ABSTRACT
Composite modification technology is widely used in the materials field. To enhance the property of polyurethane modified asphalt and realize its application in road engineering, the bone glue/polyurethane composite modified asphalt (CMA) was prepared using bone glue, polyurethane, and neat asphalt in this research. The bone glue content ranges 5-10%, that of the polyurethane is 1-5%. The relationship between the modifier's content and the conventional properties and rheological properties of CMA was revealed by response surface methodology (RSM). The CMA performance was further verified under the optimal content of the bone glue and polyurethane. The differences of properties of styrene-butadienestyrene (SBS) modified asphalt mixture, neat asphalt mixture, and bone glue/polyurethane CMA mixture were compared and analyzed by using the pavement performance test. The results showed that the CMA's conventional properties and rheological properties are improved. The optimal bone glue content and polyurethane content determined by RSM are 6.848% and 2.759%, respectively. The low-temperature crack resistance and water stability of the CMA mixture are enhanced, better than neat asphalt mixture and SBS modified asphalt mixture. The CMA mixture's dynamic stability is 85% of SBS modified asphalt mixture, but it is 2.4 times of neat asphalt mixture. The result indicated that the bone glue/polyurethane CMA mixture still has certain advantages of high-temperature stability. In this research, the composite modification of bone glue and polyurethane can significantly enhance the characteristic of asphalt and asphalt mixture and provide a new method for applying and promoting polyurethane modified asphalt in road engineering.
ABSTRACT
OBJECTIVE: To investigate the feasibility, clinical indications and significance of one-stage radical eradication, wedged vertebral osteotomy and instrumentation in the treatment of tuberculosis of thoracic and lumbar spine associated with kyphosis or scoliokyphosis through a purely posterior procedure. METHODS: Sixteen cases with tuberculosis of thoracic and lumbar spine associated with kyphosis or scoliokyphosis were treated by one-stage radical eradication, wedged vertebral osteotomy and instrumentation fixation through posterior procedure. All patients included 12 males and 4 females, and the average age was 37.1 years (from 17 to 53 years). The preoperative average Cobb angle of kyphosis was 78.3 degrees (range from 54 degrees to 138 degrees ). There were 2 cases associated with scoliosis (the Cobb angle of scoliosis was 31 degrees and 24 degrees), and 1 case with lateral transition. Spinal cord compression were found in 7 cases. According to the Frankel's classification, 2 cases belonged to C degree, and 5 cases to D degree. There were 2 cases with caudal equina or nerve root lesions. RESULTS: The average blood loss during the operation was 1100 ml (range from 450 to 2200 ml), and the average operation time was 265 min (range from 215 to 325 min). The postoperative results were satisfactory, 14 cases were excellent and 2 cases were good. Obvious improvement was obtained in 9 cases with neurological dysfunction. The postoperative average Cobb' angle was 28.5 degrees (range from 0 degrees to 67 degrees), and the corrective rate was 63.6%. The followed-up was ranged from 14 to 52 months with an average of 26.3 months. There were no major complications related to the fixations, loss of correction and the fusion were achieved in all patients. CONCLUSIONS: One-stage radical eradication, wedged vertebral osteotomy and instrumentation is a feasible and an effective procedure in the treatment of spinal tuberculosis associated with kyphosis or scoliokyphosis. Compared with combined anterior and posterior procedure, the surgical technique may decrease injuries and has better result.
