PSI - Issue 5

Aalil Issam et al. / Procedia Structural Integrity 5 (2017) 1123–1128 Aalil Issam/ Structural Integrity Procedia 00 (2017) 000 – 000

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Fig. 3. (a) calcarenite stone; b) capillary water absorption test; c) colorimetry test ; d) P wave velocity test.

The compressive strength test was carried out on oven-dried specimens, according to the NF P94-420 standard for the calcarenite stone at a displacement rate of 0.05 mm/min and following the EN 1015-11 standard for the mortar samples at a loading rate of 1000 N/s. The P wave velocity of samples was investigated using a PUNDIT pulse apparatus (fig.3d). The dynamic E-modulus was calculated from the P wave velocity assuming the Poisson coefficient ν=0.25. The color of samples was assessed by a Konika spectro -photo-colorimeter in the CIELAB system L*a*b* (fig.3c), where L* is the lightness/darkness coordinate, a* the red/green coordinate (+a* red and – a* green), and b* the yellow/blue coordinate (+b* yellow and – b* blue). The difference of color ∆E between the calcarenite stone and the mortars was calculated using equation (1): )² )² ( * * )² ( * * ² ( * * stone stone stone b b a a E L L        (1) 3. Results and discussion The results of the laboratory characterization conducted on the calcarenite stone samples are presented in table 2. It is a porous stone with 16.9 % of accessible porosity and 2.20 g/cm3 of bulk density. Its matrix density is about 2.65 g /cm3; this value is close to the densities of its main minerals, i.e. calcite (2.71 g /cm3) and quartz (2.65 g /cm3) (Siegesmund & Dürrast 2011). The calcarenite stone is a medium absorbing stone since its capillary water absorption coefficient is about 2.18 kg/m²h0.5 (Snethlage 2005). It has a saturation coefficient of 0.79. It is a soft stone with compressive strength of 18.5 MPa. It has a P wave velocity around 3100 m/s, which is within the range of carbonate and sandstone groups (Siegesmund & Dürrast 2011), and thus a dynamic E-modulus of 17.74 GPa. Otherwise, the three chromatic coordinates L*, a*, b* indicate that the calcarenite is light (L* close to 100 than 0) , slightly red (a*>0) and yellowish (b*>0). 3.1. Calcarenite stone properties

Table 2. Calcarenite stone properties. ρb (g/cm 3 ) ρsq (g/cm 3 ) P (%)

A (kg/m 2 h 0,5 )

Scap

CS (MPa) 18.45

V (m/s) 3101

E dyn (GPa) 17.74

L*

a*

b*

2.20

2.65

16.9

2.03

0.79

78.28 2.53 14.09

3.2. Properties of the restoration mortars

Tables 3 and 4 give the physical and mechanical properties of the nine formulated mortars. The results of the mortars M3, M6 and M9 indicate that substituting part of the lime by brick dust increases the bulk and matrix densities and decreases the porosity and the capillary absorption. This trend may be due to the reduction in water demand which leads to small capillary spaces (Isebaert et al. 2014; Theodoridou & Charalambous 2016). Besides, it increases the compressive strength, the P wave velocity and the dynamic E-modulus. This could be explained by the formation of