Experimental Study to Determine the Failure Criteria of Concrete at Its Early-Age

Table 5

The values of normal stress and the shear stress in an octahedral stress space for the ultimate strength of a C20 concrete at an early-age (MPa).

Test	Age
	Standard curing; for 3 days		Standard curing; for 4 days		Standard curing; for 5 days		Standard curing; for 6 days		Standard curing; for 7 days
	Uniaxial tension	0.39	0.56	0.42	0.59	0.44	0.62	0.45	0.64	0.46	0.65
Biaxial tension-compression 1	−0.34	1.24	−0.32	1.25	−0.30	1.28	−0.28	1.30	−0.27	1.32
Biaxial tension-compression 2	−0.71	1.65	−0.69	1.68	−0.67	1.69	−0.66	1.71	−0.63	1.73
Uniaxial compression	−4.27	6.03	−5.07	7.16	−5.63	7.97	−6.07	8.58	−6.30	9.00
Biaxial compression-compression 1	−5.50	6.42	−6.27	7.49	−7.10	8.66	−8.13	9.46	−8.50	9.97
Biaxial compression-compression 2	−7.07	7.35	−7.80	8.36	−8.83	9.18	−9.87	10.0	−10.2	10.5
Biaxial compression-compression 3	−7.90	7.35	−9.23	8.59	−10.3	9.58	−11.2	10.2	−11.6	10.6