Analysis of constructive parameters of vertical reinforced concrete structure with self-compacting concrete

Serra, Jordana Herbster Ferraz; Cabral, Antonio Eduardo Bezerra

doi:10.1590/S1983-41952020000500001

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ORIGINAL ARTICLE • Rev. IBRACON Estrut. Mater. 13 (5) • 2020 • https://doi.org/10.1590/S1983-41952020000500001 copy

Analysis of constructive parameters of vertical reinforced concrete structure with self-compacting concrete

Análise de parâmetros construtivos de estrutura de concreto armado vertical com concreto autoadensável

Authorship SCIMAGO INSTITUTIONS RANKINGS

abstract:

The objective of this paper is to quantify the improvements due to the use of self-compacting concrete (SCC) as a replacement to a conventional Portland Cement Concrete (PCC) in the production of a reinforced concrete structure of a typical residential building in Brazil. To achieve the proposed objectives, a SCC mix was developed in the laboratory and tests were performed in the fresh and hardened states. Two floors, consisting of columns, beams and slabs, were built with SCC and a third with PCC. Pouring time and its generated noise, appearance of pathological manifestations after pouring, amount of labor required for pouring, costs and the risk of work-related accidents were evaluated. The results indicate that the floors produced with the SCC obtained 60.5% less pouring time, a reduction of 50% and 62.8% in the quantity and costs of labor, respectively; 260.8% reduction in the accident risk factor and, finally, a reduction of 56.4% in the total cost.

Keywords:
self-compacting concrete; productivity; unit production ratio; costs

Chemical composition (%)
		Standards limits (NBR 11578)
Loss of ignition	4.90%	< 6.5%
MgO content	3.41%	< 6.5%
SO₃ content	3.15%	< 4.0%
Fe₂O₃ content	3.25%	-
Al₂O₃ content	4.45%	-
CaO content	60.67%	-
SiO₂ content	19.48%	-
Insoluble waste	1.94%	< 2.5%
Physical properties
Compressive strength		Standards limits
3 days	31.5 MPa	> 10 MPa
7 days	35.3 MPa	> 20 MPa
28 days	39.4 MPa	> 32 MPa
Fineness
#200	1.83%	< 12%
#325	9.33%	Not applicable
Blaine	4568 cm²/g	> 2600 cm²/g
Consistency water	27.49%	Not applicable
Setting time
Begin	2h:05min	> 1h
End	3h:04min	< 10h
Hot expansibility	0.38mm	< 5mm

Granulometry
Sieve #	Fine (sand)		Coarse (gravel)
Sieve #	% Average Retained	% Retained Accumulated	% Average Retained	% Retained Accumulated
12.7	-	-	0.3	0
9.5	-	-	11.8	12
6.3	-	-	46.1	58
4.8	8	8	20.5	78.6
2.36	5	13	16.6	95.2
1.18	13.7	26.7	2.6	97.8
0.6	33.7	60.4	0.5	98.3
0.3	30.9	91.3	0.5	98.8
0.15	5.4	96.7	1.2	100
Bottom	3	100	0	-
Maximum Dimension	6.3mm		12.7
F.M.	2.96		5.8
Physical Indexes
	Sand	Standard method	Gravel	Standard method
Specific gravity	2.60 g/cm³	NBR NM 52 e 53	2.69 g/cm³	NBR NM 52 e 53
Bulk density	1.52 g/cm³	NBR NM 45	1.45 g/cm³	NBR NM 45

Physical characteristics
Humidity (%)	0.3
Bulk density (g/cm³)	1.2
pH	9
Chemical Characteristics
CaCO₃ (%)	92.5
CaO (%)	52.5
Fe₂O₃ (%)	0.05
Al₂O₃ (%)	0.03
SiO₂ (%)	0.35
MgO (%)	1.5
Pb (mg/g)	0.06
Cd (mg/g)	0.009
Loss of ignition (900ºC) (%)	42.5

Material	PCC	SCC
Cement (kg)	349	406
Limestone filler (kg)	-	125
Sand (kg)	787	779
Gravel type 1 (kg)	749	-
Gravel type 0 (kg)	249	-
Gravel 9,5 (kg)	-	819
Gravel 12,7 (kg)	-	-
Superplasticizer (L)	2.16	2.7
Plasticizer (L)	-	2
Water (L)	188	200

Office	Number of workers			Occupation
Office	1ª SCC	2ª SCC	CPC	Occupation
Blacksmith	1	1	1	Hardware monitoring
Carpenter	1	1	2	Review of forms
Masons	2	2	3	Scraping
Servant	1	1	1	Pump hose boom
Servant	4	2	4	Pulling / lathing the concrete
Servant	-	-	4	Vibrator
Aux. Electrician	-	-	1	Maintenance of vibrators / possible temporary installation
TOTAL	9	7	16

Test	Laboratory SCC	SCC in the site		Classification	Test Method
Test	Laboratory SCC	1ª pouring	2ª pouring	Classification	Test Method
Slump Flow	690 mm	677 mm	675 mm	SF 2	ABNT, 2010 a
T₅₀₀	1.8 s	1.6 s	1.7 s	VS 1	ABNT, 2010 a
V funnel	5 s	2.8 s	3.0 s	VF 1	ABNT, 2010 b
L box	0.8	0.8	0.8	PL 2	ABNT, 2010 c
J ring	685 mm	685 mm	-	PJ 2	ABNT, 2010 f

Test	SCC at the laboratory	SSC at site – 1^st pouring	SSC at site – 2^nd pouring	PCC at site	Test method
Absorption	4.65%	-	-	-	NBR 9778 (ABNT, 2009)
Voids index	10.4%	-	-	-
Specific gravity	2.21 g/cm³	-	-	-
Compressive strength at 3 days	33.4 MPa	27 MPa	24 MPa	21.5 MPa	NBR 5739 (ABNT, 2007)
Compressive strength at 7 days	-	30 MPa	28 MPa	27.6 MPa
Compressive strength at 28 days	41.7 MPa	37 MPa	37 MPa	35 MPa

Type of concrete	Waiting time for the beginning of pouring (hours)
1^st SCC	03:15
2^nd SCC	04:10
PCC	01:35

Quantity	Occupation	Rental price (daily)	Total
02	Use	R$ 66.00	R$ 132.00
02	Reservation	R$ 66.00	R$ 132.00
TOTAL			R$ 264.00

1^st SCC pouring
Costs	Quant.	N° Floors	Unit Cost (R$)	Total Cost (R$)
Labor	1 day	22	260.51	5,731.22
Equipment	0	22	0.00	0.00
Concrete	88 m³	22	332.50	643,720.00
Forms	1	-	107,734.50	107,734.50
Total				757,185.72
2^nd SCC pouring
Costs	Quant.	N° Floors	Unit Cost (R$)	Total Cost (R$)
Labor	1 day	22	235.09	5,171.98
Equipment	0	22	0.00	0.00
Concrete	88 m³	22	332.50	643,720.00
Forms	1	-	107,734.50	107,734.50
Total				756,626.48
PCC pouring
Costs	Quant.	N° Floors	Unit Cost (R$)	Total Cost (R$)
Labor	1 day	22	666.52	14,663.44
Equipment	1 day	22	264.00	5,808.00
Concrete	88 m³	22	280.00	542,080.00
Forms	2	-	107,734.50	215,469.00
Total				778,020.44

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: Antonio Eduardo Bezerra Cabral. E-mail: eduardo.cabral@ufc.br