An Experiment for Effects of Different Additives on Strength of Sediment Solidification

The solidification method is a significant and resultful method for the disposal of dredged sediment. Solidified agents can be employed to improve the unconfined compressive strength (UCS) of sediment solidification. In this work, considering of economy and practicability, three kinds of optimized compound additives are selected and investigated on the effects of UCS of sediment solidification. 7d., 14d.and 28d. solidification stadium were taken to test the UCS of samples. Results showed that the activator had the best effect on increasing the UCS. The comparative tests also indicated that adding any kind of additive into the cement-based materials could improve the UCS of sediment solidification, the highest value of UCS was 11.02MPa (SCAHR). By means of scan electron microscope (SEM) technology, the microstructure images of the raw sample and solidified sample were obtained, which help to understand the development of UCS of the solidified sediments.

Preparation and Properties of Cationic Starch with High Degree of Substitution

Using sodium hydroxide as its alkali catalyzer, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride as its quaternary agents, cationic starch with high degree of substitution was made by semi-dry process. The prepared cationic starch contains quaternary ammonium groups by the infrared spectrum analysis. From the scan electron microscope pictures of starch and cationic starch, cationic starch can be clearly seen to have substituted the quaternary ammonium salt groups and the structure of mutual penetration of flexible quaternary ammonium salt groups and rigid starch has formed. The tensile strength of paper improved by cationic starch with high degree of substitution is far more than that by cationic starch with low degree of substitution and poly diallyl dimethyl ammonium chloride. The scan electron microscope pictures of the surface and fracture of the paper show that the distribution of the paper fiber which added additives are apparently tight and uniform and there are many small fibers obtained on the surface of paper samples. The fibers of the paper sample which added additives have more fracture themselves and have less extraction entirely. It indicates that the force between fibers has been strengthened by cationic starch additive.

Preparation and Mechanism of Natural Brucite Nanofibers

Test results indicate that brucite fibers could be well dispersed by using OT as the dispersant at the water/solid ratio of 20:1, at the dosage of 15% of fiber quality and in the dispersing duration of 30 minutes. The prepared nanofibers were characterized with a scan electron microscope (SEM) and a transmission electron microscope (TEM). Test results indicate that the prepared single brucite nanofiber was around 30nm long in diameter and the talus of non-single brucite nanofibers was about 50nm∼150nm long in diameter. Brucite nanofibers may be used as a fortifier for compound such as the SiO2 aerogel super insulating materials. Since brucite is also an excellent fire retardant, brucite nanofibers are expected to be used widely in the high-molecular materials sector.