Issue 52

M.F. Bouali et alii, Frattura ed Integrità Strutturale, 52 (2020) 82-97; DOI: 10.3221/IGF-ESIS.52.07

E exp_Ke

E 0 Ke

E 0.125 Ke

E 0.250 Ke

E 0.375 Ke

E 0.450 Ke

0/4 650A 4/10 550A 4/10 430A 4/10 520S 4/8 750S 0/4 650A 4/10 550A 4/10 430A 4/10 520S 4/8 750S 0/4 650A 4/10 550A 4/10 430A 4/10 520S 4/8 750S

28.588

23.539 26.157 24.900 25.135 27.367

20.665 21.680 21.391 22.471 26.262 23.712 24.934 23.778 26.521 30.987 26.753 27.991 26.033 27.998 33.845

16.743 17.900 17.293 19.428 25.281 19.871 21.358 20.818 22.188 30.146 22.427 23.684 22.296 24.340 32.945

15.669 16.606 15.699 18.286 24.324 17.175 19.696 18.935 20.184 29.311 20.346 21.724 20.082 22.024 33.002

M8

33.183 29.396 29.159 27.568 29.480 31.931

M9

35.397

31.147 32.089 30.220 32.783 34.213

M10

Table 3: Characteristics of LWAC tested by Ke Y et al.  9  (GPa).

0/4 650A 6.870

4/10 550A 6.790

4/10 430A 4.340

4/10 520S 6.490

4/8 750S

LWA

Eg

19.900

Table 4: Mechanical properties of lightweight aggregate tested by Ke Y et al.  9  (GPa).

R ESULTS AND DISCUSSIONS

Comparative analysis omparison between the estimative results of effective elastic modulus of LWAC obtained as a result of calculations of the Eqns. (2-9) and those of experimental data have been presented in Tabs. 5, 6 and 7 respectively. A confrontation of LWAC Young’s modulus between experimental results in  7, 8, 9  and the predictions of 07 composite models material models are shown in Fig. 2, Fig. 3 and Fig. 4 respectively. The differences between the various predictive composite models and the experimental results in  7, 8, 9  have been computed according to the proportion of reinforcement Vg in LWAC. When the volume fraction of aggregates Vg grows, the errors between the predictions and the experimental results increase for all composite material models. Since the weakest component of LWAC is not the cement matrix but the lightweight aggregates, the effect of volume fraction of lightweight aggregate on Young’s modulus of LWAC is very clear. The increase in the volume fraction of lightweight aggregates Vg substantially reduces the Young’s modulus of the LWAC. To compare the experimental and predicted Young’s modulus of LWAC, the error percentage E  . is determined using the following expression: C

   

   

c_anal E E 

    E %

exp



(10)

100

E

exp

  E Abs E    , Absolute value of E 

It appears for first time that all models are generally suitable for predicting the modulus of elasticity of the LWAC. Tabs. 8-9-10 give the error percentages of the composite material models and experimental results in  7, 8, 9  respectively. In order to choose the models which have good performances, the error percentages below 10% are chosen as desired range and the model’s error percentages below this value are indicated in bold. Therefore, the models which verified this condition have been underlined.

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