Adherence between steel bars and lightweight concrete with EPS beads

SARTORI, A. L.; PINHEIRO, L. M.; DA SILVA, R. M.; FREITAS, S. B.; CESAR, T. G.

doi:10.1590/S1983-41952017000100007

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Articles • Rev. IBRACON Estrut. Mater. 10 (01) • Feb 2017 • https://doi.org/10.1590/S1983-41952017000100007 copy

Adherence between steel bars and lightweight concrete with EPS beads

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

This paper describes the adherence behavior of a structural lightweight concrete with EPS beads (SLCEB) in a monotonic loading, based in a bibliographic review and in pull-out tests. The results of these SLCEB tests were compared with those of an ordinary concrete (OC) and with the values based in indications of the Brazilian code ABNT NBR 6118:2014 - Design of concrete structures. The pull-out tests of two batches of SLCEB and one of OC were analyzed, in a total of 60 tests. Mechanical characteristics were determined too, such as: compressive strength and tensile strength in split cylinder test. The calculated results according to the above mentioned standard were very different from those obtained in the tests, indicating that the theoretical values are more conservative than the experimental ones. It was also verified that it is possible to use SLCEB in structures with respect to the adequate adherence of reinforcement in the concrete.

Keywords:
lightweight concrete with EPS; anchoring by adherence; sliding; splitting; adherence stress.

Batch	Number of Models	Diameter (mm)	Height of concrete (cm)	Bond length (cm)	Age in the test¹
Preliminary test	2	10	20	15	24 hours
	2	10	30	25
SLCEB 1^st Batch	4	5	9	4	29 and 30 days²
	4	6.3	10	5
	4	8	12	7
	4	10	14	9
	4	12.5	16	11
SLCEB 2^nd Batch	4	5	9	4	155 days
	4	6.3	10	5
	4	8	12	7
	4	10	14	9
	4	12.5	16	11
SLCEB 3^rd Batch	4	5	5	2.5	127 days
	4	6.3	6.3	3.15
	4	8	8	4
	4	10	10	5
OC	4	5	9	4	35 and 36 days³
	4	6.3	10	5
	4	8	12	7
	4	10	14	9
	4	12.5	16	11

SP	Compression		Splitting test		Tension	Notes
SP	F_ci (kN)	f_ci (MPa)	F_ct,sp (kN)	f_ct,sp (MPa)	f_ct (MPa)
1	334.8	42.63	60.4	1.92	1.73	It didn’t segregate
2	348.1	44.33	86.8	2.76	2.49	It didn’t segregate
3	330.2	42.05	105.5	3.36	3.02	It didn’t segregate
4	343.4	43.72	94.0	2.99	2.69	It didn’t segregate
Average	339.13	43.18	86.68	2.76	2.48	-

SP	Compression		Splitting test		Tension	Notes
SP	F_ci (kN)	f_ci (MPa)	F_ct,sp (kN)	f_ct,sp (MPa)	f_ct (MPa)
1	9.6	4.90	7.3	0.90	0.81	It didn’t segregate
2	13.0	6.60	8.6	1.10	0.99	It didn’t segregate
Average	11.3	5.75	7.9	1.00	0.90	-

SP	Compression		Splitting test		Tension	Notes
SP	F_ci (kN)	f_ci (MPa)	F_ct,sp (kN)	f_ct,sp (MPa)	f_ct (MPa)
1	93.3	11.88	41.7	1.33	1.19	It didn’t segregate
2	79.6	10.13	34.8	1.11	0.99	It didn’t segregate
3	86.3	10.99	34.0	1.08	0.98	It didn’t segregate
4	81.5	10.37	37.4	1.19	1.07	It didn’t segregate
Average	85.2	10.84	36.9	1.18	1.06	-

SP	Compression		Splitting test		Tension	Notes
SP	F_ci (kN)	f_ci (MPa)	F_ct,sp (kN)	f_ct,sp (MPa)	f_ct (MPa)
1	18.3	2.33	42.2	1.33	1.20	It segregated
2	18.6	2.36	21.0	0.67	0.60	It didn’t segregate
3	20.5	2.61	19.8	0.63	0.57	It didn’t segregate
4	15.0	1.90	27.0	0.86	0.77	It didn’t segregate
Average	18.1	2.30	27.5	0.87	0.79	-

SP	Compression		Splitting test		Tension	Notes
SP	F_ci (kN)	f_ci (MPa)	F_ct,sp (kN)	f_ct,sp (MPa)	f_ct (MPa)
1	86.6	11.28	36.0	1.15	1.03	It didn’t segregate
2	103.5	13.18	38.6	1.23	1.11	It didn’t segregate
3	93.8	11.94	38.6	1.23	1.11	It didn’t segregate
4	99.6	12.68	35.2	1.12	1.01	It didn’t segregate
Average	95.9	12.27	37.1	1.18	1.06	-

SP	A_máx (N.m)	A_5mm (N.m)	ℓ_b (cm)	F_máx (kN)	F_0.10mm (kN)	τ_máx (MPa)	(_0.10mm (MPa)	f_bd (MPa)
1 (20 cm)	1.21	39.43	15	23.3	21.6	4.95	4.58	1.01
2 (20 cm)	1.50	19.04	15	27.9	27.7	5.94	5.88	1.01
1 (30 cm)	1.92	44.95	25	42.9	42.5	5.46	5.41	1.01
2 (30 cm)	6.25	53.64	25	50.1	50.1	6.38	6.38	1.01

Diameter of the bar (mm)	SP	A_máx (N.m)	A_5mm (N.m)	ℓ_b (cm)	F_máx (kN)	F_0.10mm (kN)	(_máx (MPa)	(_0.10mm (MPa)	f_bd (MPa)
5	1	6.26	17.82	4	6.23	1.47	9.91	2.34	2.79
	2	9.38	29.28	4	9.11	3.85	14.50	6.13	2.79
	3	12.73	39.03	4	10.99	6.18	17.49	9.84	2.79
	4	12.03	39.03	4	10.99	6.18	17.49	9.84	2.79
	Average	10.10	31.29		9.33	4.42	14.85	7.03	2.79
6.3	1	17.92	18.21	5	22.43	15.11	22.67	15.27	2.79
	2	22.20	22.64	5	21.93	13.64	22.16	13.78	2.79
	3	30.30	70.97	5	19.87	13.55	20.08	13.69	2.79
	4	24.83	71.03	5	20.47	7.05	20.68	7.12	2.79
	Average	23.81	45.71		21.17	12.34	21.40	12.47	2.79
8	1	16.97	67.07	7	20.47	10.48	11.63	5.96	2.79
	2	19.90	90.08	7	24.72	14.38	14.05	8.17	2.79
	3	16.70	92.24	7	25.78	17.08	14.65	9.71	2.79
	4	30.04	92.56	7	24.68	13.74	14.03	7.81	2.79
	Average	20.90	85.49		23.91	13.92	13.59	7.91	2.79
10	1	34.15	126.88	9	37.72	17.08	13.34	6.04	2.79
	2	40.84	189.90	9	47.93	26.97	16.95	9.54	2.79
	3	25.40	176.02	9	47.06	29.30	16.65	10.36	2.79
	4	27.42	135.16	9	35.21	11.72	12.45	4.15	2.79
	Average	31.95	156.99		41.98	21.27	14.85	7.52	2.79
12.5	1	88.84	104.66	11	62.17	31.36	14.39	7.26	2.79
	2	41.36	41.36	11	61.30	38.73	14.19	8.97	2.79
	3	48.35	108.81	11	66.38	39.05	15.37	9.04	2.79
	4	83.88	199.10	11	65.51	31.22	15.17	7.23	2.79
	Average	65.61	113.49		63.84	35.09	14.78	8.12	2.79

Diameter of the bar (mm)	SP	A_máx (N.m)	A_5mm (N.m)	ℓ_b (cm)	F_máx (kN)	F_0.10mm (kN)	(_máx (MPa)	(_0.10mm (MPa)	f_bd (MPa)
5	1	0.51	12.93	4	4.08	3.75	6.49	5.97	1.19
	2	5.19	19.17	4	5.59	4.67	8,89	7.43	119
	3	0.76	15.61	4	6.41	6.27	10.20	9.98	1.19
	4	6.74	21.94	4	6.73	2.79	10.71	4.44	1.19
	Average	3.30	17.41		5.70	4.37	9.07	6.96	1.19
6.3	1	1.03	33.27	5	12.96	12.95	13.09	13.09	1.19
	2	0.88	13.94	5	9.29	8.88	9.39	8.97	1.19
	3	1.50	41.60	5	13.64	13.37	13.79	13.51	1.19
	4	2.28	24.41	5	12.22	11.49	12.35	11.61	1.19
	Average	1.42	28.30		12.03	11.67	12.16	11.80	1.19
8	1	3.23	41.59	7	23.40	22.80	13.30	12.96	1.19
	2	1.19	37.56	7	19.96	19.87	11.35	11.29	1.19
	3	3.91	35.42	7	19.37	19.37	11.01	11.01	1.19
	4	7.68	41.43	7	20.65	20.60	11.74	11.71	1.19
	Average	4.00	39.00		20.84	20.66	11.85	11.74	1.19
10	1	24.73	75.50	9	36.12	34.98	12.78	12.37	1.19
	2	3.38	65.02	9	30.08	29.48	10.64	10.43	1.19
	3	4.57	76.06	9	38.55	38.37	13.63	13.57	1.19
	4	18.38	62.92	9	30.40	28.75	10.75	10.17	1.19
	Average	12.77	69.88		33.79	32.90	11.95	11.63	1.19
12.5	1	9.15	124.74	11	46.38	44.36	10.74	10.27	1.19
	2	10.67	117.13	11	47.38	42.67	10.97	9.88	1.19
	3	3.85	108.39	11	37.27	36.81	8.63	8.52	1.19
	4	7.21	140.57	11	42.07	39.46	9.74	9.13	1.19
	Average	7.72	122.71		43.28	40.83	10.02	9.45	1.19

Diameter of the bar (mm)	SP	A_máx (N.m)	A_5mm (N.m)	ℓ_b (cm)	F_máx (kN)	F_0.10mm (kN)	(_máx (MPa)	(_0.10mm (MPa)	f_bd (MPa)
5	1	2.30	7.75	2.5	5.31	5.31	13.52	13.52	1.19
	2	1.43	8.08	2.5	5.81	5.54	14.81	14.11	1.19
	3	2.01	12.01	2.5	6.68	6.50	17.02	16.65	1.19
	4	0.42	11.45	2.5	4.26	4.26	10.84	10.85	1.19
	Average	1.54	9.82		5.52	5.40	14.05	13.76	1.19
6.3	1	0.70	5.84	3.15	8.06	8.06	12.92	12.93	1.19
	2	0.53	8.53	3.15	7.78	7.65	12.48	12.27	1.19
	3	3.08	13.47	3.15	8.74	8.74	14.03	14.02	1.19
	4	0.48	13.87	3.15	7.69	7.65	12.34	12.27	1.19
	Average	1.20	10.43		8.07	8.03	12.94	12.87	1.19
8	1	2.04	27.54	4	15.89	15,89	15.80	15.81	1.19
	2	1.32	22.15	4	13.09	13,09	13.02	13.02	1.19
	3	0.88	30.77	4	14.24	14,15	14.16	14.08	1.19
	4	4.61	20.94	4	12.59	12,59	12.52	12.52	1.19
	Average	2.21	25.35		13.95	13,93	13.88	13.86	1.19
10	1	4.73	22.16	5	17.17	17,16	10.93	10.92	1.19
	2	12.24	36.39	5	21.52	21,52	13.70	13.70	1.19
	3	10.47	32.94	5	20.69	20.69	13.17	13.17	1.19
	4	11.50	34.37	5	18.86	18.86	12.01	12.01	1.19
	Average	9.74	31.47		19.56	19.56	12.45	12.45	1.19

Batch	Diameter of the bar (mm)	τ_máx (MPa)	τ_0.10mm (MPa)	f_bd (MPa)	Failure mode	τ_0.10mm/f_bd
OC	5	14.85	7.03	2.79	Sliding of the bar	2.52
	6.3	21.4	12.47	2.79	Yielding and subsequent sliding of the bar	4.47
	8	13.59	7.91	2.79	Sliding of the bar	2.84
	10	14.85	7.52	2.79	Yielding and subsequent sliding of the bar	2.70
	12.5	14.78	8.12	2.79	Sliding of the bar with concrete splitting	2.91
	Average	15.89	8.61 (-45.81%)¹	2.79		3.09
SLCEB 1^st Batch	5	9.07	6.96	1.19	Sliding of the bar	5.85
	6.3	12.16	11.80	1.19	Sliding of the bar	9.92
	8	11.85	11.74	1.19	Sliding of the bar	9.87
	10	11.95	11.63	1.19	Sliding of the bar	9.77
	12.5	10.02	9.45	1.19	Sliding of the bar with concrete splitting	7.94
	Average	11.01	10.32 (-6.27%)¹	1.19		8.67
SLCEB 3^rd Batch	5	14.05	13.76	1.19	Sliding of the bar	11.56
	6.3	12.94	12.87	1.19	Sliding of the bar	10.82
	8	13.88	13.86	1.19	Sliding of the bar	11.50
	10	12.45	12.45	1.19	Sliding of the bar	10.46
	Average	13.33	13.24 (-0.68%)¹	1.19		11.13
Preliminary test	10	5.45	5.23 (-4.04%)¹	1.01	Yielding and subsequent sliding of the bar	5.18

Batch	f_cm (MPa)	τ_máx (MPa)	τ_0.10mm (MPa)	f_cm/τ_máx	f_cm/τ_0.10mm
OC	43.18	15.89	8.61	2.72	5.02
SLCEB 1^st Batch	10.84	11.01	10.32	0.98	1.05
SLCEB 3^rd Batch	12.27	13.33	13.24	0.92	0.93
SLCEB Preliminary Test	5.75	5.45	5.23	1.06	1.10

IBRACON - Instituto Brasileiro do Concreto Instituto Brasileiro do Concreto (IBRACON), Av. Queiroz Filho, nº 1700 sala 407/408 Torre D, Villa Lobos Office Park, CEP 05319-000, São Paulo, SP - Brasil, Tel. (55 11) 3735-0202, Fax: (55 11) 3733-2190 - São Paulo - SP - Brazil
E-mail: arlene@ibracon.org.br

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[TFN1] ¹
Ages varied according to the availability of test equipment;

[TFN2] ²
The tests at 29 days were those of the models with 5 mm diameter bars, 6.3 mm, and 8 mm;

[TFN3] ³
The tests at 35 days were those of the models with 5 mm diameter bars, and 6.3 mm.