 day whereas in CA2, ultimate strength has been attained in 14 days and in C12A7 in 1 day. DSC results have been correlated with the rate of strength developments.

Novel drying additives and their evaluation for self-flowing refractory castables

Abstract: The drying step of dense refractory castables containing hydraulic binders is a critical process, which usually requires using slow heating rates due to the high explosion trend of such materials during their first thermal treatment. Thus, this work investigated the performance of alternative additives to induce faster and safer drying of self-flowing high-alumina refractory castables bonded with calcium aluminate cement (CAC) or hydratable alumina (HA). The following materials were analyzed for this purpose: polymeric fibers, a permeability enhancing compound (RefPac MIPORE 20) and an organic additive (aluminum salt of 2-hydroxypropanoic acid). The drying behavior and explosion resistance of the cured samples were evaluated when subjecting the prepared castables to heating rates of 2, 5 or 20 °C/min and the obtained data were then correlated to the potential of the drying agents to improve the permeability and mechanical strength level of the refractories at different temperatures. The collected results attested that the selected additives were more efficient in optimizing the drying behavior of the CAC-bonded compositions, whereas the HA-containing castables performed better when the aluminum-based salt was blended with a small amount of CAC (0.5 wt%), which changed the binders hydration reaction sequence and optimized the permeability level of the resulting microstructure. Consequently, some of the designed compositions evaluated in this work showed improved drying behavior and no explosion was observed even during the tests carried out under a high heating rate (20 °C/min).

Ultrasonic measurements during early-stage hydration of ordinary Portland cement.

Abstract: The variations of ultrasonic pulse velocity, peak amplitude of transmitted pulse and heat evolution rate were measured during the hydration process of ordinary Portland cement with water/cement ratio (W/C ratio) ranging from 0.4 to 0.6 at environmental temperatures between 20 and 40° C. The change of heat evolution rate reflected the kinetics of hydration and was sensitively affected by the W/C ratio and environmental temperature. The velocity and peak amplitude were compared with the heat evolution rate to investigate the correlation of elastic properties and structural development with the kinetics of hydration. The dependence of the velocity and the peak amplitude on W/C ratio and environmental temperature are discussed in terms of the concentration of solid phase in the cement paste varying with W/C ratio and the extent of hydration.

An investigation of the hydration of calcium aluminate through ultrasonic wave propagation

Abstract: The hydration process of a high alumina cement was investigated through ultrasonic wave propagation techniques A correlation between wave amplitude and velocity and breaking strength of the cement is demonstrated The wave behaviour through hydrating cements was found to be a function of the cement-to-water ratio between values of 2 and 4 Changes in the temperature of the hydrating samples were found to exhibit a similar dependence