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How to prevent the occurrence of Alkali Aggregate Reaction (AAR) in bridge structures?

How to solve the problem?

What is best method of repair or solution to overcome the defect?

in Bridge 39,250 points

1 Answer

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As you know that the AAR is happen to all bridge structure not in Malaysia but problem for entire of world. This is occur when quartz in the aggregate react directly to the existing moisture in the concrete and produce alkaline reaction. This alkaline will effect to the concrete structure and produce spalling and crack to the concrete body. A lot of studies had been carried by the researchers on this problem and our local university also take part on this research like UTM and UKM itself (can refer to the journal). From my reading, it could be say that most of the studies focus on identify reactive aggregates (alkaline present) through the testing like Mortar Bar Test (ASTM C1260) and Petrographic Examination (ASTM C295). To be proven by study and research thats Malaysian granite which produced aggregates are contain quartz and surely AAR occured (refer journal and paper by UTM).

From my view it can summarize that the effect of quartz in aggregate with moisture will produce the alkaline reaction and it can be control the reaction through recommendation as per belows:

1) Design of abutment need to reconsider by build as far as possible from the edge of river which to minimize the effect of moisture to the concrete body (effect up and down of river water level).

2) Using the blended cement together with OPC in concrete mixture such as fly ash or something else that prevention of water infiltration (moisture) in the concrete.

3) Coating the concrete structure (external) using local product like waterproofing base to prevent water infiltration.
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