随着混凝土强度的提高,其韧性会明显下降,对于高强与超高强混凝土而言,如何降低其脆性,提高其韧性乃是一个重要的技术关键。国内、外的研究工作表明,掺加纤维是改善混凝土韧性的有效措施之一。在多种纤维材料中,以钢纤维的使用为最方便,不必改变混凝土的拌制工艺与设备,即可使一定量的钢纤维较均匀地掺入混凝土中,并可采用一般的捣实工艺。为充分发挥钢纤维在混凝土中的增强与增韧作用,应设法改善纤维与混凝土基材的界面粘结。由于增加纤维长度与直径的比值(俗称长径比),会引起拌制上的困难,纤维往往会在拌制过程中互相缠结,因而严重削弱了纤维的增强作用。为此国内、外均十分重视异形钢纤维的研制与开发,试图改变钢纤维的外形以期改善纤维与混凝土的粘结。改善钢纤维与混凝土界面粘结的另一技术途径为掺加适量的硅灰。国外研究表明,掺加硅灰可在减少单位水泥耗量的情况下制得高强度的钢纤维混凝土。国内研究表明,掺加硅灰有助于改善钢纤维与水泥基材的界面层,减少氢氧化钙在界面的富集并削弱其取向性,因而可相应地提高钢纤维增强水泥复合材料的力学性能。试验得知,当硅粉掺量为5～10％时,对提高钢纤维与水泥砂浆的粘结强度有明显的效果。本文的研究目的为在选用合宜的异形钢纤维的基础上,选定硅灰的最宜掺量(用内掺法),以配制高强度、高韧性的纤维混凝土。 With the increase of concrete strength, its toughness will be significantly reduced. For high-strength and ultra-high-strength concrete, how to reduce its brittleness and improve its toughness is an important technical key. Domestic and foreign research shows that adding fiber is one of the effective measures to improve the toughness of concrete. In a variety of fiber materials, the use of steel fiber is the most convenient, without having to change the concrete mixing process and equipment, a certain amount of steel fiber can be more evenly incorporated into the concrete, and can be used general tamping process . In order to give full play to the reinforcement and toughening effect of steel fibers in concrete, efforts should be made to improve the interfacial adhesion between fibers and concrete substrates. The increase in the ratio of fiber length to diameter (commonly known as the aspect ratio) can cause difficulties in mixing. Fibers tend to entangle with each other during the mixing process, thereby seriously impairing the reinforcing effect of the fibers. To this end, both at home and abroad attach great importance to the development and development of special-shaped steel fiber, trying to change the appearance of steel fiber in order to improve the adhesion of fiber and concrete. Another technical way to improve the interfacial adhesion between steel fibers and concrete is to add appropriate amounts of silica fume. Foreign studies have shown that the addition of silica fume can produce high-strength steel fiber reinforced concrete with a reduction in unit cement consumption. Domestic studies show that the addition of silica fume contributes to the improvement of the interfacial layer between the steel fiber and the cement substrate, reduces the enrichment of calcium hydroxide at the interface and weakens its orientation, and accordingly can increase the mechanical properties of steel fiber reinforced cement composites. performance. The test shows that when the silicon powder content is 5 to 10%, it has a significant effect on improving the bonding strength between steel fiber and cement mortar. The purpose of this paper is to select the optimum amount of silica fume on the basis of the selection of appropriate deformed steel fibers (with internal doping method) to formulate fiber concrete with high strength and high toughness.