Ultrasound Pulse Velocity Research Articles

Temperature dependent effect of nano-scale phase change materials on fresh and hardened cement based mortar

One of the smart and innovative materials used to produce environmentally friendly energy-saving concrete is temperature dependent phase change (PCM) materials. In this study, the fresh and hardened concrete properties of the mortars including PCM in different ratios (0%, 2.5%, 5%) were investigated experimentally. Rheological properties such as slump-flow, specific viscosity, and yield stress tests were determined at different temperatures (from 20 to 50 °C). Time-dependent physical, mechanical, and thermal properties such as ultrasound pulse velocity (UPV), electrical resistivity, dynamic modulus of elasticity, compressive and flexural strength, thermogravimetric (TGA), and thermal conductivity tests were carried out. According to the experimental findings, the workability and hardened properties of mortars were decreased by using PCM. However, the rheological properties of fresh mortar change depending on temperature due to PCM absorbing the heat. Therefore, the fresh properties of mortar with PCM can be controlled by temperature. It was also found that the phase change of mortars with PCM can be obtained by measuring the electrical or UPV tests at different temperatures.

Assessment of select direct and indirect pozzolanic reactivity test outcomes with robust regression and ranking analysis

The use of pozzolanic materials as a sustainable partial replacement option for portland cement in concrete has been extensively studied over the last few decades. This study aimed to assess the pozzolanic reactivity of seven different powdered materials: pottery cull, brick powder, lightweight aggregate fines, class C fly ash, silica fume, glass powder, and dolostone. Pozzolanic reactivity was evaluated using seven different direct and indirect methods, including the Frattini test, strength activity index (SAI), ultrasound pulse velocity index (UPVI), thermogravimetric and differential thermal analyses (TG/DTA), calorimetry, electrical conductivity, and pH. Robust correlations and a ranking analysis were performed to evaluate the relationship and efficiency between various direct and indirect test methods. Results of the robust regression analyses showed that Frattini and TGA, SAI and electrical conductivity, SAI and calorimetry, and UPVI and calorimetry were well correlated, suggesting that these methods may be suitable alternatives to each other. According to the ranking method, electrical conductivity and calorimetry are the most rapid and efficient methods for the assessment of different pozzolans in comparison to other longer-duration test methods examined in this study.

Characterization of Anisotropic Salt Weathering through Nondestructive Techniques Mapping Using a GIS Environment.

Doctrinal texts on architectural heritage conservation emphasize the importance of fully understanding the structural and material characteristics and utilizing information systems. Photogrammetry allows for the generation of detailed, geo-referenced Digital Elevation Models of architectural elements at a low cost, while GIS software enables the addition of layers of material characteristic data to these models, creating different property maps that can be combined through map algebra. This paper presents the results of the mechanical characterization of materials and salt-related decay forms of the polygonal apse of the 13th-century monastery of Santa María de Bonaval (Guadalajara, Spain), which is primarily affected by salt crystallization. Rock strength is estimated using on-site nondestructive testing (ultrasound pulse velocity and Leeb hardness). They are mapped and combined through map algebra to derive a single mechanical soundness index (MSI) to determine whether the decay of the walls could be dependent on the orientation. The presented results show that salt decay in the building is anisotropic, with the south-facing side of the apse displaying an overall lower MSI than the others. The relative overheating of the south-facing side of the apse enhances the effect of salt crystallization, thereby promoting phase transitions between epsomite and hexahydrite.

An assessment of the durability of untreated and water repellent-treated cultural heritage stone (Döğer tuff-Turkey) by salt mist and salt crystallization tests

Salt mist and salt crystallization tests were conducted to determine the resistance of the untreated and water-repellent-treated Döğer tuff samples to salt damage. The Döğer tuffs are of volcanic origin and consist of porous pyroclastic rocks. A series of characterization studies were performed to determine the physicochemical and chemical properties (XRF), mineralogical-petrographic characteristics (polarizing optical microscopy, XRD, and SEM), and pore-size distribution (MIP) of the Döğer tuff prior to the aging tests. Following the aging experiments, the changes in weight, ultrasound pulse velocity, uniaxial compressive strength, and variations in pore size distribution were examined in the tested tuffs. In addition, SEM studies were conducted to analyze the microstructures. The untreated tuff samples were more severely affected by salt crystallization. The increases in dry weight for untreated and water-repellent-treated Döğer tuff samples were 0.27% and 0.13% after 60 cycles of salt mist exposure and 7.2% and 3.76% after salt crystallization cycles using a sodium chloride solution, respectively. Both conditions resulted from the accumulation of NaCl crystals on the tuff surface and within the pores. Salt crystal formation in a sodium sulfate solution led to dry weight change of 2.02% and 0.29% in the untreated and water-repellent-treated samples, respectively. The uniaxial compressive strength of the untreated tuff samples decreased by 36.71% in the presence of sodium chloride solution and by 72.58% in the presence of sodium sulfate solution. The ultrasound pulse velocity values decreased in all tuff samples after the salt crystallization test. However, the Döğer tuff samples were still distinguishable after both tests and their physical integrity remained intact.

Research on the long-term strength development of Datça Pozzolan-based geopolymer

This study examined the influence of long-term curing duration on the properties of geopoly- mers produced through the geopolymerization reaction between Datça Pozzolan and sodium silicate and potassium hydroxide solutions. The specimens were heat cured at 90 °C, 95±5% RH for 24 h initially and then kept under ambient conditions until the tests were conducted at 7, 90, and 365 days. The results showed that applied initial heat curing was appropriate to achieve high early and long-term strength. Geopolymer mortars with 12.5 M and 2.5 activator ratios had the lowest porosity (20.90%) and the highest ultrasound pulse velocity (UPV) (3.10 km/s), compressive strength (10.57 MPa), and flexural strength (5.20 MPa) after seven days. While the porosity of the identical specimens decreased by up to 15.77%, the UPV, compres- sive strength and flexural strength increased by 3.37 km/s, 15.32 MPa, and 6.06 MPa, respectively, after 365 days. The physical and mechanical improvement in the first 90 days exceeded 90–365 days. A higher rate of improvement was obtained when the activator ratio was low, i.e., the improvement decreased inversely as the sodium silicate content of the mortar increased. An increasing trend was observed in the plot of compressive strength as a function of UPV, and the slope values presented a strongly related linear function relation.

PERFORMANCE OF NATURAL POZZOLAN-BASED GEOPOLYMER REINFORCED WITH BANANA FIBERS

ABSTRACT Türkiye has approximately 50.000 acres of banana plantations. Banana cultivation produces a huge amount of waste that has no commercial value. The main purpose of this study is to investigate the possibilities of using waste banana fiber in natural pozzolan-based geopolymer mortar to increase its ductile fracture behavior. The effects of fiber content and length on physical and mechanical properties were experimentally carried out. The optimum banana fiber content and length were found to be 1.5% and 20 mm, respectively. Above this limit, fibers made it difficult to obtain a workable matrix and generated fiber agglomeration. Although increasing the fiber content from 0.5% to 1.5% and length above 20 mm led to a decrease in the ultrasound pulse velocity, modulus of elasticity and compressive strength due to the higher porosity of the matrix, the increasing ratios of the flexural strength and toughness were consistent. Furthermore, banana fiber-reinforced geopolymer mortars have adequate porosity (22.87%), water absorption ratio (9.25%), swelling thickness (0.58%), saturation coefficient (78%), drying shrinkage (195x10–6), water vapor diffusion resistance index (5.73), flexural strength (6.88 MPa), compressive strength (8.75 MPa), and comply with the performance requirements of the related standards. By considering the adequate physical, mechanical and ductile fracture performance of the material, waste banana fiber can be utilized in the production of geopolymers.

Influence of fines less than 0.125 mm on abrasion resistance of concrete

Abrasion resistance is very important in concrete intended for making roads, canals, floors or pavements and it can be defined as the ability of a surface to resist wear due to rubbing. It is tested by grinding the specimen according to the standard procedure and the measurements are done through volumetric loss of the specimen. Abrasion resistance is influenced by many factors such as the type of aggregate, placement, concrete composition, etc. It is desirable that the concrete contains less cement matrix and that this cement matrix achieves as much strength as possible. Cement matrix achieves the highest strength if it consists of a binder without or with small amount of very fine aggregate particles. The purpose of this paper is to examine the influence of these particles on abrasion resistance and compressive strength of concrete. Six concrete mixes were made, which differ in the granulometric composition of the aggregates and the origin of the aggregates. Same type and quantity of the cement and superplasticizer were used in all mixtures with the same water/cement ratio. The workability of the concrete was tested using the slump method. The ultrasound pulse velocity (UPV), density, dynamic modulus of elasticity, compressive strength and abrasion resistance were tested after 28 days of specimens curing. The measured UPV are within the limits of 3989.36 to 4128.44 m/s, which indicates a good quality of concrete. Compressive strengths ranging from 61.6 to 95.6 MPa were achieved. Abrasion resistance was determined by the loss of volume of the specimen in cm3 in an area of 50 cm2, and values from 21.6 to 27.3 cm3/50 cm2 were measured. According to the test results, no harmful effect of very fine aggregate particles on the abrasion resistance of concrete was observed in this investigation. Also, the positive effect of quartz sand on abrasion resistance was confirmed.

Comparatively Study of Non-Destructive test with different methods in various curing days

In non-destructive testing, materials, components, or assemblies are inspected, tested, or evaluated without being destroyed. In nondestructive testing, materials, components, and assemblies are evaluated for quality and integrity without damaging them. The use of non-destructive testing (NDT) is a popular method for assessing the strength and durability of existing concrete structures. An ultrasound pulse velocity test and a rebound hammer test are included in the NDT test. An NDT test includes both ultrasound pulse velocity testing and rebound hammer testing. Strength tests are conducted with rebound hammers, while quality tests are conducted with ultrasonic pulse velocity tests. A lab-made concrete cube was tested on three different ages-seven, fourteen, and 28 days-without destroying it. There were 15 cubes that were treated using non-destructive methods. Using both Schmidt rebound hammer and ultrasonic pulse velocity tests, we determined which non-destructive testing method was faster. In addition to surfaces, Schmidt rebound hammers are the toughest tools to use. Rebound number and concrete strength seem to be connected. Schmidt hammers were employed in both vertical and horizontal settings. Concrete’s ultrasonic pulse velocity is mostly determined by its identity and modulus of elasticity, that are motivated by the substances used in making the concrete in addition to its placement, compaction, and curing techniques.

Residual mechanical properties of concrete incorporated with nano supplementary cementitious materials exposed to elevated temperature

Abstract The construction industry commonly employs concrete as a construction material, which sometimes may be subjected to fire exposure. It is important to adopt fire safety measures while planning and constructing such structures to ensure the safety of the occupants and the structural integrity of the concrete. So, determining its performance at elevated temperatures is of utmost importance. The main objective of this study was to investigate the impact of mineral incorporations, namely, nano bentonite clay (NBC) and nano fly ash (NFA), on the retained properties of concrete at normal (27°C) and at elevated temperatures. The feasibility of partly substituting ordinary Portland cement utilizing a mixture of NBC (0–5%) and NFA (0–50%) in concrete was assessed under the exposure to an elevated temperature ranging from 200 to 600°C. Several parameters were examined, including compressive strength, flexural strength, split tensile capacity, water penetration, loss of mass, ultrasound pulse velocity, and microstructure properties. After the experimental analysis, it was observed that the fire endurance was shown to be improved with the inclusion of nanoparticles (BC and FA). A reduction in the loss of mass by samples subjected to elevated heat was observed with the addition of nano bentonite and NFA. The mechanical strength results were obtained as maximum for the concrete specimens with 2% NBC and 20% NFA and further, the specimens performed better when exposed to elevated temperature as compared with normal concrete specimens. The microstructure of the concrete also upgraded with better impermeability owing to the use of NBC and NFA.

Acoustic Characterization Study of Beef Loins Using Ultrasonic Transducers

The objective of this study was to non-destructively characterize samples of fresh beef loin by low-intensity ultrasound inspection at various frequencies and to correlate the acoustic parameters of these inspections with quality parameters. In this regard, ultrasonic parameters such as ultrasound pulse velocity (UPV) and variables related to attenuation and frequency components obtained from fast Fourier transform (FFT) were considered. For this, pulsed ultrasonic signal transducers with a frequency of 0.5 and 1.0 MHz were used. Acoustic parameters and those obtained through traditional instrumental analyses (physicochemical and texture) underwent a Pearson correlation analysis. The acoustic determinations revealed numerous significant correlations with the rest of the studied parameters. The results demonstrate that ultrasonic inspection has the ability to characterize samples with a non-destructive nature, and likewise, this methodology can be postulated as a promising predictive tool for determining quality parameters in beef loin samples.

Spatially resolved analysis of the progression of freeze‐thaw damage in concrete

AbstractTo assess the durability of concrete structures, it is necessary to understand not only how deterioration evolves over time but also how the damage progresses through the structure. To determine the evolution of the freeze‐thaw damage, different damage criteria were examined in a spatially resolved manner during the CIF test. By measuring the ultrasound pulse velocity (UPV) in different axes, depth‐dependent changes of the relative dynamic modulus of elasticity (RDME) were investigated. The RDME started to decrease in regions close to the surface, whereas the RDME in regions farther from the test surface decreased with higher speed. Changes in the water content during the CIF test were examined by nuclear magnetic resonance (NMR). The freeze‐thaw exposed specimens showed an increase in their water content that is assumed due to the micro‐ice‐lens pump as well as microstructural changes. These changes progressed from the surface into deeper layers of the specimens, following an increase of saturation also progressing into the concrete. To consider the frost damage evolution in service life design, the authors propose the use of depth‐dependent threshold values for freeze‐thaw exposed concrete structures.

Effects of Hemp Fibers on Durability and Strength Properties of Concrete to be Used In Agricultural Buildings

Concrete is the most common construction material used worldwide. It is also commonly used in construction of agricultural buildings. With the rapid developments in technology, different building materials with superior properties are being researched in order to improve different properties of concrete and eliminate its disadvantaged aspects and to obtain lighter, insulated, more economical and useful construction materials. One of the applications to improve the negative properties of concrete with low tensile strength is to add various fibers into the concrete mixtures. Hemp stalks play an important role in recycling vegetable wastes. Therefore, it is highly significant to recycle or transform these materials. In this study, hemp fibers were supplemented into concrete mixtures in different ratios (1, 2.5 and 5%). Slump and unit weight tests were conducted on fresh samples and compressive strength, tensile strength, water absorption, freeze-thaw resistance, thermal conductivity and ultrasound pulse velocity tests were conducted on 28-day cured cube specimens. Compressive strength, specific gravity, ultrasound pulse velocity and thermal conductivity coefficients decreased, but tensile strengths and water absorption ratios increased with increasing hemp fiber ratios. Hemp fiber supplementation into concrete mixtures yielded a material with higher tensile strength, lower thermal conductivity and suitable for cold climate conditions

Influence of Incorporating PVC Waste on the Mechanical Properties of Cement Mortar

Currently, recycling of industrial wastes to reduce the environmental impact is the major concerns of researchers. Polyvinyl chloride (PVC) is one of the waste materials worldwide, with considerable impacts on environmental. Recycling PVC wastes in the concrete or mortar industry is one of the adopted ways to decrease such impact. The purpose of this paper is the reuse of PVC waste deriving from the workshops manufactured doors and windows which made of PVC material. The waste of polyvinyl chloride was collected from one of the factories located in AL-Khoms, then the waste was sieved, the sample that passed through Sieve No.4 and retained on sieve No.10 was taken. The PVC waste proportions of (0.06 ˛ 0.08 ˛ 0.1) by weight of cement was added to the mix mortar. The tests carried out during this study were; air content of fresh cement mortar, flow table, dry density of hardened cement mortar, flexural and compression, free shrinkage and finally ultrasound pulse velocity. The results obtained showed a significant improvement in the sound insulation and a decrease in the dry density of the mortar. While the compressive and flexural strength results were slightly lower compared to the standard mortar. In addition, a decrease in the values of flow, free shrinkage and air content was observed with an increase in the PVC content. Nevertheless, the mortar obtained contributes to the conservation of natural resources and maintains the mechanical properties of the cement mortar in structural applications.

Data-driven based ultrasonics analysis for evaluating the bond strength of concrete layers

In accelerated bridge constructions, the 3D printing process, and structural retrofitting, the bond condition between concrete layers considerably affects their structural safety and functionality. Nondestructive tests can effectively and efficiently monitor these structures' bond conditions. This paper used the convolutional neural network (CNN) and multilayer perceptron (MLP) to estimate the bond strength of concrete layers based on vital ultrasound parameters. In this regard, ultrasound pulse velocity, attenuation, maximum amplitude, and energy loss of the ultrasound wave were assessed as the inputs of the machine learning models. The target was the bi-surface shear strength of the specimens. Two different approaches were considered to evaluate the energy loss of the wave 1) in the whole specimen and 2) at the bond zone, and the models based on each dataset's accuracy were compared. Parameters resulting from the second approach were more reliable and had better consistency with bond strength variation than the first one. Moreover, the ultrasonic parameters were investigated to determine the most sensitive ultrasound factor to the different bond treatments. Accordingly, attenuation was the most susceptible parameter toward the change of bond strength.

Feasibility of waste foundry sand in high-strength self-compacting concrete and the effects of elevated temperatures

The disposal and recycling of waste foundry sand (WFS) as industrial solid waste can effectively solve potential environmental pollution problems. This paper conducted an experimental investigation on the effects of elevated temperatures on mechanical properties and microstructural characteristics of high-strength self-compacting concrete (HSSCC) incorporating WFS for substituting river sand with different contents (i.e., 0%, 25%, 50%, 75% and 100% by weight). The workability of fresh concrete including slump flow, J-ring, T500, and V-tunnel box tests were first measured. A series of tests including ultrasound pulse velocity (UPV), residual compressive strength and the behavior of capillary water absorption were conducted before and after different temperatures (100 °C, 200 °C, 300 °C, 400 °C) following an air-cooling time. Further, the thermal analysis and microstructural observation were conducted for the evaluation of high-temperature damage evolution by using thermogravimetry (TG), differential scanning calorimetry (DSC), and scanning electron microscope (SEM). The test results showed that the specimens obtained excellent self-compaction performance at 50% WFS replacement rate. The coupling effect of WFS substitution rate and temperature level has a large effect on the mechanical properties and thermal resistance. Compared with the control group, the 28-day compressive strength of HSSCC-WFS50 was increased by 8.2%. In addition, thermal analysis tests (TG/DTG/DSC) and SEM also elucidated the changes of HSSCC-WFS products and microstructures at high temperature from a fine microscopic perspective to reveal the deterioration mechanism of HSSCC-WFS durability after high temperature damage.

Statistical analysis of heat-induced rock physics and mineralogical alteration processes of monzogranite samples from Bátaapáti, Hungary

Heat-induced physical changes of rocks, as would happen in fire accidents, have crucial importance in the long-term stability of underground openings such as tunnels or radioactive waste disposal chambers. The thermal behaviour of monzogranite from the Radioactive waste repository of Bátaapáti (Hungary) was studied in that context. Room temperature (22 °C) and a series of high temperature (250 °C, 375 °C, 500 °C, 625 °C, 750 °C) heat-treated samples were tested. P and S- ultrasound pulse velocity, bulk density, Duroskop rebound, uniaxial compressive strength, and modulus of elasticity were measured and compared, detecting temperature-related changes. Descriptive statistics and non-parametric Kruskal–Wallis and Median tests were carried out to analyze the heat-induced rock mechanical and mineralogical alteration processes. Based on these results using the data set of physical parameters, it is possible to predict the heating temperature of granitic rocks when the firing or heat stress conditions are unknown. Additionally, the data could be utilized for design and monitoring systems in underground repositories or tunnel systems constructed in granitic rock settings globally. The study demonstrated that significant alteration occurs above 500 °C; all studied rock-mechanical parameters decreased rapidly. These changes are linked to the thermal expansion, micro-cracking in micro-fabric, and volumetric increase and fragmentation of quartz inversion. Consequently, the propagation velocities of P- and S-waves also decreased significantly. Bulk density and Duroskop surface strength significantly decreased above 375 °C, while uniaxial compressive strength and modulus of elasticity dropped drastically at 750 °C after a linear decrease.

Improvement of the durability of concrete by substitution of raw ground colemanite

This study investigated the effects of raw ground colemanite (GC) mineral on concrete strength and durability. Concrete mixtures were prepared at six replacement levels of GC (0%, 1%, 2%, 3%, 4% and 5%, by weight of cement). Fresh state properties of concrete samples were measured. Schmidt Hammer, ultrasound pulse velocity, abrasion, flexural, and compressive strength tests were performed on the cube, cylinder and prismatic concrete samples on the 7th, 28th, and 90th days. As concrete durability has a negative impact on many physical and chemical factors, the durability properties of the samples after wet-dry, freeze-thaw, sulphate, and chloride exposure were investigated, resulting in the finding that GC substitution up to 5% yields the desired compressive strength for the C30/37 concrete class. The optimal GC substitution ratio was determined to be 3%, as this ratio increases the strength and durability probabilities. It was decided that raw GC mineral substitution with an average particle size of 12 µm and increasing adhesion force in concrete production is convenient, particularly in the context of improving material properties against environmental circumstances, saving cement, and utilizing boron minerals.

Expanded glass sphere/lauryl alcohol composite in gypsum: Physico-mechanical properties, energy storage performance and environmental impact assessment

In recent years, thermal energy storage systems, which are a promising solution to improve the thermal comfort of buildings and reduce energy demand, are a critical issue. This study aims to develop a new shape-stable gypsum composite using expanded glass sphere (EGS) and lauryl alcohol (LA) and analyses its thermal performances. For this purpose, EGS was impregnated with LA in different mass fractions (25 and 50%) by direct impregnation technique. DSC results exposed that melting temperature and melting enthalpy of shape-stable EGS/LA composite were 20.97 °C and 83.1 J/g, respectively. FTIR investigations confirmed the existence of well chemical compatibility between EGS and LA. TGA analysis revealed that the operating temperature of EGS/LA was considerably lower than its thermal degradation temperature. While incorporation of EGS and EGS/LA composite increases water absorption and porosity; caused a decrease in compressive strength, dry unit weight and ultrasound pulse velocity properties. EGS/Gypsum composite with LA (50%) provided a warmer room temperature for more than 12 h between midnight and solar noon hours. It achieved about 2 ℃ warmer room during these hours. After solar noon hours, proposed composite attained about 3.6 ℃ cooler room center temperatures. It provided cooler indoor temperatures for more than 5 h. A warmer indoor temperature was observed for EGS/Gypsum composite with LA (50%) after 18:00 until midnight to be 2 ℃. It can provide a carbon emission saving of around 3–23.2 kg-CO2/kWh, depending on fuel type for a wall cover made of EGS/Gypsum with LA.

Physical-mechanical and fresh state properties of self-compacting concrete based on different types of gravel reinforced with steel fibers: Experimental study and modeling

Due to the enormous and rapid growth in the field of construction and public works all over the world, it has become necessary to seek alternatives to the non-renewable natural resources used to protect them from waste and exhaustion on the one hand and to satisfy the environmental aspect on the other hand. Some of the ways to achieve this include recycling various concrete waste resulting from the demolition of old concrete structures or the results of natural disasters to replace natural gravel in the manufacture of different types of concrete mixes. The type of natural gravel used has a significant impact on the compatibility of recycled gravel with steel fiber reinforced self-consolidating concrete (SCCf) in the fresh state and on the improvement of its physical–mechanical performance. In this research, we studied the fresh state properties and the physical–mechanical properties of SCCf composed of natural gravel of two different types with the substitution of the natural gravel by the recycled gravel at percentages of 25%, 50% and 75% by weight. The evaluations of different fresh SCC were conducted using various tests in accordance with the recommendations of EFNARC. On cubic specimens with a side of 10 cm, we successively carried out three tests as follows: at 28, 56, 90, and 120 days, for the tests (ultrasound pulse velocity (UPV), water absorption, open porosity and compressive strength). A three-point bending strength test was also carried out on rectangular specimens (7 × 7 × 28) cm3 at different ages.The results obtained indicate that all the mixtures tested met all the SCC requirements recommended by EFNARC, the substitution of 25% recycled gravel for the two types of concrete SCCfQ and SCCfL gives better results than that of the concrete SCCfL at 28 days on the tensile strength in bending. The density of the different types of concrete decreases as the percentage of recycled gravel increases. Curing in water has a beneficial effect on reducing the open porosity of the various SCCf fiber-reinforced self-compacting concretes and on increasing the compressive strength, flexural tensile strength, ultrasonic velocity UPV (V). Finally, acceptable and encouraging correlations between the different physical and mechanical parameters of the SCC and the different types of gravel were found.

Structural properties of volcanic precursors-based geopolymers before and after natural weathering

The structural properties of geopolymers based on locally available volcanic feedstocks were here investigated in the optics of the development of sustainable non-structural building materials. Geopolymer binders and mortars based on two volcanic pyroclastic residues from Mt. Etna (ejected ash and a paleosoil, named “ghiara”) were studied to assess the effects of natural weathering.The strength and durability of the resultant products were examined before and after six months of outdoor exposure by comparing ultrasound pulse velocity (UPV), specific weight, Brazilian Disk test (BD) and Digital Image Correlation (DIC) together with Dynamic Vapour Sorption (DVS) results. DVS data were also compared to those of pure salts (e.g. sulphates and carbonates) commonly occurring in geopolymers as efflorescences.The results obtained on unexposed and exposed samples and the relationship between the moisture transportation, efflorescence development, and structure degradation have shown a better response of the volcanic ash-based geopolymers to weathering in the hot summer Mediterranean climate zone than ghiara-based products. The latter are more affected by exposure conditions as revealed by the decrease of UPV, the influence of efflorescences on moisture adsorption-desorption curves and the consequent worsening of mechanical performances.The correlation between UPV and DVS applied for the first time to the study of volcanic precursors-based geopolymers exposed to natural weathering has proven to be an effective and useful tool for assessing the durability of materials.