论文部分内容阅读
目前国内市场上的减水剂按其主要成分可分为四大类:萘磺酸盐甲醛缩合物、三聚氰胺甲醛缩合物、木质素磺酸盐类、糖类。前二类减水剂效果较好(10～15%),引气较少,掺量一般为胶凝物质重量的1%左右,缺点是作用时间一般仅维持半小时左右。新拌砼的坍落度损失较快,适用于现场拌制具有早强要求的预拌砼和预制构件厂;后二类为普通型减水剂,其减水效果为5～10%具有缓凝引气作用,掺量一般为0.2～0.3%。下面结合建站十二年来在供应商品砼过程中坚持使用外加剂的实践和体会,就砼外加剂的应用技术问题作一探讨。一、木钙减水剂是商品砼的最佳选择商品砼的特点在于:(1)砼从拌制到浇注存在着一个时间差。砼又必须在初凝前浇注入模,因而时间要求较严;(2)对于商品砼供应的对象是重点工程或重要结构,由于施工难度大,技术要求高;(3)质量可靠度要高,商品砼的质量合格率必须达到
At present, the water reducing agents on the domestic market can be divided into four categories according to their main components: naphthalene sulfonate formaldehyde condensates, melamine formaldehyde condensates, lignosulfonates, and sugars. The first two types of water-reducing agents have good effects (10 to 15%), and they have less bleed air. The amount of the water-reducing agent is generally about 1% of the weight of the gelling material. The disadvantage is that the operating time is generally only about half an hour. The slump loss of fresh mix is faster, and it is suitable for on-site mixing of premixed mixes and prefabricated component plants with early strength requirements; the latter two are common type water reducers, and its water reduction effect is 5-10% with slowness. Condensate gas, the amount is generally 0.2 ~ 0.3%. In the following, combined with the practice and experience of using admixtures during the establishment of the station for 12 years, we will discuss the application technology of concrete additives. First, the wood calcium water reducer is the best choice for commercial products. The characteristics of the product are: (1) There is a time difference between mixing and pouring. It must be poured into the mold before the initial setting, so the time requirement is more stringent; (2) The object for the supply of commodities is a key project or an important structure, due to the difficulty of construction and high technical requirements; (3) high quality reliability , The quality qualification rate of commodity crickets must reach