Conventional Mortar Research Articles

Evaluation of Polymer Modified Mortar and Bonding Agent for Structural Repair

olymer modified mortar is found to be suitable for structural repair and strengthening of damage structural elements. Conventional mortar is not preferred in repair of concrete since it has inferior mechanical property and durability performance. Polymer based mortar is an alternative to conventional mortar with enhanced mechanical properties. However, there are limited specifications and guidelines available for specifying PMM mixes for structural repair work. The research work aims to evaluate the mechanical performance of polymer based mortar with varying concentration of styrene butadiene rubber latex at laboratory scale. Another aspect in repair of corrosion damage structures is the bond between the substrate concrete and repair mortar. In order to study the effectiveness of bonding agents, the performance evaluation of bonding agents has been evaluated using slant shear test and pull-off test as per ASTM C 882 and EN 1542 respectively. Findings of study indicates that at 8-10 percent concentration of dry polymer solid by cement mass in polymer based mortar is the optimum dosage. Styrene-butadiene rubber based polymer mortar showed improvement in flow in comparison to normal mortar however, mixes with crushed sand shows decrease in flow which is due to presence of more fines. Slant shear and pull-off test method shows epoxy bonding agent give better bond strength as compared to SBR latex.

Bamboo Sawdust as a Partial Replacement of Cement for the Production of Sustainable Cementitious Materials

This paper reports on the utilization of recycled moso bamboo sawdust (BS) as a substitute in a new bio-based cementitious material. In order to improve the incompatibility between biomass and cement matrix, the study firstly investigated the effect of pretreatment methods on the BS. Cold water, hot water, and alkaline solution were used. The SEM images and mechanical results showed that alkali-treated BS presented a more favorable bonding interface in the cementitious matrix, while both compressive and flexural strength were higher than for the other two treatments. Hence, the alkaline treatment method was adopted for additional studies on the effect of BS content on the microstructural, physical, rheological, and mechanical properties of composite mortar. Cement was replaced by alkali-treated BS at 1%, 3%, 5%, and 7% by mass in the mortar mixture. An increased proportion of BS led to a delayed cement setting and a reduction in workability, but a lighter and more porous structure compared to the conventional mortar. Meanwhile, the mechanical performance of composite decreased with BS content, while the compressive and flexural strength ranged between 14.1 and 37.8 MPa and 2.4 and 4.5 MPa, respectively, but still met the minimum strength requirements of masonry construction. The cement matrix incorporated 3% and 5% BS can be classified as load-bearing lightweight concrete. This result confirms that recycled BS can be a sustainable component to produce a lightweight and structural bio-based cementitious material.

Potentiality of earth-based mortar containing bamboo particles for GHG emissions reduction

This research aims at characterizing and evaluating the physical, mechanical, and thermal properties and the greenhouse gas (GHG) emissions in the life cycle of earth-based mortars with bamboo particles (EMB). Four EMB mixtures were developed with bamboo particles’ volume fractions of 0%, 3%, 6%, and 9%. The EMB mortars were characterized in terms of physical, mechanical and thermal properties. The Life Cycle GHG Emissions Assessment methodology was used considering a cradle-to-grave scope with the proposal of an eco-efficient indicator. Reduction in the GHG emissions for the EMB ranged from 21% to 113% depending on the chosen reference conventional mortar (made of cement and hydrated lime) and the evaluated scenario considered. It was verified that the EMB with 9% bamboo particles reached a 30% efficiency indicator improvement when compared with the EMB without bamboo. This mixture presented the most significant building plastering potential for the construction industry that seeks circular and low-carbon solutions. Finally, strategies related to Circular economy for the reduction of GHG emissions of EMB mixtures are proposed in this study.

Influence of Different Waste Materials on Resistance of Cement Mortars against Carbonation and Chloride Ingress

This work is an extensive experimental study on the corrosion behavior of reinforced cementitious mortars containing industrial byproducts and waste materials. In particular, calcareous (C-class) fly ashes, iron mill scale and Electrolytic Manganese Dioxide (E.M.D.) waste were used as additives in mortars production. The abovementioned materials were used without any prior treatment or management and replaced the cement in concrete mixing by 10% wt. of cement weight. For the experimental set-up, reinforced mortars were prepared and exposed to coastal area for 12 months, while some of them were remained in a salt spray cabin for 60 days. The corrosion monitoring was performed by electrochemical and mass loss measurements, while chloride content, porosity, carbonation and mineralogy of mortars were also estimated. The results indicate, that there is a development in durability and chloride penetration resistance of composites comparing with the conventional mortars at late ages. At the same time, it was also observed that their chemical composition and fineness, control the diffusion of CO2 into the pore system and lead to increased carbonation of composite mortars. The challenge of this work is the production of eco-friendly composites with high chloride and carbon dioxide penetration resistance.

Effect of marble slurry on the microstructure of cement mortars subjected to salt crystallization and alternate wetting and drying cycles

The scarcity of river sand has triggered the utilization of industrial waste to produce concrete and mortars. One such waste is marble slurry, which is being produced in huge quantities during marble processing, was evaluated as a partial substitute to sand for the production of mortars. This study aims to assess the properties of mortar mixes of proportions 1:3 and 1:6 made with dried marble slurry of dolomitic origin by substituting 20 and 30% of fine aggregate. It was observed that mortars could be produced with lesser water content on the incorporation of this waste. This has helped improve compressive strength, while properties like tensile and flexural strengths, water absorption are comparable to conventional mortars. On examining the microstructure using scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction, the augmented formation of tobermorite and gismondine like minerals on cement hydration were detected. Traces of dedolomitization of the dolomitic marble were also identified along with the formation of calcium carbo-aluminates, enhancing the quality of the microstructure and mechanical performance. While the phenomenon of salt crystallization restricts the usage of dried marble slurry for the production of mortars with a rich mix proportion of 1:3 only, alternating cycles of wetting and drying do not significantly affect the performance of both 1:3 and 1:6 proportions on the usage of dried marble slurry as fine marble slurry.

Investigation of In-Situ Compressive Strength of Fiber-Reinforced Mortar and the Effect of Fibers on the Adhesion of Mortar/Steel

The proper connection between mortar and steel is one of the crucial issues in civil engineering. This paper has investigated the effect of polypropylene fibbers on the bond between cement mortar and steel, using “Twist-off” and “pull-off” tests. Moreover, in order to assess the in-situ mechanical properties of fibre-reinforced mortars, the correlation of records obtained from semi-destructive methods of “Twist-off” and “pull-off” with those of laboratory tests was determined, and calibration curves were provided, using the regression analyses. The mentioned tests were modelled with the ABAQUS software to evaluate the distribution of stresses and cracks developed during the semi-destructive tests. The results show that the addition of polypropylene fibbers reduces the shrinkage of mortars by about 13% and this has a direct effect on the bond between the mortar and steel. So that the shear and tensile bond of fibre-reinforced mortars at 90 days is 75% and 94% higher than conventional mortars, respectively. The reason for this is the effect of fibbers on the process of hydration of mortars and also to prevent excessive opening of cracks, which is shown by SEM. According to the results, instead of using an expensive and imported pull-off device, a cheap and internal twist-off device can be used to measure adhesion. Also, to evaluate the compressive strength of mortars, twist-off and pull-off tests can be used by placing the readings obtained in the equations y = 0.156x + 0.329 and y = 0.055x-0.001 instead of x, respectively, to evaluate the compressive strength of mortars.

Application of Construction and Demolition Waste in Civil Construction in the Brazilian Amazon-Case Study of the City of Rio Branco.

The lack of usable aggregates for civil construction in Rio Branco (capital of Acre, a Federal State in the Amazon region) makes the production and use of recycled aggregates from construction and demolition waste (CDW) an alternative of great interest. In this study, a comprehensive characterization of CDW collected from 24 construction sites of six building types and three different construction phases (structures, masonry, and finishing) was carried out. The fine and coarse recycled aggregates were produced and evaluated in 10 different compositions. The aggregates’ performance was evaluated in four mixtures designed for laying and coating mortars with a total replacement of conventional aggregates and a mixture designed for a C25 concrete with 50% and 100% replacement of conventional aggregates. CDW mortars showed lower densities and greater water retention, initial adhesion, and mechanical strength than conventional mortars. CDW concretes presented lower densities and greater resistance to chloride penetration than conventional concrete, with a small mechanical strength reduction. The recycled CDW aggregates proved to be technologically feasible for safe application in mortars and concrete; for this reason, it is believed that the alternative and proposed methodology is of great interest to the Amazonian construction industry, considering the high costs of raw materials and the need for defining and consolidating a sustainable development model for the Amazon region.

Bacillus Subtilis as Self-Healing Agent in Cement Mortar: Combined and the Separate Effect of Bacteria and Calcium Lactate on Self-Healing Behavior in Cement Mortar

Cement mortar, which is one of the most useful materials for construction applications, can deteriorate its performance by developing cracks. In order to cope with this issue, the materials’ scientist came forward with a unique biogeochemical phenomenon in which cement mortar can selfheal its crack autonomously using calcium carbonate precipitating bacteria and their feed. In this research, it was intended to study the separate and combined effect of Bacillus Subtilis (bacteria) and Calcium Lactate (feed) on the properties of conventional mortar. Cement mortars were made using conventional method and cast in the form of cylinders. Four types of samples were taken. Sample-N contains only cement and sand, Sample-B was made by addition of bacteria Bacillus Subtilis with sand and cement, Sample-C contains Calcium Lactate which is usually used as feed for Bacteria while the last sample ‘BC’ have both Bacteria as well as Calcium Lactate. The samples were observed up to 44 days for their surface characteristics and compressive strength. The Sample-N and B did not show any remarkable change in their surface appearance with respect to curing time. Sample-C and BC did show the precipitation of CaCO3 but the Sample-C precipitation was stopped soon while for Sample-BC, the precipitation was continued for a longer time. The Sample-BC showed the highest compressive strength (approximately 17.57 MPa), followed by Sample-N (approximately 13.32 MPa), Sample-B (approximately 11.04 MPa) while Sample-C displayed lowest strength (approximately 2.75 MPa). This gives an idea that Calcium Lactate which acts as feed for bacteria has the negative effect on the strength if not consumed and converted into CaCO3.

Rubberized Mortar from Rubber Tire Waste with Controlled Particle Size

The generation of new materials such as rubberized mortar presents itself as an alternative to the decrease environmental problems generated due to the inadequate management of scrap tires, reaching high economic potential and environmental sustainability. In this study, mortar composites were prepared from Portland blast-furnace slag cement (type IS) and rubber granular waste from unusable tires of different commercial-brands with the purpose of evaluating the effects of the rubber particle size and rubber content on mechanical, chemical and morphological properties of the composites. Rubberized mortar has shown considerable improvement in flexural strength, strain and apparent density when compared to the conventional mortar, while the size particle of the rubber caused insignificant changes on these properties. Thus, rubberized mortar shows promising potential for the use of the material in applications where flexural strength is essential.

Effect of Pre-Wetting Recycled Mortar Aggregate on the Mechanical Properties of Masonry Mortar.

In this research we evaluated the use of recycled fine mortar aggregate (RFMA) as a fine aggregate for new masonry mortar creation. The pre-wetting effect on the aggregate before creating the mixture was analyzed as a method to reduce its absorption potential. A control mixture of conventional mortar and two groups of recycled mortars were designed with a partial replacement of natural sand by RFMA (pre-wetted and not pre-wetted) performed in different proportions. The results established that the pre-wetting process allows a reduction in the amount of water required during the creation of new mixtures, regulating the water/cement (W/C) ratio and improving the properties of recycled mortars such as air content, fresh and hardened densities, and compressive and adhesive strength for all substitution levels. Mortar made with a 20% substitution and pre-wetted until it was at 67% of its absorption capacity displayed adhesive values higher than the ones shown by the reference mortar. The pre-wetting process proves to be an easy performance technique; it is inexpensive, environmentally friendly, and the most valuable fact is that specialized equipment is not necessarily needed. This process is the most profitable option for improving RFMA exploitation and reuse.

Thermal and environmental impact analysis of rice husk ash-based mortar as insulating wall plaster

The energy used to maintain the thermal comfort of buildings significantly contributes to the GHG emissions and global warming. In this study, a sustainable and cost-effective rice husk ash (RHA)-based mortar for wall plastering has been developed to provide better thermal insulation, reduce the operational energy and enhance the thermal comfort. Consequently, RHA was partially replaced with the sand in the conventional mortar to produce the RHA-based plaster. Initially, compressive strengths and thermal conductivities of the selected mortar mixes were assessed. The results highlight that the RHA can be replaced up to 30% instead of sand in mortar to produce the thermally enhanced wall plaster. Further, two identical prototype model houses were constructed with RHA-based (i.e. 30% of RHA) and conventional plasters to evaluate their heat transfer, heat flux, and the characteristics of internal and external wall surface temperatures in open weather conditions. It was noted that the average peak heat flux reduction formed by the RHA-based plaster was 10%. The average daily heat transfer reduction across the wall with RHA-based plaster was about 26%. Results also show that RHA-based plaster can reduce the energy that required to maintain thermal comfort by about 9% than the conventional plaster. Moreover, the environmental impact analysis was also conducted to assess the sustainability performance of RHA-based mortars. The environmental impact assessment revealed that the RHA-based plaster has less environmental impact than the conventional mortar. Furthermore, the CO2 emission generated by the production of RHA-based mortar is about 14% less than the conventional plaster.

Mechanical Properties of Translucent Concrete Using Plexiglass Bars and Fiberglass

This research aims to investigate the efficiency of using plexiglass material as an alternative to optical fibers in the production of transparent concrete through studying the mechanical properties of transparent cement mortar. The importance of the current study comes to introduce innovative structural material with high aesthetic and structural specifications and meets the needs of the new concepts of sustainable buildings as well. The novelty of the proposed material lies in innovating a new type of transparent concrete using plexiglass material that allows light to cross through different directions, where such a polymer material can be embedded into the concrete as well-designed distributed bars. The proposed composite performance was evaluated by conducting relevant laboratory experiments on prepared mortar specimens to investigate compressive strength, flexural strength, and bond strength. The plexiglass bars were represented 6% and 16% of the specimen cross-section area, and volume respectively. Experiments were conducted in two time stages, after 7 days and after 28 days of preparing the mortar with plexiglass and fiberglass. Results show that the composite does not harm the mechanical specifications comparing with the conventional mortar, and obtaining new features of concrete with an emphasis on consistency to the requirements of environmental sustainability in the field of architectural construction.

Replacement of Natural Sand with Expanded Vermiculite in Fly Ash-Based Geopolymer Mortars

Increasing the thermal insulation of building components to reduce the thermal energy loss of buildings has received significant attention. Owing to its porous structure, using expanded vermiculite as an alternative to natural river sand in the development of building materials would result in improvement of the thermal performance of buildings. This study investigates the properties of fly ash (FA)-based geopolymer mortars prepared with expanded vermiculite. The main aim of this study was to produce geopolymer mortar with lower thermal conductivity than conventional mortar for thermal insulation applications in buildings. A total of twelve batches of geopolymers were prepared for evaluating their different properties. The obtained results show that, at a given FA and expanded vermiculite content, the geopolymers prepared with a 10 molar NaOH solution exhibited a higher flowability, water absorption and porosity, as well as a lower dry unit weight, compressive strength, ultrasound pulse velocity and thermal conductivity compared with those prepared with a 15 molar NaOH solution. As is also shown, the geopolymers containing expanded vermiculite (15%) developed a lower flowability (~6%), dry unit weight (~6%), compressive strength (~7%), ultrasound pulse velocity (~6%) and thermal conductivity (~18%), as well as a higher apparent porosity (~6%) and water absorption (~9%) compared with those without expanded vermiculite at a given FA content and NaOH concentration. The findings of this study suggest that incorporating expanded vermiculite in FA-based geopolymer mortar can provide eco-friendly and lightweight building composites with improved sound and thermal insulation properties, contributing toward the reduction of the environmental effects of waste materials and conservation of natural sand.

Properties of Mortar Incorporating Spent Garnet as Fine Aggregates Replacement

The rapid growth in the construction industry has increased the consumption of fine aggregates whereby it depletes the natural resources. Also, garnet is a material that can be reused for several times in the ship cleaning process. However, when this garnet can no longer be used, it is then disposed in landfill, oceans and rivers, thus increase the volume of landfill waste and causing environmental problems. Therefore, this research is aimed to study the effect of spent garnet as a fine aggregates replacement in terms of physical, fresh and hardened properties of mortar. In this study, several specimens are prepared by using different percentage of spent garnet range from 0%, 25%, 50%, 75% and 100% as a fine aggregates replacement in mortar. The specimens are cast using 50 mm x 50 mm x 50 mm mould and the materials used in preparing the mortar sample are cement, fine aggregates, water and spent garnet. The samples are then cured in the water before tested at the age of 7, 14, and 28 days. The characteristic of the materials, fresh and hardened properties of mortar were investigated. It was found that the workability of mortar increases with the increasing amount of spent garnet. Overall, it is found out that the spent garnet can be used as fine aggregates replacement in mortar up to 50% since it has a comparable strength (40 MPa at 28 days) with a conventional mortar with 16% improvement in water absorption test. In addition, the environmental impact can also be reduced through the use of spent abrasive waste by preserving the use of natural resources.

Characterization study on the influence of limestone and shell lime as a fine aggregate substitute: A traditional approach on lime plaster restoration

The present scenario on the rapid globalization and industrial use of natural resources across the globe has made this investigation to benefit on the utilization of crushed limestone (LSM) and shell lime (SLM) as aggregate substitutes to conventional lime mortar. Physio-chemical and modern analytical methods like XRD, TGA, FT-IR and strength test were performed, evaluating the performance of mortars with modern substitutes. Carbonate polymorphs such as calcite, vaterite & aragonite were majorly depicted in all the mortars. XRD reveals the high ranged CSH formation in limestone and shell lime mortar for 28 & 56 days. FT-IR results indicated the presence of high range calcite peaks and increased portlandite peaks at 3640 cm−1 for shell lime and limestone mortar on 56 days respectively. TGA concluded with high decarbonation occurred at 750–760 °C for shell lime & limestone mortar. The mechanical strength of LSM has peaked up to 1.58 and 1.77 MPa along with gradual strength gain around 1.54 and 1.57 MPa for SLM mix with 0.98 & 1.55 MPa for conventional mortar for 28 and 56 days respectively. Modified Limestone mortar revealed the enhanced strength up to 11.2% on natural carbonation.

Geopolymer mortar integrated with phase change materials for improvement of thermal efficiency in buildings: A review

The integration of Phase Change Materials (PCMs) in buildings as an energy efficient material has gained interest in construction industry. This review mainly discusses the effect of incorporation of PCM on the thermal and mechanical properties of geopolymer mortar. The study also reviews the properties of PCM when incorporated into mortar based on different binders such as cement, lime and gypsum. Based on the reviewed literature, it is evident that integration of PCM in geopolymer materials is economical and environment-friendly; contributing to better mechanical and thermal properties than PCM integrated conventional mortar.

Thermal energy storage cement mortar with direct incorporation of organic and inorganic phase change materials

Direct incorporation of phase change materials (PCMs) in the mortar matrix increases the effective thermal mass of a structure without increasing the size or significantly changing its weight; thereby reduces the energy consumption and brings comfort/well-being throughout the various seasons. Hence, the effect of direct incorporation of various types of PCMs in a mortar matrix needs to be addressed to optimize PCM addition and its type. In the present study, five different PCMs, two in-organic, and three organics were directly incorporated into the cement matrix from 5 to 15% as partial replacement of cement. Various studies such as compressive strength, flexural strength, acid and sulphate attack, Differential scanning calorimetry (DSC) analysis, Fourier transform infrared spectroscopy, thermal conductivity, stability of PCM (1000 thermal cycle test), thermal performance, and leakage test were conducted. Organic (n-BS, PEG-600, and OM29) PCMs have significantly decreased the strength of cement mortar with a peak reduction of 74% for HS24 (15%); whereas inorganic (HS24 and HS29) PCMs gave considerably equal strength of conventional mortar up to 10 wt%. A statistical technique using Minitab was used to validate the actual experimental values (compressive strength of HS24) with predicted values, and it was observed that the error in experimental values and the predicted values is less than 5% for 28 and 60 days curing thereby showing a confidence level of 95%. Acid attack tests on mortar specimens with PCMs gave a drastic reduction in compressive strength at 90 days. DSC analysis was conducted on all pure PCM materials and found that its temperature range and enthalpy exist in the human comfort zone. The stability for HS24 gave an enthalpy of 145.8 J/g and 122.6 J/g for melting and freezing point after 1000 cycles. The temperature variation of organic PCMs was nearly the same as normal cement mortar, and the maximum reduction of 5 °C was attained with inorganic PCMs. No leakage was observed for HS24, n-BS, and HS29 PCMs.

Thermal performance of Rice Husk Ash mixed mortar in concrete and masonry buildings

Rice Husk (RH) is an agricultural waste which is produced in huge amounts from the milling process of paddy rice. Rice Husk Ash (RHA) is a by-product material obtained from the combustion of rice husk. The amorphous silica-rich RHA (84-90 wt%) has a wide range of applications. This research focused on the possibility of utilizing RHA in the process of developing a mortar with low thermal conductivity to enhance the thermal comfort in concrete and masonry buildings. The thermal conductivity of mortar was determined by Lee’s Disc method, and the results were compared to the data for conventional mortar as well as commercial thermal insulation materials. The results indicate a significant reduction in thermal conductivity in the mortar developed with RHA

Autogenous Shrinkage of Internally Cured Conventional, Latex-Modified, and Very High Early Strength Latex-Modified Concrete and Mortar

Abstract Internally cured concrete has been shown to help mitigate early-age cracking and to provide improved durability performance in concrete elements. The increased absorptive capacity of lightweight aggregates (LWA) facilitates delivery of moisture to concrete internally during the curing process. In this study, a range of concrete mortar mixtures representative of mortar contained in bridge deck and pavement concrete mixtures were batched and tested for autogenous shrinkage. Two significantly different LWAs were utilized in this study: one LWA with an absorption typical of most manufactured LWA and one with a relatively low absorption for a manufactured LWA. Autogenous shrinkage test results clearly demonstrated the impact of use of prewetted LWA for internal curing. Reductions in autogenous strain ranged from 30 to 56 % depending on the type of LWA used as well as the percentage replacement of prewetted LWA for normal-weight fine aggregate. The reduction in autogenous shrinkage correlated with LWA replacement rate, and shrinkage was even further reduced for mixtures that included fly ash. Findings indicated that the lower-absorption LWA provides internal curing benefits when used at suitable replacement levels, which may exceed those currently specified by some state highway agencies. Use of the approach to computing LWA substitution rate provided in ACI (308-213)R-13, Report on Internally Cured Concrete Using Prewetted Absorptive Lightweight Aggregate, should provide adequate moisture delivery to support reduction in autogenous shrinkage and internal curing benefits and is suitable for proportioning of both the typical and lower absorption LWA to support internal curing. In addition to reduced autogenous shrinkage, use of prewetted LWA in very high early strength latex-modified concrete mixtures provided workability and work-time advantages.

Study of the Potential of Adhesion to the Substrate of Masonry and Tensile in the Flexion in Mortars of Coating with Gray of the Sewage Sludge

This work evaluates mortars using sewage sludge calcined at temperatures of 600°C and 700°C as a hydraulic binder replacing the cement. The percentages incorporated by mass to replace the Portland cement were 10%, 20% and 30%, using the 1:3:0,60 (cement: sand: factor a/c) trace. Sludge ash was characterized and tensile strength at flexion as well as tensile strength (pullout test) were evaluated. As a way of performing a comparison with conventional mortars, the same tests were carried out using reference mortar. The results of the flexural tensile strength tests indicated that results were higher than the reference traces of the mortars with the calcined sludge at a temperature of 700°C, a factor related to the increase of the calcination temperature and the incorporated percentage. With respect to the tests on the determination of tensile strength, it was observed that the specimens submitted to the test suffered rupture in the mortar, and that the calcination temperature of the sewage sludge was not influenced. The results obtained with the mortars using sewage sludge ash with partial replacement of the cement are shown within the normative standards and approximate to the results obtained with the tests executed with the reference mortar.