ZHANG Wenhua (1982-), male, Ph. D., Associate Professor. E-mail: zhangwenhua2009@163.com
A nano-, micron-, and millimeter-sized multi-scale fiber composite reinforced ultra-high performance concrete (UHPC) was proposed. The mechanical properties of UHPC can be improved by suppressing the defects of different sizes with different fibers. Carbon nanotubes, micron-sized calcium carbonate whiskers, and millimeter-sized steel fibers were used to design 7 groups of UHPC specimens. The axial tensile and compressive stress-strain curves of UHPC were measured. The results show that the initial crack strength and strain of UHPC are determined by the millimeter-sized steel fiber in a macro-scale. However, micron- and nano-sized fibers have little effect on the initial crack strength and strain. The addition of calcium carbonate whiskers and carbon nanotubes changes the tensile behavior of UHPC specimens after cracking, thus enhancing the strain hardening capability. The tensile and compressive properties of UHPC with different sizes of fibers are similar. The addition of calcium carbonate whisker has a positive effect rather than that of carbon nanotube when mixing with steel fiber. The effect becomes optimum when adding calcium carbonate whiskers and carbon nanotubes.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |