Table 6.

Crack initiation fracture toughness $K_{\mathrm{IC}}^{ini}$ and unstable fracture toughness $K_{\mathrm{IC}}^{un}$ of plain concrete specimens calculated by DKFM. $K_{\mathrm{IC}}^{ini}$ is determined from cracking load P_ini and initial crack size a₀. $K_{\mathrm{IC}}^{un}$ corresponds to the peak load P_u and equivalent crack size a_c just before the onset of unstable fracture.

Specimen	Pini (kN)	a0 (mm)	α0	F(α0)	${\mathit{K}}_{\mathbf{IC}}^{\mathit{i}\mathit{n}\mathit{i}}$ ($\mathbf{M}\mathbf{P}\mathbf{a}·\sqrt{\mathbf{m}}$)	Pu (kN)	CMODc (mm)	γ	αc	ac (mm)	F(αc)	${\mathit{K}}_{\mathbf{IC}}^{\mathit{i}\mathit{n}\mathit{i}}$ ($\mathbf{M}\mathbf{P}\mathbf{a}·\sqrt{\mathbf{m}}$)
JZ-W-2-1	13.03	20	0.1	1.01	0.62	24.81	0.03	0.75	0.21	42.42	0.99	1.69
JZ-W-2-2	12.74	20	0.1	1.01	0.61	24.06	0.05	1.28	0.31	62.07	1.05	2.11
JZ-W-2-3	10.1	20	0.1	1.01	0.48	23.12	0.04	1.07	0.28	55.14	1.02	1.86
JZ-W-2-4	21.51	20	0.1	1.01	1.02	25.59	0.05	1.20	0.30	59.72	1.04	2.18
JZ-W-2-5	21.61	20	0.1	1.01	1.03	24.04	0.04	1.03	0.27	53.70	1.02	1.90
JZ-W-2-6	22.76	20	0.1	1.01	1.08	24.34	0.04	1.01	0.27	53.24	1.02	1.91
WJ-1	N.A. *	20	0.1	1.01	N.A. *	21.66	0.05	1.42	0.33	66.12	1.08	2.01
WJ-2	N.A. *	20	0.1	1.01	N.A. *	27.11	0.05	1.14	0.29	57.54	1.03	2.24
WJ-3	N.A. *	20	0.1	1.01	N.A. *	28.77	0.05	1.07	0.28	55.31	1.02	2.31
WJ-4	N.A. *	20	0.1	1.01	N.A. *	28.31	0.05	1.09	0.28	55.91	1.03	2.30
WJ-5	N.A. *	20	0.1	1.01	N.A. *	33.39	0.04	0.74	0.21	42.11	0.99	2.26
WJ-6	N.A. *	20	0.1	1.01	N.A. *	21.99	0.06	1.68	0.36	72.61	1.12	2.22
JZ-W-4-1	11.61	40	0.2	0.99	0.77	20.16	0.06	1.83	0.38	75.99	1.14	2.13
JZ-W-4-2	16.58	40	0.2	0.99	1.10	20.06	0.05	1.54	0.35	69.10	1.10	1.93
JZ-W-4-3	8.62	40	0.2	0.99	0.57	17.31	0.06	2.14	0.41	81.88	1.20	1.98
JZ-W-4-4	12.61	40	0.2	0.99	0.84	16.57	0.06	2.23	0.42	83.55	1.21	1.94
JZ-W-6-1	6.45	60	0.3	1.04	0.56	12.21	0.07	3.53	0.50	100.61	1.43	1.85
JZ-W-6-2	7.65	60	0.3	1.04	0.66	12.07	0.08	4.08	0.53	105.70	1.51	1.99
JZ-W-6-4	5.82	60	0.3	1.04	0.51	13.14	0.07	3.28	0.49	97.97	1.39	1.91
JZ-W-8-2	7.81	80	0.4	1.18	0.88	11.76	0.07	3.67	0.51	101.94	1.45	1.83
JZ-W-8-3	9.48	80	0.4	1.18	1.06	11.55	0.07	3.74	0.51	102.58	1.46	1.81
JZ-W-8-4	5.48	80	0.4	1.18	0.62	8.74	0.05	3.53	0.50	100.53	1.42	1.33
JZ-W-10-1	4.85	100	0.5	1.42	0.74	7.03	0.06	5.26	0.57	114.20	1.68	1.35
JZ-W-10-2	4.67	100	0.5	1.42	0.71	7.95	0.06	4.65	0.55	110.13	1.60	1.42
JZ-W-10-3	3.85	100	0.5	1.42	0.59	9.04	0.07	4.77	0.55	110.99	1.61	1.64
JZ-W-10-4	7.81	100	0.5	1.42	1.18	9.83	0.11	6.90	0.61	122.71	1.91	2.21

* Cracking load was not measured for specimens WJ-1 to WJ-6.