Mortar Plate Research Articles

Constitutive relationship of soil in contact with mortar under continuous loading

Mortars will remain critical in future land wars due to their flexibility and versatility. When mortars are fired continuously, the contact soil is gradually compacted by the mortar base plate, and dynamic research into this process is the basis for innovative mortar design. However, the discontinuity and nonlinearity of soil contact absolutely necessitate the constitutive relationship of soil contact, which is difficult to study. Therefore, this study conducted experimental research and theoretical derivation to establish an accurate dynamic model of the mortar system. First, based on the nonlinear elastic–plastic theory and the stress–strain relationship of soil under cyclic loading, a theoretical analysis method for the constitutive relationship of contact soil under continuous loading was proposed. Second, an experimental and testing system was designed to simulate launch loads, and the stress–strain response of soil under continuous impact loads was obtained experimentally. Subsequently, based on theoretical analysis and experimental data, the stress–strain relationship during the gradual compaction of soil was established using the least squares method. Finally, a constitutive relationship model of the contact soil in the mortar system was established in ABAQUS using the VUMAT subroutine interface, and the calculated results were compared and analyzed with traditional calculation results. The results indicated that studying the constitutive relationship of mortar in contact with soil during continuous firing using this method can improve the accuracy of dynamically modeling mortar systems. Moreover, this study has practical value in the engineering design of mortar systems.

Capacitive compressive stress self-sensing behavior of cement mortar and its dependence on the thickness

Capacitance based compressive stress/strain self-sensing properties and its dependence on thickness is presented for the fist time. Coplanar electrode configuration is used for the electrical measurements and known weights are used to create cyclic stresses on the mortar samples with different thicknesses. Mortar plates with 6 mm, 10 mm and 15 mm thicknesses are produced and capacitance change with stress application is measured with an inductance-capacitance-resistance meter (LCR meter). Capacitance value of the mortar with 6 mm, 10 mm and 15 mm thicknesses are 450 pF, 532 pF and 607 pF, respectively. Capacitance increases as thickness increases. However, stress sensitivities of the mortar with 6 mm, 10 mm and 15 mm thicknesses are measured as 3.1 × 10–6 P−1, 3.1 × 10–7 P−1 and 1.1 × 10–7 P−1. Stress sensitivity decreases with increasing the mortar thickness. While capacitive self-sensing is effective when the mortar thickness is known, capacitive self-sensing is ineffective with varying mortar thickness. This research contributes valuable insights into the practical application of capacitance-based sensing in materials subjected to compressive stresses, highlighting the need for considerations regarding thickness variations in real-world applications such as load monitoring and weighing.

Experimental Study On The Use Of Strapping Band Variation As A Substitute For Steel Reinforcement In The Manufacture Of Precast Foundation For Coastal Construction

A solid foundation is a concrete mix using steel reinforcement, but the reinforcement has the disadvantage of being corrosive when used in coastal areas. Therefore, this research uses strapping bands as a substitute for steel reinforcement. This research is focused on the manufacture of mortar plates for lightweight construction, especially in foundation parts such as footing foundations. This research used 5 (five) variations of slab mixture including, variation A1 which is mortar slab without additional strapping band, variation B1 which is mortar slab with additional 3 pieces of strapping band as thick as 1 layer on each top and bottom layer, so on up to variation B4 as thick as 4 layers. The results of the mortar plate bending test obtained the value of the bending moment of variations A1, B1, B2, B3, and B4 are 0.148 kN.m; 0.183 kN.m; 0.222 kN.m; 0.278 kN.m; 0.325 kN.m. Then the maximum bending moment value is averaged in the variation that uses a 4-layer thick strapping band. From this research it can be concluded that to get a high bending moment value, the more strapping bands are used.

The influence of the variability of the support of the mortar base plate on the quality of the results obtained in the process of its numerical design

Due to the high costs associated with the purchase of ammunition and firing in certified training ground centers, tests of retaining plate deformations are increasingly replaced by computer simulations using numerical models. Computer programs usually use a single-parameter subsoil model (Winkler-Zimmermann) for calculations, which requires providing the subgrade susceptibility coefficient. The subgrade compliance coefficient is intended to determine the mutual reaction of the subgrade and the structure due to the pressure exerted on the soil by the retaining slab, which settles. When designing slabs in computer programs, it is assumed that the substrate compliance coefficient is constant. Determining the impact of the soil on the retaining slab is important when analyzing its deformations. The subject of the work was the analysis of the influence of ground support on the results obtained during modeling of the retaining slab. In order to obtain data for FEM analysis and validation, the actual strains occurring on the thrust plate were measured using strain gauge rosettes. The plate deformations were measured during field shooting tests. In order to vary the influence of supporting the slab on the ground and obtain reliable stress values on the slab surface, a method of successive iterations was proposed. Calculations are performed using this method until the error is smaller than the assumed one.

Surface patterns of mortar plates influence Spirulina platensis biofilm attached cultivation: Experiment and modeling

Substrata selection is a key problem for engineering application of microalgae biofilm attached cultivation technology. In this work, 40 kinds of mortar plates with different surface patterns were fabricated and evaluated using Spirulina platensis biofilm cultivation. Results show surface patterns have great influences on S. platensis cultivation behaviors. Surface pitted patterns have the highest algal holding capacities, furrowed patterns are the second and bossed patterns are the lowest. After three days of cultivation, furrow patterned mortar plates have the fastest growth rate ranging at 13– 15 g m−2 d−1, the highest surface coverage ratio over 99 % and the strongest water erosion resistibility. Pit patterned mortar plates are the second, while surface bossed patterns are the worst, having the slowest grow rate, only 85–93 % surface coverage and more than 40– 50 % water erosion ratio. The surface furrow patterned mortar plates are the best engineerable supporting materials for S. platensis biofilm attached cultivation. A mathematical model has been constructed and successfully simulated the complex processes of S. platensis biofilm cultivation from inoculation adhesion, growth to biofilm development and water erosion.

Industrial manufacture and on site application of plaster boards for ceilings with plaster mixes and polyurethane rigid foam waste

The European LIFE Project, Repolyuse – “REcovery of POLYurethane for reUSE in eco-efficient materials” seeks to solve the environmental challenge of resource scarcity and waste management in order to mitigate the effects of climate change. The material is a prefabricated gypsum mortar in the form of a removable roofing plate to which residues of rigid polyurethane foam have been added. That system reduces the weight of the plates about 30%. The investigation has consisted of the final design of the mixtures of plaster mortar with residues of rigid polyurethane foam, mineral fibers, additives and water to achieve the adequate industrial manufacturing system of “Plaster mortar plates lightened with polyurethane foam waste” to put in roofs detachable. In the industry’s own production chain, the plasticity, moulding and drying of the plates can be similar to the process of the standard plates. The final result of the plates shows that the Flexural strength, Flatness, Angular deviation, Thermal conductivity, Superficial hardness, Reaction to the fire and Resistance to humidity have been similar to the results obtained in the laboratory. In the end, the plates were placed in two buildings in Spain. Consequently these results have enough been to achieve the CE marking

Tensile Behavior of Basalt-Fiber-Grid-Reinforced Mortar before and after Exposure to Elevated Temperature

This paper presents an experimental study on the tensile behavior of basalt-fiber-grid-reinforced mortar (BGRM) before and after exposure to an elevated temperature of 300 °C considering the effect of fiber grid type, short polyvinyl alcohol fiber (PVA), and high-temperature exposure time. The experimental results show that the mortar plates reinforced with woven textile T25 and fiber-reinforced polymer (FRP) grid G50 exhibited more pronounced strain-hardening behavior. The highest peak stress was obtained for the T25-reinforced plate, which was 85% and 32% higher than that of the T5- and G50-reinforced plates, respectively. Meanwhile, the bridging effect of PVA fibers in mortar can improve the tensile properties. As the high-temperature exposure time increased, the cracking and peak stress of BGRM decreased significantly. Especially for the T5-reinforced plate after exposure to elevated temperature for 2 h, the cracking and peak stress decreased by 60.5% and 38%, respectively. The positive effect of short PVA fibers on the tensile properties of the BGRM became obsolete owing to the melting of short fibers at high temperature. Furthermore, an exponential strength degradation model related to high-temperature exposure time was proposed.

Mechanical properties and fractography of cement-based composites reinforced by natural piassava and jute fibers

Today’s demand for environmentally friendly and energy-efficient solutions to the construction industry has driven researchers to match natural resources with traditional technics to develop new building technologies. However, there are literature limitations about the correlation of fiber-matrix interface with the failure of natural fibers in mortar plates, which hinders the advances in understanding the mechanical properties of these composites on a structural scale. The present work investigated the mechanical behavior and fractography of cement-based composites reinforced by natural piassava and jute fibers. The experimental program included flexural tests and scanning electron microscopy analyzes. The developed composite material under flexural tests demonstrated a flexural-softening behavior, reaching up to 5.7 MPa, with a considerable residual strength ruled by toughness. The fractography analyses presented the fibers’ structure after mechanical tests and how effective its interaction with the matrix was. The piassava fibers demonstrated significant adherence when favorably oriented, while jute fibers (used as twisted yarn) provided voids in the composite by its partial matrix-covered filaments.

Experimental Study on the Bending Properties of Grouting Butt Joints Reinforced by Steel Plate Embedded in Bamboo Tube

The construction of grouting butt joints of bamboo tubes is simple and efficient. However, when the joint is bent, the low tensile strength of the mortar easily leads to cracking of the mortar prior to the failure of the bamboo tube. In this paper, a comparative test of the bending capacity was performed on grouting butt joints reinforced by nonperforated, fully perforated, and semiperforated steel plates embedded in bamboo tubes to obtain the load-displacement curves and ultimate bearing capacity of various specimens. The strengthening effect of CFRP pasted on bamboo tubes was also studied. The results show that the opening at the end of the steel plate is beneficial to resist the slip between the mortar and steel plate, while the complete section in the middle of the steel plate is conducive to making full use of the tensile strength of the steel plate. Therefore, it is best to insert the semiperforated steel plate with openings in the end and without openings in the middle into the mortar to enhance the bending properties of the grouting butt joint, which can make the failure mode of the joint change from brittle failure of mortar to ductile compression failure of bamboo tube. In addition, pasting CFRP sheets on the external wall of the bamboo tube helps to reduce the tensile stress of the mortar, while increasing the width of the steel plate can increase the bending moment of inertia of the mixture of the steel plate and mortar. These two complementary measures are very effective in delaying the cracking of the bamboo tube and improving the bending capacity of the joint.

Pengaruh Pola Anyaman terhadap Perilaku Lentur Textile Reinforced Concrete (TRC) dengan Perkuatan Serat Rami

The demand of concrete has increased in Indonesia. A reinforced concrete innovation being developed is Textile Reinforced Concrete (TRC). Ramie fiber has great potential to be used as a construction material because it has advantages over other natural fibers, such as tensile strength properties. The research aims to analyzed flexural behaviour of Ramie fiber TRC. This research was conducted from February until June 2021 at IPB University. The research was carried out through several stages, that are testing of TRC materials, mix design, weaving and coating ramie fiber, manufacturing and curing test objects, and testing. The flexural behavior analyzed flexural strength, stiffness, ductility, and crack behavior. Ramie fiber reinforcement can improve the elasticity and ductility of mortar plates. However, woven ramie fiber with a certain woven pattern can reduce flexural strength. Coating ramie fiber with Unsaturated Polyester Resin (UPR) provides an increase in flexural strength, elastic properties, and ductility. Phases of crack behaviour of UPR-coated are uncracked, crack formation, crack stabilization, and failure. The woven pattern that produces the highest flexural strength is the two-axis woven pattern for UPR-coated ramie, which is 7.84 MPa.

Dynamic properties of floating floor system and its influence on heavy-weight impact sound in residential buildings.

We investigated the effects of a floating floor on heavy impact sound in the low-frequency range below 100 Hz with focus on the structural vibration. To verify the mechanism of amplifying the floor impact sound, field measurements were conducted before and after the installation of a floating floor while the other conditions were kept constant. Field tests were performed on five apartment units where the material properties of the resilient materials in the floating floors differed. Slab accelerations and sound pressure levels were measured simultaneously. The test results indicated that the low-frequency responses of slab acceleration and the corresponding heavy impact sounds were amplified in all apartment units after the installation of the floating floor, while high-frequency responses greater than 100 Hz were significantly reduced. The amplified responses were attributed to the interactions between the mortar plate (floating floor) and concrete slab, which were connected by a resilient material layer. The degree of amplification tended to increase as the loss factor of the resilient material decreased while the amplified frequency range was determined by the stiffness of the resilient material layer. The result was numerically verified using a simplified mass-spring model.

Quantification of plastic shrinkage and cracking in mortars containing different recycled powders using digital image correlation technique

This research assessed the shrinkage of mortar containing recycled powder generated from aerated blocks and bricks by replacing cement with a ratio of 30%. Five mix proportions were formulated to prepare mortar plate specimens. AP represents the mixes with aerated block powder and BP represent the mixes with sintered brick powder. Among all of the mixes, AP1 and BP1 was formulated at the same water binder ratio as that of the reference mix, and the same fluidity as the reference was maintained in AP2 and BP2 by adjusting the water content. Digital image correlation (DIC) technique was used to evaluate the strain distribution during the plastic shrinkage stage. The results showed that the mortar containing the aerated block powder presented a higher risk of cracking. On the contrary, the brick powder had a lower water requirement, as a result, a lower risk of cracking. The aerated block powder particles contain pores of 2–3 μm size, which seriously reduces the fluidity of the mortar and causes a tremendous shrinkage.

Topological Design of a Mortar Base Plate under Impact Loads

In this work, the topology optimization of a mortar base plate is analysed under impact loading conditions. Usually, in this case, only ordinary topology optimization under volume constraints is considered. However, to reduce the quality of the mortar base plate and facilitate engineering applications, the topological optimization problem of the continuum of the base plate under the engineering and quality constraint is considered. A finite element model has been established and verified by testing for the mortar base plate. The variable density method was used to obtain the topological optimization results of the base plate based on the force transmission path, and then the structure was reconstructed. The mass of the optimization model of the base plate is 12.78% lower than that of the original model. In comparison with the original base plate before optimization, the results show that the maximum deformation and stress of the base plate decreased by 16.85% and 35.52%, respectively. Also, the firing stability of the mortar meets requirements, which not only meet the design requirement but also provide a reference for the performance improvement and structural optimization design of the base plate.

Lightweight design of a certain mortar base plate based on sensitivity analysis

In order to resolve the inconvenience in usage and transport pertaining to a certain mortar base plate due to its large mass, dimension optimization, topology optimization and composite material optimization were first applied in an integrated manner to the lightweight design of the base plate on the premise of ensuring the strength and good firing stability of the base plate; and the lightweight design of the base plate was realized. The finite element model of the mortar base plate was established; and the correctness of the model was verified by modal testing. Sensitivity analysis was conducted on the five main structural parameters influencing the stiffness and strength of the base plate by a sensitivity analysis method based on DOE and regression analysis, so as to provide an effective basis for the lightweight design of the base plate. Dimension optimization was performed on the parameter greatly influencing the maximum stress on the base plate and topology optimization on the parameter region that has minor influence to obtain the main force transmission path in this region. Composite materials were used to replace the materials in the non-main force transmission region to design a composite base plate; and the thickness of the laminate was optimized. The results of numerical calculation showed that the base plate lost 30.33% of weight after the lightweight design and that the strength and firing stability fully met the requirements. This study provided a new clear design idea for the lightweight design of mortar base plate and provided reference for the lightweight design of other models of mortar base plate.

Strengthening of preloaded RC beams using prestressed carbon textile reinforced mortar plates

Carbon textile reinforced mortar (CTRM) is an advanced composite material that has excellent fire resistance, high strength and ductility, and good energy dissipation ability. Nevertheless, its full potential has not been fully investigated in the literature. In this paper, the flexural behaviour of preloaded reinforced concrete (RC) beams strengthened with a prestressed CTRM plate is explored. RC beams with and without an attached CTRM plate under various preloading conditions are tested. Their load-deflection and load-strain properties, bending capacity, ductility, and crack pattern and width are subsequently examined. The test results show that the prestressed CTRM plates can effectively inhibit the propagation of cracking and significantly increase the cracking and ultimate loads. The findings from this study are useful in advancing the use of CTRM to repair, retrofit and strengthen existing RC structures.

Plastic Shrinkage and Cracking Behavior of Mortar Containing Recycled Sand from Aerated Blocks and Clay Bricks

This research assessed the shrinkage behavior of mortar containing recycled sand generated from aerated blocks and clay bricks by replacing natural sand with a volume ratio of 30%. Five mix proportions were prepared to cast mortar plate specimens. They were named as the control, ABs1, ABs2, CBs1 and CBs2. Among them, ABs1 and CBs1, containing recycled sand from aerated blocks and clay bricks respectively, have the same water/cement ratio as the control. ABs2 and CBs2 had the same workability as the control by adjusting the required amount of water. Digital image correlation (DIC) was adopted to determine the strain distribution during the plastic shrinking period. The results showed that, when no extra water was added, the mortar containing the aerated blocks sand had a lower risk of cracking, because of the internal curing effects brought by the low–weight fine aggregates. However, when the extra water was added to ensure the same fluidity with the control, there were obvious visible cracks in group ABs2, and the average distance between cracks reached 25 mm. On the contrary, the brick sand has no obviously higher water requirement, as a result, it did not lead to higher risk of cracking. The aerated block sand particles contain 2–50 μm pores, which is the reason why aerated block sand tremendously reduced the fluidity of the mortar.

Flexural failure of fabric reinforced cementitious mortar (FRCM) plates under punctual loads: Experimental test, analytical approach and numerical simulation

Fabric-reinforced cementitious matrix (FCRMs) are composites that produce lighter and more durable strengthening solutions. In this study, carbon and basalt fabrics were used to manufactured FRCM plate specimens. These plates were subjected to a centered punctual load with different punch diameters. Flexural failure mode was observed. Experimental tests showed that carbon and basalt fabrics improved notably the load capacity and the stiffness of mortar plates compared to unreinforced ones. Moreover, failure in the reinforced plates was progressive, preventing the sudden brittle failure of the unreinforced ones. Analytical and numerical models were adjusted and validated from experimental results, and both have proved to be effective calculation tools. What is more, numerical model allowed to determine a sliding tensile stress for the carbon fabric used in this study.

Fabrication and Piezoresistive/Piezoelectric Sensing Characteristics of Carbon Nanotube/PVA/Nano-ZnO Flexible Composite

Flexible sensors with a high sensitivity and wide-frequency response are essential for structural health monitoring (SHM) while they are attached. Here, carbon nanotube (CNT) films doped with various PVA fractions (CNT/PVA) and ZnO nanowires (nano-ZnO) on zinc sheets were first fabricated by functionalized self-assembly and hydrothermal synthesis processes. A CNT/PVA/nano-ZnO flexible composite (CNT/PVA/ZnO) sandwiched with a zinc wafer was then prepared by the spin-coating method. The piezoresistive and/or piezoelectric capabilities of the CNT/PVA/ZnO composite were comprehensively investigated under cyclic bending and impact loading after it was firmly adhered to a substrate (polypropylene sheet or mortar plate). The results show that the piezoresistive sensitivity and linear stability of the CNT/PVA films doped with 20%, 50%, and 100% PVA during bending are 5.47%/mm, 11.082%/mm, and 11.95%/mm and 2.3%, 3.42%, and 4.78%, respectively. The piezoelectric sensitivity, linear stability, and response accuracy of the CNT/PVA/ZnO composite under impulse loading are 4.87 mV/lbf, 3.42%, and 1.496 ms, respectively. These merits support the use of CNT/PVA/ZnO as a piezoresistive and/or piezoelectric compound sensor to monitor the static/dynamic loads on concrete structures while it is attached.

Local strengthening and repair of concrete bridge girders using shape memory alloy precast prestressing plate

Whether due to accidents, natural hazards, or harsh environmental conditions, concrete structures and bridges, in particular, experience local damages throughout their service life. Based on their severity, these damages can compromise the integrity of the structure. External prestressing is often used as an effective strengthening or repair technique for vulnerable or damaged structures, respectively. However, applying external prestressing in local regions of the structure with limited space can be problematic and not feasible for conventional prestressing techniques. This study investigates an innovative method for applying external prestressing in local regions of bridge girders using externally mounted precast prestressing plate reinforced with shape memory alloy wires. A thin mortar plate with embedded curved shape memory alloy wire was experimentally tested to validate the proposed prestressing concept. Afterward, finite element analysis was performed on a concrete bridge girder to numerically investigate the performance of shape memory alloy precast prestressing plate in enhancing the shear and flexural behavior of the girder. Experimental and numerical results evidently demonstrated the feasibility and effectiveness of the innovative method in strengthening and repairing concrete structures through external local prestressing.

Innovative prestressing technique using curved shape memory alloy reinforcement

Concrete prestressing techniques have been widely used in various structural applications. However, the application of local prestressing has been limited due to complexities related to the on-site implementation of anchorage devices and mechanical jacking systems. In this work, a novel method is introduced to apply local prestressing using curved Shape Memory Alloy (SMA) reinforcement. The experimental part of the study involves casting and prestressing a mortar plate with embedded curved prestrained SMA wire. The prestressing of the SMA wire is conducted by applying temperature using electrical resistivity. Next, an experimental study is carried out to explore the feasibility of using a mortar plate with embedded SMA as a precast prestressing plate (PPP) for existing concrete. A comparison is carried out between different installation methods to ensure effective connection between the PPP and concrete. Digital Image Correlation (DIC) and strain gage measurements are adopted to monitor the value and distribution of prestress in specimens. The experimental results are used to validate a Finite Element (FE) model of the SMA-reinforced PPP. The model is used to conduct a parametric study to explore the effect of SMA geometric configuration on the prestressing level. The experimental and numerical results show that the proposed prestressing technique is valid and can be used effectively for local prestressing.