| The concrete face slab of rockfill dam has been widely used in engineering because of its excellent anti-seepage performance,but most of the concrete face slabs have different degrees of cracks,and many of the completed concrete face slab surface of rockfill dam is prone to produce horizontal cracks with strong regularity,which seriously restricts the development of concrete face slab.Therefore,based on the existing research results of anti cracking concrete,this paper studies the influence of different fibers and admixtures on the mechanical properties and anti cracking properties of concrete by optimizing the raw materials.The main research results are as follows:(1)Based on the quantitative analysis of chemical composition of fly ash and cement,the anti cracking mechanism of fly ash and cement is revealed.The ball effect of fly ash can be exerted,the content of C3A and C3S can be reduced,the water consumption and shrinkage rate of concrete can be reduced,and the fluidity of concrete can be enhanced and shrinkage rate of concrete can be reduced by appropriate specific surface area and variety of cement.(2)The crack resistance of different fibers and admixtures are tested by the method of restricted shrinkage circle and the method of restricted shrinkage plate.It is found that the method of restricted shrinkage circle is not suitable for evaluating the crack resistance of expansive concrete.Combined with the micro morphology of different fibers and admixtures,it is found that the use of expansion agent and air entraining agent should be avoided at the same time.(3)The mechanical properties and crack resistance of concrete are tested.The synergistic effect of concrete in different periods on mechanical properties and crack resistance is studied.It is found that reducing water loss shrinkage deformation and improving deformation ability are the main factors to prevent the early crack resistance of concrete,and improving the later tensile strength of concrete is the main factor to prevent the later crack resistance of concrete.(4)Based on the analysis of the concrete crack forms and the influence of different angles on the crack resistance of the inclined concrete face slab,it is determined that the gravity is the main factor to intensify the crack of the concrete face slab.Based on the construction technology of concrete face slab of rockfill dam,it is found that the formed concrete face slab on the dam slope will produce the upward tension of parallel dam slope due to its own weight,and at this time,the concrete poured by the slab is in the plastic state and has no tensile capacity,which will make the newly poured concrete face slab very easy to produce horizontal cracks. |
