Evaluation of stone impact resistance of laminated glass used for transparent soundproof panels in road noise barriers

In Korea, the criterion for the evaluation of the stone impact resistance of transparent soundproof panels is that there should be no cracks or damages after the ball drop test. However, it is not sufficient to evaluate the impact resistance of panels, as the test specimen is a transparent sheet with an area of 610×610 mm, not a panel. Although the results of the drop ball test on tempered laminated glass show good impact resistance, glass damage occurs frequently at road sites. The impact resistance of glass was compared with various impactors. There are three type of glass used in the experiment: annealed laminated glass, heat strengthened laminated glass, and tempered laminated glass. Free falling impact tests were conducted using steel balls of 1,040 g (φ 63.5 mm), the impactor with steel ball (φ 10 mm) as a tip, the impactor with sharp diamond as a tip, and crushed stones used for road pavement. The pattern of cracks in tempered laminated glass on road noise barriers was much more similar to the results of the sharp-tip impactor drop test. The test results will be used to develop a new test method for stone impact resistance of transparent soundproof panels.