Adhesive Mortars Research Articles

Shear Bond Strength in Stone-Clad Façades: Effect of Polypropylene Fibers, Curing, and Mechanical Anchorage.

This study investigates the shear bond strength between four widely used façade stones-travertine, granite, marble, and crystalline marble-and concrete substrates, with a particular focus on the role of polypropylene fibers in adhesive mortars. The research evaluates the effects of curing duration, fiber dosage, and mechanical anchorage on bond strength. Results demonstrate that Z-type anchorage provided the highest bond strength, followed by butterfly-type and wire tie systems. Extended curing had a significant impact on bond strength for specimens without anchorage, particularly for travertine. The incorporation of polypropylene fibers at 0.2% volume in adhesive mortar yielded the strongest bond, although lower and higher dosages also positively impacted the bonding. Furthermore, the study introduces a novel fuzzy logic model using the Dombi family of t-norms, which outperformed linear regression in predicting bond strength, achieving an R2 of up to 0.9584. This research emphasizes the importance of optimizing fiber dosage in adhesive mortars. It proposes an advanced predictive model that could enhance the design and safety of stone-clad façades, offering valuable insights for future applications in construction materials.

Experimental insights into the seismic behaviour of flanged URM walls

Considerable attention has been given to understanding and modelling the seismic response of unreinforced masonry piers with rectangular cross-sections. However, the seismic performance of load-bearing masonry walls with flanges, commonly found in actual building configurations, remains less explored. This study investigates the behaviour of flanged walls through cyclic quasi-static tests on four full-scale C-shaped specimens comprising two primary seismic-resistant walls (webs) interconnected by a single flange. The construction of the specimens varied: two were built using standard solid calcium-silicate bricks with general-purpose mortar, while the other two utilised large-sized calcium-silicate blocks with tongue-and-groove interlocks and a thin layer of cement-based adhesive mortar. All specimens were subjected to cyclic horizontal loading parallel to the webs under consistent overburden load and double-fixed boundary conditions. The primary variable in testing the two walls of each type was the number of cyclic loading repetitions. This paper initially describes the key characteristics of the wall specimens, including geometry, construction details, and mechanical properties. Subsequently, it details the instrumentation plan and test protocol, and summarises the major observations from the tests, illustrating damage evolution and hysteretic force-displacement response. The results highlight the effect of the flange on initial stiffness and lateral force resistance, as well as the influence of block type and loading repetitions on failure mode, displacement capacity, and energy dissipation. Additionally, the study demonstrates the impact of floor slab uplift due to in-plane rocking of the webs on the top boundary conditions and the out-of-plane stability of the flange.

Determination of Thermal Properties of Autoclaved Aerated Concrete Wall Sections Constructed with Distinct Mortars by the Experimental and Theoretical Data

This study investigated the thermal properties of autoclaved aerated concrete(AAC) wall sections constructed with distinct mortars. Within the scope of the study, four distinct wall sections of 25x25x5cm dimensions were created using AAC special adhesive mortar, cement mortar, lime mortar and cement-lime mortar. The thermal conductivity(λEXP) that was determined by the heat flow meter(HFM) method and bulk density(ρEXP) of each wall section was determined in the laboratory. Specific heat values(cEXP) of mortars and aerated concrete material were determined experimentally in the study. The thermal diffusivity value(αEXP), thermal effusivity value(eEXP) and volumetric heat capacity(VHCEXP) of each wall sample were calculated using the experimental data obtained in the laboratory. In addition, αTEO, eTEO and VHCTEO of each wall sample were calculated theoretically using the thermal conductivity, bulk density and specific heat value given in the literature and standards for the same wall sections. In the study, experimental data was compared to the theoretical data. As a result, the thermal properties of walls constructed with distinct mortars and thermal differences formed in the walls due to the effect of these mortars could be determined with experimental data. However, it was observed that theoretical data were insufficient to detect these thermal differences.

The impact of incorporating waste materials on the mechanical and physical characteristics of tile adhesive materials

Abstract The goal of the investigation is to produce a cement mortar for building units and a high-performance ceramic tile adhesive by using V autoclaved aerated concrete as a partial substitute for cement. The combination consists of sand, crushed limestone, and polymeric additives. The experimental procedures were conducted utilizing contemporary laboratory equipment to facilitate the manufacturing of the product and the subsequent investigation of its characteristics, in accordance with the standards outlined in EN12004 and ASTM C1660. The laboratory tests carried out, which included splitting tensile strength, bonding strength, and open application duration, have demonstrated conformity to the product standards. The raw materials undergo many examinations prior to their utilization in the preparation process. The conducted tests encompassed chemical analysis, X-ray diffraction, and viscosity evaluation. These experiments aimed to ascertain the mixing ratios and determine the optimal quantity of water required for the preparation procedure. A thickness of 3 mm was employed, rendering it very cost-effective and environmentally sustainable due to the utilization of recycled resources. This particular adhesive possesses supplementary characteristics, such as its self-sufficiency on the site, since it is readily used without the need for extra materials, requiring only the addition of the necessary amount of water. Extensive research has been conducted on a range of mix designs and particle sizes for raw materials, together with varying proportions of additives, to determine the optimal ratio that satisfies both criteria and cost considerations. The adhesion strength of the building units was determined to be 7 N/mm2, surpassing the specified value in ASTM C1660. This indicates that the material is deemed successful and meets the required specifications for its application as a mortar for building units, as per the standard stating that an adhesion strength test exceeding 5 N/mm2 is necessary. The evaluation of the characteristics of the material employed as tile adhesive mortar was conducted in accordance with the EN1348 standard, revealing satisfactory compliance with all specified criteria. The application duration of the tile adhesive exceeds 25 min, while its tensile strength surpasses 10 N/mm2, thereby meeting the criteria for classification as a Class A tile adhesive.

Adhesion Analysis of Adhesive Mortar Joints in Ceramic Tiles under Static Loading

Ceramic detachment is a serious problem that persists in modern building constructions despite technological advances and updated regulatory documents. Most of these detachments occur at the interface between the adhesive mortar and the ceramic tile, due to the action of simultaneous tensile and shearing efforts. However, despite this understanding, experimental studies that evaluate the integrity of the adhesion of façades covering materials subjected to simultaneous stress are scarce. In this sense, this study proposes to evaluate the integrity of adhesive mortar joints using the mixed-mode flexure (MMF) crack propagation test. Force and elastic and dissipated energy data were used in this analysis. Prismatic specimens, with a size of 160 × 40 mm2 and a thickness of 6 mm, were produced consisting of two ceramic plates joined by a layer of adhesive mortar at 5 ± 0.5 mm. An acetate film was inserted into one of the mortar–ceramic interfaces in order to simulate the presence of a previous crack, and different crack sizes were used. The results showed the high stress-concentrating effect that the existence of flaws in the interface region has on fracture resistance, as well as the importance of effective contact between the materials. The energy parameters confirmed the analyses carried out based on the load values. The elastic energy of the system fell in the cracked samples, showing that there is a close relationship between the interface energy and the adhesive strength of the material. An energy release of the order of 0.053 ± 0.031 J was required for a 15 mm crack to propagate, creating a fracture surface.

Evaluation of Type III Adhesive Mortar (ACIII) and Gypsum as Precipitating Agents of Copper and Lead

Heavy metals exhibit characteristics such as nonbiodegradable nature, toxic character, bioaccumulation capability, and ability to transit over long distances. The widespread application of these metal ions in various industrial sectors has led to an increase in their release into the environment. Chemical precipitation has been one of the technologies used to remove heavy metals from wastewater, involving a process in which chemical agents are added to wastewater with dissolved toxic metal ions, which react with the metals, forming insoluble precipitates. Therefore, the present study aimed to assess the potential of gypsum and adhesive mortar type III (ACIII) as precipitating agents for lead (Pb) and copper (Cu) ions, as well as to evaluate the toxicity of precipitation products on Drosophila melanogaster. Experiments using ACIII mortar waste as a precipitating agent for Cu ions were obtained using a glass filter composed of 04 chambers and 04 antechambers, while the potential of gypsum as a Pb ion precipitant was evaluated by adding gypsum powder to a beaker containing a Pb ions solution. The toxicity of the precipitation products was evaluated by observing the mortality and negative geotaxis parameters on D. melanogaster. In the tests using ACIII mortar as a precipitating agent for Cu, retention percentages progressively varied, obtaining 98.82% at a concentration of 30 mg/L. Meanwhile, gypsum obtained retention percentages that varied from 32.83 to 98.61% for Pb. It was found that the precipitates of Cu and Pb resulted in alterations in the survival and locomotion rates of D. melanogaster only at the highest evaluated concentrations. In conclusion, the results obtained indicated that geomaterials such as ACIII mortar and gypsum have potential for the removal of Cu and Pb from aqueous solutions. Moreover, the precipitation stages by these materials also impact in decreasing the toxicity of metal ions to the evaluated model organism.

Mechanical and thermal properties of non-structural adhesive mortar using linear low-density polyethylene (LLDPE) aggregate substitution with vinyl acetate/ethylene (VAE) interface

Mechanical and thermal properties of non-structural adhesive mortar using linear low-density polyethylene (LLDPE) aggregate substitution with vinyl acetate/ethylene (VAE) interface

AAC-block walls with surface application of non-structural plastering materials as newly configured and improved structures subjected to diagonal compression

This research evaluates the use of non-structural materials, in the form of plastering grids and adhesive mortars, to create a newly configured structure with better shear properties than the original one, i.e. AAC blocks walls. Four types of glass fibre grid and two adhesive mortars were used. The results of 35 tested models subjected to diagonal compression show significantly improved performance by avoiding brittle failure, providing a significant increase in strength and ensuring relatively safe working conditions at large deformations. The best improvement in shear properties provided a relatively ‘weak’ grid with small openings and a highly deformable mortar.

The influence of hydroxyalkyl methylcellulose on early skin formation in cement‐based tile adhesive

AbstractThe effect of cellulose ethers (CE) with same water retention (WR) level but different molecular weight on the early skin formation of cement adhesive mortars was studied. In drymix mortars CE provide WR higher molecular weight and dosage of CE both improve WR. In this study all CE concentrations were adjusted to provide same WR independently from molecular weight of CE. Adjusted concentrations were obtained from zero‐shear viscosities measured in aqueous CE solutions.Measurements with cement‐based mortars identified the interstitial pore solution viscosity to determine WR level. Data show comparable WR for equal interstitial pore solutions, independently from the molecular weight of the CE if its concentration was adjusted accordingly. However, for cement adhesive mortars formulated with CE having different molecular weight which all provide equal WR, early skin formation was found to vary notably. Higher dosed low molecular weight CE outperforms CE with lower dosage but high molecular weight. This effect can be explained through the formation of a CE containing layer upon evaporation of water from the water‐air interface of the mortar.

Influence of High-Speed Mixer Characteristics on the Strength of Adhesive Mortar for Wall Tiles

Influence of High-Speed Mixer Characteristics on the Strength of Adhesive Mortar for Wall Tiles

Adherence of Brazilian dimension stones by mortar adhesion: influence of temperature

The influence of temperature variation on the adherence of granite slabs was simulated by a set of TBS tensile bond strength tests carried out using three types of rocks of established commercial use and with good technological qualities, known as “Branco Desireé”, “Vermelho Capão Bonito” and “Cinza Andorinha”. Specimens of these materials were fixed with two types of adhesive mortars, one commercial and the other produced in the laboratory, with white cement CPI. After the standardized cure, 186 TBS tests were carried out in 5 temperature ranges laboratory-controlled, ranging from 23 °C to 60 °C. The test results showed the temperature increase implies the loss of tensile strength. The commercial mortar presented TBS final values lower or nearby to 1 MPa, the standard threshold for ceramic slabs. The mortar prepared with white cement showed better performance, with adherence values above the 68% mentioned limit. This expressive result recommends the continuation of research with other types of rocks fixed with mortar prepared with white cement. The microstructure behavior of the material sets subjected to adherence tests was also investigated. The inspections showed clear contact between the stone plates (with both rough and smooth contact surfaces), without the occurrence of reaction edges or pervasion of the mortar in the stone. Anchoring, therefore, took place only in the contact between the standard substrate and mortar.

Strengthening of autoclaved aerated concrete (AAC) masonry wallettes with fabric reinforced cementitious matrix for in-plane shear and out-of-plane loads

Autoclaved aerated concrete (AAC) masonry is popularly used for the construction of infill and partition walls in the RC and steel-framed structures. However, past research highlighted that AAC masonry may exhibit poor performance during seismic events due to its low tensile capacity. In this study, the flexural and shear performance of AAC masonry was enhanced by using the fabric-reinforced cementitious matrix (FRCM). This strengthening scheme was applied in two modes: direct mode using anchor and sandwich method using adhesive mortar. These strengthening schemes were different from each other in the method of placing of the fabric. The experimental results showed that the proposed strengthening methods could improve the strength and ductility of the masonry under shear and flexural loads. The test results showed comparable strengths for both types of strengthening methodologies and either of two methods of fabric application may be chosen for the strengthening of AAC masonry, depending on the availability of materials and ease in construction. Moreover, the outcome of the conducted tests were compared with the respective theoretical predictions estimated using available analytical models and equations.

Relationships between the surface roughness of Brazilian dimension stones and the adhesion to mortars

The effect of different surface roughness for ceramic and metals on their adhesive bond strength is widely studied in the field of tribology, but still little investigated for stone claddings, which are natural and quite heterogeneous materials. The main objective of this study was to investigate the relationships between the surface roughness of ornamental stone slabs and their adhesion to mortars were determined by TBS tensile bond strength tests, including observation of types of failure in each test. Slabs with different roughness of the migmatitic stone, commercially known as in Brazil "Jacarandá Rosado", were fixed with two types of adhesive mortars, one commercial and the other produced in the laboratory (here referred to as “PM” mortar). Average TBS adhesion values were higher for the rougher plates, as expected, since in this condition there is a larger exposed surface of the minerals, resulting in a greater number of electrochemical charges available to interact with the adhesive mortars. In quantitative terms, the results indicate average values of 1.39 MPa and 1.16 MPa, respectively, for the higher and lower roughness of specimens fixed with Commercial mortar. Regarding the adhesion for PM mortar, values obtained in specimens with smooth, moderately rough and rough surfaces, respectively, were, on average TBS of 2.06 MPa, 1.42 MPa and 1.47 MPa, values higher than for the CM mortar. Importantly, in these last two test conditions, all failures occurred in the stone, indicating that the PM mortar adhered very well to rougher surfaces, i.e., the stone and the standard substrate. So, it is plausible to consider that TBS values of the PM Mortar should be, in practical terms, higher than measured in the tests, since they reflected more conditions of the rock than the mortar. Such information indicates that detailed evaluation of the types of failure in the adhesion tests was important to corroborate the better TBS results for the mortar prepared in the laboratory with CPV-ARI cement.

FE‐analysis of long‐term performance of an epoxy bonded anchor based on nanoindentation and CT‐scan

AbstractEpoxy‐based adhesive mortars are applied as bonding materials for the heavy‐duty fastener in buildings and constructions worldwide. The long‐term behavior of the adhesive mortars is a significant influencing factor on the sustained load and lifetime of bonded anchors. An adhesive mortar is a heterogeneous material consisting of resin and fillers. For the analysis of the long‐term performance of the bonded anchor, it is fundamental to understand the long‐term behavior of the bonding material on the microscale. This contribution presents a novel prediction approach for the long‐term load capacity of the epoxy‐based bonded anchor by using nanoindentation and FE‐simulation. The long‐term mechanical properties of the adhesive mortar were measured by using the precise nanoindentation technology on the micro level for the investigation of: (a) the loading rate effect on the load behavior of the resin, (b) the heterogeneous mechanical phases of the mortar, (c) the aging of the microstructures, and (d) the long‐term load behavior of the components of the mortar. Based on the experimental nanoindentation results, the numerical long‐term time‐independent material parameters were characterized in a concrete model by means of stochastic simulation. For analysis of the imperfection effect of a real bonded anchor, the nanoindentation was employed on the micro level to investigate the error load transfer on the interface between mortar and concrete drillhole without drill‐hole cleaning. On the macro level, the macroscale defects of an installed bonded anchor were found by using the computer tomography. It is demonstrated that the FE‐model based on the nanoindentation results can correctly predict the long‐term performances of a bonded anchorage system.

Tensile bond strength of adhesive mortars with hydroxypropyl methyl cellulose and vinyl acetate-ethylene polymers after thermal storage.

The properties of adhesive mortars can change due to heating, compromising the durability of the coating systems. The aim of this article was to evaluate the influence of cement and polymer contents on the tensile bond strength of adhesive mortars after thermal storage. Ceramic tiling system specimens were prepared with seventeen formulations of adhesive mortars. These specimens were stored under dry (reference) at temperature of 23 ± 2 °C and 60 ± 5% of relative humidity and thermal (temperature of 70 ± 2 °C) conditions. The results showed that the cement content was the major factor concerning tensile bond strength. The vinyl acetate-ethylene (VAE) polymer improved the tensile bond strength of mortars under thermal storage. However, the hydroxypropyl methyl cellulose (HPMC) content contributed to the tensile bond strength only when higher cement contents were used. Besides, microstructure analysis showed that ettringite was degraded during thermal storage.

A review of quality of recycled aggregate and its effect on durability of recycled aggregate concrete

Due to their high porosity and many interface transition zones, the low-quality recycled aggregates (RA) used in recycled concrete have a higher permeability than those used in new concrete. This makes it easier for hazardous ions to enter the concrete and increases the permeability. The components of the aggregates, the content of the mortar attached to aggregates, and the original concrete strength all play a role in the recycled aggregate’s quality. The components of recycled aggregate are complex, and the loose porous structure of bricks will increase the amount of water that recycled concrete absorbs. Additionally, external moisture and ions are more likely to reach the core of the concrete, reducing its durability. If more adhesive mortar is attached or if the original concrete’s strength is decreased, recycled concrete may absorb more water. The attached mortar can be filled using slurry soaking, microbial mineralization deposition, carbonization curing, and other methods to strengthen recycled concrete. Finally, this work offers a reference for future research on the use of recycled aggregates in engineering.

Assessment of Chemical Resistance of Polymer Repair Mortars

This paper deals with the problematics of polymer repair and adhesive mortars. In this study, the vinyl ester and epoxy resins filled with siliceous filler are used. This paper studies physical-mechanical properties and chemical resistance of developed mortars. The compressive strength, flexural strength and visual evaluation of reaction and degradation of polymer mortars in presence of common acids, alkalis and other compounds are compared. The results show, the amine-based epoxy mortar can withstand against a large variety of solutions, but the overall chemical resistance of vinyl ester mortar is higher.

Comprehensive Evaluation of the Sustainability of Waste Concrete towards Structural Concrete Application in Freeze-Thaw Environment

To promote the in-situ and structural application of waste concrete in cold regions, the sustainable application potential of waste concrete in a freeze-thaw (F-T) environment was comprehensively evaluated from three aspects of performance, environmental load, and economic benefit. The recycled aggregate concrete (RAC) was produced by recycled coarse aggregate (RCA), which was obtained from the crushing of natural aggregate concrete (NAC) after every F-T 150 cycles until F-T failure. The effects of F-T damage of parent concrete on the physical properties of RCA and mechanical and frost resistance of RAC under 35% flexural stress were studied. Besides, the sustainability of NAC and RAC was compared and analyzed by emergy theory. The results suggested that the physical properties of RCA deteriorated gradually with the accumulation of F-T damage to parent concrete. The RCA obtained from parent concrete that suffered F-T damage could be used as coarse aggregate for structural concrete when F-T damage is smaller than 0.367. The F-T damage of parent concrete had an adverse effect on the mechanical properties and frost resistance of RAC. The frost resistance of RAC obtained from parent concrete with larger F-T damage was worse. The RAC prepared from parent concrete without F-T failure can serve 50 years in cold regions, while that with F-T failure can only serve 30 years. The F-T damage microelements were dispersed in the adhesive mortar of RCA and transferred to RAC, resulting in the reduction of the mechanical properties and frost resistance of RAC. Emergy analysis showed that the reuse of waste concrete after F-T failure required higher economic input, higher environment load, lower output efficiency, and sustainability. The performance, environmental load and economic benefit of RAC prepared by using waste concrete after F-T failure were inferior to that of waste concrete without F-T failure. Waste concrete after F-T failure is not recommended to be used as coarse aggregate for structural concrete.

Повышение теплотехнической однородности стен из ячеистобетонных блоков

The development of effective protecting structures is currently one of the most popular areas in the construction industry. Masonry made of aerated concrete blocks is used in conditions of ensuring energy efficiency and environmental safety in the construction of civil buildings as enclosing structures. It has high thermal protection properties. The issue of filling through seams of aerated concrete masonry is acute, since adhesive and cement-sand mortars in masonry have low thermal conductivity and are temperature bridges. The authors have developed a two-row energy-efficient wall masonry made of aerated concrete blocks using polyurethane glue as a filler for through and dressing joints. The article discusses the effect of horizontal through joints made of cement-sand mortar and blocking of blocks on the resistance to heat transfer of masonry from aerated concrete blocks. In addition, it presents a study of the reduced resistance to heat transfer of the enclosing structure, taking into account heat-conducting inclusions, presented in the form of a traditional two-row aerated concrete masonry through a row, made on a thin-layer adhesive solution, as well as the masonry developed by the authors. It is concluded that the energy efficiency of the developed wall fencing is ensured due to the increased thermal homogeneity of the masonry.

Mortar Bond Strength: A Brief Literature Review, Tests for Analysis, New Research Needs and Initial Experiments.

Despite technological advances in the production processes of the materials for ceramic façade coatings, the problems of detachments are still frequent. Therefore, this work aims to investigate, through a literature review, the existing gaps related to the adhesion ability of adhesive mortars, identifying new research needs that can better explain the behavior of the material. In addition, an experimental procedure was developed to evaluate the mechanical capacity of adhesive mortars when subjected to cyclic stresses. Dynamic stress measurements are presented for several blocks of mortar and on similar blocks but with a slot drilled prior to measurements (intended to represent failure). From these data we calculated values of stress energy, elastic energy, and dissipated energy. The experimental results showed that the energy involved in the test process accompanied the load values and current stress values. The mortar samples with the previous failure absorbed and dissipated less energy than mortars without failure, showing that materials that have less energy to dissipate, are materials that have developed less capacity to adhere, that is, to keep their parts together.