Red mud was activated to be a mineral admixture for Portland cement by means of heating at different elevated temperatures from 400 ℃ to 700 ℃ . Results show that heating was ef-fective, among which thermal activati...Red mud was activated to be a mineral admixture for Portland cement by means of heating at different elevated temperatures from 400 ℃ to 700 ℃ . Results show that heating was ef-fective, among which thermal activation of red mud at 600 ℃ was most effective. Chemical analysis suggested that cement added with 600 ℃ thermally activated red mud yielded more calcium ion dur-ing the early stage of hydration and less at later stage in liquid phase of cement water suspension sys-tem, more combined water and less calcium hydroxide in its hardened cement paste. MIP measure-ment and SEM observation proved that the hardened cement paste had a similar total porosity and a less portion of large size pores hence a denser microstructure compared with that added with original red mud.展开更多
The investigation focuses on evaluating the effect of varying % of Red Mud (RM) reinforcement with Ordinary Portland Slag Cement (OPSC). Characterisation is done by adding 10%, 20%, 30%, 40% and 50% of RM by weight to...The investigation focuses on evaluating the effect of varying % of Red Mud (RM) reinforcement with Ordinary Portland Slag Cement (OPSC). Characterisation is done by adding 10%, 20%, 30%, 40% and 50% of RM by weight to OPSC. RM + OPSC composite mortars are made in an 8.5 × 5 × 4 cm<sup>3</sup> cast iron mould with external vibration keeping water-binder ratio 0.4 by weight. The mortars are cured in water for 28 days and their physio-chemical characteristics are investigated. Mortar performances like compressive strength, hardness, XRD, FTIR, SEM are diagnosed. The composite mortars cementing properties are compared with original OPSC. The result reveals the augmentation of RM with OPSC increases the hydration capacity of OPSC with improved compressive strength. The experimental optimization shows a maximum value up to 10% - 20% OPSC can be replaced by RM as filling material.展开更多
Red mud was firstly used as a raw material in sintering field road cement. Then, the radioactive element distribution characteristics of red mud based field road cement（RFC） before and after hydration were comparati...Red mud was firstly used as a raw material in sintering field road cement. Then, the radioactive element distribution characteristics of red mud based field road cement（RFC） before and after hydration were comparatively investigated. The experimental results indicated that the specific activity of ^（226）Ra and ^（232）Th increased after sintering process from raw material to clinker, as a result of concentrating effect on ^（226）Ra and ^（232）Th during sintering process, but the specific activity of ^（40）K decreased after sintering process as a result of volatilization effect. Radionuclide ^（226）Ra mainly distributed in RFC silicate phases（C_xS）, ^（232）Th distributed more in RFC interstitial phases than RFC silicate phases（C_xS）, ^（40）K mainly distributed in RFC interstitial phases. With increasing hydration ages of RFC pastes, the specific activity of ^（226）Ra kept increasing, ^（232）Th remained consistency all the same and ^（40）K declined. The radioactivity of RFC was in the recommended safe limit of Chinese National Standards GB6566-2010 during its preparation and application process.展开更多
基金Funded by the National 973 Program of China (No. 2001CB610703)
文摘Red mud was activated to be a mineral admixture for Portland cement by means of heating at different elevated temperatures from 400 ℃ to 700 ℃ . Results show that heating was ef-fective, among which thermal activation of red mud at 600 ℃ was most effective. Chemical analysis suggested that cement added with 600 ℃ thermally activated red mud yielded more calcium ion dur-ing the early stage of hydration and less at later stage in liquid phase of cement water suspension sys-tem, more combined water and less calcium hydroxide in its hardened cement paste. MIP measure-ment and SEM observation proved that the hardened cement paste had a similar total porosity and a less portion of large size pores hence a denser microstructure compared with that added with original red mud.
文摘The investigation focuses on evaluating the effect of varying % of Red Mud (RM) reinforcement with Ordinary Portland Slag Cement (OPSC). Characterisation is done by adding 10%, 20%, 30%, 40% and 50% of RM by weight to OPSC. RM + OPSC composite mortars are made in an 8.5 × 5 × 4 cm<sup>3</sup> cast iron mould with external vibration keeping water-binder ratio 0.4 by weight. The mortars are cured in water for 28 days and their physio-chemical characteristics are investigated. Mortar performances like compressive strength, hardness, XRD, FTIR, SEM are diagnosed. The composite mortars cementing properties are compared with original OPSC. The result reveals the augmentation of RM with OPSC increases the hydration capacity of OPSC with improved compressive strength. The experimental optimization shows a maximum value up to 10% - 20% OPSC can be replaced by RM as filling material.
基金Funded by the National Natural Science Foundation of China(No.51172155)
文摘Red mud was firstly used as a raw material in sintering field road cement. Then, the radioactive element distribution characteristics of red mud based field road cement（RFC） before and after hydration were comparatively investigated. The experimental results indicated that the specific activity of ^（226）Ra and ^（232）Th increased after sintering process from raw material to clinker, as a result of concentrating effect on ^（226）Ra and ^（232）Th during sintering process, but the specific activity of ^（40）K decreased after sintering process as a result of volatilization effect. Radionuclide ^（226）Ra mainly distributed in RFC silicate phases（C_xS）, ^（232）Th distributed more in RFC interstitial phases than RFC silicate phases（C_xS）, ^（40）K mainly distributed in RFC interstitial phases. With increasing hydration ages of RFC pastes, the specific activity of ^（226）Ra kept increasing, ^（232）Th remained consistency all the same and ^（40）K declined. The radioactivity of RFC was in the recommended safe limit of Chinese National Standards GB6566-2010 during its preparation and application process.
