Workability Of Mortar Research Articles

Proposal of New Natural Hydraulic Lime-Based Mortars for the Conservation of Historical Buildings

NHL mortars are known to be compatible materials for the conservation of architectural heritage. To improve their properties with regard to salt resistance and lower their carbon footprint, NHL-based mortars with salt inhibitor agents were studied and different formulations were produced: NHL-based mortars (MSs), composed of natural hydraulic lime; and sand and cocciopesto mortars (MSCs), in which NHL, sand and brick powder were admixed with two different products, diethylenetriaminapenta and chitosan, in different concentrations. The mortar performance was tested against freeze–thaw and salt crystallization through immersion–drying cycles in a 14% sodium sulfate solution. The results highlighted that the addition of cocciopesto was effective in increasing the salt resistance, but increased the water intake during the freeze–thaw tests. The use of DTPMP produced less thixotropic mortars and decreased the water uptake, but worsened the salt resistance of hardened mortars. Chitosan allowed a good workability of fresh mortar; its water uptake was similar to the reference mortar and slightly increased the salt resistance. In the cocciopesto samples, both additives reduced the weight variation during freeze–thaw tests; meanwhile, for the lime samples, the additives increased the weight variation during the final cycles.

Preparation and application of Na2SiO3@EC microcapsules for self-healing alkali-activated slag

Alkali activated slag (AAS) is a promising green building material, but its application has been limited by the high risk of cracking. In this study, the self-healing technology was used in AAS system by introducing self-healing microcapsules. The Na2SiO3@EC microcapsules were designed with sodium silicate (Na2SiO3) as the core material and ethyl cellulose (EC) as the shell material, and the prepared microcapsules were characterized by leaching test and SEM-EDS. The effect of microcapsules on the self-healing of AAS mortars was verified by the post-repair compressive strength test, and the mechanism was discussed based on MIP and hydration heat. The results showed that the core–shell structured Na2SiO3@EC microcapsules were prepared with a core content of 69.42 wt%. The addition of microcapsules could improve workability and mechanical property of AAS mortars. The AAS mortars with Na2SiO3@EC microcapsules had a compressive strength recovery ratio of up to 26.82%. The Na2SiO3 released from microcapsules promoted the secondary hydration of the AAS mortars, and the hydration products refined the pore structure. Image processing methods were effective in visualizing and quantifying the changes in the cracks, and the image results further confirmed the long-term effectiveness of the microcapsules. This study provides guidance on the application of self-healing microcapsules in the AAS system and the visualization of self-healing behavior.

Workability, physical & mechanical properties of the cement mortars strengthened with metakaolin and steel/basalt fibers exposed to freezing-thawing periods

Mortar samples' strength and durability properties can be improved by adding different pozzolanic materials and fibers to their mixtures against freeze–thaw (F-T) periods. For this purpose, metakaolin (MK) was used as a pozzolanic material in mortar mixtures by replacing 10% with cement. In the blends, hooked-end macro-steel (ST) fibers with 30 mm and 24 mm macro-basalt (BA) fibers were used in a single form and hybrid form with micro-basalt BA fibers of 6 mm in length. The study results showed that MK improved the strength and durability properties of the samples after the F-T periods. The primary reason is that MK filled the voids with the filler effect and formed calcium-silicate-hydrate (C-S-H) gels in the matrix due to its high pozzolanic activity. In addition, ST and BA fibers contributed positively to the improvement of the strength and durability properties of the samples after the F-T periods. This contribution is because ST and BA fibers effectively restrict the formation and development of micro- and macro-cracks originating from the F-T periods at the weak fiber/matrix interfacial zones. Besides, ST fibers improved samples' strength and durability properties in both single and hybrid use compared to BA fibers. In addition, using ST and BA fibers in hybrid form increases the samples' strength and durability properties slightly more than their single use. The most important reason is that micro-BA fibers play a crucial role in preventing micro-cracks formation in the inner structure due to F-T periods and their transformation into larger macro-cracks.

Influence of aluminum waste on the thermo-mechanical properties of lightweight composite mortars based on sand and recycled high-density polyethylene

The development of new construction materials must take into consideration several factors, including the environmental impact, cost price, mechanical performance and thermal comfort. The present study falls within this context. It essentially aims to valorize high-density polyethylene plastic waste as a fine aggregate in substitution of sand at 10% and 30% in order to produce lightweight composite mortars. The incorporation of aluminum waste (powder), which is as an expansive agent, was made at 0.5% and 1% of cement weight in order to further lighten the products that are primarily intended for thermal insulation. This study also seeks to investigate properties in the fresh state such as the workability of mortar, and other properties in the hardened state such as the density, the compressive strength and tensile strength by bending, and finally the thermal conductivity. The results obtained showed that the density of the product obtained decreased as a function of the rate of replacement of natural fine aggregates by high-density polyethylene and also of the aluminum content. In addition, it was observed that the mechanical strengths decreased while the thermal conductivity of the composite mortars obtained improved significantly by approximately 48% in comparison with that of the control mortar.

Combined Effects of Waste Glass and Nano-Silica Powder on Workability, Durability and Mechanical Properties of Fiber-Reinforced Self-Compacting Mortar

Combined Effects of Waste Glass and Nano-Silica Powder on Workability, Durability and Mechanical Properties of Fiber-Reinforced Self-Compacting Mortar

Investigation of Physical and Mechanical Properties of Cement Mortar Incorporating Waste Cotton Fibres

There is a lack of effective disposal methods for the increasing amount of textile waste that is being generated worldwide. This is creating environmental concerns and burdening waste management facilities. In this study, we propose that cotton fibres that have been recycled from textile waste could be used as fibre reinforcement in cement mortar. Seven mix designs were prepared, which were based on the quantity (0.4%, 0.8%, 1.6% and 2.0% by the weight of the cement) and length (20 mm, 30 mm and 40 mm) of the cotton fibres. The physical properties, including workability, compressive strength, flexural strength, density and water absorption, were investigated. The workability of the cement mortar was reduced with the addition of the cotton fibres. The flexural strength of the cement mortar with the added cotton fibres was improved by up to 9%, compared to the flexural strength of the control samples. The compressive strengths of the samples generally decreased with the increase in the fibre content and length. However, the C0.8 mix showed a comparable compressive strength to the control mix at all curing ages, with a slight decrease of 2.5% on day 56 of curing. The results were further clarified using SEM images. The improvement in the flexural properties showed that the cotton fibres could be implemented as fibre reinforcement in cementitious composites.

Analyzing Influence of Mix Design Constituents on Compressive Strength, Setting Times, and Workability of Geopolymer Mortar and Paste

Geopolymer concrete and mortar have evolved over the years as potential alternatives for reducing the greenhouse gases associated with cement production. This current research was aimed at investigating the optimum dosage and concentration of sodium hydroxide required to leach out silica and alumina oxides in the fly ash for geopolymerization to take place. Blackish grey fly ash from Morupule, Botswana, was synthesized by varying sodium hydroxide (NaOH) of 98% purity between 8 M and 14 M, respectively. The ratio influence of sodium hydroxide to fly ash in dissolving the oxides was carried out at the values of 0.55, 0.62, and 0.75. The results showed that the workability of the geopolymer mortar and paste decreased with the increase in the ratio of fly ash to alkaline activator. The highest workability was achieved at a ratio of 0.75 : 1. The compressive strength, setting time, and workability of geopolymer mortar and paste can be controlled by adjusting the ratio of fly ash to alkaline activator. A ratio of 1.5 : 1 was found to be the most suitable for achieving high compressive strength, while a ratio of 0.75 : 1 was found to be the most suitable for achieving high workability. Furthermore, the workability values were in the range of 105 to 143 mm, while the ranges of initial and final setting times were found to be between 280–350 and 950–1170 minutes, respectively. This study is significant because no previous study has carried out geopolmerization of the Morupule fly ash as a result of its unique characteristics. These findings have important implications for the development of sustainable construction materials. The main finding was that for optimum reaction to take place, and NaOH/fly ash ratio should be kept at 0.55 and molarity of 12 to avoid leaching of other oxides that might weaken the strength.

Cow Dung Ash in Mortar: An Experimental Study

This study investigated the impact of using cow dung ash (CDA) as a partial replacement for ordinary Portland cement (OPC) in mortar. Mortar mixes are prepared by replacing OPC with CDA at varying levels: 5%, 10%, 15%, 20%, 25%, and 30%. The chemical composition of CDA shows that it is composed primarily of SiO2, Al2O3, and Fe2O3, with a significant amount of loss of ignition. The workability, hardened properties, and microstructure of CDA-containing mortars are also analyzed. The increasing CDA content in mortar reduces workability and, beyond 5%, it causes high water absorption due to CDA’s porous nature and unremoved organic compounds. This impacts the density and compressive strength of the hardened mortar as well as compromising its homogeneous characteristics. When using 5% CDA, the bulk density and compressive strength of the mortar are comparable to those of the control mixes. Nonetheless, as the proportion of CDA increases, both the bulk density and compressive strength of the mortar diminish. The thermal stability of mortar mixes with 10%, 20%, and 30% CDA is unaffected at temperatures between 500 °C and 600 °C. The Fourier-transform infrared spectroscopy (FTIR) analysis reveals the presence of unreacted particles and wide stretched C–S–H gels in the mortar samples. In general, the results suggest that CDA can be utilized as a substitute for OPC at a ratio of up to 10% in the manufacturing of mortar and can serve as a feasible alternative cementitious material.

Prediction and multi-objective optimization of workability and compressive strength of recycled self-consolidating mortar using Taguchi design method

Concrete is the most consumed material in the construction industry. Using recycled aggregates (RA) and silica fume (SF) in concrete and mortar could preserve natural aggregates (NA) and reduce CO2 emissions and construction and demolition waste (C&DW) generation. Optimizing the mixture design based on both fresh and hardened properties of recycled self-consolidating mortar (RSCM) has not been performed. In this study, multi-objective optimization of mechanical properties and workability of RSCM containing SF was performed via Taguchi Design Method (TDM) with four main variables including cement content, W/C ratio, SF content and superplasticizer content at three different levels. SF was used to decrease the environmental pollution caused by cement production as well as compensating the negative effect of RA on the mechanical properties of RSCM. The results revealed that TDM could appropriately predict the workability and compressive strength of RSCM. Also, mixture design containing W/C = 0.39, SF = 6%, cement = 750 kg/m3 and SP = 0.33% was found as the optimum mixture having the highest compressive strength and acceptable workability as well as low cost and environmental concerns.

A Neural Network-Based Prediction of Superplasticizers Effect on the Workability and Compressive Characteristics of Portland Pozzolana Cement-Based Mortars

Portland Pozzolana Cement (PPC) mortars are predominantly employed in plastering works to achieve better workability, superior surface finish, and higher fineness to offer better cohesion with fine aggregates than the ordinary Portland cement (OPC) mortars. To achieve high performance in the cement mortar similar to cement concrete, the addition of a superplasticizer is recommended. The present study investigates the impact of addition of sulphonated naphthalene formaldehyde- (SNF)-based (0.5%, 0.6%, 0.7%, and 0.8%) and lignosulphate- (LS)-based (0.2%, 0.3%, 0.4%, and 0.5%) superplasticizers on the workability and compressive strength characteristics of PPC mortars. Plastering mortars of ratio 1 : 4 were prepared with natural sand and manufacturing sand (M sand) as fine aggregates. A flow table test was conducted on all the mortar mix proportions, and the effects of the inclusion of superplasticizers on flow properties were recorded at different time intervals (0, 30, 60, 90, and 120 minutes). PPC mortar cubes were prepared, cured, and examined to assess the inclusion of chemical admixtures on compressive strength at different ages (1, 3, 7, 14, and 28 days). The experimental findings from the workability and compressive strength of PPC mortars were analyzed, and the corresponding results were predicted using artificial intelligence. Experimental investigations demonstrated that the desired flow characteristics and higher compressive strength results were achieved from a 0.7% dosage of ligno-based superplasticizer. The predicted workability and compressive strength results at various ages acquired by implementing an Artificial Neural Network (ANN) were found to be in close agreement with the experimental results.

Evaluation of rheological and mechanical properties of bottom ash based masonry mortar with graphene oxide

This paper evaluates the rheological and mechanical properties of lignite based bottom ash as fine aggregate in cement mortar with GO as an additive. The annual extraction of such a huge amount of bottom ash needs a massive transfer to the field, as it constitutes a threat to the environment. The utilization of such residue as a partial replacement of fine aggregate in masonry mortar is not fully explored. Hence, an attempt has been made to utilize the bottom ash as FA in cement mortar composites, and studied the influence of graphene oxide (GO) in the properties of mortar matrix. In this study, bottom ash replacement from 0 to 60% and GO at dosage of 0.1, 0.15 and 0.20% by weight of cement were used. Compressive and flexural strengths of composites were improved significantly at GO = 0.15%. Mechanical properties at 40% bottom ash replacement level only have shown minor improvement. It was observed from the flow table test that addition of bottom ash leads to reduction in workability of masonry mortar, and GO enhanced both the rheological and mechanical properties of mortar matrix.

Optimization of Bending and Compressive Strength Behavior of Agave americana Fiber Reinforced Cementitious Composite Using Response Surface Methodology

The purpose of this research is to optimize several variables, including fiber length, volumetric fiber percentage, and sodium hydroxide (NaOH) solution concentration, which influence the bending and compression behavior of cementitious composites reinforced with plant-based fibers from Agave americana. Samples of composites based on fibers extracted from Agave americana and a cement matrix were manufactured and prepared according to a reference mortar. Box-Behnken Design (BBD) of Response Surface Methodology (RSM) was employed to build an experimental design to explore their mechanical behavior and to construct a set of mathematical models predictive of their behavior. The first stage of the work includes the extraction and processing of Agave americana fibers and the preparation of cement and Agave americana mortar specimens. The second phase aims to establish mathematical models to forecast the workability of the cement mortar and its strength at 28 days while emphasizing the correlations and interactions between the different components through the Design Expert software.

Development of sustainable geopolymer composites for repair application: Workability and setting time evaluation

One of the most used construction materials worldwide is concrete. It has a lot of advantages over the other construction materials. However, the production process of concrete produces a huge amount of carbon dioxide. Geopolymer composites are gained attention as eco-friendly alternative to traditional cement. In this research an attempt has been done to optimize a sustainable geopolymer mortar made of ground-granulated blast furnace slag (GGBS) and fly ash (FA). The optimized geopolymer mortar is designed to be convenient and practical for repairing damaged reinforced concrete members. Accordingly, this research is focused on improving setting time and workability of an ambient cured geopolymer mortar. In this research an attempt has been done to study the impact of using different superplasticizer dosages, different GGBS percentages, and different alkaline activator solution ratios on the setting time and flowability of an ambient cured geopolymer mortar. The obtained findings of this study showed that, alkaline activator ratio is one of the most significant parameters that affect workability and setting time of the geopolymer mortar. In this study, fifteen different mixes were tested and evaluated. Modified Vicat apparatus and Flow Table test were used to evaluate setting time and workability for the mortars. The outcome of the optimization showed that, the most convenient and practical mix which provided the highest setting time and reasonable flowability contained of 25% GGBS, 75% FA and 5% superplasticizer. The obtained workability for the optimum mix was about 156.25 mm and the achieved setting time was about 30 min.

Effect of ethylene vinyl acetate on cement mortar – A review

Mortar is a mixture of sand, a binder and water. It is used as a paste, which hardens and fuses the masonry components used in the construction, such as stones, bricks or concrete. Polymers have been incorporated in Portland cement as property enhancers for a while. Since then, polymers have been used to improve the water retention, permeability, adhesive strength, workability and deformability of mortars and concretes. Cement concrete structures’ bearing capacity and durability are adversely affected by the brittleness of the cement material, which makes it simple to break under the influence of an external force. Various mechanical and physical properties of cement-based materials can be improved by using polymers, which have good elastic deformation capabilities, acid and alkali corrosion resistance, flexibility and compatibility with cement materials. Ethylene and vinyl acetate are copolymerized to form EVA or ethylene vinyl acetate. Excellent flex-crack and puncture resistance, a wide range of polar and nonporous substrate adhesion, and good hot-tack performance are just a few of the appealing qualities of EVA. The majority of research has demonstrated a beneficial effect of EVA on mortar performance. Foam rubber or Expanded rubber are the other popular names of EVA. EVA copolymers are adhesives that are utilised in packaging, bookbinding, and textile, for bonding plastic films, coated paper, and metal surfaces. The effectiveness of the EVA-modified mortar is examined in this paper. According to studies, the EVA-modified mortar's interface performance significantly increased as EVA was added to the mortar. While Scanning electron microscope studies were conducted for analysing the internal structure of EVA-added mortar, it was discovered that the EVA-cement composite had a three-dimensional net structure. Consequently, the mortar's cohesive strength rose. Also, Samples incorporated with EVA polymer waste had shown the ability of noise insulation. Incorporating EVA with CaO showed a positive effect on mortar performance. The risk of cracking was reduced in EVA-incorporated mortar. Thus, reviewing all the research papers it was found that the addition of EVA can considerably enhance the mortar’s physical as well as mechanical properties.

Potential of Palm Oil Fuel Ash as a Partial Replacement of Fine Aggregates for Improved Fresh and Hardened Mortar Performance

The growth of Malaysia has caused many industries to grow rapidly, especially construction industries due to the demand for more homes, buildings, and infrastructure. The production of concrete and mortar is highly requested. Therefore, the demand for fine aggregate becomes higher because fine aggregate is one of the main elements in concrete and mortar production. The high demand for fine aggregates will create a worrying situation where the fine aggregate crisis will worsen. An alternative was introduced to replace the fine aggregate known as palm oil fuel ash (POFA) in order to reduce the use of natural resources such as fine aggregates and lead to the reduction of fine aggregate mining activity. POFA produced from palm oil fibre, palm oil shell, and mesocarp at high temperature has no benefits in the commercial return. Thus, POFA that has accumulated in landfill has the ability to create environmental pollution. Due to the pozzolanic behaviour of POFA, it could be relevant when POFA is used in the production of mortar as a partially fine aggregate replacement. There is a limited study on the effects of POFA as a partially fine aggregate replacement in the production of mortar. The aim of this research is to study the effects of POFA on the workability of fresh mortar, and for the hardened mortar, compressive strength and microstructural analysis will be analysed. A total of 45 cubes with dimensions of 100 mm × 100 mm × 100 mm were cast at different percentages of POFA at 0%, 2.5%, 5%, 7.5%, and 10% by the weight of fine aggregates. Slump and flow table tests were conducted during the casting process to determine the workability. All the specimens were water cured at days 3, 7, and 28 before being tested with a compression test and scanning electron microscope (SEM) on the hardened mortar. It was discovered that 0% POFA recorded the highest workability. Furthermore, the laboratory results showed that the 2.5% POFA in the mortar recorded the highest compressive strength compared to other specimens. Moreover, the microstructure of the mortar specimen was observed to be denser, and the pores were refined with the presence of POFA, compared to the control specimen. Based on the findings, this research enables us to give an understanding of the effect of POFA incorporated in mortar as a partially fine aggregate replacement in terms of workability, compressive strength, and microstructural analysis. Based on the results from this research, the advantage of POFA can be fully utilized and can help reduce the environmental problems.

Effect of Recycled Foundry Sand on the Workability and Mechanical Properties of Mortar

Modern society requires a large number of metal components manufactured by sand casting, which involves the generation of a waste product known as Used Foundry Sand (UFS), of which approximately 100 Mt are generated on an annual basis. Virtually all UFS is currently landfilled, despite the economic and environmental cost overruns that this entails. Here, the recovery of UFS as fine aggregates for the manufacture of concrete is proposed. Since the presence of UFS will mainly affect the mortar that binds the aggregates in the manufacture of concrete, it was decided to isolate this fraction and study only the effect of UFS in mortars. This study evaluated a total of 32 different mixes combining different W/C ratios varying between 0.5 and 0.7 with 5 replacement ratios of natural sand by UFS: 0, 25, 50, 75 and 100%, respectively. The combined effect was evaluated of the W/C ratio and the replacement ratio on the workability, physical properties, mechanical properties, mechanical durability, and microstructure of the mortars. The incorporation of UFS decreases the workability of the mortars due to the absorption of the residue. For the physical properties of the mortars, density decreased and porosity and absorption increased at all replacement percentages. Flexural and compressive strength decreased when the replacement percentage was higher than 25 wt.%. In terms of mechanical durability, the mortars with UFS showed abrasion marks within the limits of the EN-1338 standard. From the results obtained, it is possible to conclude that the mortars with UFS require a higher amount of water. Therefore, while small replacement levels lead to a slight improvement in the mechanical properties, this trend breaks down for high replacement levels due to the negative effect of the high W/C ratios required. The authors recommend that for replacements higher than 25 wt.% of UFS, the W/C ratio has to be taken into consideration to obtain the same workability as the control mortar, although this decreases the mechanical properties.

Effect of micro-sized lead oxide on the workability, mechanical strength and durability of alkali-activated slag mortar

This is the first attempt to investigate the effect of micro-sized lead oxide (mPbO) on the properties of alkali-activated slag (AAS) mortars. Various ratios of mPbO ranging from 2.5 wt% to 10 wt% were added to the neat AAS mortar specimens. The variation in the workability, mechanical strength development, transport properties and accelerated aging resistance were investigated. The available advanced devices were used to analyze the results. The results indicated a positive effect of mPbO on the flowability of the mixtures. The addition of mPbO increased the mechanical strength and the resistance of accelerated aging, where 7.5% was the optimal. A higher ratio of mPbO than 7.5% (i.e 10%) did not show additional improvement, but an adverse effect was observed compared to that of 7.5% mPbO. The transport properties and accelerated aging resistance were improved with the addition of 2.5–7.5% mPbO, but slightly worsen with the addition of 10% mPbO compared to that of 7.5% mPbO. The microstructure was improved and refined with the addition of suitable ratios of mPbO.

Workability and strength characteristics of alkali activated mortar with various binder systems

Determining the workability and mechanical behaviour of alkali-activated mortar (AAM) cured under atmospheric air conditions with diverse industrial waste materials as binder precursors are the prime goals of the current research. The different combinations of slag and fly ash with class C and class F grades were utilized for preparing the AAM and flow table test, compressive strength test and flexural strength test were done in the laboratory to assess the performance of mortar. The results showed that the increase in slag content improves the mechanical behaviour while adversely affecting workability. This study suggests that alkali-activated systems could replace conventional cement concrete in construction projects if properly designed with.

Workability, compressive strength, and microstructures of one-part rubberized geopolymer mortar

Rubberized geopolymers are attracting attention as solutions to ecological issues caused by increased production of industrial waste and used tires. However, the inconvenience of handling alkaline solutions limits the use of conventional two-part geopolymer materials. Therefore, a one-part rubberized geopolymer mortar (ORGM) activated by a solid alkali activator was developed in this study. An experimental investigation was conducted on the setting time, fluidity, density, and compressive strength, of the ORGM, and the test findings were compared with two-part rubberized geopolymer mortar (TRGM). In addition, the cost efficiency and environmental impact of the rubberized geopolymer mortars (RGMs) were evaluated. The results showed that the ORGM activated by anhydrous Na2SiO3 powder (ORGM-NS) had superior economic and environmental benefits compared with ordinary Portland cement mortar. Although the addition of rubber reduced the compressive strength, the ORGM-NS with a 10% rubber content still displayed a 28-d compressive strength of 40.7 MPa, which was approximately 170% higher than those activated by NaOH powder combined with instant Na2SiO3 powder (ORGM-NH). Compared with TRGM, the ORGM has a similar functional cost, a more convenient preparation method and a slower polymerization process.

Effect of Municipal Solid Waste Slag on the Durability of Cementitious Composites in Terms of Resistance to Freeze-Thaw Cycling.

The article presents durability results for cement mortars made with the addition of slag from municipal waste incineration plants as a replacement for natural aggregate. The undertaken durability tests included frost resistance tests and evaluation of strength, microstructure, water absorption and abrasiveness before and after 150 freeze-thaw cycles. The work reveals that MSWI slag in amounts up to 50 vol. % caused deterioration in the workability and water absorption of cement mortars, regardless of the type of cement used. This, in turn, resulted in a reduction in the compressive and flexural strengths of the composites compared to mortars made with sand alone. Nevertheless, the use of a higher grade of cement, CEM I 52.5 R, resulted in an increase in compressive strength and thus increased the mortars' frost and abrasion resistance. In addition, after the induced freeze-thaw cycles, mortars made with MSWI slag showed comparable or higher frost and abrasion resistance than those made using natural aggregate.