| Title |
A Study on the Expansion Model of Cement Paste Used Ettringite-Gypsum Type Expansive Additive |
| Keywords |
High Performance Concrete ; Autogenous Shrinkage ; Expansion Model ; Ettringite-Gypsum Expansive Additive |
| Abstract |
As concrete structures become stronger, more highly flowing, and more durable, the use of high performance concrete is increasingly needed to meet such requirements, and actual use of high performance concrete can be seen in construction work. For high performance concrete, the amount of unit cement is large, which occurs rapid hydration reaction of cement. That causes self-desiccation of the interior of the hardened cement paste at early age and, consequently, the hardened paste undergoes shrinkage deformation owing to autogenous shrinkage. One method that is generally considered effective for reducing autogenous shrinkage of high performance concrete is to compensate for the shrinkage by incorporating expansive additives. Existing studies on autogenous shrinkage of high performance concrete based on expansive additives have been structured around experiments. In order to quantitatively assess the amount of reduction in expansive additive-driven autogenous shrinkage of high performance concrete, we believe that it is imperative to first establish a expansion model for cement paste used expansive additive. This study presents a expansion model for cement paste used expansive additive, where an ettringite-gypsum type additive, which is designed to show rapid expansion at early age to reduce autogenous shrinkage, is considered. This study also reviews and analyzes the feasibility of the model, both experimentally and empirically. |