Structure characteristics of three kinds of ceramsite with different water absorption and the influence on microstructure of interfacial zone as well as performance of chloride permeabil-ity and frost resistance of co...Structure characteristics of three kinds of ceramsite with different water absorption and the influence on microstructure of interfacial zone as well as performance of chloride permeabil-ity and frost resistance of combined aggregate concrete were investigated. The results show that, dense shell and closed internal pore have sharp effects on lowering water absorption of ceramsite. However, the ceramsite with high water absorption has obvious effect on the densification of interfa-cial paste which would develop a structure with lower porosity, finer aperture and higher microhard-ness. Furthermore, the impermeability and frost-resistance of concrete can be improved due to the ef-fect of water absorption and releasing by ceramsite with higher water absorption.展开更多
The strength curves of lightweight aggregate concrete （LWAC） were tested based on detecting LWAC with density of 1 400-1 900 kg/m3 and LWAC with strength grade of LC15-LC50 by rebound method and ultrasonic-rebound c...The strength curves of lightweight aggregate concrete （LWAC） were tested based on detecting LWAC with density of 1 400-1 900 kg/m3 and LWAC with strength grade of LC15-LC50 by rebound method and ultrasonic-rebound combined method.The results show that the common measured strength curves tested by above two methods can not satisfy the required accuracy of LWAC strength test.In addition,specified compressive strength curves of testing LWAC by rebound method and ultrasonic-rebound combined method are obtained,respectively.展开更多
We studied changes in the concentrations of aggregate-cementing agents after different reclamation times and with different fertilization regimes,as well as the formation mechanism of aggregates in reclaimed soil,to p...We studied changes in the concentrations of aggregate-cementing agents after different reclamation times and with different fertilization regimes,as well as the formation mechanism of aggregates in reclaimed soil,to provide a theoretical basis for rapid reclamation of soil fertility in the subsidence area of coal mines in Shanxi Province,China.In this study,soil samples of 0–20 cm depth were collected from four fertilization treatments of a longterm experiment started in 2008:no fertilizer (CK),inorganic fertilizer (NPK),chicken manure compost (M),and50%inorganic fertilizer plus 50%chicken manure compost (MNPK).The concentrations of cementing agents and changes in soil aggregate size distribution and stability were analysed.The results showed that the formation of>2 mm aggregates,the aggregate mean weight diameter (MWD),and the proportion of>0.25 mm water-stable aggregates (WR_(0.25)) increased significantly after 6 and 11 years of reclamation.The concentration of organic cementing agents tended to increase with reclamation time,whereas free iron oxide (Fed) and free aluminium oxide(Ald) concentrations initially increased but then decreased.In general,the MNPK treatment signi?cantly increased the concentrations of organic cementing agents and CaCO_(3),and CaCO_(3) increased by 60.4%at 11 years after reclamation.Additionally,CaCO_(3) had the greatest effect on the stability of aggregates,promoting the formation of>0.25 mm aggregates and accounting for 54.4%of the variance in the proportion and stability of the aggregates.It was concluded that long-term reclamation is bene?cial for improving soil structure.The MNPK treatment was the most effective measure for increasing maize grain yield and concentration of organic cementing agents and CaCO_(3).展开更多
基金Funded by the Western Transportation Construction of Communication Ministry (No. 200331882008)
文摘Structure characteristics of three kinds of ceramsite with different water absorption and the influence on microstructure of interfacial zone as well as performance of chloride permeabil-ity and frost resistance of combined aggregate concrete were investigated. The results show that, dense shell and closed internal pore have sharp effects on lowering water absorption of ceramsite. However, the ceramsite with high water absorption has obvious effect on the densification of interfa-cial paste which would develop a structure with lower porosity, finer aperture and higher microhard-ness. Furthermore, the impermeability and frost-resistance of concrete can be improved due to the ef-fect of water absorption and releasing by ceramsite with higher water absorption.
文摘The strength curves of lightweight aggregate concrete （LWAC） were tested based on detecting LWAC with density of 1 400-1 900 kg/m3 and LWAC with strength grade of LC15-LC50 by rebound method and ultrasonic-rebound combined method.The results show that the common measured strength curves tested by above two methods can not satisfy the required accuracy of LWAC strength test.In addition,specified compressive strength curves of testing LWAC by rebound method and ultrasonic-rebound combined method are obtained,respectively.
基金supported financially by the National Natural Science Foundation of China(41807102,U1710255-3 and 41907215)the Special Fund for Science and Technology Innovation Teams of Shanxi Province,China(202304051001042)the Distinguished and Excellent Young Scholar Cultivation Project of Shanxi Agricultural University,China(2022YQPYGC05)。
文摘We studied changes in the concentrations of aggregate-cementing agents after different reclamation times and with different fertilization regimes,as well as the formation mechanism of aggregates in reclaimed soil,to provide a theoretical basis for rapid reclamation of soil fertility in the subsidence area of coal mines in Shanxi Province,China.In this study,soil samples of 0–20 cm depth were collected from four fertilization treatments of a longterm experiment started in 2008:no fertilizer (CK),inorganic fertilizer (NPK),chicken manure compost (M),and50%inorganic fertilizer plus 50%chicken manure compost (MNPK).The concentrations of cementing agents and changes in soil aggregate size distribution and stability were analysed.The results showed that the formation of>2 mm aggregates,the aggregate mean weight diameter (MWD),and the proportion of>0.25 mm water-stable aggregates (WR_(0.25)) increased significantly after 6 and 11 years of reclamation.The concentration of organic cementing agents tended to increase with reclamation time,whereas free iron oxide (Fed) and free aluminium oxide(Ald) concentrations initially increased but then decreased.In general,the MNPK treatment signi?cantly increased the concentrations of organic cementing agents and CaCO_(3),and CaCO_(3) increased by 60.4%at 11 years after reclamation.Additionally,CaCO_(3) had the greatest effect on the stability of aggregates,promoting the formation of>0.25 mm aggregates and accounting for 54.4%of the variance in the proportion and stability of the aggregates.It was concluded that long-term reclamation is bene?cial for improving soil structure.The MNPK treatment was the most effective measure for increasing maize grain yield and concentration of organic cementing agents and CaCO_(3).
