Brick Surface Research Articles

Effects of Infills in the Seismic Performance of an RC Factory Building in Pakistan

Infilled reinforced concrete (IRC) frames are a very common construction typology, not only in developing countries such as Pakistan but also in southern Europe and Western countries, due to their ease of construction and less technical skills required for the construction. Their performance during past earthquakes has been in some cases satisfactory and in other cases inadequate. Significant effort has been made among researchers to improve such performance, but few have highlighted the influence of construction materials used in the infill walls. In some building codes, infills are still considered as non-structural elements, both in the design of new buildings and, sometimes, in the assessment of existing buildings. This is mainly due to some difficulties in modeling their mechanical behavior and also the large variety of typologies, which are difficult to categorize. Some building codes, for example, Eurocode, already address the influence of infill walls in design, but there is still a lack of homogeneity among different codes. For example, the Pakistan building code (PBC) does not address infills, despite being a common construction technique in the country. Past earthquake survey records show that construction materials and infill types significantly affect the seismic response of buildings, thus highlighting the importance of investigating such parameters. This is the object of this work, where a numerical model for infill walls is introduced, which aims at predicting their failure mode, as a function of some essential parameters, such as the friction coefficient between mortar and brick surface and mortar strength, usually disregarded in previous models. A comprehensive case study is presented of a three-story IRC frame located in the city of Mirpur, Pakistan, hit by an earthquake of magnitude 5.9 on 24 September 2019. The results obtained from the numerical model show good agreement with the damage patterns observed in situ, thus highlighting the importance of correctly modeling the infill walls when seismically designing or assessing Pakistani buildings that make use of this technology.

Physical-chemical exfoliation of pristine graphite flakes

Two-dimensional (2D) nanomaterials, especially graphene, have received increasing attention due to their mechanical, electronic, optical, chemical, and thermal properties. A set of physical-chemical techniques was applied to increase the exfoliation effect's promotion and characterization over the natural graphite flakes. More than 30 natural impurities were determined in raw graphite flakes by instrumental neutron activation analyses. A possible graphite exfoliation mechanism combining ultrasonication and low temperatures in liquid nitrogen was postulated using density functional theory (DFT) calculation. The sonication shock waves act on the graphite surfaces resulting in compressive stress propagating throughout the graphite bulk. The most observed effect was the corner's damage, promoting gas interlayer adsorption pathways, followed by explosive desorption. The applied sequence of treatments results in an increasing defect level. Intense exfoliation was observed with several graphite layers, visible after gamma radiation treatment in doses ranging from 0.1 MGy to 6.0 MGy on standard ambient temperature and pressure. The increasing irradiation dose mostly affects the surface of the flakes. The pristine Graflake shows a homogeneous carbon surface with no signs of oxidation. At the presence of oxygen peroxide under oxygen atmosphere, samples irradiated at 0.3 MGy already show more brick surface signs. The irradiation dose associated with the oxidation generates a much less homogeneous surface, the result is a more bricked and somehow smaller flakes. Under the same oxidizing atmosphere at a higher irradiation dose, the effect has mostly increased in all surfaces compromised by oxidation, favoring the flakes' dispersion. The treatment association results in a bricked surface with much smaller particles of the original Graflake, favoring the exfoliation.

Enhanced erosion resistance of cement-treated bricks using multiple biological surface treatments

Water erosion can deteriorate cement-treated bricks. The goal of this study was to investigate the use of multiple biological surface treatments (BSTs) on cement-treated bricks to enhance their resistance to water erosion. Calcite crystals were precipitated on the surface of cement-treated sand bricks by the microbial-induced calcite precipitation (MICP) technique. Multiple BSTs with MICP were used to enhance the properties of the cement-treated bricks further. The experimental results showed that, after a single BST, the flexural strength of the cement-treated bricks increased from 500 kPa to 750 kPa and the compressive strength increased from 3000 kPa to 4000 kPa. Erosion and water absorption were reduced by 71.2% and 16.3%, respectively. Compared with cement-treated bricks without any BST, the cement-treated bricks with triple MICP BSTs showed increases of nearly 140% and 100% in peak flexural and compressive strength, respectively. In addition, the triple BSTs resulted in 32% less water absorption compared with cement-treated samples without any BST. The surface of cement-treated bricks with triple BSTs was found to resist accelerated erosion over a 60 min time period. Overall, the results showed that BST can strengthen the erosion resistance of cement-treated bricks.

Study on parameters on cutting AAC by wires

Autoclaved Aerated Concrete (AAC) is a Lightweight, Load-bearing, High-insulating, Durable building product, which is produced in a wide range of sizes and strengths. AAC Blocks is lightweight and when compared to the red bricks, AAC blocks are three times lighter. AAC block is rapidly developing in Vietnam. The block has more advantages such as precast, and easy installation. AAC is produced from the common materials: lime, sand, cement and water, and a small amount of rising agent. After mixing and molding, it is then autoclaved under heat and pressure to create its unique properties. Then, the AAC block will be cut into block brick by steel wire. When cutting the ACC block, the block brick surface must be smooth so that it is unnecessary to mortar. Furthermore, the roughness of the surface must be smaller than 0.1mm to paint the wall easily. The block dimension also need high precision so that the wall will be straight when blocks are superposed. However, in this paper, the roughness of the block surface will be only researched because the roughness will decide the cost, and the dimension decide the estheticism of wall. The block is made by using steel wires to cut big AAC blocks into small blocks. Effects of processing parameters on the performance of the steel wire sawing processes are wire speed, feed rate and tension. Each parameter will affect surface quality with different effects. In addition, these parameters affect each other, which causes scratches on the AAC surface. Experiments will be made to measure the height of roughness with the change of wire speed, feed rate and tension. The best parameters will be found, which helps the AAC manufacturer to obtain the higher quality.

Hygrothermal performance of six insulation systems for internal retrofitting solid masonry walls

The study investigated the hygrothermal performance and risk of fungal growth in a phenolic foam system with a closed cell structure and a diffusion-open and capillary active lime-cork based insulating plaster, for internal retrofitting purposes. The setup comprised two 40-feet (12.2 m) insulated reefer container with controlled indoor climate, reconfigured with 24 holes (1 × 2 m each) containing solid masonry walls with embedded wooden elements on the interior side. Focus was on the conditions in the masonry/insulation interface and embedded wooden elements, and the performance of the two systems were compared to three diffusion-open insulation systems and one diffusion-tight. The effect of exterior hydrophobisation was also investigated. Relative humidity and temperature were measured in several locations in the test walls over 2½ years, and the risk of fungal growth was evaluated by on-site measurements and the VTT mould-growth model. The findings indicate that internally insulated walls with bare brick exterior surfaces performed poorly with high risk of fungal growth. The effect of exterior hydrophobisation was found to vary with the orientation and the installed insulation system, with a generally positive effect on walls facing south-west but limited effect for north-east. Furthermore, the more diffusion-tight insulation systems were found to perform better in combination with exterior hydrophobisation than the highly diffusion-open systems. The lime-cork insulating plaster showed high relative humidity and risk of moisture-induced problems. The on-site fungal tests showed no growth in the masonry/insulation interface inside the two insulation systems, probably due to high initial pH-value.

Production of colored bi-layered bricks from stone processing wastes: Structural and spectroscopic characterization

Stone processing wastes, being inherently colored, present an attractive option to develop the building façade products. In this study, four different types of stone processing wastes are characterized using X-ray diffraction, FTIR & Raman spectroscopies, and their suitability is evaluated to develop the colored bi-layered bricks. The stone processing wastes are blended with ground granulated blast-furnace slag to produce colored geopolymer mortars, and their compressive strengths are compared. Incorporation of stone waste decreased the compressive strength of geopolymer mortars. Particularly, Ca-rich stone wastes decreased the compressive strength less as compared to Si-rich stone waste. However, the stone waste blended geopolymer mortars still attained a value greater than 10 MPa, while achieving the desired color property. This corroborates the high potential of stone waste for producing colored masonry bricks equivalent to class designation 10 fly ash bricks as per IS 12894. The bi-layered bricks are conceptualized to make them economically viable, and their manufacturability is demonstrated at the laboratory scale via a four-step process in an existing industrial set-up (used for conventional fly ash bricks). The economic viability of these colored bi-layered bricks is compared against conventional single-layered fly ash bricks. It is found that colored bi-layered bricks have tremendous potential for cost-saving of up to 35% of the overall cost (accounting for the cost of a finished brick surface). This study presents a first-of-its-kind detailed study to produce colored bi-layered bricks using stone processing wastes. These new bricks combine the desired features of aesthetics and durability, and therefore, show a great promise as a cost-effective alternative to conventional fly ash bricks.

Thermal analysis of hollow clay bricks submitted to a sinusoidal heating

The aim of the present work is to study numerically, in a transient state, the thermal behavior of three types of hollow bricks mostly used in the construction of building walls in Morocco. The coupled heat transfer by conduction through the surrounding walls, natural convection and surface radiation is taken into account. The outside vertical surface is submitted to a sinusoidal thermal excitation, while the inside vertical surface is maintained at a constant temperature. The top and bottom horizontal sides are assumed to be adiabatic. The governing equations for conservation of mass, momentum and energy are discretized by the finite volume approach and solved by the SIMPLE algorithm. The main parameters governing the problem are the amplitude, the period of the exciting temperature and the emissivity of the walls. The effect of these parameters on the global heat transfer through each structure is presented and examined. The results report that the hollow brick of type 3 allows a good reduction of heat transfer from exterior to interior surfaces of the building walls and hence providing an adequate thermal comfort. The emissivity of the internal surfaces affect considerably the heat transfer through the hollow bricks. The use of low emissivity materials on internal surfaces of the hollow bricks would greatly help in improving the energy consumption in buildings.

Experimental and numerical investigation on the compressive properties of interlocking blocks

Masonry construction with interlocking bricks could effectively reduce construction time, minimize labour cost and improve construction quality. Existing interlocking bricks are mostly designed to provide easy alignment only, therefore the effect of interlocking mechanism on the mechanical performance of the interlocking block is not well investigated. This paper presents a laboratory and numerical study on the mechanical properties of a new type of interlocking brick featured with large shear keys for better mechanical performance. The theoretical compressive strength of a unit brick prism is derived using fracture mechanics theory, which is validated with laboratory compression test. Then, further tests on prisms with multiple interlocking bricks show the number of bricks strongly influences the performance of prism compressive strength. Detailed 3D numerical models of interlocking brick prisms are generated using ABAQUS. The numerical modelling results are compared with experimental test results. The damage and failure modes of the interlocking blocks are numerically and experimentally studied. Localized stress concentration at block interlocking surfaces is investigated. Parametric study is then carried out to quantify the influences of different design parameters including the number of blocks, brick surface roughness amplitude due to brick manufacturing tolerance and surface unevenness, and material strength. A modified formula based on the analytical solution is derived by fitting the numerical simulation and experimental results to predict the compressive capacity of interlocking brick prisms. A semi-empirical prediction method is also derived to predict the axial stiffness of the interlocking brick prism for use in design analysis of masonry structures made of mortar-less interlocking bricks.

Surface modification of brick by zinc oxide and silver nanoparticles to improve performance properties

Due to its versatility, durability, and mechanical stability, brick is an important construction material. In the current study, the brick surface was coated by ZnO nanoparticles based on chemical deposition and modified by silver nanoparticles to create a hydrophobic property on the brick surface as well as photocatalytic and antibacterial properties. The modified brick nanocomposite was characterized by FESEM, XRD, and UV–Visible and then, hydrophobicity, photocatalytic, and antibacterial properties were investigated. Suitable values of bandgap energy of 3.25 eV and 3.22 eV were obtained for the brick modified by ZnO and ZnO/Ag, respectively. By using the dye degradation test under UV irradiation, the brick modification significantly increased the photocatalytic property. The antibacterial property of the nanocomposite was investigated by the disk diffusion method based on staphylococcus aureus and bacillus cereus as gram-positive bacteria and Escherichia coli and pseudomonas aeruginosa as gram-negative bacteria and the experiments showed acceptable results. The results of flexural strength and efflorescence test showed that flexural strength of the brick modified by ZnO/Ag is almost 1.8 times more than non-coated brick and the modified brick represented less efflorescence on the surface. The results showed the improvement of the applicable properties of the brick.

The novel use of a spray-on rubber coating to recover cellular material from the surface of bricks

Currently, forensic investigators utilise various types of swabs and tape lifts to recover cellular material from coarse surfaces identified during a criminal investigation. However, a number of challenges prevent successful recovery and therefore warrants the need for an alternative method. Plasti dip® is peel-off rubber coating that can be applied to most surfaces and may have an application in the recovery of DNA from coarse surfaces. The aim of this study was to determine the effectiveness of Plasti dip® to recover DNA from coarse brick surfaces and assess how this method compares to current techniques. Cellular material was deposited onto brick pieces in varying concentrations and recovered with either flocked, foam or rayon swabs, or Plasti dip®. Material recovered, using each technique, was extracted and quantitated for comparison of DNA yields. At low and medium cell concentrations, an observable but not statistically significant difference was observed between the swabbing methods and Plasti dip®. At high cell concentrations Plasti dip® was able to recover a significantly higher DNA concentration than all three swabbing methods. Quantitation results indicated no degradation of DNA. This is a novel approach to the collection of trace DNA from surfaces that have historically proven difficult to sample. While there is further validation required, this landmark study demonstrates the potential that spray-on rubber coatings have for casework involving rough, porous surfaces like bricks, stones or rocks.

The Production Technology of the Ceramic Brick Soft Molding Based on Opoka-Like Rocks

The results of the scientific research and pilot tests on the production technology of soft molded ceramic bricks based on siliceous opoka-like rocks are presented. A description of soft-molded brick, which is distinguished by a huge variety of appearance and unusual design, which has earned recognition from architects and designers, is given. It is emphasized that the main limiting factor for the wide distribution of this type of brick is its high cost, due to the very small volumes of its production in Russia. It is indicated that the current situation poses a very difficult and urgent task for the wall ceramics industry - to establish the widespread production of soft-molded bricks, which in addition to the aesthetic properties will have the good operational properties. The opoka-like rocks’ characteristics and the results of studying their ceramic properties in relation to the technology of soft molding are given. The classification of the soft molded brick front surface types is presented for discussion. The main technological parameters of production, the relationship and the influence of various technological factors on the properties of the products obtained, as well as the mechanism for forming the structure of the calcined products are determined. A variable technological scheme for the production of soft molded ashlar brick has been developed. It is emphasized that the presented research results will be of interest to a wide circle of the molded ceramic bricks’ manufacturers and will help to establish the wide production of soft-molded bricks in Russia.

Upgrading the Quality of Recycled Aggregates from Construction and Demolition Waste by Using a Novel Brick Separation and Surface Treatment Method.

Mixed recycled aggregates (MRA) from construction and demolition waste (CDW) with high-purity and environmental performance are required for highway construction application in base layer and precast concrete curbs. The main problematic constituents that reduce the quality level of the recycled aggregates applications are brick components, flaky particles, and attached mortar, which make up a large proportion of CDW in some countries. This paper studies the potential of brick separation technology based on shape characteristics in order to increase the recycled concrete aggregates (RCA) purity for MRA quality improvement. MRA after purification was also processed with surface treatment experiment by rotating in a cylinder to improve the shape characteristics and to remove the attached mortar. The purity, strength property, densities, water absorption ratio, shape index, and mortar removal ratio of MRA were studied before and after the use of the brick separation and surface treatment proposed in this study. Finally, the recycled aggregates upgradation solution was adopted in a stationary recycling plant designed for a length of 113 km highway construction. The properties of CDW mixed concrete for precast curbs manufacturing were conducted. The results indicate that problematic fractions (brick components, particle shape, and surface weakness) in the MRA were significantly reduced by using brick separation and surface treatment solution. Above all, it is very important that the proposed brick separation method was verified to be practically adopted in CDW recycling plant for highway base layer construction and concrete curbs manufacturing at a low cost.

ИССЛЕДОВАНИЕ ВЛИЯНИЯ ПЛАЗМОХИМИЧЕСКОГО МОДИФИЦИРОВАНИЯ НА МАКРО- И МИКРОСТРУКТУРУ ПОВЕРХНОСТНОГО СЛОЯ АВТОКЛАВНЫХ СТЕНОВЫХ МАТЕРИАЛОВ

studies of the high-temperature effect of a plasma torch on the formation of a multilayer structure of the protective and decorative coating of autoclave wall materials are presented. The tasks of the work included studies: a temperature gradient in a multilayer protective-decorative coating; chemical composition of the fused, intermediate and deep layers of the protective and decorative coating; influence of sodium liquid glass on the formation of macro- and microstructures of protective and decorative coatings under the influence of plasma; processes of thermal diffusion and redistribution of oxides in the fused, intermediate and deep layers.
 It was found that when the plasma torch was treated with autoclave wall materials, the surface layer was heated to a depth of 3000 μm, and the maximum surface temperature reached 2000 °C. The pattern of the change in the structure of the fused and intermediate layer is revealed. It is shown that the preliminary impregnation of the surface of silica brick during plasma treatment due to the formation of a low-melting melt eliminates microcracks in its deep layers, and high plasma temperatures promote intensive evaporation of sodium and calcium oxides from the fused layer.

Modelling of slag flow and prediction of corrosion state of refractory bricks in an entrained-flow gasifier

The corrosion rate of refractory brick is a key factor for long-term and stable operation of a gasifier. In situ measurement of refractory brick corrosion was always a challenging topic due to the extreme temperature and pressure in the gasifier. In this paper, numerical simulations were adopted to accurately predict the corrosion depth of the refractory brick. Models for slag flow and refractory brick heat transfer were built, and various models of refractory brick corrosion rate were derived in detail. Heat transfer and brick corrosion models were validated with available industry data and the prediction accuracies of the different models were compared and discussed. Results showed that the external diffusion model could accurately predict the corrosion state, and the correlation coefficient with industry data was 0.998. The slag shear rate on the surface of the refractory brick was a key control parameter for corrosion, especially for a top single-burner down-flow gasifier.

Characterization of Powder Obtained from Surface of Waste-Plastic Bricks

The basic aim of this work is to perform characterization of the powder obtained from surface of waste plastic brick which in turn provides a base to study the physical and chemical composition of bricks made from waste plastic bags and sand (Plastic bricks). The powder used for characterization was obtained from the surface of waste plastic bricks by scratching the surface of bricks with knife-like stainless-steel instruments. Before characterization, this powder was strained through a double layer strainer (mesh number 325, pore size 44 microns) to obtain fine powder particles. This fine powder was further characterised for determining the particle size, crystallinity percentage, elemental composition and to find functional groups present. The techniques used in characterization of powder includes X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Field Emission Scanning Electron Microscopy / Energy Dispersive X-ray Spectroscopy (FESEM/EDS). The results obtained from XRD data analysis showed the particle size to be 9.595 nanometres with a crystallinity percentage of 2.113275 percent. EDS and FTIR results when studied simultaneously showed presence of clay minerals like MgO, SiO2, Al2O3, etc.

Comparative recovery of Listeria spp. From dairy environmental surfaces using 3M™ and World Bioproducts© environmental swabs with standard enrichment and enumeration methods

Preventing Listeria contamination of artisan cheeses requires routine and effective environmental monitoring of product contact surfaces within the production environment. Consideration of the efficacy of environmental monitoring methods is essential when testing for the presence of Listeria spp. within the processing environment as a way to control the risk of cheese contamination. Four environmental surfaces (dairy brick, stainless steel, plastic, and wood; n = 27/surface type at high concentrations; n = 405/surface type at low concentrations) were inoculated with L. innocua (expressing Green Fluorescent Protein), L. monocytogenes. (L.m.), ATTC® 19115 and L.m. 1042B, at high (106–107 CFU/cm2) and low (0.01–1 CFU/cm2) target concentrations. Inoculated surfaces were swabbed with World Bioproducts© EZ Reach™ environmental swabs with HiCap (WBHC) and Dey-Engley (WBDE) neutralizing broths, and 3M™ environmental swabs (3M™) with Dey-Engley neutralizing broth. 3M™ Listeria Environmental Plate and Aerobic Plate Count Petrifilm™ enumeration methods and FDA, modified FDA, MOPS-BLEB, and modified USDA enrichment methods were used to compare sensitivity of recovery between environmental swabs. When applied at low concentrations, 3M™, WBDE, and WBHC swabs recovered Listeria spp. from 90.9%, 88.4% and 83.2% of plastic, stainless steel, and dairy brick surfaces, respectively, but only 65.7% of wooden surfaces; recovering 14.8%, 77%, and 96.3% at 0.01, 0.1, and 1 CFU/cm2, respectively (p < 0.05). Slight differences in recovery (84.8% for WBDE, 78.1% for WBHC, and 80.9% for 3M™) were observed for all surfaces. Variable recovery was influenced by strain, where L.m. 1042B was recovered more effectively from wooden surfaces by 3M™, WBDE, and WBHC swabs, followed by L.m. 19115, and lastly L. innocua. Equivalent performance between swab formats was observed for all tested surfaces except wood, therefore porosity of environmental surfaces should be taken into consideration when implementing environmental sampling plans.

NUMERICAL ANALISIS OF THE STRAINS AND STRESS STATES REINFORCED CLAY BRICK MASONRY WALLS HORIZONTALLY SHEARED

This paper presents the results: stress and strain of bed joints mortar, masonry units, reinforcement bars and mechanism of cracking of numerical simulations using ANSYS of reinforced brick wall in the horizontal shear. Willam-Warnke (WW-5) failure criterion for mortar and bricks and Huber-Mises-Hencky (HMH) plasticity surface for bed joints steel reinforcement (steel smooth bars and truss type reinforcement) has been used. Coulomb-Mohr (CM) criterion in the contact surfaces of mortar and bricks have been used in the interface elements. Numerical calculations showed satisfactory convergence of research in the patterns of cracking; and the load-strain relationship was similar to the results of research with regard only to the cracking time. Destructive force numerical models Hu,cal correspond to the forces observed at the first cracks in the walls Hu,mv. Reduction of transverse and longitudinal deformation of mortar bed joints have been reported in the immediate vicinity of the bars, and the reduction of the main stress of the bricks is reported in the case of the use reinforcement.

Qualitative and Quantitative Coating Tests: A Comparison in Magnesia–Spinel Refractory Bricks

In cement processing, which involves the production of clinker in rotary kilns, the main refractories used in the transition and burning zones are magnesia–spinel bricks. These bricks present suitable chemical and thermomechanical properties, not to mention that they can be easily landfilled. Among the main wear mechanisms of these bricks in the kiln, the infiltration of alkaline salts is noteworthy and occurs through the open pores of the refractory. In this way, the coating—a clinker layer adhered to the brick surface—appears as a protection mechanism of the lining against infiltration. Thus, the objective of this investigation is to run a qualitative coating test based on the contact method, and quantitative coating test based on the sandwich method to check the suitability of the methodologies and to evaluate the coating adherence on two different magnesia–spinel bricks. It was possible to distinguish the superior adherence ability of brick B in both coatings due to the higher porosity and the presence of nonreacted ZrO2. Despite the similarity between the test results, the quantitative sandwich-coating test is preferable because it does not depend on subjective analysis.

Effect of Lattice Setting Density on Fluid Flow and Convective Heat Transfer Characteristics of Bricks in Tunnel Kilns

Abstract This paper reports the effect of setting density on flow uniformity, pressure drop, pumping power, and convective heat transfer coefficients (CHTCs). High-density setting (HDS) comprises 768 bricks, and low-density setting (LDS) contains 512 bricks are tested for different inlet air velocities using both local and average approaches. The investigation is carried out using a 3D-computational fluid dynamics (CFD) model with k–ω turbulence model. Both settings are validated against experimental data reported in the literature with errors less than 1.9% for pressure drop and −1.0% for brick surface temperature. The reported results indicated that the LDS has distinct benefits over the HDS as it enhances the flow uniformity, particularly in the stack channels. Also, LDS attains lower pressure drop, pumping power, and firing time than HDS by 45.93%, 50%, and 35%, respectively. In addition, LDS produces larger CHTCs, rates of heat transfer for individual bricks, and the ratio of heat transfer to pumping power than HDS by 24.53%, 35%, and 34%, respectively. Moreover, LDS produces more homogenous heating of the setting bricks than HDS as the maximum difference of CHTCs between bricks is about 4.39% for LDS and 19.62% for HDS. The best performance of the firing process is accomplished at low inlet air velocity (3 m/s), whereas the highest productivity is achieved at high inlet air velocity (9 m/s).

Gypsum efflorescence on clay brick masonry: Analysis of potential efflorescence origins

Gypsum efflorescence on clay brick masonry is a growing problem, leading to a persistent grey-white staining of masonry facades. Gypsum efflorescence has been reported in the United Kingdom, the Netherlands and Belgium, with a specific occurrence on masonry facades erected over the last few decades. This article investigates the origin of this recent occurrence of gypsum efflorescence, with accelerated testing of the gypsum efflorescence sensitivity of separate and combined masonry components. It is demonstrated that both brick and mortar may provide a gypsum source, respectively, via the dissolution of anhydrite and the carbonation of ettringite. Neither does however directly result in gypsum efflorescence, as the released gypsum commonly subfloresces below the brick surface. The efflorescence is instead triggered by mortar admixtures, the application of which has indeed risen strongly in recent decades. Avoiding gypsum efflorescence on clay brick masonry hence requires an inert alternative for the mortar admixtures.