Chapter 39 A Study on Behaviour of Soil Bonding State Using Wave Propagation Method Nur ‘Ain Mat Yusof and Noorfaizah Hamzah Abstract Nondestructive Testing (NDT) technique has a very important role to play due to new demands that required advanced characterization technique to monitor the bonding state condition of soil structures. In the technique not only the material under test is not impaired but also information on test results gathered is much faster and easier without any disturbance to the sample test. The broad usage of NDT will also include detection flaw, thickness measurement, classification of material, and others. Here, the NDT technique based on wave propagation method is conducted experimentally and reviewed in order to evaluate the better method in the determination of bonding state of soil. The dynamic properties of soil are evaluated by a Free–Free Resonant Column (FFRC) test to determine the P-wave and S-wave velocities after which an Impact-Echo (IE) method is then used to obtain the bonding state of soil based on signal obtained from time–frequency domain analysis The result shows a contour shape. Various bonding conditions (i.e., fully bonded, debonded, and void) are discovered suggesting that bonding state condition of soil can be evaluated through these contour shapes. It also can be deduced that bonding condition becomes worse when the tail is longer on time axis than the frequency axis. Keywords Bonding condition Á Bonding state Á Contour shape Impact-Echo (IE) Á Wave propagation N. ‘A. Mat Yusof (&) Faculty of Civil Engineering, Universiti Teknologi MARA Pahang, Bandar Tun Abdul Razak Jengka, Pahang, Malaysia e-mail: nurain_humayraa@yahoo.com; nurainyusof@pahang.uitm.edu.my N. Hamzah Faculty of Civil Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia e-mail: noorfaizah1209@salam.uitm.edu.my © Springer Nature Singapore Pte Ltd. 2018 N. A. Yacob et al. (eds.), Regional Conference on Science, Technology and Social Sciences (RCSTSS 2016), https://doi.org/10.1007/978-981-13-0074-5_39 403