Enhancing the rehabilitation of timber piles using fiber reinforced polymer: An acoustic emission analysis under compressive stress

Timber is extensively utilized as a foundational component in the construction of bridge supports, known as timber piles. These structures are vulnerable to deterioration due to environmental influences, presenting potential risks to public safety. The application of fiber-reinforced polymer (FRP) has emerged as a prevalent approach for the rehabilitation of timber piles, favored for its installation efficiency. This paper introduces a novel contribution through the adoption of Acoustic Emission (AE) as an innovative, non-destructive method for evaluating the integrity of timber piles with and without FRP rehabilitation. In this paper, seven timber piles with varying degrees of damage have been prepared. Four of these piles were rehabilitated using fiber reinforced polymer (FRP) jackets and damaged regions were filled with either resin or grout. Two different FRP jackets were investigated, a glass FRP (GFRP) bi-directional laminate and a unidirectional prepreg filled with sun-curing resin. Compression tests were conducted on each specimen and acoustic emission sensors were installed on the piles to assess the effectiveness of the repair and to evaluate the extent of damage as the load increased. Results of compression tests show that the most effective method was the use of the GFRP laminate filled with grout for piles with large areas of natural damage and the GFRP laminate filled with resin for piles with smaller areas of damage. The AE results demonstrated that AE is a useful non-destructive technique, and the analysis of cumulative signal strength (CSS), intensity and cumulative hits can be applied to unrehabilitated and rehabilitated timber piles to gauge damage in members.