A Study On Alkali-Aggregate Reactiona Influence On Reinforcing Concrete Durability

The Alkali-Aggregate Reactiona as one of the concrete-structure durabe questions is researched in thesis. The principal tasks are as follows:The classification of AAR is difined in the thesis. AAR can be assorted two classification:Alkali-Silica Reaction(ASR), Alkali-Carbonate Reaction(ACR) and Aklali-silicate Reaction(ASR).The intrinsic hypostasis and the motive mechanism of the ARR of concrete project is researched in this thesis. If the concrete project happens the AAR, it must have three conditions. First of all, the content of alkali of raw materials of concrete must be high. Secondly, the skeletal material must have active ingredient. Thirdly , the surroundings must be moist and can provide abundant moisture and moist air. The prevention and identification of AAR are defined. In order to prevent the AAR, we must control the content of alkali of cement and control the content of alkali of concrete under 3kg and control the degree of the moist of concrete and add mixture material(for example: fly ash and so on)and use chemical additive and use the inactive material. We define the count-method of the content of alkali of concrete in detail, the examination and judgment of the content of alkali of concrete.Through the experiment, we can analyse restraining function of fly ash for the AAR; research the extent of expand of adding fly ash in the sample with different aggregates, and restrain function for the content of AAR. From this experiment of this paper indicated that: fly ash have restraining function for the AAR. We can conclude that comparing with sample with no adding fly ash, the expand of fly ash, the expand of AAR of the sample with adding fly ash reduce. Regarding the sample with different aggregates, the reduced extent of expand is different because of the content of alkali. When we add fly ash to concrete, the fly ash can adsorb some Na+ and K+ through its adsorption of internal surface and the change of ion. All this can restrain the happening of AAR.Combining real example of synthetical building project, we can make know the hazard of AAR in concrete, and importance of preference.