PSI - Issue 11

Stefanie A. Campos et al. / Procedia Structural Integrity 11 (2018) 145–152 Stefanie A. Campos et al./ Structural Integrity Procedia 00 (2018) 000–000

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the water/cement factor determined for each trait presented. They remained in the mold for 48 ± 24 hours and after this period were demolded. At the ages of 7 and 28 days they were disrupted to obtain the resistance values. The tensile bond strength was measured in a panel made for each trait after the age of 28 days, each having 12 specimens for each trait (ABNT, 2010). The coating was constituted by slab and plaster, as a single layer coating, having a thickness of 20 mm, considering the thickness admissible for internal and external walls. The distribution was performed in a random manner, considering joints and blocks, obeying the spacings between them, of the corners and corners in at least 50 mm. Samples were also separated for moisture determination for each panel corresponding to the established trace, and three samples of each trace were collected. Finally, aiming at a more detailed analysis of the behavior of mortars with the substitution of natural sand for steel slag, an analysis of variance (ANOVA) was performed, using the method of comparison of Duncan averages. To obtain quality control of the coatings, visual inspection of the coating was performed, analyzing the texture and possible emergence of pathological manifestations, such as cracks, stains and efflorescence, besides obtaining adhesion values, resulting in the acceptance or not of the coatings. mortar coating.

3. Results and discussion

By trial and error, water / cement factor was discovered for each percentage of slag replacement in the mixture. Table 3 shows the consumption of each material for 1 m³ of mortar, as well as of water.

Table 3. Material consumption in kg/m³ and water in L/m³ for each w/c factor found. Percentage of slag replacement Cement (kg/m³) Fine aggregate (kg/m³)

Steel slag (kg/m³)

Water (L/m³)

0%

276.7 274.4 275.9 277.4

1503.7 1342.2 1199.6 1055.5

0.0

334.8 340.3 336.6 332.9

10% 20% 30%

208.7 419.6 633.0

The mass density values of blend were ranging from 1.99 to 2.14 g/cm³ and air content incorporated for each trace varied from 6 to 7% of the reference to 30% slag replacement. From obtained results, it can be noticed that a greater percentage of slag substitution by sand causes a greater mass density obtained, because the specific mass of the slag is greater than of sand. In relation to incorporated air content, there is an average of 6% of air incorporated in the four mixtures, being the lowest reached in the substitution of 20% and the highest when replacing 10 and 30% of sand. In hardened condition, the tensile strengths at flexion were analyzed at 7 and 28 days, as shown in Figure 5. Regarding the tensile strength at flexion, no significant influence of the mixes was observed in 7 and 28-day resistances, with similar results for all traces. Statistical analysis ANOVA revealed p value of 0.198 at 7 days and 0.317 at 28 days. In the compressive strength, the 10 and 20% substitution traces reached the same resistance range at 28 days of the reference trace, but the 30% substitution trace did not achieve the same performance and its resistance was lower than that of the reference trace at the test’s end. Statistical analysis ANOVA showed that the trace has a significant influence on resistance’s value, with p value of 0.00049. Afterwards, means were analyzed by Duncan test, showing that averages have a significant difference. The mean that differs from the others is the one of 30% trace, as shown in Figure 6.