An experiment was conducted to determine the effects of application of various levels of GML （ground magnesium limestone） for sweet corn production on two Ultisols, viz.： Bungor and Rengam series soil. The treatmen...An experiment was conducted to determine the effects of application of various levels of GML （ground magnesium limestone） for sweet corn production on two Ultisols, viz.： Bungor and Rengam series soil. The treatments consisted of six levels of GML 0, 0.5, 1.0,2.0,4.0 and 8.0 Mg·ML·ha^-1 incorporated into the top 15 cm, a control which received no GML and no fertilizer. Two crops of sweet corn were planted with a crop of groundnut in a sequence of corn-groundnut-corn. Results indicated that application of 4.0 Mg·GML·ha^-1 and 2.0 Mg·GML·ha^-1 on Bungor and Rengan series soil respectively gave the highest yields in terms of saleable cob number. Soil analysis showed that application of 4.0 and 2.0 Mg·ha^-1 to Bungor and Rengam series soils respectively reduced Al saturation in both soils to 2.0% and increased soil pH to 5.7 and 4.8, respectively.展开更多
A new type of cement was prepared with ground limestone powder, blastfumace slag, steel slag and gypsum without calcination. The fraction of ground limestone powder in the cement was as high as 40 wt%-60 wt% without P...A new type of cement was prepared with ground limestone powder, blastfumace slag, steel slag and gypsum without calcination. The fraction of ground limestone powder in the cement was as high as 40 wt%-60 wt% without Portland clinker. All of its physical properties can meet the requirements of masonry cement standards. The impact of limestone content on physical properties of the cement and determined its impact on law was investigated. The steel slag can excit the aquation activity of this cement effectively, and the influence of its quantity on the strength of the materials was studied, which shows that the optimum quantity of mixing is 10%. By way of changing the different content of the lime stone by quartzy sample, the law of the compression strength and the PH value was determined, confirming that the lime stone can promote the early aquation of the slag and improve the early strength. The main hydration product of this cement is calcium aluminate hydrate, ettringite and calcium silicate hydrate, as indicated by XRD and SEM analysis.展开更多
A limestone mine in Ohio has had instability problems that have led to massive roof falls extending to the surface. This study focuses on the role that weak, moisture-sensitive floor has in the instability issues.Prev...A limestone mine in Ohio has had instability problems that have led to massive roof falls extending to the surface. This study focuses on the role that weak, moisture-sensitive floor has in the instability issues.Previous NIOSH research related to this subject did not include analysis for weak floor or weak bands and recommended that when such issues arise they should be investigated further using a more advanced analysis. Therefore, to further investigate the observed instability occurring on a large scale at the Ohio mine, FLAC3 D numerical models were employed to demonstrate the effect that a weak floor has on roof and pillar stability. This case study will provide important information to limestone mine operators regarding the impact of weak floor causing the potential for roof collapse, pillar failure, and subsequent subsidence of the ground surface.展开更多
文摘An experiment was conducted to determine the effects of application of various levels of GML （ground magnesium limestone） for sweet corn production on two Ultisols, viz.： Bungor and Rengam series soil. The treatments consisted of six levels of GML 0, 0.5, 1.0,2.0,4.0 and 8.0 Mg·ML·ha^-1 incorporated into the top 15 cm, a control which received no GML and no fertilizer. Two crops of sweet corn were planted with a crop of groundnut in a sequence of corn-groundnut-corn. Results indicated that application of 4.0 Mg·GML·ha^-1 and 2.0 Mg·GML·ha^-1 on Bungor and Rengan series soil respectively gave the highest yields in terms of saleable cob number. Soil analysis showed that application of 4.0 and 2.0 Mg·ha^-1 to Bungor and Rengam series soils respectively reduced Al saturation in both soils to 2.0% and increased soil pH to 5.7 and 4.8, respectively.
文摘A new type of cement was prepared with ground limestone powder, blastfumace slag, steel slag and gypsum without calcination. The fraction of ground limestone powder in the cement was as high as 40 wt%-60 wt% without Portland clinker. All of its physical properties can meet the requirements of masonry cement standards. The impact of limestone content on physical properties of the cement and determined its impact on law was investigated. The steel slag can excit the aquation activity of this cement effectively, and the influence of its quantity on the strength of the materials was studied, which shows that the optimum quantity of mixing is 10%. By way of changing the different content of the lime stone by quartzy sample, the law of the compression strength and the PH value was determined, confirming that the lime stone can promote the early aquation of the slag and improve the early strength. The main hydration product of this cement is calcium aluminate hydrate, ettringite and calcium silicate hydrate, as indicated by XRD and SEM analysis.
基金conducted as part of the research program of the Office of Mine Safety and Health Research of the National Institute for Occupational Safety and Health(NIOSH)
文摘A limestone mine in Ohio has had instability problems that have led to massive roof falls extending to the surface. This study focuses on the role that weak, moisture-sensitive floor has in the instability issues.Previous NIOSH research related to this subject did not include analysis for weak floor or weak bands and recommended that when such issues arise they should be investigated further using a more advanced analysis. Therefore, to further investigate the observed instability occurring on a large scale at the Ohio mine, FLAC3 D numerical models were employed to demonstrate the effect that a weak floor has on roof and pillar stability. This case study will provide important information to limestone mine operators regarding the impact of weak floor causing the potential for roof collapse, pillar failure, and subsequent subsidence of the ground surface.
