Study on Concrete Pier Impact Performance after Implementing Equal Cross-Section Stainless Steel with Protection from Closed-Cell Aluminum Foam

Table 9

Changes in the ultrasonic speeds of the concrete.

Specimen	Height of drop hammer (m)	Average impact velocity (m/s)	Average sound velocity (km/s)		Reduction of the sound velocity (km/s)	Total reduction of the sound velocity (km/s)	Change rate of the sound velocity (%)
			Before impact	After impact
S1-16	2	0.72	4.323	4.305	0.018	−0.895	−20.7
	4	1.10	4.305	4.256	0.049
	6	1.42	4.256	4.183	0.073
	8	1.67	4.183	4.016	0.167
	10	1.84	4.016	3.739	0.277
	12	2.08	3.739	3.428	0.311
Z2-16	2	0.72	4.68	4.642	0.038	−1.784	−38.12
	4	1.10	4.642	4.579	0.063
	6	1.42	4.579	4.489	0.09
	8	1.67	4.489	4.175	0.314
	10	1.84	4.175	3.579	0.596
	12	2.08	3.579	2.896	0.683
S1-20	2	0.72	4.031	4.018	0.013	−0.611	−15.16
	4	1.10	4.018	3.985	0.033
	6	1.42	3.985	3.929	0.056
	8	1.67	3.929	3.849	0.08
	10	1.84	3.849	3.724	0.125
	12	2.08	3.724	3.42	0.304
Z2-20	2	0.72	4.51	4.485	0.025	−1.001	−22.2
	4	1.10	4.485	4.433	0.052
	6	1.42	4.433	4.362	0.071
	8	1.67	4.362	4.18	0.182
	10	1.84	4.18	3.875	0.305
	12	2.08	3.875	3.509	0.366