Assessing the influence of the mixing method on porosity and durability of NHL-based renders based on key parameters

Assessing the effect of a white Portland cement admixture on the early frost-thaw resistance of NHL-based masonry mortar

“…1. The fresh mortar mixtures, which have been used to prepare the sample prisms and the three-stone specimen, were produced in a laboratory mixer according to actual cement standardization O ¨NORM EN 196-1 [24], using a total mixing time of 1 min (see [15]). The consolidation of the prisms was conducted by ''jolting'' oriented on the jolting table method, where the removal of air bubbles out of the fresh mortar occurs by beating the prism molds on a hard substrate as described in the testing standard for mortar flexural and compressive strength O ¨NORM EN 1015-11 [24].…”

“…The capillary absorption coefficient C w was calculated by using the time interval between 10 and 30 min. The so-obtained data were used to calculate key parameters (see Table 4), first reported in a previous study [15], to prove their suitability for benchmarking the durability. Thereby, possible correlations of characteristic values describing the porosity and water transport behavior were related to the results of cyclic frost-thaw testing.…”

“…The frost-thaw cycle resistance tests (oriented on [13,14]) were operated on standardized samples in the laboratory. The compressive strength comparison was assessed as suitable indicator to quantify the potential internal deterioration of mortar structures within a previous study by the authors [15,16]. Moreover, it is the most commonly used value for the representation of mechanical strength in several publications (e.g.…”

Mechanical properties of hydraulic lime mortars and fired clay bricks subjected to dry-wet cycles

“…As shown by green marking, NHL5 had the largest area consisting of pores, followed by NHL3.5 and NHL2 and/or CEM. It has been shown that the porosity affects strength properties, water transport and durability, particularly when the material is subjected to forced drying [71,72]. Through the interconnected network, the pores are responsible for water transport [72], with sizes varying between 0.01 microns and a few millimetres, depending on the binder and its hydraulic content [73,74].…”

“…It has been shown that the porosity affects strength properties, water transport and durability, particularly when the material is subjected to forced drying [71,72]. Through the interconnected network, the pores are responsible for water transport [72], with sizes varying between 0.01 microns and a few millimetres, depending on the binder and its hydraulic content [73,74]. In lime mortars, dimensions of spherical air pores and cracks ("elongated pores") vary between 100 µm and a few millimetres [73].…”