Development Of Mortar Research Articles

Weather ageing effects on the long-term thermal conductivity and biological colonisation of thermal insulating mortars with EPS, cork and aerogel

The use of thermal insulation materials in the opaque walls is one of the best strategies toward the improvement of the thermal performance of the building envelope, thereby contributing to increase the energy efficiency of the built environment. In this context, an increasing number of studies are focusing on the development of mortars with enhanced thermal performance, i.e., thermal insulating mortars. However, considering the innovative character of these materials, reliable data on their long-term performance is still lacking, particularly concerning the thermal performance and suitability to refurbishment works. The aim of this paper is to evaluate the long-term thermal conductivity and biological colonisation of industrially produced and experimentally designed thermal mortars with EPS, cork and silica aerogel aggregates. The long-term performance of the mortars was assessed prior, during and after exposure to three accelerated ageing tests including elevated temperature, freeze–thaw cycles and high humidity levels. For each test, an empirical model (i.e., Arrhenius law, Peck model, and Coffin-Manson equation) was used to compute the acceleration factor, thus allowing to correlate the accelerated and natural ageing results and to estimate the degradation levels that would be obtained after 10 years of exposure to natural weather conditions. The results of the thermal conductivity show that a maximum increase of 10 % and 30 % can be obtained after ageing for the industrially produced and experimentally designed mortars, respectively. Moreover, all mortars were susceptible to mould growth, with the greatest biological colonisation levels obtained after the high moisture content ageing for the experimentally designed mortars.

Produção sustentável de argamassa com substituição parcial do agregado miúdo por embalagens cartonadas trituradas

ABSTRACT Post-consumer carton packaging has the potential to be utilized as raw material in the manufacturing of new products. This research analyzed the performance of partially replacing fine aggregate with Powdered Carton Packaging Waste (PCPW) in mortar development through of collection, preparation, and milling of carton packaging, as well as the characterization of raw materials. Reference and experimental compositions were defined, followed by the execution of technological tests and analysis of the results. X-Ray Fluorescence (XRF) and Scanning Electron Microscopy (SEM) were used to characterize the by-product, PCPW, through chemical analysis. A reference ratio of 1:6 between the volume of cement and fine aggregate was adopted, while Experimental Compositions were determined with substitutions of 5%, 10%, and 15% of the aggregate volume with PCPW. These compositions were molded and tested using five cylindrical specimens per composition. The produced material exhibited consistency within normative parameters. The strengths of the three compositions with replacement fell within the range of 7.57 MPa, 6.52 MPa, and 6.07 MPa, respectively. Water Absorption by Immersion showed satisfactory results. SEM analysis of the fractured surfaces revealed the presence of empty spaces and microfissures in the samples with the highest percentages of PCPW.

Development of Mortars That Use Recycled Aggregates from a Sodium Silicate Process and the Influence of Graphene Oxide as a Nano-Addition.

This research analyses how different cement mortars behave in terms of their physical and mechanical properties. Several components were necessary to make seven mixes of mortars, such as Portland cement, standard sand, and solid waste from a factory of sodium silicate, in addition to graphene oxide. Furthermore, graphene oxide (GO) was selected to reduce the micropores and increase the nanopores in the cement mortar. Hence, some tests were carried out to determine their density, humidity content, water absorption capacity, open void porosity, the alkali-silica reaction, as well as flexural and mechanical strength and acid resistance. Thus, standard-sand-manufactured mortars' mechanical properties were proved to be slightly better than those manufactured with recycled waste; the mortars with this recycled aggregate presented problems of alkali-silica reaction. In addition, GO (in a ratio GO/cement = 0.0003) performed as a filler, improving the mechanical properties (30%), alkali-silica (80%), and acid resistance.

“Solid industrial waste generation and its valorization in developing sustainable building materials- A state of the art review”

Eco-efficient product development is going to be essential for the construction industry from the sustainability point of view as one way it lower down the environmental burden and another way it emphasizes on solid waste management to protect the mother nature. This study is intended to carry out the literature review to identify the various waste which has been used in mortar developments in 21st century (from year 2000 to year 2022). Waste has been selected from various industry i.e. Glass Waste, Marble Waste, Sandstone Waste, Limestone, Plastic Waste, Wood Waste, Construction and Demolition Waste, Ceramic Waste, Sludge from treatment Plants, Shell Waste, Rubber Waste, Bio Waste, Ashes etc. the literature review shows that these wastes can be utilized in the mortar development with a certain quantity as a substitute to fine aggregate or Natural Sand. The amount of substitution depends on the various parameter of the waste i.e. Physical, Chemical, morphological characteristics along with the ease of production, Transportation, Durability etc. in recent time most predominantly used waste in mortar development is found to be Glass Waste, Manufacturing Industry Waste, Construction and Demolition Waste and ceramic Waste. The literature collected for two decades from year 2000 to year 2022 has suggested optimum fraction of sand substitutions as 20% to 30% subjected to fresh and hardened properties, Durability, Morphological consideration, Microstructural Assessment. The ideal and most commonly used fraction of waste for mortar development can also be determined.

Contribution of fly ash to mortar strength development under steam and internal curing

The purpose of this study is to quantitatively evaluate the effects of steam curing and internal curing on contribution of fly ash to strength development of mortar by using cementing efficiency factor (k-value) that represents strength development performance as a binder of fly ash. In addition, the pozzolanic reaction of fly ash was evaluated from the viewpoint of calcium hydroxide consumption by using thermogravimetry and differential thermal analysis as well as the degree of fly ash reaction by using selective dissolution method. The result indicated that steam curing improved early compressive strength and internal curing improved compressive strength and k-value at all ages. Also, a linearrelationship between the degree of fly ash reaction and the k-value was shown regardless of the age and the replacement ratio of fly ash.

Mechanical and durability assessment of cement-based and\xa0alkali-activated coating mortars in an aggressive marine environment

Coatings are used as practical solutions against the intrusion of corrosive ions into concrete structures, particularly, in the harsh marine environment. In the present study, the effectiveness of using cement-based and geopolymer-based coatings produced using by-product materials has been evaluated. Silica fume and GGBFS at their optimum dosages were incorporated into mortar mixtures as a cement replacement, and mixtures of NaOH or KOH and sodium silicate solutions were used in the alkali-activated mortars. Shrinkage test, RCMT, and capillary absorption test as common experiments for durability analysis, as well as tests related to the mechanical and bonding properties including compressive strength test, pull-off test, and shear bonding strength test were carried out on the specimens. According to the results, both geopolymer and cement-based mortars improved the compressive and bonding strengths, and chloride diffusion resistance of coatings compared to the OPC mortar. Silica fume was found to be more effective in the strength development of mortars at young ages, while GGBFS was more responsible for acting as a filler and producing further gel in the older ages. The major drawback with geopolymer mortars is the high rate of water absorption and shrinkage coefficient in the early hours, which shows the importance of curing of these mortars at young ages. Overall, the mix design produced with 30% GGBFS and 7.5% silica fume showed the highest durability and mechanical properties and proved to be more compatible with the harsh environment of the Persian Gulf.

Evaluation of Mechanical and Shrinkage Behavior of Lowered Temperatures Cementitious Mortars Mixed with Nitrite-Nitrate Based Accelerator.

Recently, calcium nitrite (Ca(NO2)2) and calcium nitrate (Ca(NO3)2) have been increasingly used as the main components of salt- and alkali-free anti-freezing agents, for promoting concrete hydration in cold-weather concreting. With an increase in the amount of nitrite-based accelerator, the hydration of C3A, C3S, and βC2S in the cement is accelerated, thereby improving its early strength and effectively preventing the initial frost damage. Meanwhile, with an increase in the amount of nitrite-based accelerator, the expansion and shrinkage of the concrete—and, therefore, the crack occurrence—are expected to increase. In this study, various experiments were conducted on shrinkage, crack initiation, and the development of mortar containing a considerable amount of a nitrite-based accelerator. The result confirmed that, as the amount of nitrite-based accelerator was increased, the shrinkage was increased, and cracking in early age was more likely to occur, compared to the cases without the addition of this accelerator.

Multifunctional wall coating combining photocatalysis, self-cleaning and latent heat storage

Mortars, one of the most common construction materials, have not received any substantial modification for many decades. This has changed in recent years; new compositions are now being developed, with new properties, using nano-additives, fibres and capsules. In this work, surfaces with new and innovative functionalities that promote energy savings and improve air quality have been developed and studied. Incorporation of phase change materials (PCM) and titanium dioxide (TiO2) nanoparticles in construction products is currently under study by different research groups. However, these studies only address their incorporation separately. Adding new additives into the mortar’s matrix can be complex—due to microstructural modifications that will influence both fresh and hardened state properties. Moving from a single additive to multiple additions, as in this study, increases the system’s complexity. Only with a good understanding of the microstructural properties, it is possible to add multiple additives (including nano and microparticles) to mortars, without damaging its final quality. This work demonstrates that a higher additive content is not always a guarantee of better results; lower additions can often provide a better compromise between performance and final mechanical properties. The results presented in this paper confirmed this and show that combining PCM microcapsules and TiO2 nanoparticles open a new path in the development of mortars with multiple functionalities. In this study, a new material with depolluting, self-cleaning and heat storage was created. For the development of new and innovative mortars, a proper balance of multiple additives, supported by the study of microstructural changes, can lead to an optimization of the compositions, ensuring that the mortar’s final properties are not affected.

The impact of lithium nitrate on the physical and mechanical properties of Portland cement)

The effectiveness of lithium nitrate as a chemical additive which reduces the negative effects of alkali aggregate reaction was subject to research by scientists in many centres around the world. The literature data on the impact of lithium nitrate on the physical and mechanical properties of cements are rare. Without a precise definition of the impact of lithium nitrate on the cement properties, it is extremely hard to determine its real advantages in practical usage. In this paper, studies were undertaken to assess the impact of LiNO3 on the properties of pastes and mortars with Portland cement. The rate of hydration of the cement with lithium additive was examined by isothermal calorimetry, measurements of setting time and phase composition of cement pastes in the initial stages of hydration. The influence of the admixture on the compressive strength development of mortars after 2, 7 and 28 days of hardening was also researched. Results indicate that lithium nitrate accelerates the early hydration of Portland cement, affecting the precipitation of hydration products. The compressive strength of mortars with lithium admixture decrease after 28 days, although 2 an 7-day strength were greater than the control mortars.

Eco-efficient mortars with incorporation of phase change materials

Nowadays, the construction is one of the main European sectors responsible for the high levels of energy consumption and raw material extraction. Increasingly, the energy consumption from renewable sources and industrial waste reuse are the only ways to minimize these environmental and societal problems. Simultaneous incorporation of phase change materials and fly ash in the mortars increases the energy efficiency and decreases the waste materials landfilled. The development of mortars with phase change materials and fly ash incorporation contributes to a significant improvement of the building comfort parameters and the environmental quality. The phase change materials possess the capability to normalize the temperature flux inside the buildings, using the solar energy as resource. The main purposes of this study were the physical, mechanical, and thermal characterization of mortars with phase change materials and fly ash incorporation. It was concluded that the phase change materials and fly ash simultaneous incorporation leads to homogeneous and suitable mortars with increased thermal behavior compared with the phase change material addition alone.

Effect of Corrosion Inhibitor on the Compressive Strength of Polymer-Modified Cement Mortars

This study examined initial flow and compressive strength development of polymer-modified cement mortar according to the addition of corrosion inhibitor. Test results showed that with the increase of the amount of corrosion inhibitor, the initial flow of mortars increased whereas compressive strength decreased. The strength development of mortar specimens could be reasonably predicted using the modified ACI 209 equations.

Influence Of Volcanic Scoria On Mechanical Strength, Chemical Resistance And Drying Shrinkage Of Mortars

Abstract In the study, three types of cement have been prepared; one CEM I type (the control sample) and two blended cements: CEM II/A-P and CEM II/B-P (EN 197-1), each of them with three replacement levels of volcanic scoria: (10 %, 15 %, 20 % wt.) and (25 %, 30 %, 35 % wt.), respectively. Strength development of mortars has been investigated at 2, 7, 28 and 90 days curing. Evaluation of chemical resistance of mortars containing scoria-based cements has been investigated through exposure to 5 % sulphate and 5 % sulphuric acid solutions in accordance with ASTM C1012 & ASTM 267, respectively. Drying shrinkage has been evaluated in accordance with ASTM C596. Test results showed that at early ages, the mortars containing CEM II/B-P binders had strengths much lower than that of the control mortar. However, at 90 days curing, the strengths were comparable to the control mortar. In addition, the increase of scoria significantly improved the sulphate resistance of mortars. Further, an increase in scoria addition improved the sulphuric acid resistance of mortar, especially at the early days of exposure. The results of drying shrinkage revealed that the CEM II/B-P mortar bars exhibited a greater contraction when compared to the control mortar, especially at early ages. However, drying shrinkage of mortars was not influenced much at longer times.

Development of a novel mortar for use with unfired clay bricks

Interest in traditional unfired clay building materials, including cob, earth brick, and rammed earth, has grown in the UK in recent years. Although the use of vernacular techniques, such as cob and rammed earth, has raised the profile of earthen architecture, a wider impact on modern construction is more likely to come from modern innovations such as unfired extruded clay masonry units and premixed plasters. Traditional unfired clay walls often have basal widths of 300 mm or more, providing an inherent stability and resistance to toppling through self-weight. Masonry units extracted from UK brick production lines before the firing process are typically 100 mm wide, which requires good mortar-brick bond strength to meet structural robustness requirements in a typical 2.4 m high wall. In testing, traditional mortars based on clay, cement or lime, have not provided sufficient strength. This paper examines the bonding of unfired clay units with unconventional mortars based on novel binders. It reports on the development of a mortar which appears to be suitable for a wide range of clay types. This mortar can be readily recycled and has a carbon footprint lower than many alternative binders. Results of long-term bond strengths and the structural performance of masonry walls are given, which demonstrate the suitability of this mortar for use with unfired clay masonry units.

Activation Alkaline Waste Kaolin for Fabrication of Building Blocks

In the state of Paraíba, one of the activities of great economic importance is that of the kaolin processing industry. This type of processing generates large amounts of waste that are displayed randomly in the environment, which has attracted attention, because the environmental impact caused by it and the lack of established process of recycling. The University Federal o Paraíba has been developing several research to explore the potential for recycling of industrial waste from Paraíba, mainly waste of kaolin. This research have pointed to the feasibility of using waste as aggregate and pozzolan in the development of mortars use multiple. These wastes have different size fractions, depending on the stage of processing: a sandy (termed in this study of RGC) containing mainly quartz, mica and calcite; and other clay (termed in this study of RFC) is thinner, containing higher amounts of kaolinite. This study aims to evaluate the potential of alkaline activation from waste kaolin (RGC and RFC) by comparing the activation using sodium silicate and hidroxide of calcium. With the objective of studying the potential of waste as a material pozzolanic, it was processing through grinding at 80.000, 60.000, 40.000, 20.000 and 10.000 rotations and with the purpose of evaluating the reactivity of materials, these wastes were calcined at 750°C/2h. For the mechanical characterization was using an equipment universal testing of Shimadzu Servopulser, where it was observed that only RFC, when calcined, developed strength in both activations, and the activated with silicate sodium with higher strength. The RGC, both in the state in natura and calcined did not show satisfactory mechanical strength to the test under the conditions of synthesis used in this research. Thus, the waste RFC's studied in this work has the potential to be used as constituent materials for building blocks in terms of its mechanical properties.

Physico-mechanical and microstructural characteristics of historic and restoration mortars based on gypsum: current knowledge and perspective

Abstract The use of gypsum based mortar can be traced back over 4500 years. In Germany, in the vicinity of natural gypsum outcrops, in addition to lime mortars, calcium sulphate based mortars were widely used for joints in exterior walls of sacred buildings. There are several medieval buildings with well-preserved calcium sulphate-based mortars. The high water solubility of gypsum (CaSO 4 •2H 2 O) is a disadvantage that makes it difficult in general to handle calcium sulphate based building materials in areas exposed to weathering. Physico-mechanical as well as mineralogical investigations of historic calcium sulphate based mortars have shown that long-term weathered mortars have a much denser microstructure, larger average grain sizes, and a higher compressive strength than laboratory prepared mortars. Porosity models of these mortars will be presented which are helpful to prepare calcium sulphate based mortars with a higher water resistance for restoration purposes. The reason for the change of crystal size and morphology as well as of porosity and strength can be explained by crystallization and recrystallization processes of these calcium sulphate based mortars, as a consequence of long-term weathering. Since it is obvious that crystal size and its distribution have an enormous effect on the weathering resistance, the development of mortars with comparable structural properties is of present interest. In current use are chemical additives which modify the morphology and size of gypsum crystals of set mortars. Another possibility to influence the weathering resistance is the addition of hydraulic and/or latent hydraulic admixtures.

Influence of Aggregates on the Strength and Elastic Modulus of High Strength Mortars Containing Microsilica

AbstractThe strength development of mortars made with a high strength paste containing microsilica was investigated as a function of aggregate type and content. Strength could be modelled using composite theory; the predicted strengths of the paste and aggregate component reflected the influence of the cement-aggregate bond. Scanning electron microscopic examinations gave a qualitative idea of the extent of bond failure, which correlated satisfactorily with the predicted behavior. The modulus of elasticity for SiC mortars could be predicted well by Hirsch's model or the aggregate model.