PSI - Issue 44

Mariateresa Guadagnuolo et al. / Procedia Structural Integrity 44 (2023) 878–885 M. Guadagnuolo et al. / Structural Integrity Procedia 00 (2022) 000–000

884

7

Table 4. extract of Italian Code masonry classification Masonry

Compressive Strength f m (MPa)

Young’s modulus E (MPa)

Min

Max

Min 900

Max 1260 1620

Irregular softstone masonry Squared softstone masonry

1.4 2.0

2.2 3.2

1200

The values of E modulus have been linearly interpolated from table 3, used the fm parameter calculated with equations 2. It can be defined d MQI as the ratio between the E calculated value according to equation 3 and experimental E, and d NTC18 as the ratio between E obtained interpolating the Italian Code and the experimental E. Figure 3 shows the comparison between d MQI and d NTC18 . 2D Graph 1

2,00

1,75

1,50

1,25

1,00

d

0,75

0,50

0,25

0,00

Masonries M1 M2 M3 M4 M5 M6 M7 M8 M9 M10

d MQI d NTC 2018 masonries referral vs REFERRAL

Fig. 3 d MQI (deep green), d NTC18 (light green) and reference value (red line)

Figure 3 shows that the correlation by equations 3 underestimates the E value with an average error of about 13%, while Code-derived E values fit the experimental parameters with an average error of about 3%. For M4 and M9 masonry the error is greater, but as shown in table 1, the E values are very low compared to the fm values, with a lower than average E / fm ratio. 5. Conclusion The present paper evaluates the masonry quality yellow tuff masonries in Campania (South of Italy). In particular, based on the analysis of ten selected masonry samples, the authors focused on the possibility of using the MQI classification, which provides also the correlation between the f m parameter and the E value, for defining masonry mechanical features. To better evaluate mortars' state of degradation, the MQI method has been applied also considering the results of penetrometer tests to assess the m parameter. It has been stated that the f m values given by the MQI procedure method fit correctly the experimental values obtained by the double flat jacks test, while the elastic modulus E is not adequately estimated. For this reason, the E modulus could be calculated starting from the f m values obtained by the application of the Borri method, by using the E-f m Italian Code correlation. In fact, it has been ascertain that for the investigated samples the NTC18 correlation fits the experimental parameters with an error of about 3%, while the Borri’s correlation data underestimates E values with an average error of about 13%. In the whole, the analysis provided proves that a procedure based on the use of the Italian Code in combination with the non-destructive MQI method for the evaluation of f m could be profitably adopted for evaluating the mechanical features of tuff masonries in Campania. Also, the application of the MQI method could be even improved by introducing an objective estimation of the parameter m , which is used to judge the mortar quality, by means of mechanical penetrometer test.