水泥一粉煤灰基植生固沙材料的正交优化和氮、磷、钾初期释放速率研究

Study on the N,P,and K Initial Release Rates and Orthogonal Optimization of Cement-fly Ash-based Plant-growing Fixing-sand Materials

以本实验室设计的配方来制备水泥-粉煤灰基固沙材料,以3～4个月释放期的美国Osmocote 14-14-14为控释肥肥源,以PAM、自制SAP1和SAP2为吸水保水剂,采用沙柱法对植生固沙材料的吸水剂种类、吸水剂用量、肥料用量和水灰比材料参数进行正交优化试验,研究材料参数与NPK释放速率和材料抗压、抗折强度的关系。结果表明,影响N释放速率的主要因素是肥料用量和吸水剂种类,影响抗折强度的主要因素是水灰比和吸水剂种类,优化配方是1.5%PAM,0.8gOsmocote/100g沙和水灰比为1.2。在水泥-粉煤灰基固沙材料中NPK的28d初期释放量大小顺序为K>N>P,其原因是水泥基材料富钾和固磷特性使得增K减P,水泥基材料毛细孔多孔特征使得N将以气态氨和液态銨释放。N的初期释放率受N的水溶肿胀和控释肥薄膜孔缝扩大速度的影响。

Using 3~4 months release period Osmocote 14-14-14 made in the United States as controlled-release fertilizer source,PAM,SAP1 and SAP2 as water-absorbents,and cement-fly ash-based sand-fixing materials made by our laboratory formula as sand-fixing materials,types of absorbent,absorbent dosage,fertilizer usage and water-cement ratio of cement-fly ash-based plant-growing fixing-sand materials were orthogonally optimized by the sand column leaching method. The relationship among the material parameters,the release rate of N,P,K,and compressive strength and flexural strength of materials was investigated. The results showed that the main factors affecting the N release rate are fertilizer usage and the type of water absorbent,and the main factors affect flexture strength are water-cement ratio and water absorbent usage. The optimizing formula is 1.5% PAM,0.8 g Osmocote/100 g sand and water-cement ratio of 1.2. In cement-fly ash-based sand-fixing materials,the order of 28 days initial release of N,P,and K is K〉N〉P since potassium-rich and fixing-phosphorus of cement-based materials made K reduced and P increased; and the porous feature of cement-based materials makes the N released by gaseous ammonia and liquid ammonia. The crack extension rate and water-soluble swelling of controlled-release fertilizer outside film will affect the initial release rate of N.