Split Hopkinson pressure bar(SHPB)was used to investigate the dynamic compressive properties of sisal fiber reinforced coral aggregate concrete(SFCAC).The results showed that,with the increase of strain rate,the dynam...Split Hopkinson pressure bar(SHPB)was used to investigate the dynamic compressive properties of sisal fiber reinforced coral aggregate concrete(SFCAC).The results showed that,with the increase of strain rate,the dynamic compressive strength,peak strain and toughness index of SFCAC are all greater than its static properties,indicating that SFCAC is a kind of rate-sensitive material.When the sisal fiber was blended,the failure mode showed obvious ductility.At high strain rates,the SFCAC without sisal fiber specimen was comminuted,and the SFCAC showed a"cracked without breaking"state.The results indicated that the sisal fiber played a significant role in reinforcing and strengthening the properties of concrete.The finite element software LS-DYNA was used to simulate two working conditions with strain rates of 78 and 101 s-1.The stressstrain curves and failure patterns obtained were in good agreement with the experimental results.展开更多
A new magnesium phosphate bone cement （MPBC） was prepared as a byproduct of boroncontaining magnesium oxide （B-MgO） after extracting Li2CO3 from salt lakes. We analyzed the elementary composition of the B-MgO raw ...A new magnesium phosphate bone cement （MPBC） was prepared as a byproduct of boroncontaining magnesium oxide （B-MgO） after extracting Li2CO3 from salt lakes. We analyzed the elementary composition of the B-MgO raw materials and the effects of calcination temperature on the performance of MPBC. The phase composition and microstructure of the B-MgO raw materials and the hydration products （KMgPO4.6H2O） of MPBC were analyzed by X-ray diffraction and scanning electron microscopy. The results showed that ionic impurities and the levels of toxic elements were sufficiently low in B-MgO raw materials to meet the medical requirements for MgO （Chinese Pharmacopeia, 2O10 Edition） and for hydroxyapatite surgical implants （GB23101.1-2O08）. The temperature of B-MgO calcination had a marked influence on the hydration and hardening of MPBC pastes. Increasing calcination temperature prolonged the time required for the MPBC slurry to set, significantly decreased the hydration temperature, and prolonged the time required to reach the highest hydration temperature. However, the compressive strength of hardened MPBC did not increase with higher calcination temperatures. In the 900-1 000 ~C temperature range, the hardened MPBC had a higher compressive strength. Imaging analysis suggested that the setting time and the highest hydration temperature of MPBC pastes were dependent on the size and crystal morphology of the B-MgO materials. The production and microstructure compactness of KMgPOa＇6H2O, the main hydration product, determined the compressive strength.展开更多
基金National Natural Science Foundation of China(Nos.51508272,11832013,51878350,52078250)。
文摘Split Hopkinson pressure bar(SHPB)was used to investigate the dynamic compressive properties of sisal fiber reinforced coral aggregate concrete(SFCAC).The results showed that,with the increase of strain rate,the dynamic compressive strength,peak strain and toughness index of SFCAC are all greater than its static properties,indicating that SFCAC is a kind of rate-sensitive material.When the sisal fiber was blended,the failure mode showed obvious ductility.At high strain rates,the SFCAC without sisal fiber specimen was comminuted,and the SFCAC showed a"cracked without breaking"state.The results indicated that the sisal fiber played a significant role in reinforcing and strengthening the properties of concrete.The finite element software LS-DYNA was used to simulate two working conditions with strain rates of 78 and 101 s-1.The stressstrain curves and failure patterns obtained were in good agreement with the experimental results.
基金Funded by the National Natural Science Foundation of China(No.21276264)the Qinghai Province Science and TechnologyDepartment(No.2013-G-208)
文摘A new magnesium phosphate bone cement （MPBC） was prepared as a byproduct of boroncontaining magnesium oxide （B-MgO） after extracting Li2CO3 from salt lakes. We analyzed the elementary composition of the B-MgO raw materials and the effects of calcination temperature on the performance of MPBC. The phase composition and microstructure of the B-MgO raw materials and the hydration products （KMgPO4.6H2O） of MPBC were analyzed by X-ray diffraction and scanning electron microscopy. The results showed that ionic impurities and the levels of toxic elements were sufficiently low in B-MgO raw materials to meet the medical requirements for MgO （Chinese Pharmacopeia, 2O10 Edition） and for hydroxyapatite surgical implants （GB23101.1-2O08）. The temperature of B-MgO calcination had a marked influence on the hydration and hardening of MPBC pastes. Increasing calcination temperature prolonged the time required for the MPBC slurry to set, significantly decreased the hydration temperature, and prolonged the time required to reach the highest hydration temperature. However, the compressive strength of hardened MPBC did not increase with higher calcination temperatures. In the 900-1 000 ~C temperature range, the hardened MPBC had a higher compressive strength. Imaging analysis suggested that the setting time and the highest hydration temperature of MPBC pastes were dependent on the size and crystal morphology of the B-MgO materials. The production and microstructure compactness of KMgPOa＇6H2O, the main hydration product, determined the compressive strength.
