PSI - Issue 11

Felipe Alves Amancio et al. / Procedia Structural Integrity 11 (2018) 91–98 Felipe Alves Amancio et al. / Structural Integrity Procedia 00 (2018) 000–000

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2. Experimental program The guiding idea of this research was to evaluate the changes in concrete properties with the addition of polypropylene fibers when subjected to high temperatures. Concrete mixes used are shown in Table 1 with the materials and their amounts. A slump of 80 ± 20 mm, obtained according to ABNT NBR NM 67, was adopted for concrete consistency.

Table 1 - Consumption of materials per cubic meter (m³) of concrete, in kilograms.

Coarse Aggregate 19 mm

Coarse Aggregate 12,5mm

Plasticizer (%)

Polypropylene fiber

w/c ratio 0.54 0.54 0.54

Fck (MPa) Cement

Fine Aggregate

Mix

T30

30,0 30,0 30,0 30,0

332 332 332 332

794 794 794 794

264 264 264 264

703 703 703 703

0.72 0.76 0.85 0.94

-

T30+1,2 T30+1,8 T30+2,4

1.20 kg/m³ 1.80 kg/m³ 2.40 kg/m³

0.54 To perform the tests, Portland Cement Type II with pozzolan (CP II Z 32) was used. Table 2 shows the physical and chemical properties of this material. Table 2. Chemical and physical characteristics of cement used. Properties Standard Unit Results Especification – Standard NBR 11578/91 Loss to fire NM 18/12 % 5.99 ≤ 6.5 Magnesium oxide - MgO NM 11-2/12 % 4.60 ≤ 6.5 Sulfuric Anhydride – SO 3 NM 16/12 % 2.74 ≤ 4.0 Insoluble Residue NM 15/12 % 14.58 ≤ 16.0 Carbonic anhydride – CO 2 11578/91 % 4.61 ≤ 5.0 Specific area (Blaine) 16372/15 cm 2 /g 4127 ≥ 2600 cm 2 /g Specific weight NM 23/01 g/cm 3 2.96 Not applicable Fineness (#200) 11579/12 % 3.4 ≤ 12.0 Fineness (#325) 12826/14 % 14.6 Not applicable Setting time (begin) NM 65/03 h:min 2:15 ≥ 1.0 Setting time (end) NM 65/03 h:min 3:15 ≤ 10.0 Expansibility NBR 11582/16 mm 0.10 ≤ 5.0 The fine and coarse aggregates used in this research were from the Metropolitan Region of Fortaleza, where the fine aggregate is quartz from river and coarse aggregates is granite rocks crushed. Table 3 presents a summary of the standards used to characterize the aggregates, as well as the results obtained.

Table 3. Chemical and physical characteristics of cement used. Tests Standard

Coarse aggregate 12.5mm

Coarse aggregate 19 mm

Unit Fine aggregate

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

Finesses Modulus Unitary weight Water absorption Specific weight Powdery material

-

6.84 1.37 0.94 2.61

1.5 0.2

ABNT NBR NM 45:2006 g/cm³

%

ABNT NBR NM 52:2009

2.64

ABNT NBR NM 52:2009 g/cm³

ABNT NBR NM 46:2003

%

1.7

0.9

The plasticizer used is composed by 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. Table 4 shows the characteristics of the polypropylene fiber according to the manufacture’s data.