ABSTRACT
Pure self-compacting concrete has many disadvantages, such as early shrinkage and cracking. The addition of fibers can effectively improve the properties of resistance to tension and cracking of self-compacting concrete, thereby the effect of improving its strength and toughness can be achieved. Basalt fiber is a "new green industrial material" that has unique advantages, such as high crack resistance and being lightweight compared with other fiber materials. In order to study the mechanical properties and crack resistance of basalt fiber self-compacting high-strength concrete intensively, the self-compacting high-strength concrete of C50 was designed and obtained using the absolute volume method with multiple proportions. Orthogonal experimental methods were used to study the influence of the water binder ratio, fiber volume fraction, fiber length, and fly ash content on the mechanical properties of the basalt fiber self-compacting high-strength concrete. Meanwhile, the efficiency coefficient method was used to determine the best experiment plan (water binder ratio 0.3, fiber volume ratio 0.2%, fiber length 12 mm, fly ash content 30%), and the effect of fiber volume fraction and fiber length on the crack resistance of the self-compacting high-performance concrete was investigated using improved plate confinement experiments. The results show that (1) the water binder ratio had the greatest impact on the compressive strength of basalt fiber self-compacting high-strength concrete, and as the fiber volume fraction increased, the splitting tensile strength and flexural strength both increased; (2) there was an optimal value for the effect of the fiber length on the mechanical properties; (3) with the increase in fiber volume fraction, the total crack area of the fiber self-compacting high-strength concrete significantly decreased. When the fiber length increased, the maximum crack width first decreased and then slowly increased. The best crack resistance effect was achieved when the fiber volume fraction was 0.3% and the fiber length was 12 mm. Therefore, basalt fiber self-compacting high-strength concrete can be widely used in engineering fields, such as national defense construction, transportation, and building structure reinforcement and repair, due to its excellent mechanical and crack resistance properties.
ABSTRACT
Au/TiO2 mesocrystals (Au/TMCs) were synthesized via a template-free solvothermal approach, followed with in situ photoreduction of gold chloride tetrahydrate for deposition of Au nanoparticles (AuNPs). The microstructure and components of the photocatalysts were characterized with various techniques. The results indicated that the AuNPs selectively anchored on the (101) facet of TiO2 mesocrystals (TMCs). More interestingly, the strong interactions occurred between AuNP and TMC support, due to the formation of a close Schottky heterointerface, combined with Ti-O-Au chemical bonds partially formed. Unexpectedly, it was found that the AuNPs typically aligned with their [111] direction, parallelling to the [101] direction of TMC in many cases. Au/TMCs exhibited high selectivity and activity for the transformation of nitroarenes to corresponding azoxyarenes, which could be attributed to not only the plasmonic effect of AuNPs and the unique superstructure of TMC, but also the highly strong interaction between AuNPs and TMCs through the close Schottky heterointerface.
