Cement-sand Mortar Research Articles

Recycling thermoset plastic waste for manufacturing green cement mortar

Highly crosslinked thermoset plastic waste is generally regarded as unrecycled materials and dumped into landfills. To divert the waste from landfills, recycling thermoset waste as fine particles in cementitious composites is a potential approach. However, weak interface bonding between thermosets and cement hydrates causes significant strength degradation in cementitious composites, which has constituted a long-term stumbling block. Herein, we innovate a green recycling solution for recycling thermoset waste as fillers in order to engineer sustainable cement mortar with the help of a green surface adhesion promoter – a silane coupling agent. The feasibility of the proposed approach was experimentally validated in terms of workability performance and compressive strength in order to meet requirements in practice. The results show that thermoset waste can substitute for at least 15% of sand in cement mortar, following workability requirements. In addition, the optimal replacement level of thermoset waste for sand in cement mortars with the highest compressive strength is 5%, beyond which the compressive strength exhibits a continuing drop. The strength alteration mechanisms are elucidated by scanning electron microscope (SEM) analyses. We demonstrate that the developed thermoset cement mortars with 5% thermoset waste have the great potential to achieve a highly dense microstructure, robust interfacial transition zone, and better hydrate crystal growth, which are the microscopic origins determining the inherent strength enhancement. The findings of this study enable the design of eco-friendly cement mortar formulations, which can both benefit the construction industry and relieve the severe environmental burden caused by landfilling thermoset waste after its end-of-life use.

Effect of Graphene oxide Addition on Cement-Sand Mortar

The effect of addition of graphene oxide (GO) to the cement-sand mortar on its fluidity and strength was investigated. The dosages of GO addition were varied from 0.03% to 0.06% by weight of cement. The GO was sonicated with required water for uniform mixing and added to the dry mixture of Ordinary Portland Cement and sand of proportion 1:2 (by weight). The incorporation of GO in cement- sand mortar reduced its fluidity compared to control mortar (without GO). A maximum reduction in fluidity of 32% was noted for the GO addition of 0.03%. The compressive strength of mortar was enhanced with the addition of GO (up to 0.05%). However, such enhancement was reduced with further addition of GO. The 0.05% of GO addition increased the compressive strength of mortar by 49.8%, 25.6% and 20.3% compare to that of control sample at 3 days, 7 days and 28 days respectively. The flexural strength of GO based cement sand mortar was also increased substantially compared to control mortar at 0.05% GO addition. More flake like hydration products were observed in GO based cement sand mortars by field emission scanning electron microscopy (FESEM).

Calculation of effective schemes for strengthening shallow foundations by contour reinforcement with hard elements

An effective way to strengthen shallow foundations is contour reinforcement - the execution of vertical elements in the soil base along the edges of the foundation. The introduction of reinforcement elements that perform the function of a "compression wall" leads to a noticeable decrease in deformations and an increase in the bearing capacity of the soil at the base of the reinforced foundations. As reinforcing elements, various structures and materials with strength properties that exceed the corresponding properties of the soil can be used. A positively recommended method for the formation of reinforcement elements is group high-pressure injection. The essence of the method lies in the simultaneous supply of a cement-sand mortar through several sources installed in a row, under pressure exceeding the structural strength of the soil and the subsequent creation of flat vertical injection bodies of conditionally rectangular shape in the soil. An important issue in contour reinforcement is the determination of the optimal injection parameters - the number and spacing of injection bodies in plan and in depth, which can lead to a significant reduction in cost of work. To determine the rational parameters of the contour reinforcement with injection bodies, a set of numerical experiments was performed to calculate the stress-strain state of the soil foundation for different reinforcement schemes in the MIDAS GTS NX 2019 software package. The calculations were carried out in a 3D formulation, taking into account the nonlinear nature of the soil operation. Based on the results of the calculation, the most effective schemes for the location of reinforcement elements were determined when strengthening shallow foundations with contour reinforcement with injection bodies, and the technology for consistent reinforcement work with a gradual increase in the number of reinforcement elements was substantiated.

Strength test of the industrial building’s load-bearing structures

Experimental studies were carried out in the molding shop. Tests were carried out for brickwork materials of enclosing walls by the shock pulse method. The compressive strength grades of ceramic brick fences and cement-sand mortar were determined experimentally. When testing concrete, a non-destructive strength control method and the necessary devices were used. The concrete class was determined by compressive strength in reinforced concrete columns of the building, in reinforced concrete beams of the coating and in reinforced concrete slabs of the coating. According to the proposed methodology, verification calculations were carried out. The verification calculations showed sufficient bearing capacity of the columns and foundations of the workshop building and the coating beams for the full design load. A calibration calculation of the workshop frame was also performed, which showed sufficient strength of the entire load-bearing structures of an industrial building. The proposed methodology can be used for testing similar building materials and objects.

Experimental Study on Mechanism of Graphene Oxide-Modified Coral Sand Cement Mortar to Resist Sulfate Erosion

Coral sand particles with low strength and rich pores affect the mechanical properties and durability of their cement-based materials. This paper investigates the mechanical properties and internal pore evolution of graphene oxide-modified coral sand cement mortar under sulfate erosion environment, aiming to better understand the effect of graphene oxide on the mechanical properties of coral sand cement mortar under an erosion environment, especially in wet and dry cycles. Mechanical properties of coral sand cement mortar were tested with different amounts of graphene oxide and different erosion cycles to understand the relationship between the change of flexural and compressive strength and the content and erosion cycle. The microscopic parameters of hydration products and internal dissolution pores were analyzed by XRD and SEM. The results showed that the degree of erosion performance improvement is related to the content of GO, and the two are positively correlated at first and then negatively correlated. At 0.03 wt% content, the retardation effect is the best. There were more orderly pore arrangement with less morphological complexity, when the dissolution amount of Ca(OH)2, porosity, total pore area, pore number, probability entropy, average form factor, and fractal dimension decreased. Coral sand cement mortar increases resistance to sulfate attack, which graphene oxide inhibits the formation of new dissolution pores and the expansion of original pores.

Effect of Aloe Vera Dosed in Cement-Sand Mortar Crystallization and Energy Reducing

Effect of Aloe Vera Dosed in Cement-Sand Mortar Crystallization and Energy Reducing

Compressive and Flexural Strengths of Mortars Containing ABS and WEEE Based Plastic Aggregates.

The incorporation of plastic aggregates as a partial replacement of natural aggregates in cementitious materials is interesting in several ways. From a mechanical point of view, the partial substitution of sand with plastic aggregates could improve some properties (e.g., ductility, thermal insulation). This paper deals with the mechanical strength of mortars containing plastic aggregates as a partial replacement of sand. Part of the volume of sand in cement mortars is substituted with plastic aggregates which originate from WEEE (Waste from Electrical and Electronic Equipment) and consist of a mix of ABS (acrylonitrile-butadiene styrene), HIPS (high impact polystyrene) and PP (Polypropylene), or of monomaterial ABS from WEEE sorting. Three rates of replacement (by volume of sand) were tested: 10%, 15% and 30%. Mechanical tests were performed according to European standard EN196-1. The results show that compressive and flexural strength decrease with rate of replacement, but remain satisfactory for structural purposes. In addition, the density of mortar is reduced with the incorporation of plastic aggregates. The decrease of mechanical strength is mainly due to the weak bond between cement paste and plastic aggregates leading to the increase of porosity. Furthermore, it appears that mortars containing plastic aggregates could present a ductile rupture.

A smart building with integrated energy management: Steps toward the creation of a smart city

This study was conducted the 7-story building in Jakarta, Indonesia and was selected as a research sample. The study aimed to enhancing smart buildings' energy management. Descriptive and analytical methods were used in this study. Analyzing the building's materials (Facade stone, cement sand mortar, Leca block, gypsum and soil mortar, gypsum soft with thermal resistance of 0.41 and heat capacity of 4.5), windows, and energy consumption, it was determined that the lighting sector consumes the most energy. Maximum energy consumption reduction in residential buildings occurs in the lighting sector, and the smart management system cuts residential energy consumption by up to 37%. In addition to providing security and peace of mind, system features such as alarms for natural and abnormal occurrences may also give safety. With the integration of smart management systems in residential buildings, such as security control devices, seismic controllers, imaging controllers, fire alarm systems, and fire extinguishing systems, building resilience will be increased. With the assistance of an smart management system, a reduction in energy consumption of between 20% and 27% will be accomplished.

Experimental studies on the effect of natural and synthetic fibers on properties of fresh and hardened mortar

• Effects of fibers were similar for cement-lime mortars and cement mortars. • Sisal fibers affect air content in mortars more than other fibers. • Compressive and flexural strength of jute fiber mortars are better than others. • Jute and polypropylene fibers decrease shrinkage of mortars. • Sisal fibers increase amount of pores of large diameters. The study investigates various properties of fresh and hardened mortar reinforced with natural fibers (jute and sisal) and synthetic fibers (polypropylene) dosages ranging from 1% to 2%. Experimental studies of mortar (cement-sand mortar, cement-lime mortar, and mortar with air-entraining admixture) were conducted, including air content, consistency, compressive strength, flexural strength, and shrinkage, porosimetry MIP and SEM photography. According to the findings of the research, the use of natural waste fibers has distinct advantages over synthetic fibers. Finally, because of its beneficial effect, this paper recommends using jute fiber with mortar for any structural purpose.

Mechanical properties and microscopic characterization of mortar with recycled aggregate from waste road

In order to explore the practicability of recycled aggregate replacing river sand in cement mortar, the research on recycled aggregate mortar (RAM) was carried out from the aspects of mechanical properties and microstructure. Compressive test, flexural test, consistency test and scanning electron microscopy (SEM) were conducted when the ratio of river sand replaced with recycled aggregate (RSA) was 0, 20 %, 40 %, 60 %, 80 % and 100 %. The compressive test results show that recycled aggregate can reduce the brittleness index and increase the toughness of mortar. The flexural test show that the fracture energy increases with the increase of RSA. The consistency test results show that the consistency decreases slowly and then rapidly with the increase of RSA. When RSA≤ 40 %, its consistency is above 30 mm and can meet the application requirements of practical engineering. SEM tests show that after replacing the recycled aggregate with river sand, the cementation effect between hydration products and particles is more obvious. To sum up, the compressive strength, flexural strength and consistency of RAM are better than those of the benchmark group. When RSA = 40 %, the mechanical properties of RAM reach the optimal value and has high practicability.

Sustainable use of coco pith in cement-sand mortar for masonry block production: Mechanical characteristics, durability and environmental benefit

The present study performs a comprehensive analysis that includes the assessment of mechanical and durability characteristics of cement blocks, cost-effectiveness and eco-benefit analysis of incorporating coco pith in the production of cement blocks. As coco pith is often considered waste material and dumped in landfills, the usage of coco pith in cement blocks is encouraged to promote sustainable construction practices. In this study, a total of 504 cubes (100 mm × 100 mm × 100 mm) and 24 blocks (200 mm × 100 mm × 60 mm) were prepared. The samples were tested with mortar containing 0, 4, 6 and 8% of coconut coir as a fraction of cement weight. Experimental programs conducted on fresh and hardened mortar included determining workability and setting time; physical parameters such as densities at different moisture conditions and water absorption rates; mechanical characteristics including compressive strength at different moisture conditions and flexural tensile strength; durability aspects such as sorption, evaporation rate, resistance against wet-dry cycle, and resistance against the severe environmental condition. In addition, to evaluate the cost-benefit and sustainability of coco pith incorporation in cement-sand blocks, the material consumption, embodied energy and CO2 emission for mortar mixes production was calculated. Results showed that the inclusion of 4% coco pith in the mortar increased air-dried compressive strength by 8% compared to that of the control mortar. However, further increase in coco pith content decreased compressive strength. For 6% and 8% coco pith content, the decrease in compressive strength was 3% and 25%, respectively. A similar trend was observed for the flexural strength of mortar blocks. However, even for mortar with 8% coco pith content, the flexural tensile strength was higher than that of the control mortar. Higher coco pith content in mortar tended to increase water absorption and sorption by capillary action. Still, for cement mortar with 4% coco pith content, both water absorption rate and sorpitivity were within the allowable limit. When cost per unit volume per strength was considered, mortar with 4% coco pith was more beneficial as it was 11.7% lesser than that of the control mortar. When energy consumption and carbon emission per unit volume per strength were considered, mortar with 4% coco pith was more effective as it was 11.6% and 11.5% lesser than that of the control mortar, respectively. So, it is recommended to use coco pith up to 4%, which provides better mechanical characteristics and sustainable production without compromising important durability properties.

Experimental assessment of proposed seismic strengthening scheme for adobe structures

A new scheme of seismic strengthening of adobe structures has been proposed in this paper. The scheme involves horizontal and vertical bands of steel wire mesh plastered with cement-sand mortar. The effectiveness of the proposed scheme is assessed by dynamically testing a half-scale model of the adobe structure on a shaking table. The acceleration time history record of the 1995 Kobe earthquake was used to simulate the ground motion for the strengthened model which was increased sequentially in increments of 25% of peak ground acceleration (PGA). Initial (hairline) cracks were observed in the in-plane wall of the model at a PGA of 0.439 g. Although the out-of-plane walls also sustained damages, the in-plane walls were the most damaged parts of the structure. The proposed strengthening method reduced the torsional irregularity of the structure. It also increased strength, ductility and energy dissipation capacities of the walls. The data of observed structural damages and building drift were used to propose four performance levels for the strengthened adobe structures corresponding to the applied PGAs of ground motion.

Partial Replacement of Municipal Incinerated Bottom Ash and PET Pellets as Fine Aggregate in Cement Mortars.

The objective of this study was to examine the optimal mixing ratio of municipal incinerated bottom ash (MIBA) and PET pellets used as a partial replacement of fine aggregates in the manufacture of cement mortars. As a partial replacement for sand, 15 mortar specimens were prepared by mixing 0%, 10%, 20%, 30%, and 40% municipal incinerated bottom ash (MIBA) (A) and 0%, 10%, and 20% PET pellets (P) in 5 cm × 5 cm × 5 cm cube molds. The cement/aggregate ratio was 1:3, and the water/cement ratio was 0.5 for all specimens. The results showed that the compressive strength of cement mortars decreased when increasing the amount of MIBA and PET pellets. The mortar specimens with 10% PET pellets achieved the highest compressive strength (49.53 MPa), whereas the mortar specimens with 40% MIBA and 20% PET pellets achieved the lowest compressive strength (24.44 MPa). Based on this finding, replacing 10% and 20% sand in cement mortar with only MIBA or only PET pellets could result in compressive strengths ranging from 46.00 MPa to 49.53 MPa.

Моделирование напряженного состояния и определение прочностных характеристик материалов несущих конструкций промышленного цеха

The paper presents a part of the results of a full-scale inspection of the molding shop of an industrial enterprise. The results of tests of masonry materials of the shop's enclosing walls by the shock pulse method using the ONIKS 2.5 device are presented. As a result, it was found that the grade for the compressive strength of the ceramic bricks of the walls corresponds to M100, and the grade of the masonry cement-sand mortar of the walls of the building corresponds to M50. The results of concrete testing by the non-destructive method of testing the strength using the DigiShmidt 2000 device were presented. As a result, it was established that the compressive strength class of concrete in reinforced concrete slabs of the pavement corresponds to B10, in reinforced concrete beams of the pavement - B40, in reinforced concrete crane beams of the covering - B15, in reinforced concrete columns of the building - B15. Instrumental studies were carried out using non-destructive testing methods, and verification calculations were carried out using a computer. The results of the verification calculations carried out according to the proposed method showed the sufficient bearing capacity of the roof beams, columns and foundations of the workshop building under the full design load. Based on the results of the survey, a verification calculation of the workshop frame was carried out. In general, the calculation showed sufficient strength of the entire load-bearing structures of an industrial building.

ЕКСПЕРИМЕНТАЛЬНІ ДОСЛІДЖЕННЯ АДГЕЗІЇ БАЗАЛЬТОВИХ ЕЛЕМЕНТІВ ТА ЦЕМЕНТНО-ПІЩАНОГО РОЗЧИНУ ДЛЯ ДОЦІЛЬНОСТІ ВИКОРИСТАННЯ В КАНАЛІЗАЦІЙНОМУ СЕРЕДОВИЩІ

At present, there is a tendency in the world to replace steel and cast iron with composite materials with high chemical resistance and durability, which primarily include fiberglass, which has a set of high performance properties. However, currently the requirements for composites have increased, especially in terms of their heat and chemical resistance, resistance to microorganisms, groundwater and wastewater. Composites based on basalt fibers are significantly superior to traditional materials and alloys in their mechanical and physicochemical properties. They have corrosion resistance, chemical inertness, low thermal conductivity, high specific mechanical properties, low specific gravity. Basalt-based products have a number of advantages: high strength, relatively low weight, reliability in operation over a wide range of temperatures, not prone to corrosion and have high chemical resistance. Production and use of basalt fiber materials, composites and products from them are promising and economically feasible. Taking into account the physical- chemical properties of basalt fibers, the use of basalt elements from them as lining of sewer networks and structures is a promising method of their restoration. However, the durability of this depends primarily on the adhesion of basalt elements with cement-sand mortar. The article analyzes the mineral resource base of rocks as a one-component raw material for the manufacture of basalt fiber materials and composites based on them. The analysis of the properties of basalt continuous fibers in comparison with glass fibers of type E and S, carbon and aramid fibers is carried out. The results of the experimental study of the adhesion of basalt elements and cement-sand mortar are presented. The results of the research allow the use of basalt materials to perform repair and restoration work on sewers and structures.

Cyclic in-plane behavior of unreinforced and confined masonry walls retrofitted by shotcrete: Experimental investigation

This study aimed to investigate the efficiency of shotcrete retrofitting method for seismic rehabilitation of conventional unreinforced and confined masonry walls. In this regard, six large-scale masonry walls have been built using fired clay bricks and sand-cement mortar. The specimens were listed as unreinforced and confined masonry walls with vertical concrete ties before and after retrofitting using shotcrete overlay. Moreover, a relatively new approach was adopted for seismic retrofitting of unreinforced masonry (URM) walls as an alternative to vertical concrete ties. Correspondingly, a series of material tests were carried out to obtain the mechanical properties of the masonry, in particular the compression test on masonry prisms, shear triplet, and diagonal compression tests. The masonry walls were tested under simultaneous gravity and reversed cyclic in-plane loading. The dominant failure mode of the URM wall was rocking, while in the case of shotcrete-retrofitted specimens, the failure mechanism was predominantly bed-joint sliding. Besides, the confined masonry walls with vertical ties failed mainly due to diagonal cracking. Evaluation of the cyclic performance of the specimens showed that vertical concrete ties significantly increased the ultimate lateral resistance and the cyclic dissipated energy, though a reduction in the ductility capacity was identified. The specimens retrofitted by shotcrete exhibited a significant enhancement in the lateral strength and a more gradual strength deterioration in the post-peak behavior, even though the shotcrete reinforcing bars were neither anchored to the foundation nor to the concrete ties. Furthermore, the shotcrete-retrofitted specimens exhibited maximum dissipated energy and minimum stiffness degradation among the specimens.

Use of Quarry Dust in the Binding Mortar and Its Effect on Mechanical Characteristics of Brick Masonry

The strength characteristics of masonry is greatly affected by the brick strength, mortar strength and bond between brick-mortar interface. Especially, binding mortar significantly affects the shear and flexural strength of the masonry. In conventional masonry construction, river sand or natural sand is mixed with cement and used as binding mortar. However, due scarcity of good quality river sand, the extensive focus is on finding alternative materials for river sand for construction purposes. Quarry dust is one of the best alternatives for river sand, which can be used as fine aggregates in binding mortar. This study investigates the strength characteristic of the masonry made of quarry dust incorporated binding mortar instead of conventional cement-sand mortar. The binding mortar with four different river sand replacement levels of 0%, 33.3%, 66.7% and 100% quarry dust, was used for construction masonry. Compression test, direct shear test and cross-couplet test were conducted to evaluate the strength characteristic. The test results revealed that compressive, shear and bond strength of masonry was improved with increased quarry dust content in the binding mortar.

Повышение теплотехнической однородности стен из ячеистобетонных блоков

The development of effective protecting structures is currently one of the most popular areas in the construction industry. Masonry made of aerated concrete blocks is used in conditions of ensuring energy efficiency and environmental safety in the construction of civil buildings as enclosing structures. It has high thermal protection properties. The issue of filling through seams of aerated concrete masonry is acute, since adhesive and cement-sand mortars in masonry have low thermal conductivity and are temperature bridges. The authors have developed a two-row energy-efficient wall masonry made of aerated concrete blocks using polyurethane glue as a filler for through and dressing joints. The article discusses the effect of horizontal through joints made of cement-sand mortar and blocking of blocks on the resistance to heat transfer of masonry from aerated concrete blocks. In addition, it presents a study of the reduced resistance to heat transfer of the enclosing structure, taking into account heat-conducting inclusions, presented in the form of a traditional two-row aerated concrete masonry through a row, made on a thin-layer adhesive solution, as well as the masonry developed by the authors. It is concluded that the energy efficiency of the developed wall fencing is ensured due to the increased thermal homogeneity of the masonry.

Dynamic behavior of carbon nanotubes and basalt fiber reinforced coral sand cement mortar at high strain rates

This study investigated the dynamic mechanical behavior of basalt fiber (BF) and carbon nanotube (CNT) reinforced coral sand cement (CSC) mortars. Based on the Split Hopkinson Pressure Bar (SHPB) tests and micro analysis, the stress–strain behavior, and failure mode of the CNT and fiber reinforced CSC specimens were quantitatively analyzed. The quantitative relationships among the dissipated energy density, impact air pressure, dynamic compressive strength, and incident energy were explored. Furthermore, the reinforcement effect of a glass fiber reinforced polymer (GFRP) tube on the BF reinforced specimens and CNTs reinforced specimens was also evaluated. It was found that the dynamic compressive strength and toughness of coral sand cement mortar were enhanced by CNT and BF with the maximum strength growth rate up to 106% and 73%, respectively. There was an optimal fiber content for the BF reinforced specimens and the CNTs reinforced specimens at a specific condition. In this study, the optimal fiber content of CNT and BF was 0.04% and 0.3%, respectively. The BF reinforced specimens and CNTs reinforced specimens hooped with GFRP tubes showed a significant improvement of dynamic compressive strength compared with those without GFRP tubes, with the maximum strength increase rate of up to 168% and 130%, respectively.

Influence of Taheri Consciousness Bond Field on the Crystallization and Strength of Cement Mortar (Concrete)

In this study, the behavior of cement mortar under the Consciousness Bond Field was investigated. Taheri Consciousness Fields (TCFs) were founded and introduced by Mohammad Ali Taheri as new Fields more than four decades ago. These Fields are neither material nor energetic. Therefore, they do not have the quantity, but they have direct effects on both matter and energy. In other words, although TCFs cannot be directly measured, we can investigate their effects indirectly through various reproducible experiments. In all tests of this research, type II cement and standard sand were used. The samples preparation and their strength measurement were done under the ISIR 393 standard, and each group includes 3 prism samples. Three series of experiments were performed with a number of different groups, in each series one group was as control and the others were under Consciousness Bond Field. Series 1 included five groups of cement sand mortar. Compressive and flexural strengths were measured at 7, 28, and 42 days of age. Series 2 included four groups of cement sand mortar which were measured at 7, 28, and 42 days of age. Series 3 included four groups of cement sand mortar made exactly according to the above-said condition. And strength was measured at 7, 28, 42, and 90 days of age. Due to the results received from FT-IR (Fourier-transform infrared spectroscopy), SEM (Scanning electron microscopy), XRF (X-Ray Fluorescence), and XRD (X-ray Diffraction), the growth trend of the strength of the samples under the Consciousness Bond Field were more significant than the control samples. The results of other analyzes showed that the abundance of chemical compounds containing calcium (CaCO3 from 20 to 80% and Ca3SiO5 from 25 to 75%) in the samples under the Consciousness Bond Field at 90 days was higher than the control. While silicon-containing compounds were higher in control samples at the same age. Sodium (Na), Potassium (K), and Phosphorus (P) were reduced by approximately (an average of 30%) in samples under Consciousness Bond Field at 90 days, while the abundance of Aluminum and Calcium was increased (about 7% on average). Differences in the appearance and chemical composition of the crystals, including the amount of ettringite formation in the samples under the Consciousness Bond Field, were observable in SEM imaging.