RESUMEN
The mix design of ultra-high performance concrete (UHPC) is complicated by the presence of many "ingredients." The fundamental packing density allows a simpler mix design with fewer ingredients to achieve optimum packing density and dense microstructure. The optimum particle grading increases the flowability of UHPC and eliminates entrapped air. This study presents a simplified particle grading design approach that positively influences the strength, autogenous shrinkage, and microstructure characteristics of UHPC. Carbon nanofibers (CNFs) of superior mechanical properties were added to enhance the strength of UHPC and to reduce its autogenous shrinkage. In addition, ground granulated blast-furnace slag (GGBS) was used as a cement replacement material to reduce the amount of cement in UHPC mixes. Test results showed that the presence of homogeneously dispersed CNF increased the compressive strength and compensated the autogenous shrinkage of UHPC. The findings indicated that an ideal particle distribution, which is close to the modified Andreasen and Andersen grading model, contributed to achieving high compressive strength and CNFs were capable of providing nano-bridges to compensate the shrinkage caused by GGBS.
RESUMEN
In a prospective study, 40 patients were fitted with synthetic plaster splints to assess the use of such material for hand and/or wrist splints. Factors assessed in both splint fabrication and use included molding properties, elastic traction fixation, weight, ventilation, durability, patient comfort, effectiveness, practicability, time, and cost. The patients were divided into three groups according to basic pathology: tendon/nerve injuries; bone and joint disorders; and rheumatoid disease deformities. Recovery of 50-100% of active range of motion was considered a good result. Good results were obtained in 37 patients (92.5%), whereas in the remaining three patients (7.5%) the results were poor. It is suggested that synthetic plaster is a suitable material for the fabrication of splints in hand rehabilitation.