Study On Influence Factors Of Plastic Shrinkage Based On HPC Pavement With Low Clinker In Cold Area

HPC (high performance concrete) as the durability for a design index is a new type of concrete. Its practical engineering application is growing. With the development of the concrete, the crackings become one of the inevitable problems. And the cracking in the early stage of shrinkage is a top priority. Therefore, the analysis of influencing factors on the plastic cracking of low clinker HPC is of great significance. This paper studied the plastic shrinkage of low clinker HPC, through mix ratio and external conditions. Analyze the influence factors comprehensively, mainly by slab test method test and supplemented by the ring test, and proposed the optimal mixture ratio.Study the influence of different factors against 28d flexural strength and wet density of low clinker HPC. Mixed mineral admixture, fly ash have a negative effect to 28d flexural strength and wet density. Mineral powder and silicon powder have a positive effect to 28d flexural strength and wet density. With the increase of water/cement ratio, flexural strength and wet density decreases. While, after incorporating fiber, flexural strength and wet density increased.Through the analysis of internal factors of low clinker HPC plastic shrinkage, it is concluded that different kinds of mineral admixtures have different effects on shrinkage of low clinker plastic HPC. With the increase of fly ash, concrete cracking area gradually reduced. With the increase of mineral powder, concrete plastic shrinkage increased. With the increasing of silicon powder, concrete plastic shrinkage significantly increased, and its crack resistance from large to small is:fly ash> mineral powder>silicon powder. Water/cement ratio has a positive complex effect on plastic shrinkage. The effect depends on the suitability that matched with water reducer. Fiber and rubber powder can effectively restrain the plastic shrinkage. Under the condition of same slump, species 1 water reducer anti-cracking performance is weak in species 2 and 3. But it can be used in low dosage considering the actual application value. With the increase of sand ratio, dosage of cement, concrete plastic shrinkage enhanced. At the same time, Research and analyze the external influence factors of low clinker HPC plastic shrinkage. The greater the wind speed or temperature is, the bigger the concrete plastic shrinkage is. The greater the humidity is, the less concrete plastic cracking area is. It is preferred to low wind speed, high humidity and low temperature condition in the concrete curing.Ring test results verify the conclusion of slab test method. Further proves the water-binder ratio and mineral admixtures are the important factors influencing the plastic shrinkage of low clinker HPC.