Sixteen controlled low-strength material( CLSM)mixtures with various cement-to-sand( C/Sa) ratios and water-to-solid( W/So) ratios were prepared using recycled fine aggregate from urban red brick based construction wa...Sixteen controlled low-strength material( CLSM)mixtures with various cement-to-sand( C/Sa) ratios and water-to-solid( W/So) ratios were prepared using recycled fine aggregate from urban red brick based construction waste.The fluidity and bleeding of the fresh CLSM mixtures were measured via the modified test methods, and the hardened CLSM mixtures were then molded to evaluate their compressive strength and durability. The results showthat the fluidity of the fresh CLSM mixtures is 105 to 227 mm with the corresponding bleeding rate of 3. 7% to 15. 5%, which increases with the increase in fluidity. After aging for 28 d,the compressive strength of the hardened CLSM mixtures reaches 1. 15 to 13. 96 M Pa, and their strength can be further enhanced with longer curing ages. Additionally, the strength increases with the increase of the C/Sa ratio, and decreases with the increase of the W/So ratio under the same curing age. Based on the obtained compressive strength, a fitting model for accurately predicting the compressive strength of the CLSM mixtures was established, which takes into account the above two independent variables( C/Sa and W/So ratios).M oreover, the durability of the hardened CLSM mixtures is enhanced for samples with higher C/Sa ratios.展开更多
Guided bone regeneration(GBR)is a therapeutic procedure used to enhance alveolar bone volume before dental implants.Commercial non-absorbable membranes(i.e.,titanium membranes)typically require a second surgery to rem...Guided bone regeneration(GBR)is a therapeutic procedure used to enhance alveolar bone volume before dental implants.Commercial non-absorbable membranes(i.e.,titanium membranes)typically require a second surgery to remove,whereas absorbable membranes(i.e.,collagen membranes)will fail when put over extensive bone lesions due to their low mechanical strength.The GBR membrane that has been sought is still being developed.Biodegradable metals(BMs),particularly Mg and Zn,have recently been postulated as promising barrier membrane candidates.Herein,the goal of this research is to evaluate the mechanical and biological feasibility of using BMs as GBR membranes.It shows that BMs have a wide range of potential applications as GBR membranes,owing to their benign biocompatibility,sufficient mechanical support,tunable degradation rate,good osteogenic capabilities,broad-spectrum antibacterial behavior,and improved wound healing ability.The rapid degradation rate,hydrogen evolution impact,and stress corrosion cracking behavior all pose obstacles to the use of Mg-based membranes,which can be improved by surface modifications,heat treatment,alloying,etc.Due to its acceptable degradation rate and lack of gas production,Zn appears to be a better candidate for usage as a GBR membrane.In general,advances in the development of BMs have paved the door for BMs to be used as GBR membranes in oral clinical trials.展开更多
基金The National Science and Technology Support Program of China(No.2014BAC07B03)the Science and Technology Project of Transportation Committee of Beijing Government(No.2016-LZJKJ-01-006)the National Natural Science Foundation of China(No.51278016)
文摘Sixteen controlled low-strength material( CLSM)mixtures with various cement-to-sand( C/Sa) ratios and water-to-solid( W/So) ratios were prepared using recycled fine aggregate from urban red brick based construction waste.The fluidity and bleeding of the fresh CLSM mixtures were measured via the modified test methods, and the hardened CLSM mixtures were then molded to evaluate their compressive strength and durability. The results showthat the fluidity of the fresh CLSM mixtures is 105 to 227 mm with the corresponding bleeding rate of 3. 7% to 15. 5%, which increases with the increase in fluidity. After aging for 28 d,the compressive strength of the hardened CLSM mixtures reaches 1. 15 to 13. 96 M Pa, and their strength can be further enhanced with longer curing ages. Additionally, the strength increases with the increase of the C/Sa ratio, and decreases with the increase of the W/So ratio under the same curing age. Based on the obtained compressive strength, a fitting model for accurately predicting the compressive strength of the CLSM mixtures was established, which takes into account the above two independent variables( C/Sa and W/So ratios).M oreover, the durability of the hardened CLSM mixtures is enhanced for samples with higher C/Sa ratios.
基金supported by the National Key R&D Program of China(2018YFC1106600)the National Natural Science Foundation of China(52071008,and U20A20390)Beijing Natural Science Foundation(2192027)。
文摘Guided bone regeneration(GBR)is a therapeutic procedure used to enhance alveolar bone volume before dental implants.Commercial non-absorbable membranes(i.e.,titanium membranes)typically require a second surgery to remove,whereas absorbable membranes(i.e.,collagen membranes)will fail when put over extensive bone lesions due to their low mechanical strength.The GBR membrane that has been sought is still being developed.Biodegradable metals(BMs),particularly Mg and Zn,have recently been postulated as promising barrier membrane candidates.Herein,the goal of this research is to evaluate the mechanical and biological feasibility of using BMs as GBR membranes.It shows that BMs have a wide range of potential applications as GBR membranes,owing to their benign biocompatibility,sufficient mechanical support,tunable degradation rate,good osteogenic capabilities,broad-spectrum antibacterial behavior,and improved wound healing ability.The rapid degradation rate,hydrogen evolution impact,and stress corrosion cracking behavior all pose obstacles to the use of Mg-based membranes,which can be improved by surface modifications,heat treatment,alloying,etc.Due to its acceptable degradation rate and lack of gas production,Zn appears to be a better candidate for usage as a GBR membrane.In general,advances in the development of BMs have paved the door for BMs to be used as GBR membranes in oral clinical trials.
