Issue 66

S.E. Daguiani et alii, Frattura ed Integrità Strutturale, 66 (2023) 88-111; DOI: 10.3221/IGF-ESIS.66.05

R ESULTS AND DISCUSSION

T

able 3 illustrates the results of experimental characterisation tests for fifteen mixtures entered into JMP 16 software to be converted into mathematical models. These models can describe the effects of the type of addition (PC, WGP and GGBS) on the studied tests (consistency, initial and final setting time, soundness, and Strength-activity index). These models simplify the assessment of evaluating the impact of each factor separately and in combination with other factors. The statistical approach based on the calculation of errors from the experimental test and the mathematical model was used to evaluate the validity of the mathematical models. The most appropriate models are those that have higher correlation coefficients.

Mean 7 days strength (MPa)

Mean 28 days strength (MPa)

Strength activity index

Initial setting time (min)

Final setting time (min)

Consistency (%)

Soundness (mm)

Mix N°

7 days (%) 28 days (%)

27.90 28.60 28.52 28.40 28.20 28.66 28.60 28.70 28.70 28.60 28.80 28.68 28.44 28.84 28.30

195 191 193 197 205 190 198 203 208 195 209 205 204 215 207

329 335 346 350 425 410 335 348 407 425 409 430 429 433 439

0.6 0.5 0.5 0.5 0.1 0.5 0.9 0.5 0.9 0.5 0.8 0.4 1 1 1

41.68 38.00 33.72 31.15 30.64 40.50 37.32 31.74 29.61 36.89 33.81 30.53 34.41 30.35 32.05

48.47

100

100

1 2 3 4 5 6 7 8 9

47.6

91.18 80.90 74.74 73.51 97.17 89.54 76.15 71.04 88.51 81.12 73.25 82.56 72.82 76.90

98.21 90.26 84.59 78.91

43.75 41.00 38.25 53.57 48.50 44.30 42.49 49.29 47.32 46.00 48.32 46.61 47.50

110.52 100.10

91.40 87.66

101.70

10 11 12 13 14 15

97.63 94.90 99.69 96.16

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Table 3: Results of experimental tests.

Mathematical models The correlation coefficients were relatively high, as shown in Tab. 4. It means that a good correlation exists between the findings from the experimental test and the results that the model expected. It is also important to highlight that a regression method based on the least square optimisation criteria was used to determine these coefficients.

Initial setting time

Final setting time

Term

Consistency

Soundness

7-day S.A.I

28-day S.A.I

R 2 =0.78

R 2 =0.83

R 2 =0.85

R 2 =0.87

R 2 =0.97

R 2 =0.92

p value

p value

p value

p value

p value

Coeff.

Coeff.

Coeff.

Coeff. p-value Coef.

Coeff.

28.08 <.0001 192.14 <.0001 346.93 <.0001 28.18 <.0001 203.36 <.0001 420.21 <.0001 28.30 <.0001 209.21 <.0001 444.43 <.0001

0.50 0.15 0.32 1.11

0.0012 101.04 <.0001 103.24 <.0001

X 1 :PC

0.1918 0.0147

72.18 <.0001 75.86 <.0001

78.78 <.0001 96.56 <.0001

X 2 :WGP X 3 :GGBS X 12 : PC-WGP X 13 : PC-GGBS

1.62

0.0150 -14.57 0.3239 -237.7

0.012

0.0374 -18.56 0.0265

-1.40

0.8913

1.65

0.0136

-14

0.3422

87.71

0.280

0.66

0.1840

7.71

0.3000 17.30 0.1152

X 23 : WGP-GGBS

2.22

0.0026

19.43

0.1975 -71.71

0.372

3.37

<.0001

-6.23

0.3974 23.40 0.0427

Table 4: Results of experimental tests.

96