Research On Preparation And Property Of Sacrificial Concrete

In recent years, with the promotion and application of the third-generation nuclear power technology of EPR, sacrificial concrete which is a necessary protective material, will be applied more widely in our country. The study of the development of sacrificial concrete and its performance has also become an urgent problem to be solved. Due to the actual situation of the raw materials in our country, this paper studied preparation technique, physico-mechanical property, chemical composition, performance of water loss, crack resistance capacity and high-temperature properties of sacrificial concrete, which took into account the performance requirements of sacrificial concrete. According to the experiments and theoretical analysis, the following conclusions are obtained:1. The fluidity and cohesiveness of sacrificial concrete is increased as the addition of the cementitious material. To satisfy the pumpability requirements, the cementitious materials should be chosen more than400kg/m3; The mixing of polycarboxylic water-reducing agent or mineral admixture can improve the fluidity apparently, but the workability of fiber reiforced sacrificial concretes decrease with increased fiber dosage.2. The density of the sacrificial concrete range from2600to2700kg/m3, which is higher than ordinary concrete. As the addition of mineral admixture, the compressive strength of sacrificial concrete are decreased obviously, but has nothing to do with the flexural strength; The experimental results show that the influence of polypropylene firer and basalt firer content on compressive strength of sacrificial concrete is ignorable, however the flexural strength of fiber reiforced concretes increase by10-15%, and concrete mixing basalt fiber increases higher than the polypropylene fiber. According to the design requirement of the compressive strength, it is proposed that:①400kg/m3, slag0-50wt%;②450kg/m3, fly ash0-35wt%or slag0-50wt%.3. The water loss evolution of sacrificial concrete in heating and drying test is similar to outdoor exposure drying test. The results show that water loss rate of various concrete samples increase as a logarithmic function and tend to be a constant after a period of time. Futhermore, the best way to decrease water content of sacrificial concrete is to reduce the fresh concrete water-binder ratio.4. The risk of the early-age cracking will increase, when cementitious materials are added to sacrificial concrete; Results indicate that both the maximum width and the total areas of cracks decrease sharply as the addition of multi-mineral admixtures ratio; Compared with the concrete mixed basalt fiber, polypropylene firer can not only postpone the cracking of sacrificial concrete, but also effectively alleviate the negative impact brought by the addition of the cementitious materials. And the fiber dosage is up to1.5kg/m3, the polypropylene fiber can significantly improve crack resistance capacity of sacrificial concrete.5. Results of experiment show that sacrificial concrete has good high-temperature stability. Integrity of specimen appearance maintained well after different temperature and there was no spalling phenomenon during the experiment. The mass loss and compressive strength of sacrificial concrete are decreased, as the temperature that sacrificial concrete is subjected to increased. However, sacrificial concrete was found to be prone to rebound phenomena when subjected to high temperature, which usually occurs after high temperature of400℃. The melting temperature of sacrificial concrete is about1200℃. Results of numerical simulation show that transient temperature field of sacrificial concrete exhibited zone distribution along thickness when subjected to ultra-high temperature. At the same time, temperature concentration occurred at the cracked part. On the other hand, the melting depth of sacrificial concrete gradually increased with the addition of time.