Types Of Mortars Research Articles

Exposing Sustainable Mortars with Nanosilica, Zinc Stearate, and Ethyl Silicate Coating to Sulfuric Acid Attack

Obtaining durable materials that lengthen the service life of constructions and thereby contribute to sustainability requires research into products that improve the durability of cementitious materials under aggressive conditions. This paper studies the effects of sulfuric acid exposure on four mortar types (control mortar, mortar with nanosilica, mortar with zinc stearate, and mortar with an ethyl silicate coating), and evaluates which of them have better performance against the acid attack. After 28 days of curing, the samples were exposed to a sulfuric acid attack by immersing them in a 3% w/w of H2SO4 solution. Physical changes (mass loss, ultrasonic pulse velocity, open porosity, and water absorption), and mechanical changes (compressive strength) were determined after the sulfuric acid exposure. A scanning electron microscope (SEM) was used to characterize the morphology of the surface mortars after the exposure. The control mortar had the highest compressive strength after the acid attack, although of the four types, the zinc stearate mortar showed the lowest percentage of strength loss. The zinc stearate mortar had the lowest mass loss after the acid exposure; moreover, it had the lowest capillary water absorption coefficient (demonstrating its hydrophobic effect) both in a non-aggressive environment and acid attack.

Evolution of mechanical properties in aerial lime mortars of traditional manufacturing, the relationship between putty and powder lime

In recent years, numerous studies have been published on the technology of industrial aerial lime mortars. These papers refer to the incidence of carbonation process and mechanical behavior in its properties as construction material, of interest for its application in Cultural Heritage conservation. Among other issues, the importance of the type of aggregate (composition and granulometry) and relation binder/water (B/W) in its properties are highlighted. There are fewer papers in which the type of lime is about, especially on the basis of its manufacturing process (traditional or industrial), on the presentation of the product (powder or putty), or referred to the different types of mortars (prepared in situ or pre-dosed). In this paper, the behavior of aerial lime mortars elaborated with traditional lime has been determined and a comparative study has been carried out with pre-dosed mortars of powder (mCL) and in putty (mSPL) lime for its application in render mortar (B) and plaster mortar (F). The control parameters have been mechanical resistances-elasticity, ultrasound velocity, carbonation process and distribution pore size and surface area by mercury porosimetry. It is concluded that the behavior of traditional lime mortars, both in putty and powder, depends on the B/W ratio, the type of aggregates and the lime content. The importance of the application of the product in the building as the behavior of the mortar is very sensitive to kneading water content it shows; aspects that define the plasticity of the mortar. It is also concluded that the carbonation of traditional lime mortars is not slow and that, under optimal dosages conditions, can be finished before 90 days. It is also verified that a higher carbonation rate does not imply better properties of the mortar in its long-term construction. The utility of ultrasound velocity test as a non-destructive test and easy to apply on building for the quality control of traditional lime mortars and its consistence values it highlights, as is a macroscopic property of easy control during the elaboration of the product.

Overall stabilization of underground workings in limestone-shells

The characteristic properties of limestone-shell used as the base of foundation are described. Using the example of multi-storey residential building design, comprehensive solution has been proposed for plugging workings in an array of limestone-shell for the subsequent construction of slab-pile foundation, which includes engineering and geological surveys, geotechnical design, the choice of mortars and their compositions, as well as continuous monitoring plugging conditions. It is stated that two types of cement-sand mortar are used for plugging workings: the first is with the addition of superplasticizers, which provide high solution mobility, low water loss and non-shrinkage after hardening; the second is without adding superplasticizers with fluidity high degree. The results of laboratory studies to select the composition of soil-cement are given.

The laboratory analyses for the plasters prepared with river sand aggregate and hydraulic lime binder

In historical building restorations, the selection of mortar mixture type should be determined in accordance with particularrequirements of the historical buildings. In this study, it has been examined that how the sound absorption coefficients of plaster layers can be increased in ways that are compatible with the historical structures. In the scope of lab analyses, mixtures produced with river sand aggregate and hydraulic lime binder were examined. Material properties of samples were investigated by means of the experimental analyses which can be listed as sound absorption, open porosity, capillarity of water absorption, flexural and compressive strength. The effects of the binder ratio and aggregate particle size range in mortar mixtures were investigated in order to increase the sound absorption in the plaster layer. Moreover, the effects of polypropylene fiber, flax fiber and crumb rubber additive were investigated as well. After the measurement results are obtained, the outcomes of the experiments were discussed. In this research, it is demonstrated that the sound absorption can be increased by the content of the mixture. Especially, it is observed that the reduction of the binder ratio in the mixture may increase sound absorption and the use of very fine aggregates in the mixture can adversely affect sound absorption. In brief, a systematic research was carried out in order to increase sound absorption coefficients in accordance with the content of the plasters used on historical buildings.

Influence of Boron Carbide Addition on Performance and Neutron Shielding Ability of Cement Mortar Mix

Renewable source of energy is the best form of consumable energy that can be harnessed from the earth’s available resources in a sustainable manner. Nuclear energy obtained from nuclear fission reactions from the nuclear reactors is an example of such kind of energy, but deeply requires caution in the handling of operations. Leakage of fast moving high energy neutrons creates harm to both the environment and mankind and hence should be shielded from all available means. One such effort to shield this high energy radiation is by using boron carbide infused cement mortar that can be used for plastering and other similar applications in the construction of nuclear reactors. The strength and performance based characteristics of such type of mortar are studied and improved by adding super-plasticiser and pozzolanic materials like microsilica and metakaolin. Also durability studies like alkalinity, water absorption etc are done to analyse the lifetime of the design mix. EDS and SEM analysis were also performed extensively to study the microstructure of the casted specimen and to analyse the elemental composition cum distribution (by EDS mapping) for the calculation of the neutron attenuation of the specimen mix. Based on these an optimum combination is arrived at for practical applications that has a desirable strength, performance, durability and neutron shielding property.

Critical studies on bond strengths of masonry units

Performance of masonry is normally attributed to compressive strength of individual units, water absorption of individual units, strength of masonry mortar and the bond between mortar and individual units. Many researches in the past have contributed towards the bond strength and relevance of compressive strength of mortar in achieving good bonds. However, the quality of bricks available in India significantly vary from region the region. Thus, a need is felt in understanding bond strength of masonry. In this paper three types of mortars(total nine combinations), two types of bricks (red clay brick and fly ash brick) are considered, tests such as compressive strength, water absorption of the bricks, compressive strength of various mortar combinations, flexure bond strength and shear bond strength are presented. Failure patterns of the masonry units are also discussed. Results of the two tests show noticeable variation in bond strengths, however the shear bond strength has significant relationship with the compressive strength of mortar. The research outcome also points towards using bricks in saturated condition for achieving adequate performance.

Cesium diffusion in mortars from different cements used in radioactive waste repositories

Cement-based materials are widely used for stabilizing and conditioning radioactive waste in low- and intermediate-level repositories.In this study, the adequacy of four different types of mortars, obtained from four different commercial cements, CEM I, II and IV (A and B), to act as barrier to 137Cs migration was analysed. Diffusion experiments using the in-diffusion (ID) method with constant tracer concentration in the reservoirs were carried out, at increasing experimental times (150, 380 and 1500 days approximately).In the experiments of less duration, and especially in CEM II and CEM I, two different pathways for diffusion were identified (fast and slow), leading to a double porosity system. However, the “fast” contribution to Cs diffusion, in all cases, could be neglected at larger experimental time, indicating a rearrangement of the pore structure that becomes more tight and homogeneous over time. Thus, if the experiments last enough time, only one diffusion coefficient properly describe Cs transport in these systems.Apparent diffusion coefficients, Da, obtained for Cs, range between 6.0·10−13 and 1.0·10−14 m2/s. Mortars produced with CEM IV (A and B) are the most efficient barrier for cesium transport, amongst those analysed in this study. Mortars with CEM II, which contain blast furnace slag, present the highest diffusion coefficient.

Accelerating carbonation in lime-based mortar in high CO2 environments

To accelerate the carbonation of lime, mortar samples were cured in chambers with high CO2 concentration. Two types of lime mortar were prepared, which are similar to Roman mortar types: lime and standard sand (M1) and extra ceramic dust and fragments (M2). After demolding, half of the samples were placed in the climate chamber where conditions were constant (20 °C, 60%, 1600 ppm) for six months, and the rest were left in laboratory conditions (25 °C, 34%, 703 ppm). The carbonation of the samples was evaluated at 28, 90, 120 and 180 days as well as microstructural, physical, hydric and mechanical properties. CO2 curing had pronounced effects on both types of mortar. M2 mortar samples showed advanced calcite precipitation and early improvement in various properties. At later stages, cracks caused drops in those properties.

Lime-cement mortars designed with steelmaking slags as aggregates and validation study of their properties using mathematical models

In this paper, ecological masonry mortars as a new building material are design, using a mix of calcium lime and Portland cement as binder, together with steelmaking waste aggregate (Electric Arc Furnace Slag and Ladle Furnace Slag), in substitution of natural aggregate and, subsequently a comparative study was made using mathematical models. To do so, different reference mortar types were prepared with various proportions of calcium lime CL-90-S and Portland Cement CEM I 42.5 R as binder, together with a natural siliceous aggregate. Subsequently, and separately, the natural siliceous aggregate (NA) was progressively substituted by LF and EAF slags. The mixtures designed were analyzed in the laboratory through characterization tests (European Standard), and a comparative study was made with the reference mortars. Surface Response Methodology (RSM) was applied to test whether the mathematical model could acceptably predict the behaviours of these types of mortars, analytical process that allow predicting the behaviour of a material without having to complete the entire series of necessary laboratory tests. Comparing the results obtained in the laboratory and those estimated through mathematical models RSM of each of the properties, it can be affirmed that the methods of mathematical prediction were useful for the study of these ecological mortars for use in construction.

Experimental study of expanded polystyrene (EPS) External Thermal Insulation Composite Systems (ETICS) masonery façade reaction-to-fire performance

External Thermal Insulation Composite Systems (ETICS) consisting of insulation core and decoration surface materials, are quite common in new constructions and refurbishment buildings with design-oriented goals of sustainability and energy efficiency. However, combustible insulation core has caused serious result due to the ravages of fire disasters. Thermoplastic expanded polystyrene (EPS) acting as an insulation core is widely and vertically installed in ETICS. Presently, with an aim to evaluate EPS ETICS fire performance, a series of EPS ETICS specimen varying EPS thickness from 50 mm to 300 mm, polymer mortar type including SBR polymer mortar and acrylic resin mortar, reinforcement including one layer and two layer’s glass fiber mesh, and opening edge treatment method differs from back-wrapping method to fire barrier method are tested by a large-scale Japanese façade fire propagation method JIS A 1310 with heating intensity from 100 kW to 1100 kW. A comprehensive fire risk evaluation INDEX method of EPS ETICS based on EPS burn area and façade surface temperature profiles of JIS A 1310 tests is proposed. It could easily classify the effects of mortar, reinforcement, EPS thickness and opening edge treatment method on EPS ETICS fire performance. It is concluded that in JIS A 1310 method, the fire risk of EPS ETICS could be classified by INDEX method as the followings: the INDEX ≤ 0.825 is an acceptable level; the INDEX ≥ 0.836 is the unacceptable level; 0.825 ≤ INDEX ≤ 0.836 is the critical level. The fire propagation index (FPI) is believed to be a potential prediction method for EPS ETICS fire risk evaluation before JIS A 1310 tests. The FPI is classified as the followings: the FPI ≤ 17.3 is an acceptable level; the FPI ≥ 21.4 is the unacceptable level; 17.3 ≤ FPI ≤ 21.4 is the critical level.

Effect of microwave heating damage on the electrical, thermal and mechanical properties of fibre-reinforced cement mortars

Nowadays, refurbishing of existing structures has gained interest in order to reduce both the construction materials used and the construction and demolition waste production. For that purpose, there are several methods for demolishing the damaged parts, but most of the alternatives involve high noise and dust production, which are in contraposition when structures are in urban areas. Among all the existing methods, this paper studies the possibility of using microwave heating as a demolition method, either by damaging the bulk material or the mortar to concrete interface. With that in mind, the effect of microwave heating time (range 120–600 s) on the physical, thermal, electrical, mechanical and bonding properties of steel fibre-reinforced and non-reinforced cement mortars was analysed. The aim of the paper is to establish possible correlations between the mentioned properties and the damage level caused by microwave heating. Although the results prove that pore pressure increment due to microwave heating can cause the reduction of flexural strength up to the rupture of the specimens, this fact cannot be extended to all the properties or mortar types. The fibre reinforcement plays a key role to restrain the damage. Thermal conductivity and electrical resistivity are obviously different in reinforced and non-reinforced mortars due to the inclusions of the metallic fibres. However, after undergoing microwave heating those properties were not noticeably altered nor follow a trend linked to the heating time. It is assumed that the water migration and evaporation processes are the main cause. Although the flexural strength reduction was gradual for non-reinforced mortars until total failure, the reinforced specimens only showed a 13% of reduction for the first 120 s, remaining almost constant afterwards. Although it was proved that the fibres increase the temperature on the specimen surface and its adhesion to the matrix is altered, their crack bridging effect overcomes further damage.

Revisiting the ASTM C876 standard for corrosion of reinforcing steel: On the correlation between corrosion potential and polarization resistance during the curing of different cement mortars

This paper presents a probabilistic analysis of almost 700 potential and polarization resistance measurements of reinforcing steel embedded in 15 types of mortars of different nature and chloride contamination levels exposed to controlled conditions of temperature and relative humidity. Besides indicating that the ASTM C876 standard can be a robust and reliable commissioning tool for strategic assets in terms of effectiveness of reinforcing steel passivation, results show that the polarization resistance values follow different probability density functions at different potential levels, which means they do correspond to distinct interfacial processes.

Use of uncontaminated marine sediments in mortar and concrete by partial substitution of cement

The disposal of dredged marine sediments has become a major economic and environmental issue in the world. In this study, uncontaminated marine sediments dredged in the harbor of Dunkirk (France) were dried and ground and then used in partial substitution of cement in the manufacture of mortars and concretes. A given volume of cement has been replaced by the same volume of sediment for three substitution contents (10%, 20%, 30%) of a Portland cement CEM I 52.5. The flexural and compressive strengths of mortars decreased when the sediment replacement content increased. However, the mechanical properties of the mortar with 20% replacement of cement with sediments were better than those of a mortar made from cement CEM II/A-LL 32.5 containing a proportion of limestone similar to the sediment substitution. The total porosity measured by mercury intrusion porosimetry of different types of mortars showed that the porosity increased as the sediment substitution content increased but the pore size distribution was shifted toward smaller pores. Finally, it was demonstrated that concrete C30/37 could be designed with 20% cement replaced by sediment without the use of admixture. Additionally, this concrete fulfilled the standards with respect to the total chloride content required for unreinforced concrete. As a conclusion, dried and finely ground uncontaminated sediments appeared to be a very interesting constituent for partially substituting up to 20% of cement as its efficiency overpass limestone filler.

Performance of single skin masonry walls subjected to hydraulic loading

Property owners are facing increasing threats from flooding and in response are likely to turn to products designed to waterproof or ‘seal’ the outside of the building in an effort to prevent the ingress of flood water. However, very limited research has been conducted on the effect of this sealing action and the consequent hydraulic load acting upon the structure of the building. The theoretical safe application of waterproofing products has been suggested to be between 0.6 and 1 m (published guidance suggests 0.9 m), although the experimental evidence supporting these suggestions is either absent or limited in nature. This paper presents the findings of an experimental programme that has examined the effect of out-of-plane hydrostatic loading on masonry walls typical of domestic or commercial buildings. The study, conducted at 1/6th scale using a geotechnical centrifuge considers wall panels constructed from a variety of masonry units (autoclaved aerated concrete block, brick and brick-block) bound together with two different types of mortar. The wall panels were subject to an axial load representative of 1 storey of loading and were simply supported on all 4 sides. The load—out-of-plane deflection response of the panels was captured by a 3D digital image correlation system, and the water level at failure was compared to that predicted from previous research and the established yield line analysis method with encouraging results. When partial material and load factors were taken into consideration the results illustrated that a safe sealing height of 0.9 m, as quoted in the literature, would generally be inappropriate, whilst the safe sealing height of 0.6 m was not suitable for every case investigated. This supports the need for a suitable approach for the calculation of water levels at failure rather than the use of fixed values given in published literature.

A review on properties of fresh and hardened geopolymer mortar

Geopolymer mortar refers to the mortar manufactured with sand and geopolymer, which is composed by the base materials containing affluent aluminium and silicon that was activated by adopting alkaline solution to serve as a binder. The investigation of the properties and application of the geopolymer mortar has attracted more and more attention of the researchers and cement based industries because of its sustainability advantages. This study reviews the properties of the geopolymer mortars including fresh performance (workability, setting time, and temperature of fresh mortar), physical properties, mechanical properties (compressive strength, tensile strength , elastic properties, flexural performance, bonding behavior, and fracture behavior), durability properties (acid resistance, resistance to elevated temperature, frost resistance , water absorption, and shrinkage properties) and microstructure analysis . This study also reviews the properties of different types of geopolymer mortars prepared using various source materials as base materials. The current study results indicate that the geopolymer mortar has exhibited significant feasibility and application prospect to be used as an environmental friendly building material, which may be an appropriate replacement to the traditional cement mortar in the future. • 119 papers are reviewed on the properties of geopolymer mortars. • Fresh and physical properties of geopolymer mortars are discussed. • Mechanical properties and durability of geopolymer mortars are also addressed. • Microstructure analysis of geopolymer mortars is reviewed.

Metakaolin-based geopolymer mortars with different alkaline activators (Na+ and K+)

In this study, the influence of different alkaline activators (Na+ and K+) on the mechanical, thermal, and microstructural behaviors of metakaolin-based geopolymer mortars was investigated. Four types of mortars were manufactured, and the only difference between them was the alkaline-activating solution. Potassium and alkaline sodium silicates and potassium and sodium hydroxides were used in combination as the alkaline-activating solutions. Compressive strengths, indirect tensile strengths, and longitudinal moduli of elasticity of the mortars were evaluated along with thermal property analysis (thermogravimetric analysis and differential thermal analysis) and scanning electron microscopy (SEM). All the mortars exhibited similar compressive strength, >80 MPa, at 28 days. It was possible to observe a high gain in the mechanical strength in the early ages, which is characteristic of geopolymers. The increase in mechanical strength ranged approximately from 72% to 81% after 3 days and from 86% to 93% after 7 days with respect to the strength at 28 days. Mortars produced with alkaline sodium silicate exhibited a heterogeneous microstructure with a large number of pores, while those containing potassium silicate were denser and exhibited low porosity. Such different morphologies of the mortars are a result of the type of the alkaline cations used; their effect could also be perceived in the thermal performance of the mortars, with better performance induced by potassium silicate and potassium hydroxide.

Statistical analysis of test methods to evaluate rendering surface properties

Abstract The objective of this study is to discuss the results of two test methods used to evaluate rendering surface properties: the superficial tensile strength (STS) and the pendulum rebound hammer (which provides the rebound index - RI), besides evaluating, additionally, the tensile bond strength (BS). The studied variables were the type of mortar (job-site mortar and dry-mix mortar) and the render moisture at the time of testing (in four contents). For each test, a minimum of 45 determinations was planned per analyzed situation, totaling 1411 valid results, which allowed a consistent statistical analysis and an in-depth discussion of the methods. The STS and RI tests were sensitive at a 95% confidence level to differentiate mortars from different strengths and were therefore approved for this evaluation. The most significant effect in all statistical models tested was the type of mortar. The variable moisture condition of the render was significant only for the results of STS and BS. In such cases, tests performed with wet or saturated renders presented much lower strength results compared to those carried out with air- dried renders. It was possible to obtain a significant correlation between STS and BS, with a high coefficient of determination.

Evaluation of early age cracking in rendering mortars with polypropylene fibers

Abstract The incorporation of fibers in concrete produces an improvement in the characteristics of the material as observed in different studies. In order to obtain the same good results, fibers are added to rendering mortars to reduce some of their drawbacks. However, this type of mortar has some specific characteristics, such as hydrated-lime utilization or higher air, which is not usual in concrete. Thus, this study aims to evaluate the potential of polypropylene fibers to reduce early age cracking caused by restrained shrinkage in rendering mortars. Two types of mortars were used to verify possible differences in the way they responded to the introduction of fiber. The influence of the fiber content was also investigated. Mortars were evaluated in fresh state, and mechanical behaviors were measured at several ages. The restrained shrinkage cracking was followed for 21 days using the ring test method. The use of polypropylene fibers leads a smaller value of total crack width and a delay of the first crack. Also, the elastic modulus shows a higher correlation with the mortars crack width. Both parameters were successfully used to predict the mortars crack width. The ring test method may be a suitable test method to evaluate the capacity of fibers to control the crack formation in rendering mortars.

Stiffness plasticity degradation of masonry mortar under compression: preliminar results

Abstract The main goal of this research is to determine the mechanical properties of bedding mortar by assessing the mortar damage onset, the stiffness plasticity degradation and the apparent Poisson´s ratio under compression. Two mortar types, 1:0.5:4 and 1:1:6 (cement:lime:sand ratio), were used and tested at 28 days; specimens had diameter-to-height (d/h) ratios of 0.3 and 1.0. These diameter-to-height (d/h) ratios were chosen to evaluate the effect of confinement caused by the friction between the steel plates of the testing machine and the sample. Numerical models were developed, and their response compared with the experimental results. From the experimental results, it was concluded that there are meaningful differences in their responses with weak and strong mortar types and different d/h ratios. The d/h ratio influences the relationship between the stress and strength and the apparent Poisson´s ratio of the specimen, which is defined herein as the ratio of the horizontal to vertical strain, regardless of cracking of the specimen. The mortar damage onset and stiffness plasticity degradation for both mortar types and d/h ratio are different and depend on the stress/strength ratio level. All samples with a d/h ratio of 0.3 show a constant decrease in the volumetric strain until failure but with negligible expansion on the horizontal deformation. In contrast, samples with a d/h ratio of 1.0 present an increase of stiffness after development of the first crack, which causes the increase of the sample volume. Numerical simulation and experimental results for mortar 1:0.5:4 with a d/h ratio of 0.3 are similar until approximately 10 MPa, after which the numerical results diverge from the experimental results. For the d/h ratio of 1.0, the vertical strain results are also similar, but the horizontal strains results near failure are very different. The model can not represent the nonlinear increase of the horizontal strain near failure probably because the crack propagation and the stiffness plasticity degradation could not be controlled. For mortar 1:1:6, vertical strains from numerical and experimental results are similar, but again the model can not reproduce the nonlinear increase of horizontal strain near failure.

Technological and microstructural characterization of mortars and plasters from the Roman site of Qasr Azraq, in Jordan

This work presents the analytical results of the mortars and plasters characterization from Qasr Azraq, located in the city of Azraq (north-eastern Jordan). The castle has undergone several interventions and modifications during its service life; the archaeological surveys have shown that the actual building is a medieval reconstruction of a Roman fort, still reflecting the original structure. This research paper encompasses 64 samples from different historical periods and structures of the monument, aiming to reconstruct the timeline of different phases and to highlight technological choices. Conclusions are drawn on the basis of interpretation and integration of in situ observations, historical data and analytical data. The mortars were characterized following a multidisciplinary approach, combining macroscopic observation with petrographic examination, mineralogical analysis (XRD), microstructural and chemical analysis (SEM-EDS) and quasi-quantitative chemical analysis (pXRF) of mortar samples. Moreover, microstructural and mechanical properties of representative samples were studied. The results indicate the use of five different types of mortars, grouped based on composition and characteristics of binder and aggregates, ranging from pure lime mortars to hydraulic, gypsum-lime and earthen mortars. Overall, this paper contributes to the better understanding of building techniques and mortar production technology in the Near East during time.