PSI - Issue 11

Alisson Rodrigues de Oliveira Dias et al. / Procedia Structural Integrity 11 (2018) 84–90 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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2.1. Materials

To perform the tests, Portland Cement CP II Z 32 was used. Table 2 shows the physical and chemical characteristics of this material.

Table 2 - Chemical and physical characteristics of cement used. Propriets Brazilian standard

Especification – standard NBR 11578/91

Unit

Results

Loss to fire

NM 18/12

% % % % %

5,99 4,60 2,74 4,61 4127 2,96 14,6 2:15 3:15 0,10 14,58 3,4

≤ 6,5 ≤ 6,5 ≤ 4,0

Magnesium oxide - MgO Sulfuric Anhydride – SO 3

NM 11-2/12

NM 16/12 NM 15/12 11578/91 16372/15 NM 23/01 11579/12 12826/14 NM 65/03 NM 65/03 11582/16

Insoluble Residue

≤ 16,0

Carbonic anhydride – CO 2 Specific surface area (Blaine)

≤ 5,0

cm 2 /g g/cm 3

≥ 2600 cm 2 /g Not applicable

Specific weigth Fineness (#200) Fineness (#325)

% %

≤ 12,0

Not applicable

Setting time (begin) Setting time (end) Hot Expandability

h:min h:min

≥ 1,0

≤ 10,0

mm

≤ 5,0

The fine and coarse aggregates used in this research were from the Metropolitan Region of Fortaleza, where the fine aggregate is from river and coarse aggregates of granite origin. Table 3 presents a summary of the standards used to characterize the aggregates, as well as the results obtained.

Table 3 - Characteristics of the fine and coarse aggregate. Test Standard

Coarse aggregate 19 mm

Unit

Fine aggregate Coarse aggregate 12,5mm

Maximum dimensions

ABNT NM 248:2003 ABNT NM 248:2003

mm

2,36 2,52

12,5 5,99 1,41 0,89 2,61 0,29

19

Módulo de finura

adim g/cm³

6,84 1,37 0,94 2,61

1,5 0,2

Unitary mass

ABNT NBR NM 45:2006 ABNT NBR NM 52:2009 ABNT NBR NM 52:2009 ABNT NBR NM 46:2003

%

water absorption Specific weigth powdery material

g/cm³

2,64

%

1,7

0,9

The additive used was supplied by the Civil Construction Materials Laboratory (LMCC) of the Federal University of Ceará (UFC). It is composed of polycarboxylates, which causes an improvement in the dispersion of the cement particles. The additive has a yellowish color, a pH between 8.50 and 10.50 and a specific mass of about 1.055 g/cm³.

2.2. Methods

The research began with the preparation and molding of the concrete specimens in cylindrical molds with dimensions of 10x20 centimeters, then it was subjected to a moist cure for 28 days. The specimens were oven dried at the temperature of 105 °C for 24 hours, before to be submitted to the ultrasonic tests in order to eliminate the superficial water. After drying, was perfomed the ultrasonic test to determinate the UPV before the exposition. Then they were exposed to the temperatures under analysis (200 °C, 400 °C, 600 °C and 800 °C). After this procedure, the ultrasonic test was performed again to determine the UPV after heating. For the required time of exposure to fire was adopted 30 minutes as defined in ABNT NBR 14432:2001 for residential occupations of height up to 12 meters high. That standard considers this time from the beginning of propagation of the fire. But for the present study, was analyzed the behavior of the concrete in its worst situation,