Yuji HAYAMIZU
Preventive Measure against ASR with Additive and Development of Model of Expansion on ASR
Takumi SHIMOMURA
The alkali-silica reaction (ASR) in concrete is the chemical reaction between the alkalis and reactive aggregate, and ASR is known to result in expansion and cracking that causes deterioration of the structure. There are three preventive measures against ASR in Japan, use of non-reactive aggregate, control of total alkali in concrete and use of additive. The best way to avoid ASR is not to use reactive aggregates, but it is known that safe aggregate sometimes cannot be obtained around construction site. On the other hand, in case of low water to cement ratio concrete and recycle concrete, it is difficult to control total alkali content in concrete. Therefore, preventive measure against ASR with additive is expected recently. Many researchers demonstrated suppressing effect of additive against ASR, however there is not practical applicable standard.
In this study, accelerating test of mortar depending on alkalinity and reactivity of aggregate was carried out. As a result of experiment, influences of several factors on expansion of ASR were confirmed. Examined factors were alkalinity level, reactivity of aggregate, type of cement and kind of additive.
In addition, numerical model is developed based on U.F.O. model to simulate expansive behavior of ASR. Relationship between reaction product and expansion of mortar is formulated through the analysis of experimental data. Suppressing effect of additive is expressed by reduction coefficient C. As a result, it was verified that the proposed model could successfully simulate experimental result.
Please use "previous botton" to return the previous page