Effects of Alkali-Silica Reaction on Response of Concrete Squat Shear Walls

Alkali-Aggregate Reaction (AAR) problem is common in structures such as bridges, roadways, airport runways, and nuclear power plants that were built with reactive aggregate. The Alkali-Aggregate Reaction progresses with time in concrete between the alkaline cement paste and reactive amorphous silica. The reaction uses the moisture in the atmosphere and produces a gel that keeps dilating. The dilating gel causes cracks in the concrete mass thus possibly compromising the integrity of concrete. This can cause a number of issues with regard to the performance of the concrete structures caused by deteriorating concrete properties such as lowering of tensile strength, stiffness, ductility and deterioration of bond characteristics. Results from testing two squat shear walls made with normal concrete and four walls with concrete containing reactive aggregate causing alkali-silica reaction (ASR) are presented. In addition to the squat shear walls, several companion specimens were cast to evaluate the concrete material properties and perform non-destructive tests. These specimens included 21 cylinders, six modulus of rupture (MOR) beams, three expansion prisms, and six dog-bone specimens. To accel¬erate the ASR and deterioration of the concrete, the walls were stored in an environmental chamber, specially constructed with the capacity to store large specimens in a controlled high-temperature and high-humidity condition. These walls were tested in three stages under reversed cyclic lateral loads while at the same time subjected to constant axial load simulating earthquake loads. Small companion specimens revealed that ASR caused free expan¬sion of approximately 0.23%. While concrete gained compressive strength over time, its tensile strength and stiffness deteriorated significantly due to the ASR. The lateral load carrying capacity of the walls was not adversely affected. The performance of the walls, however, deteriorated significantly over time with respect to ductility and energy dissipation capacity. The absorbed strain energy capacity of the ASR shear wall at full exhaustion was approximately 25% of that of the regular concrete wall and the displacement ductility was reduced by approximately 30% due to ASR. Finally, finite element analysis technique was used to model this behaviour which gave reasonably good estimates of the experimental shear wall responses.

Department dc:contributor.department

Civil Engineering

Year dc:date.issued

2020

Author dc:creator

• Habibi, Farhad

Advisor dc:contributor.advisor

• Sheikh, Shamim A

• Alkali-Silica Reaction
• ASR
• Concrete
• Crack
• Reversed Cyclic
• Shear Wall

Handle dc:identifier.uri

http://hdl.handle.net/1807/101052

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/101052