Experimental Study Of Additive Components On Heat Evolution Of Cement

With economic development and social progress, HS-HPC has become a natural trend, which is characterized by the content of high cementing materials. Yet, the use of a large number of cementing materials will easily lead to the occurrence of temperature cracking in concrete structure. The hydration heat-induced temperature cracking in concrete structure during the construction stage has always been one of the major causes that affect the durability of the structure as well as an obstacle for the application of HS-HPC in civil engineering. In modern construction, the composite application of lots of additional components further complicates the mechanism of cement’s hydration heat, which necessitates the systematic study of the influence of various additional components on cement’s hydration heat for HS-HPC.In this paper, based on solution heat measurement principle, the author uses hydration heat meter to explore the influence of single-doped, double-doped and co-doped mineral admixtures (fly ash, mineral fines, silica fume) and additives (water-reducing agent, expanding agent, shrinkage reducing agent, internal curing agent) in HS-HPC on cement’s hydration heat and compare the roles of various additional components in controlling cement’s hydration heat.The results show that, mineral admixtures are ideal materials for reducing hydration heat; as cement is greatly replaced, the hydration heat is significantly reduced, but the reduction degrees vary a lot. Under the same amount of admixture, fly ash reduces hydration heat the most, followed by mineral fines and silica fume in sequence. Compared with cement, the amount of additives is usually very small, so their influence on cement’s hydration heat is limited. Among these additives, due to its large content, expanding agent may delay cement’s hydration heat and thus effectively reduce its hydration heat. Water-reducing agent is an ideal material for delaying cement’s hydration heat. Shrinkage-reducing agent can reduce the hydration heat of hydration reaction in the early stage and does not exert a big influence on the total hydration heat. Internal curing agent does not greatly reduce cement’s hydration heat. For most of the additional components, the influence of double-doped or co-doped components on cement’s hydration heat is equal to the combined effects of their single-doped components. However, fly ash and mineral fines can facilitate each other reaction with cement’s hydration product Ca(0H)2. Thus, the influence of the co-doped fly ash and mineral fines on cement’s hydration heat is much greater than that of the combined effects of these two admixtures on the hydration heat.