Increasing the population and infrastructure in both emerging and developed countries requires a considerable amount of cement, which significantly affects the environment. The primary materials of concrete (‘cement...Increasing the population and infrastructure in both emerging and developed countries requires a considerable amount of cement, which significantly affects the environment. The primary materials of concrete (‘cement’) production emit a large quantity of CO<sub>2</sub> into the environment. Also, the cost of conventional building materials like cement gives motivation to find geopolymer waste materials for concrete. To reduce harmful effects on the environment and cost of traditional concrete substance, alternative waste materials like rice husk ash (RHA), ground granulated blast-furnace (GGBS), fly ash (FA), and metakaolin (MK) can be used due to their pozzolanic behavior. RHA waste material with a high silica concentration obtained from burning rice husks can possibly be used as a supplementary cementitious material (SCM) in the manufacturing of concrete, and its strong pozzolanic properties can contribute to the strength and impermeability of concrete. This review paper highlights a summary of the positive effect of using RHA as a partial substitute for cement in building construction, as well as its optimal inclusion of enhanced mechanical properties like compressive strength, flexural strength, and split tensile strength of mortar and concrete.展开更多
The assessment of magnesium sulphate attack on concretes containing rice husk ash （RHA, 20wt% of the cementitious materials） with various average particle sizes was investigated. The total cementitious materials wer...The assessment of magnesium sulphate attack on concretes containing rice husk ash （RHA, 20wt% of the cementitious materials） with various average particle sizes was investigated. The total cementitious materials were 390 kg and the water-to-binder ratio （W/B） was 0.53 for all mixtures. Specimens were initially cured in water for 7 d and then immersed in the 3wt% magnesium sulphate solution for up to 111 d of exposure. The specimens were subjected to drying-wetting cycles to accelerate sulphate attack. In addition to the visual monitoring of the specimens, the concrete specimens were subsequently tested for compressive strength, dynamic modulus of elasticity, and length and mass changes. The results show that the specimens exposed to sulphate attack exhibit higher strength and dynamic modulus than those kept in water. The length change is negligible and can be attributed to the normal swelling of concrete. On the other hand, concretes suffers mass loss and surface spalling and softening; the fine RHA-concrete results in a better resistance. For the accelerated sulphate attack method used in this study, mass change and visual monitoring are recommended for assessing the deterioration degree and the effectiveness of supplementary cementitious materials to resist sulphate attack.展开更多
MM5模式系统常被用在气象科研和天气预报当中,通常运行在商业版本的Unix/Linux系统上,对非商业版本的类Unix系统并不太友好。文章详细介绍了MM5V3.7在高性能免费Unix操作系统FreeBSD 6.0上的移植及其应注意的问题,并通过一个个例分别在F...MM5模式系统常被用在气象科研和天气预报当中,通常运行在商业版本的Unix/Linux系统上,对非商业版本的类Unix系统并不太友好。文章详细介绍了MM5V3.7在高性能免费Unix操作系统FreeBSD 6.0上的移植及其应注意的问题,并通过一个个例分别在FreeBSD 6.0和Red Hat Advanced Server 4(RHAS 4)上的运行来比较其效率。通过对比发现,FreeBSD的性能要比通常所用的Linux系统有较大的提高,这对于改善实际业务中的时间迫切性问题有很大的意义。展开更多
A powerful non-destructive testing (NDT) technique is adopted to study the quality of RHA brick-1 and RHA brick-2. In that case, rice husk ash has been utilized for the preparation of bricks in full replacement of cla...A powerful non-destructive testing (NDT) technique is adopted to study the quality of RHA brick-1 and RHA brick-2. In that case, rice husk ash has been utilized for the preparation of bricks in full replacement of clay. In these studies, homogeneity of elemental distribution, water absorption and size and shape of the pores have been observed. From the studies, it was observed that elemental distribution is very good at various level, large number of porosity is presented with little bit size, initial rate of absorption (IRA) due to first five minutes immersion of water is higher compared to other immersion time (>5 minute), incremental water intrusion area increases very slowly with the increasing immersion time and the water absorption for RHA brick-2 becomes saturated very early than that of the RHA brick-1.展开更多
The effect of rhamnolipids （RL） on Cd^2＋ adsorption by Penicillium simplicissimum （P. simplicissimum） was studied. The maximum adsorption capacities of Cd^2＋ were obtained at pH 6.0 for the intact P. sirnpliciss...The effect of rhamnolipids （RL） on Cd^2＋ adsorption by Penicillium simplicissimum （P. simplicissimum） was studied. The maximum adsorption capacities of Cd^2＋ were obtained at pH 6.0 for the intact P. sirnplicissimurn and at pH 5.0 for the RL-pretreated P. simplicissimum, respectively. The adsorption equilibrium was reached after about 4 h. The experimental adsorption isotherms were in good agreement with the Langmuir model. The maximum adsorption capacities （qmax） for the intact P. simplicissimurn and for the RL-pretreated P. simplicissimum were 51.6 and 70.4 rag/g, respectively. The interactions between Cd^2＋ and functional groups on the cell wall surface of the P. simplicissimum were identified by SEM, EDAX and FTIR analysis. It is indicated that carboxyl, amino and hydroxyl groups play major roles in the Cd^2＋ adsorption. The results suggest that the RL-pretreated P. simplicissimum is a promising candidate for the removal of Cd^2＋ from aqueous solutions.展开更多
文摘Increasing the population and infrastructure in both emerging and developed countries requires a considerable amount of cement, which significantly affects the environment. The primary materials of concrete (‘cement’) production emit a large quantity of CO<sub>2</sub> into the environment. Also, the cost of conventional building materials like cement gives motivation to find geopolymer waste materials for concrete. To reduce harmful effects on the environment and cost of traditional concrete substance, alternative waste materials like rice husk ash (RHA), ground granulated blast-furnace (GGBS), fly ash (FA), and metakaolin (MK) can be used due to their pozzolanic behavior. RHA waste material with a high silica concentration obtained from burning rice husks can possibly be used as a supplementary cementitious material (SCM) in the manufacturing of concrete, and its strong pozzolanic properties can contribute to the strength and impermeability of concrete. This review paper highlights a summary of the positive effect of using RHA as a partial substitute for cement in building construction, as well as its optimal inclusion of enhanced mechanical properties like compressive strength, flexural strength, and split tensile strength of mortar and concrete.
文摘The assessment of magnesium sulphate attack on concretes containing rice husk ash （RHA, 20wt% of the cementitious materials） with various average particle sizes was investigated. The total cementitious materials were 390 kg and the water-to-binder ratio （W/B） was 0.53 for all mixtures. Specimens were initially cured in water for 7 d and then immersed in the 3wt% magnesium sulphate solution for up to 111 d of exposure. The specimens were subjected to drying-wetting cycles to accelerate sulphate attack. In addition to the visual monitoring of the specimens, the concrete specimens were subsequently tested for compressive strength, dynamic modulus of elasticity, and length and mass changes. The results show that the specimens exposed to sulphate attack exhibit higher strength and dynamic modulus than those kept in water. The length change is negligible and can be attributed to the normal swelling of concrete. On the other hand, concretes suffers mass loss and surface spalling and softening; the fine RHA-concrete results in a better resistance. For the accelerated sulphate attack method used in this study, mass change and visual monitoring are recommended for assessing the deterioration degree and the effectiveness of supplementary cementitious materials to resist sulphate attack.
文摘MM5模式系统常被用在气象科研和天气预报当中,通常运行在商业版本的Unix/Linux系统上,对非商业版本的类Unix系统并不太友好。文章详细介绍了MM5V3.7在高性能免费Unix操作系统FreeBSD 6.0上的移植及其应注意的问题,并通过一个个例分别在FreeBSD 6.0和Red Hat Advanced Server 4(RHAS 4)上的运行来比较其效率。通过对比发现,FreeBSD的性能要比通常所用的Linux系统有较大的提高,这对于改善实际业务中的时间迫切性问题有很大的意义。
文摘A powerful non-destructive testing (NDT) technique is adopted to study the quality of RHA brick-1 and RHA brick-2. In that case, rice husk ash has been utilized for the preparation of bricks in full replacement of clay. In these studies, homogeneity of elemental distribution, water absorption and size and shape of the pores have been observed. From the studies, it was observed that elemental distribution is very good at various level, large number of porosity is presented with little bit size, initial rate of absorption (IRA) due to first five minutes immersion of water is higher compared to other immersion time (>5 minute), incremental water intrusion area increases very slowly with the increasing immersion time and the water absorption for RHA brick-2 becomes saturated very early than that of the RHA brick-1.
基金Project(50978087) supported by the National Natural Science Foundation of ChinaProject(CX2010B157) supported by the Hunan Provincial Innovation Foundation for Postgraduate,China
文摘The effect of rhamnolipids （RL） on Cd^2＋ adsorption by Penicillium simplicissimum （P. simplicissimum） was studied. The maximum adsorption capacities of Cd^2＋ were obtained at pH 6.0 for the intact P. sirnplicissimurn and at pH 5.0 for the RL-pretreated P. simplicissimum, respectively. The adsorption equilibrium was reached after about 4 h. The experimental adsorption isotherms were in good agreement with the Langmuir model. The maximum adsorption capacities （qmax） for the intact P. simplicissimurn and for the RL-pretreated P. simplicissimum were 51.6 and 70.4 rag/g, respectively. The interactions between Cd^2＋ and functional groups on the cell wall surface of the P. simplicissimum were identified by SEM, EDAX and FTIR analysis. It is indicated that carboxyl, amino and hydroxyl groups play major roles in the Cd^2＋ adsorption. The results suggest that the RL-pretreated P. simplicissimum is a promising candidate for the removal of Cd^2＋ from aqueous solutions.
