Study of the influence of jigging of recycled coarse aggregate on the compressive strength of concrete

Malysz, Gabriela Nunes; Molin, Denise Carpena Coitinho Dal; Masuero, Angela Borges

doi:10.1590/S1983-41952020000500003

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Revista IBRACON de Estruturas e Materiais

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ORIGINAL ARTICLE • Rev. IBRACON Estrut. Mater. 13 (5) • 2020 • https://doi.org/10.1590/S1983-41952020000500003 copy

Study of the influence of jigging of recycled coarse aggregate on the compressive strength of concrete

Estudo da influência da jigagem do agregado graúdo reciclado na resistência à compressão do concreto

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT:

The composition heterogeneity of this type of aggregate is indicated as one of the main restrictions to its potential utilization since it generates great variability in the performance of the types of concrete produced with recycled aggregate. To reduce the use limitations of recycled coarse aggregate (RCA), this study aimed to analyze the use of a jig, a type of equipment used in mining, which performs density separation through air sprinkling in the selection of large aggregates of CDW crushing. To evaluate the equipment performance in the selection of RCA materials, specimens of concrete with recycled aggregate of three different sources were molded before and after selection in the jig, as well as reference concrete with natural aggregate. To measure the performance of the types of concrete produced, axial compressive strength tests were performed. Additionally, a statistical and comparative analysis of the results was performed to seek a better basis for possible conclusions. Analysis of the results of the axial compression strength tests showed that the variability of the recycled aggregates reflected in the inconstancy of the behavior of the concrete produced with them; it was not possible to perceive a common or uniform performance between the three sources of recycled aggregate for the mix design produced. Although some studies point to good separation results with jigging, it was found that with the use of recycled aggregates available in the local market, for the three studied sources, the selection was not able to minimize the variability of the properties of the recycled types of concrete produced with the selected aggregates.

Keywords:
construction and demolition waste (CDW); recycled coarse aggregate (RCA); jig; compressive strength; variability

Property	CP IV 32	Unit	Requirements
Fineness (waste in 75µ sieve)	0.32	%	≤ 8.0
Blaine fineness	4920	cm ² /g	≥ 3000
Start of setting	405	min	≥ 60
Setting end time	520	min	≤ 720
Compressive strength at 3 days	22.3	MPa	≥ 10
Compressive strength at 7 days	26.2	MPa	≥ 20
Compressive strength at 28 days	41.2	MPa	≥ 32
Fire loss (% in mass)	3.78	%	≤ 4.5
SO ₃ (% in loss)	2.16	%	≤ 4.0
MgO (% in loss)	4.21	%	≤ 6.5

Property	Values	Unit	Standard
Fineness Module	2.22	-	NBR NM 248 [ ¹⁷17 Associação Brasileira de Normas Técnicas, Agregados – Determinação da Composição Granulométrica, NBR NM 248, 2003. ]
Maximum Dimension	2.40	mm	NBR NM 248 [ ¹⁷17 Associação Brasileira de Normas Técnicas, Agregados – Determinação da Composição Granulométrica, NBR NM 248, 2003. ]
Specific Mass	2.507	g/cm ³	NBR NM 52 [ ¹⁹19 Associação Brasileira de Normas Técnicas, Agregado Miúdo – Determinação da Massa Específica e Massa Específica Aparente, NBR NM 52, 2009. ]
Unit mass	1.54	g/cm ³	NBR NM 45 [ ¹⁸18 Associação Brasileira de Normas Técnicas, Agregado – Determinação da Massa Unitária e dos Espaços Vazios, NBR NM 45, 2006. ]

Property	Values	Unit	Standard
Fineness Module	7.06	-	NBR NM 248 [ ¹⁷17 Associação Brasileira de Normas Técnicas, Agregados – Determinação da Composição Granulométrica, NBR NM 248, 2003. ]
Shape Index	2.20	-	NBR 7809 [ ²²22 Associação Brasileira de Normas Técnicas, Agregado Graúdo – Determinação do Índice de Forma pelo Método do Paquímetro – Método de Ensaio, NBR 7809, 2006. ]
Water Absorption	0.023	%	NBR NM 53 [ ²³23 Associação Brasileira de Normas Técnicas, Agregado Graúdo – Determinação da Massa Específica, Massa Específica Aparente e Absorção de Água, NBR NM 53, 2009. ]
Maximum Dimension	25	mm	NBR NM 248 [ ¹⁷17 Associação Brasileira de Normas Técnicas, Agregados – Determinação da Composição Granulométrica, NBR NM 248, 2003. ]
Specific Mass	2.964	g/cm ³	NBR NM 53 [ ²³23 Associação Brasileira de Normas Técnicas, Agregado Graúdo – Determinação da Massa Específica, Massa Específica Aparente e Absorção de Água, NBR NM 53, 2009. ]
Unit Mass	1.694	g/cm ³	NBR NM 45 [ ¹⁸18 Associação Brasileira de Normas Técnicas, Agregado – Determinação da Massa Unitária e dos Espaços Vazios, NBR NM 45, 2006. ]

MATERIAL	RCA1	RCA1J	RCA2	RCA2J	RCA3	RCA3J
Mortar	28.3	27.2	37.5	33.7	29.1	35.3
Concrete	11.8	11.8	4.2	4.8	6.5	6.0
Rock	32.8	36.6	18.4	21.3	38.7	32.0
Sandstone	22.6	20.9	0.8	0.8	14.7	9.8
Others	10.2	15.7	17.6	20.5	24.0	22.2
Ceramics	25.6	22.0	37.3	37.7	21.5	21.2
non-enameled	21.9	17.2	25.6	22.2	10.7	13.9
Enameled	3.7	4.8	11.7	15.5	10.8	7.3
Mixed	0.3	1.3	1.8	1.8	4.0	5.2
Tailings	1.2	1.1	0.8	0.7	0.2	0.4

Aggregate type	Unit mix	Mean (MPa)	Standard deviation (MPa)	CV (%)
NCA	2.5	35.18	0.96	2.7
	4.0	31.51	1.45	4.6
	5.5	24.88	0.04	0.1
RCA1	2.5	22.16	1.04	4.7
	4.0	18.80	0.57	3.0
	5.5	14.52	1.03	7.1
RCA1J	2.5	24.73	1.63	6.6
	4.0	22.54	0.70	3.1
	5.5	17.30	0.75	4.3
RCA2	2.5	26.35	2.22	8.4
	4.0	20.68	0.41	2.0
	5.5	14.86	1.19	8.0
RCA2J	2.5	24.96	1.44	5.8
	4.0	19.84	0.76	3.8
	5.5	16.86	0.91	5.4
RCA3	2.5	23.08	1.05	4.5
	4.0	17.83	1.55	8.7
	5.5	18.13	1.24	6.8
RCA3J	2.5	22.34	1.80	8.1
	4.0	21.14	1.55	7.3
	5.5	15.54	0.90	5.8

Variation source	SQ	GDL	MQ	Test F	Probability	Significance
A: RCA Source	5.58	2	2.79	1.82	17.70%	NO
B: Selection by Jigging	9.07	1	9.07	5.90	2.02%	YES
C: Mix	533.99	2	266.99	173.82	0.00%	YES
AB	22.83	2	11.41	7.43	0.20%	YES
AC	28.51	4	7.13	4.64	0.40%	YES
BC	5.84	2	2.92	1.90	16.43%	NO
ABC	16.26	4	4.07	2.65	4.91%	YES
Error	55.30	36	1.54
TOTAL	677.37	53

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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[1] Corresponding author:
Gabriela Nunes Malysz. E-mail: gabi14nunes@hotmail.com