ABSTRACT
Alkali-aggregate reaction (AAR) affects the durability of concrete structures which lead to the decrease in the service life of the structures. High expansion level due to AAR has an effect on the map cracking and severe cracks could occur. Carbon fibre reinforced polymers (CFRPs) is one of the best materials used for confinement the damaged concrete to restore the integrity of structure. Ten reinforced concrete columns of specified dimensions 200 mm in diameter & 500 mm in height were fabricated from concrete contained 7.5% of fused silica to total aggregate as a replacement of fine material in its ingredients to simulate the reactivity. During storage in a cabinet at 38°C temperature and 98% relative humidity, a high expansion level due to AAR was noticed between the period of 120 and 180 days which caused a sever crack in the affected columns. One, two and three layers of CFRP were used to confine the damaged columns.
As a result of the expansion due to AAR, the load capacity of the affected columns was reduced by 57%, compared with columns of NC. Confinement of damaged RC columns with CFRP is an interesting subject of study in order to determine the effectiveness of the use of this material to enhance load capacity. Results show that confinement of the damaged columns with one layer of CFRP was sufficient to reach the load capacity of unconfined NC columns and exceed it. The confinement efficiency represents the actual strength of the confined column compared with that of the unconfined column (an average of the results for two columns was taken).The confinement efficiencies of damaged columns reached 282%, 402% and 498% when the columns were wrapped with one, two and three layers of CFRP, respectively, as shown in Figure 1. Effect of confinement on columns damaged by AAR. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig55_1.tif"/>
Estimation of failure mode is essential to know the ultimate conditions of CFRP-confined concrete columns. A typical failure initiated by rupture of CFRP sheets was the general failure mode and most CFRP ruptures occurred at the top half of the columns as shown in Figure 2. Failure mode of reactive concrete with 1-layer of CFRP. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig55_2.jpg"/>
