Types Of Mortars Research Articles

The effects of dosage and production process on the mechanical and physical properties of natural hydraulic lime mortars

Natural Hydraulic Lime (NHL) mortars are well-extended in restoration works presently. However, there is still a lack of standardization on their dosage methodology. Thus, seven types of mortar were fabricated and five factors which have an influence on their properties have been studied, in particular the water-binder ratio, the mold material, the aggregate size and type and the different curing conditions. Furthermore, an advanced mechanical characterization has been performed on these mortars, including the measurement of the fracture energy. Finally, some empirical equations for determining the relationships between these mechanical properties were proposed, which could be helpful when simulating the numerical models of historical constructions.

Design and behavior of traditional lime-based plasters and renders. Review and critical appraisal of strengths and weaknesses

Traditional lime-based plasters and renders are complex multilayer systems composed of various mortars; they exhibit behavior affected by their own properties, mutual interaction, interaction with the substrate and by external conditions (e.g. environment). A full understanding of the many mechanisms which impact on system performance is essential to improve the success of interventions on ancient renders. This paper reviews the main aspects that influence the mix design and behavior of traditional lime-based multilayer plasters/renders. Special attention is paid to the differences between fine mortars (rendering mortars frequently used in the outer layers) and coarse mortars (rendering mortars used in the inner layers). The diverse pore structure of these mortar types is analyzed and related, first, to the mix design and, second, to the mechanical and hygric behavior. Finally, the interaction of each mortar layer within the multilayer system is analyzed. The functional and technical requirements of plasters/renders as regards their wall-covering role are also presented and considered in the discussion. The analysis enables a critical appraisal of the strengths and weaknesses of traditional lime-based plasters/renders and provides lines of reasoning to enable professionals working in the field to build specific solutions to real problems.

Effect of carbonation of modeled recycled coarse aggregate on the mechanical properties of modeled recycled aggregate concrete

The modeled recycled aggregate concrete (MRAC) which is an idealized model for the real recycled aggregate concrete (RAC) was used in this study. The MRCAs prepared with two types of old mortars were modified by an accelerated carbonation process. The effects of carbonation of MRCA on the micro-hardness of MRCA and the mechanical properties of MRAC were investigated. The results indicated that the micro-hardness of the old interfacial transition zone (ITZ) and the old mortar in the carbonated MRCAs was higher than that in the uncarbonated MRCAs, and the enhancement of the old ITZ was more significant than that of the old mortar. The compressive strength and modulus of MRACs increased when the carbonated MRCAs were utilized, and the improvement was more significant for MRAC prepared with a higher w/c. In addition, a numerical study was carried out and it showed that the improvement in strength by carbonation treatment was less obvious when the difference between the new and old mortar was larger.

Experimental Study of Solid and Hollow Clay Brick Masonry Walls Retrofitted by Steel Fiber-Reinforced Mortar Coating

ABSTRACTAn experimental study including reverse quasi-static cyclic tests on solid and hollow Unreinforced Masonry walls strengthened with thin steel fiber-reinforced mortar (SFRM) coating is herein presented. Three types of mortars containing nano-silica and three different typologies of short high-strength steel fibers are used.Compared to traditional coating techniques, the proposed strengthening method adopts a thin layer (25 mm tick) of SFRM anchored on the wall surface by means of steel connectors.Results show that this novel technique provides significant enhancement in terms of strength and stiffness. Critical considerations on the in-plane lateral resistance of masonry walls are reported.

A database of the structural behavior of masonry in shear

This paper reports the results of several on-site investigations carried out by the authors in the last 20 years in central Italy (Umbria, Marche, Emilia and Abruzzo regions) on masonry wall panels. The use of stone and brickwork masonry has been common for centuries not only for rural residences but also for public and religious buildings. In many areas, where the stone was abundant, stone became the material of choice for all constructions. However from rubble stone to perfectly squared stones, the mechanical properties may highly differ. Test results are reported with an accurate survey and analysis of the masonry typology and mechanical characterization was performed according to ASTM standards and consisted of measurements of shear properties. The paper also reports the experimental results of full-scale tests conducted on brickwork walls using different bonding patterns, mortar types and brick dimensions. These data were recorded in terms of shear strength, elastic properties and deformation capacity and are of critical importance for design, reinforcement or retrofit purposes in earthquake-prone areas. All tests were conducted on site from pre-existing undamaged wall panels. Finally, test results are compared with existing standards and indicate that masonry shear strength is sometimes overestimated by the Italian Building Code.

Characterization of the Lime Mortars of the Rui Barbosa House Museum in Rio De Janeiro, Brazil

The aim of this research is to characterize the mortars of the Rui Barbosa House Museum, built in 1850, in the city of Rio de Janeiro, Brazil, using X-ray diffraction (XRD), gel-CSH determination, Fourier Transform Infrared spectrometry (FTIR), Wavelength-Dispersive X-ray Fluorescence spectrometry (WDXRF), Thermo gravimetric analysis (TG-DTG), and granulometric analysis. Also, petrographic and physical characteristics such as porosity, water absorption, and apparent density of the mortars were used to identify the raw materials employed in their preparation. Mineralogical associations found are similar (quartz, calcite, kaolinite, microcline, muscovite, and albite) for the majority of samples and only vary in their proportions; the most prominent phases are quartz and calcite. The collected data, indicating that the binder is hydrated lime, lead us to conclude that the analyzed samples are lime mortars, discarding the possibility of cement as the binder material. Two samples, located on the corner of the building, which underwent repairs, present a differentiated behavior, with high levels of dolomite and the presence of pozzolanic material, with greater water absorption and higher density, indicating the use of a different mortar type. In addition, it was verified that the WDXRF and XRD methods are able to determine the trace element composition with comparable precision with respect to the methodological approach proposed by Teutonico (1988). In addition, it has been verified that the major pollutant causing degradation of building are sulfur emitted by the vehicles and saline spray.

The effects of DiloCarB as carbonation accelerator on the properties of lime mortars

This study investigates the effect of the diethyl carbonate as a carbonation accelerator on the carbonation of lime mortars. Two types of lime mortars were prepared, one using lime putty and standard sand and the other using lime putty, dust and fragments of ceramic and standard sand. After a curing time of two weeks, the accelerator product, diethyl carbonate in a solution of ethanol and water, was sprayed on half of the mortars of each type. The differences in the carbonation performance were analyzed at 28, 90, 120 and 180 days using different analytical methods. Apart from the mineralogical and petrographic characterization, the physical, mechanical and hydric properties of the samples were determined. Mechanical tests were conducted only at 90, 120 and 180 days, because at 28 days the lime mortars were considered still too soft. The mortar samples with the accelerator had steadier carbonation and slight changes in their microstructure.

The effect of mortar type and joint thickness on mechanical properties of conventional masonry walls

Masonry walls are of a complex (anisotropic) structure in terms of their mechanical properties. The mechanical properties of the walls are affected by the properties of the materials used in wall construction, joint thickness and the type of masonry bond. The carried-out studies, particularly in the seismic zones, have revealed that the most of the conventional masonry walls were constructed without considering any engineering approach. Along with that, large-scale damages were detected on such structural elements after major earthquake(s), and such damages were commonly occurred at the brick-joint interfaces. The aim of this study was to investigate the effect of joint thickness and also type of mortar on the mechanical behavior of the masonry walls. For this aim, the brick masonry walls were constructed through examination of both the literature and the conventional masonry walls. In the construction process, a single-type of brick was combined with two different types of mortar: cement mortar and hydraulic lime mortar. Three different joint thicknesses were used for each mortar type; thus, a total of six masonry walls were constructed in the laboratory. The mechanical properties of brick and mortars, and also of the constructed walls were determined. As a conclusion, it can be stated that the failure mechanism of the brick masonry walls differed due to the mechanical properties of the mortars. The use of bed joint thickness not less than 20 mm is recommended in construction of conventional masonry walls in order to maintain the act of brick in conjunction with mortar under load.

Experimental investigations on the initial shear strength of masonry with earth mortars

In this paper, a comparative study on the initial shear strength of masonry with earth mortars is presented. Triplet tests were carried out to characterise the shear bond strength of five different types of earth mortar, three purely mineral and two with vegetable additives (wood and straw chaff), using calcium silicate blocks. In spite of their lower bulk densities, mortars with chaffs reached a value of compressive strength comparable to the values shown by the purely mineral mortars. The characteristic initial shear strengths of all the tested earth mortars were between two and five times higher than the minimum values for initial shear strengths required by standards. To assess the influence of blocks pre-wetting, a comparison between calcium silicate blocks and earth blocks was performed to evaluate the results obtained from the standard test procedure compared to the more common practice of using earth mortars in combination with earthen blocks.

Experimental investigations on the initial shear strength of masonry with earth mortars

In this paper, a comparative study on the initial shear strength of masonry with earth mortars is presented. Triplet tests were carried out to characterise the shear bond strength of five different types of earth mortar, three purely mineral and two with vegetable additives (wood and straw chaff), using calcium silicate blocks. In spite of their lower bulk densities, mortars with chaffs reached a value of compressive strength comparable to the values shown by the purely mineral mortars. The characteristic initial shear strengths of all the tested earth mortars were between two and five times higher than the minimum values for initial shear strengths required by standards. To assess the influence of blocks pre-wetting, a comparison between calcium silicate blocks and earth blocks was performed to evaluate the results obtained from the standard test procedure compared to the more common practice of using earth mortars in combination with earthen blocks.

Ternary Blends of High Aluminate Cement, Fly ash and Blast-furnace slag for Sewerage Lining Mortar

High aluminate cement (HAC), fly ash (FA) and blast-furnace slag (BFS) have been treated sustainable materials for the use of cement products for wastewater infrastructure due to their capabilities of corrosion resistance. The purpose of this study is to optimize a ternary blend of above mentioned materials for a special type of mortar for sewerage lining. By the using of Taguchi method, four control parameters including water/cementitious material ratio, mix water content, fly ash content and blast-furnace slag content were considered in nine trial mix designs in this study. By evaluating target properties including (1) maximization of compressive strength, (2) maximization of electricity resistance and (3) minimization of water absorption rate, the best possible levels for each control parameter were determined and the optimal mix proportions were verified. Through the implementation of the study, a practical and completed idea for designing corrosion resistive mortar comprising HAC, FA and BSF is provided.

Mobile Spectroscopy in Archaeometry: Some Case Study

We provide an overview of recent results obtained by the innovative application of mobile spectroscopy for in situ investigation in archaeometry. Its growing relevance is linked to the great advantages of avoiding the transport and eventual damage of precious artifacts and of allowing the analysis of those specimens that are, for example, built into infrastructures or in some way permanently affixed. In this context, some case studies of combined instrumental approaches, involving X-ray fluorescence (XRF) and Raman spectroscopy, integrated by infrared thermography (IRT), are, in particular, discussed: the archaeological site of Scifì (Forza d’Agrò, province of Messina, Italy) and the Abbey of SS. Pietro e Paolo d’Agrò (Casalvecchio Siculo, province of Messina, Italy). In the first case, the elemental composition, as obtained by XRF, of two types of mortars belonging to two different chronological phases, dated back between the 3rd and the 5th century AD, allowed us to hypothesize a same origin area of their raw materials and a different production technique. Again, the combined use of XRF and Raman spectroscopies, supported by IRT technique, on pottery fragments of Greek-Hellenistic age and late imperial period, furnished important information concerning the receipts for the pigmenting agents of the finishing layer, allowing in some cases their unambiguous identification. In the second case, XRF data collected on bricks and stones from the external facade of the abbey allowed us to make some hypothesis concerning the provenance of their constituents materials, supposed to be in the area of valley of the river Agrò.

Crack initiation of selected geopolymer mortars with hemp fibers

The aim of this paper is to quantify particularly fracture properties of selected types of mortars prepared with an alkali activated binder and hemp fibers. The main attention is focused on evaluation of three-point bending fracture tests of prismatic specimens with an initial central edge notch made of alkali activated fly ash mortars. The load versus crack mouth opening displacement (F–CMOD) diagrams were recorded during the fracture tests and subsequently evaluated using the Double-K fracture model. This model allows the quantification of two different levels of crack propagation: initiation, which corresponds to the beginning of stable crack growth, and the level of unstable crack propagation. The course of fracture tests was also monitored by acoustic emission method.

Numerical Simulation of Thermal Theory of Sintered Coal Gangue Self-Insulation Block and Wall

As a new building material, sintered coal gangue self-insulation block can not only make efficient use of industrial waste but also have a stronger heat preservation effect. In this paper, we use sintered coal gangue self-insulation block with staggered rectangle holes and wall as objects which can be seen commonly in the Anhui market. Through studying block type, wall thickness and masonry mortar type's effects on the heat preservation of the wall based on ANSYS numerical modeling, it proves that with special masonry mortar, sintered coal gangue self-insulation block can reach the best energy-saving effect, which meets the need of green building and sustainable building .

Influence of slag composition on the stability of steel in alkali-activated cementitious materials

Among the minor elements found in metallurgical slags, sulfur and manganese can potentially influence the corrosion process of steel embedded in alkali-activated slag cements, as both are redox-sensitive. Particularly, it is possible that these could significantly influence the corrosion process of the steel. Two types of alkali-activated slag mortars were prepared in this study: 100% blast furnace slag and a modified slag blend (90% blast furnace slag + 10% silicomanganese slag), both activated with sodium silicate. These mortars were designed with the aim of determining the influence of varying the redox potential on the stability of steel passivation under exposure to alkaline and alkaline chloride-rich solutions. Both types of mortars presented highly negative corrosion potentials and high current density values in the presence of chloride. The steel bars extracted from mortar samples after exposure do not show evident pits or corrosion product layers, indicating that the presence of sulfides reduces the redox potential of the pore solution of slag mortars, but enables the steel to remain in an apparently passive state. The presence of a high amount of MnO in the slag does not significantly affect the corrosion process of steel under the conditions tested. Mass transport through the mortar to the metal is impeded with increasing exposure time; this is associated with refinement of the pore network as the slag continued to react while the samples were immersed.

Laboratory investigation of graphene oxide suspension as a surface sealer for cementitious mortars

This work investigated the influence of graphene oxide (GO) suspension as a surface sealer on the properties of two types of cementitious mortars (Portland cement mortar and high-volume fly ash (HVFA) mortar) under two curing conditions (wet curing and dry curing). Experimental results showed that GO surface treatment slightly improved compressive strength of wet cured HVFA mortar and dry cured cement mortar while it significantly reduced the water absorption of wet cured HVFA mortar and the gas permeability of both wet cured and dry cured cement mortars. Scanning electron microscopy (SEM) analysis suggested that the GO surface treatment facilitated the hydration process and densified the microstructure of both types of mortars. X-ray diffraction and Thermogravimetry results revealed the formation of hydroxyl grafted AFm phase at the interface of GO/HVFA mortar. Moreover, the GO surface treatment was found to decrease the carbonation of HVFA mortar but increase that of cement mortar.

On correlating the modulus of elasticity of stack-bonded flyash brick masonry using impact hammer and compression tests

Possibility of a new framework of characterising (stack-bonded) masonry properties is explored in three steps: (i) estimation of modulus of elasticity through impact hammer test (which is non-destructive and denoted as non-destructive test [NDT]); (ii) correlating the modulus of elasticity using NDT with that computed using typical destructive test (DT); and (iii) empirical relation for other masonry properties, such as compressive strength involving the modulus of elasticity. The second step is the kernel of proposed framework and once that correlation is established, in situ characterisation of masonry properties is possible without requiring any heavy equipment. Fifty-one masonry prisms are constructed using eight varieties of fly ash bricks and four types of mortar. Out of which, 33 samples are tested with impact hammer for the modulus of elasticity and followed by DT for the stress–strain plots. Correlation is developed for the moduli of elasticity computed using DT and NDT. DT is also carried out for the remaining prisms and other properties are correlated with modulus of elasticity of masonry and compressive strength of the constituting brick and mortar. Results indicate the feasibility of proposed framework, which, if adopted, is likely to enable true engineered construction for the small-scaled masonry dwellings in long run.

Radiocarbon Dating of Mortars with a Pozzolana Aggregate Using the Cryo2SoniC Protocol to Isolate the Binder

AbstractTo date, finding a technique able to effectively isolate the carbon signal from the binder of a mortar is still an open challenge. In this paper, the radiocarbon (14C) dating of one of the most challenging and diffuse types of mortar, the one with pozzolana aggregate, is investigated. Eight mortar samples from three archaeological sites near Rome (Italy) underwent a selection process called Cryo2SoniC. The selected fractions were analyzed by the accelerator mass spectrometry (AMS) 14C technique and compared to known historical references. Additional scanning electron microscopy analysis and petrographic investigations were done, respectively, to check the grain size of the fractions selected by Cryo2SoniC, and further, to characterize the original mortar samples. The masses of carbon yielded from the dated fractions were almost half of those released from some aerial mortars. The 14C dating results were accurate for pozzolana mortars, from buried and unburied structures, with calcination relics and small contamination of secondary calcite. A limitation in the purification protocol was observed on samples with a massive contamination of secondary calcite deposition of ground water origin, occluding porosity and substituting up to the 80% of the original binder matrix.

Methodological Aspect of Mortars Dating (Poznań, Poland, MODIS)

ABSTRACTAn accurate radiocarbon (14C) dating of mortars requires adjusting the sample preparation procedure to each specific mortar composition. In order to follow the influence of mortar components and the preparation procedure on dating results, a mortar intercomparison study (MODIS) was undertaken by 10 organizations (institutes and laboratories) in the analyses of four different types of mortars (see in this issue Hajdas et al. 2017 and Hayen et al. 2017). This paper presents the preparation protocol DoM v.1 applied by the Poznań team, together with dating results on a set of mortar samples used for the of intercomparison. This procedure involved petrographic observations, SEM-EDS analyses, different mechanical-chemical preparation, a test of leaching reaction for available fractions, and finally 14C dating of chosen samples. The applied preparation allows one to obtain dry-sieved grain fractions and different fractions from suspension: grain fractions from suspension collected in different times of leaching, repeated suspension (different portions), as well as suspension collected at different times of sedimentation. The obtained results show the great importance of good sampling and the influence of sample preparation on 14C dating results.

An experimental study on RC columns repaired on all four sides with cementitious mortars

This paper describes a study carried out in the ICITECH laboratories (Universitat Politècnica de València) on RC columns repaired on all four sides with cementitious-based mortars. A total of 18 specimens were tested, representing a group of square 20 × 20 mm2 columns subjected to compressive axial loads. Different repair scenarios were considered in order to study the influence of the type of mortar used and the presence or absence of bonding agents between the mortar and the column concrete. The results obtained showed that bonding agents have no appreciable effect on the behaviour of the repaired columns. Of the two types of mortar used in the study (Classes R3 and R4), the columns repaired with the lower grade mortar (R3) were seen to behave better. The main novelty of this work lies in the fact that this is the first time that two types of mortar are compared in the repair of four column sides, in addition to the possible use of bonding agents between the mortar and the column.