Results Of Compression Tests Research Articles

The aging behavior of Moso bamboo in natural weathering condition

Bamboo, recognized as an innovative green building material, is extensively utilized in practical engineering, with its durability in outdoor environments being of paramount importance. The internodes and nodes of bamboo collectively form the primary structure of the bamboo culm, exhibiting significant differences in their structural composition and fracture behavior. In this study, moso bamboo internodes and nodes were exposed to an outdoor environment for two years to investigate their aging mechanisms. The discoloration, dimensional stability, mass loss, and water absorption characteristics of weathered bamboo were assessed through physical property tests. Changes in the microstructure, cellulose crystallinity, and internal crack morphology of bamboo resulting from natural weathering were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and computed tomography (CT). Ultimately, the durability of moso bamboo was assessed based on the results of compressive tests. The results indicated that natural weathering could degrade lignin and hemicellulose on the surface of bamboo, disrupt the microstructure of vascular bundles and parenchyma cells, and impair cellulose crystallinity, leading to a reduction in mechanical properties. Moreover, compared to bamboo internodes, bamboo nodes exhibit a more complex fiber morphology. The presence of internal transverse fibers can significantly impact its compressive property parallel to the grain, but the enhanced spatial locking effect can also improve its durability perpendicular to the grain. This study enhances the understanding of biomass materials and provides valuable insights into the application of bamboo in outdoor environments.

Quasi-static and impact compression properties of Glubam at different relative humidity conditions

Glued laminated bamboo (glubam), a product of bamboo lamination, presents a distinctive combination of eco-friendliness and mechanical strength. This study delves into the quasi-static and dynamic compression behaviour of glubam, examining the influence of key factors such as moisture content and carbonization. The experiment involved one control group and two groups of different carbonized degrees, with two relative humidity controls set at 65% and 85%. The results of the quasi-static compression tests revealed that higher moisture content reduced the ultimate stress and modulus of compression while enhancing the ductility of thick-strip glubam. Cross bamboo alignment bolstered the compressive strengths of longitudinal thin-strip glubam and provided considerable compressive capacity for transverse thin-strip glubam. Poisson’s ratios of glubam were also determined. During drop-tower impact testing, an input energy of 209.5J resulted in the determination of the dynamic ultimate stress of glubam. The application of reasonable image procedures, supported by high-speed camera collections, aided in the efficient presentation of absorbed energy. Scanning electron microscope (SEM) images were employed to explore experimental results through the microstructure perspective.

THE EFFECT OF HEAT-TREATMENT ON THE MECHANICAL PROPERTIES OF EXPANDED GLASS PARTICLE/A356 SYNTACTIC FOAM

This research investigates the manufacturing of metal syntactic foams (MSFs) using a packed bed of porous (2-2.8 mm) expanded glass (EG) within an A356 alloy matrix. To this end, the counter-gravity infiltration casting technique is employed to manufacture the specimens. The density of the MSFs ranges from 1.05 to 1.17 g/cm3, making it one of the lowest densities foams, attributed to the filler particles' low bulk density. The study investigates the influence of T6 heat treatment on the mechanical properties and microstructural characteristics of the manufactured MSFs. The mechanical properties of the MSFs are characterized under quasi-static compressive loads at 1 mm/min. After heat treatment, the compression test results indicate a significant enhancement in most mechanical properties. Compression strength and plateau stress are approximately doubled compared to as-cast foams for samples with similar densities. While energy absorption of the MSFs triples in heat-treated conditions. These improvements are attributed to changes in the matrix microstructure due to thermal treatment. Microstructural analysis reveals that Si particles, initially sharp and continuous within inter-dendritic boundaries, become blurry and discontinuous through spheroidization after thermal treatment. This hinders crack growth in the cell wall and mitigates the effects of casting defects and the columnar dendritic structure. The majority of mechanical properties in both heat-treated (HT) and as-cast (AC) foams exhibited an increase in density due to an increase in the matrix fraction. However, plateau end strain and energy absorption efficiency demonstrated an independent effect of heat treatment and density.

Preparation and characterization of a novel active sediment capping material (geopolymer) for inhibiting phosphate releasing from sediment

In situ remediation of sediment can effectively control the release of phosphate in sediment and improve water eutrophication. The essential question of this remediation techniques lies in the development of stable, high-efficiency, low-cost and easily available active sediment capping materials. This study synthesised a novel sediment capping material using bulk solid waste, and phosphate inhibition mechanism of the materials was explored. Results indicated that GSCM was prepared under the conditions of NaOH concentration of 3 M, hydrothermal temperature of 160℃, hydrothermal time of 36 h and the mass ratio of 40 wt% SS to 60 wt% FA. The result of batch adsorption and compressive strength test suggested that phosphate adsorption capacity and compressive strength of GSCM were 2.15 mg/g and 24.20 MPa, respectively. The characterization result showed that GSCM was composed of sodium zeolite, riversideite, grossular and fayalite, exhibiting a uniformly distributed slit mesoporous structure. The in-situ inhibition efficiency of GSCM to P ranged from 76.65 % to 86.72 %, exceeding that of commercial zeolite. The in-situ inhibition mechanism was controlled by sodium zeolite and riversideite, and concluded by the following:1) Substitution between [SiO4] tetrahedra (within the sodium zeolite structure), -OH (on the surface of materials) and [PO4], 2) Coordination of [PO4] tetrahedra with Al active site within the sodium zeolite structure, 3) Precipitation reaction between phosphate and slow-release of Ca2+ from the riversideite.

Crashworthiness analysis of splitting-expanding structures made from magnesium alloy

This paper aims to investigate the energy absorption performance of a splitting-expanding structure made from magnesium alloy through experimental investigations, computer simulations, and theoretical analyses. The results of the quasi-static compression test showed that the addition of the expansion deformation mode allowed the splitting-expanding structure to retain the excellent stroke efficiency exhibited by the splitting structure, while effectively improving the efficiency and stability of the structure’s energy absorption. The simulation results indicated that structural parameters, such as tube thickness (T), pre-cut depth (d), number of pre-cuts (N), and the friction coefficient between the die and tube (f), significantly influence the mechanical properties of the structure. An increase in ‘T’, ‘d’, and ‘f’, along with a decrease in ‘N’, resulted in an increase in both the mean crushing force and specific energy absorption of the structure. Increasing ‘d’ and decreasing ‘T’ and ‘f’ could effectively reduce the initial peak force of the structure. In addition, the load-carrying capacity of the structure decreased with an increase in ‘d’. However, as ‘T’ and ‘N’ increased, the change in the load-carrying capacity of the structure was non-monotonic. Therefore, selecting appropriate structural parameters was essential to achieve optimal overall performance of the structure. Finally, a theoretical model for the mean crushing force of the structure was established, taking into account both split deformation and expansion deformation. The error between theoretical and experimental results was less than 5 %.

Production of microneedle patches coated with polyvinyl-alcohol/sucrose/gentamicin sulfate for skin treatment

In this study, resin-based microneedle (MN) patches were fabricated using a digital light processing (DLP) printer. The needles were coated with gentamicin sulfate (GEN)-loaded with 13.3 % PVA/25 % sucrose solution by immersion. The SEM results showed that the coating was homogeneous and uniformly conical. Analysing the in vitro release profiles of GEN, it was found that it was ultimately released within 312 h. The compression test results demonstrated that GEN addition increased the compression strength to the value of 2.17 ± 0.01 N/mm2.

Ensemble machine learning models for compressive strength and elastic modulus of recycled brick aggregate concrete

This study delivers an in-depth analysis of predicting the compressive strength and elastic modulus of recycled brick aggregate concrete (RBAC). It assembles an extensive database of 633 compression test results and develops five ensemble learning models—random forest (RF), gradient boosting regression trees (GBRT), extreme gradient boosting (XGB), light gradient boosting machine (LGBM) and stacking (St). These models are evaluated against existing empirical formulas with respect to their effectiveness. The findings reveal that machine learning (ML) models outperform existing formulas: for compressive strength prediction, traditional models achieve a maximum determination coefficient R² of 0.38, whereas ML models attain an R² range of 0.91–0.94. For elastic modulus, the highest R² values are 0.44 for traditional models and 0.97 for ML models. Notably, the LGBM and St models excel in predicting compressive strength and elastic modulus, respectively. The study also identifies critical parameters influencing RBAC’s compressive behavior and highlights their impact trends. Remarkably, while the mass-weighted water absorption of coarse aggregates and the replacement ratio of recycled brick aggregates (RBAs) have less impact on compressive strength compared to the effective water-to-cement ratio, they become more influential for elastic modulus. Additionally, the decrease in elastic modulus due to higher RBA replacement ratios or increased mass-weighted water absorption of coarse aggregates exceeds the corresponding reduction in compressive strength. This research not only deepens the understanding of RBAC’s mechanical properties but also provides valuable predictive tools for civil engineering applications.

Lime Stabilization of Tropical Soil for Resilient Pavements: Mechanical, Microscopic, and Mineralogical Characteristics.

Lime stabilization is a sustainable technique due to its use of local materials, increased durability, reduced maintenance, and improved resistance to water action. This paper examines the impact of lime stabilization on the mechanical, microscopic, and mineralogical properties of a tropical soil. Two types of lime, calcitic and dolomitic, were tested at 3% and 5% by weight. Compressive, indirect tensile and flexural test results and statistical analysis revealed that calcitic lime mixtures had higher strength and stiffness, whereas dolomitic lime mixtures exhibited greater deformability with higher tensile strain at break. Scanning electron microscopy indicated that the soil's porous matrix closed within 7 days for both lime types due to flocculation, with increased matrix interlocking over time. The calcitic lime mixture developed a more closed matrix compared to the dolomitic lime, which showed weaker cementing. X-ray diffraction analysis indicated higher consumption of clay minerals and a notable reduction in calcium hydroxide peaks in the lime-treated soils. The study concludes that calcitic lime provides better pavement performance for stabilizing the soil, enhancing its engineering properties while also being sustainable by reducing the need for raw material extraction and improving resilience to climate-related issues such as floods.

High-temperature mechanical performance and damage behavior of molybdenum tailings modified fly ash-based geopolymers

Molybdenum tailings modified fly ash based geopolymers were an eco-friendly building material with excellent mechanical performance and fracture toughness. In this work, cubic compressive test and acoustic emission technique were used to evaluate the effect patterns of molybdenum tailings contents and thermal temperature conditions on the high-temperature mechanical performance and damage behaviors of molybdenum tailings modified fly ash-based geopolymers. The molybdenum tailings contents were 0 %, 10 %, 20 %, 30 % and 40 %, and the target temperatures were 300 °C, 600 °C and 900 °C, respectively. The results of compressive tests showed that the low contents of molybdenum tailings could limit the growth of macroscopic cracks during the loading process and improve the compressive strength of fly ash-based geopolymers when the heat treatment temperature did not exceed 600 °C. The acoustic emission results showed that 20 % molybdenum tailings contents could improve the structural stability and high-temperature mechanical performance of fly ash-based geopolymers, reduced the growth of microcracks in the specimen during the loading process, and delayed the formation and cracking of macrocracks, but did not change the specimen's compressive damage mode. The 40 % contents of molybdenum tailings changed the compressive damage mode of the fly ash-based geopolymers, delayed the cracking of the matrix structure under the peak loading, and significantly improved its resistance to plastic deformation.

Experimental Study on Optimization of Consolidation Parameters of Silty Clay Based on Response Surface Methodology: A Case Study on the Protection and Restoration of the Ming and Qing Dynasty Hangzhou Seawall Site

The preservation of the ancient seawall site is a focal point and challenge in the protection of historical relics along Hangzhou’s Grand Canal in China. This endeavor holds significant historical and contemporary value in uncovering and perpetuating Hangzhou’s cultural heritage. Researchers investigating the Linping section of the seawall site aimed to address soil site deterioration by selecting environmentally friendly alkali-activated slag cementitious materials and applying the response surface method (RSM) to conduct solidification experiments on the seawall soil. Researchers used the results of unconfined compressive strength tests and microscopic electron microscopy analysis, considering the comprehensive performance of soil solidification mechanisms and mechanical properties, to establish a least-squares regression fitting model to optimize the solidification material process parameters. The experimental results indicate that the optimal mass ratio of lime, gypsum, and slag for achieving the best solidification process parameters for the seawall soil, with a 28-day curing period, is 1:1.9:6.2. This ratio was subsequently applied to the restoration and reconstruction of the seawall site, with parts of the restored seawall exhibited in a museum to promote the sustainable conservation of urban cultural heritage. This study provides theoretical support and practical guidance for the protection and restoration of soil sites.

Investigation of pull-out and mechanical performance of fibre reinforced concrete with recycled carbon fibres

This paper presents the pull-out bonding behaviour and mechanical performance of recycled carbon fibre (rCF) reinforced concrete based on the recent investigation of fibre reinforced concrete (FRC) with rCF recovered from pyrolysis. Single fibre pull-out tests have been carried out to identify the apparent interfacial shear strength of different types of rCF and virgin carbon fibre (vCF) to identify the fibre matrix connection. Furthermore, a series of tests have been carried out to identify the workability, compressive strength and tensile strength of FRC. Besides rCF, also vCF and steel fibre were used for fabrication of FRC test specimens. rCF have shown the same adhesion behaviour and strength like vCF. Furthermore, the use of unsized or acrylate-based sized rCF creates an adhesion between fibre and matrix material. During the pull-out tests, the failure does not occur as an adhesive crack between fibre and cement matrix, but as a cohesive crack in the cement matrix. The mechanical performance of FRC with rCF was compared with mortar and FRC with vCF and steel fibres. The results of compressive test conducted for FRC with vCF and rCF indicated that the influence of vCF and rCF on the compressive strength of FRC was insignificant. On the other hand, the results of tensile test conducted for FRC with vCF and rCF indicated that the tensile strength of FRC with rCF was at least 14.9% greater than that of FRC with vCF.

Structural optimization design and compression performance of porous titanium prepared by laser powder bed fusion

Porous implants composed of periodically-repeating porous units have been applied in orthopedic surgeries to replace damaged bones. An important requirement for bone implants is to find a balance between biological and mechanical properties, that is, to ensure high pore connectivity and a certain strength. In this work, center-supported and perimeter-supported porous optimization models were established by a swarm intelligence optimization algorithm, and the corresponding titanium porous samples were fabricated by laser powder bed fusion (L-PBF). The effects of cell topology and porosity on the compressive behavior of L-PBF titanium porous structures were systematically investigated by a combination of compression simulation and experiments. Compression simulation shows that the deformation failure behavior of center-supported and perimeter-supported porous structures consists of three stages: elastic deformation, plastic deformation and compression collapse, showing the characteristics of elastic-plastic porous materials. According to the compression test results, the compressive strength of center-supported and perimeter-supported structure samples are 151–188 MPa and 178–196 MPa, respectively, and the compressive stability of the perimeter-supported structure is better than that of the center-supported structure. The porosity error of center-supported structure is 1.6%–2.9%, and the porosity error of perimeter-supported structure is 3.1%–4.5%. The compressive strength of the same type of structure decreases with the increase of the porosity of the porous structure. The simulation/experimental compressive strength errors of center-supported and perimeter-supported structures are less than 6% and 5.9%, respectively. The constructed quasi-static compression model has certain guiding significance for the study of the fracture of the titanium implants under external force.

Failure mechanism of a tunnel in a soil–rock mixture based on a new combined finite–discrete element method

The mechanical properties and failure characteristics of soil–rock mixtures (SRMs) directly affect the stability of tunnels constructed in SRMs. A new SRM modelling method based on the combined finite–discrete element method (FDEM) was proposed. Using this new SRM modelling method based on the FDEM, the mechanical characteristics and failure behaviour of SRM samples under uniaxial compression, as well as the failure mechanism of SRMs around a tunnel, were further investigated. The study results support the following findings: (1) The modelling of SRM samples can be achieved using a heterogeneous rock modelling method based on the Weibull distribution. By adjusting the relevant parameters, such as the soil–rock boundaries, element sizes and modelling control points, SRM models with different rock contents and morphologies can be obtained. (2) The simulation results of uniaxial compression tests of SRM samples with different element sizes and morphologies validate the reliability and robustness of the new modelling method. In addition, with increasing rock content, VBP (volumetric block proportion), the uniaxial compressive strength and Young’s modulus increase exponentially, but the samples all undergo single shear failure within the soil or along the soil–rock interfaces, and the shear failure angles are all close to the theoretical values. (3) Tunnels in SRMs with different rock contents all exhibit X-shaped conjugate shear failure, but the fracture network propagation depth, the maximum displacement around the tunnel, and the failure degree of the tunnel in the SRM roughly decreases via a power function as the rock content increases. In addition, as the rock content increases, such as when VBP = 40%, large rocks have a significant blocking effect on fracture propagation, resulting in an asymmetric fracture network around the tunnel. (4) The comparisons of uniaxial compression and tunnel excavation simulation results with previous theoretical results, laboratory test results, and numerical simulation results verify the correctness of the new modelling method proposed in this paper.

An improved dual shear unified strength model (IDSUSM) considering strain softening effect

This study proposes an improved dual shear unified strength model by introducing the plastic internal variable which reflects the collective effects of strain softening, intermediate principal stress and unequal strength under tension and compression. The improved model is then simplified into simple forms for typical stress states, including uniaxial tension and compression, plane stress pure shear and tri-axial stress states. The smooth method and conjugate gradient method are utilized to facilitate its numerical implementation, avoiding numerical singularity and non-convergence in the solution process. The physical meanings of the parameters are further clarified and their values for self-compacting concrete are determined from the results of triaxial compression tests through a combination of direct determination, equation solution and back propagation (BP) neural network optimization. Validated against the test results, the improved model gives a more accurate prediction than the traditional dual shear unified strength model and Mohr-Coulomb model, in terms of both the overall trend and representative values. Validation results show that the improved model is applicable to materials for which the compressive strength is greater than the tensile strength and the tensile strength is greater than the shear strength.

Micro-mechanical properties of Song Dynasty tilestones based on nanoindentation tests and homogenization approach

Song Dynasty tilestones are one type of ancient Chinese building materials. Studying their mechanical properties is of great significance for the design and development of restoration materials. It is a challenge to sample and perform traditional tests (ϕ50mm × 100mm) for the tilestone cultural relics. In this work, a combination of nanoindentation techniques and the homogenization calculation method based on the Mori–Tanaka model were used to determine the mechanical parameters of Song Dynasty tilestones. The study process involved several steps: (1) Using X-ray diffraction and scanning electron microscopy to examine the surface morphology and mineral composition of the tilestones. (2) Determining the mechanical parameters (i.e., the elastic modulus, hardness and fracture toughness) through nanoindentation tests. (3) Upgrading mechanical parameters from micro to meso-scale using the Mori–Tanaka model and comparing these with uniaxial compression test results. The result shows that the red tilestones and green tilestone are mainly composed of quartz, feldspar and mica. The average elastic modulus of the red tilestones and the green tilestones are 29.47 GPa and 30.21 GPa, respectively. Compared with the parameter result obtained by upscaling, the deviation rates of the red tilestones and green tilestones are 10.3% and 9.6%, respectively, which proves that the test method is reliable. The nanoindentation test and homogenization approach in this work provide the robust theoretical and practical basis for evaluating the mechanical strength of Song Dynasty tilestones.

3D mesoscale discrete element modeling of hybrid fiber-reinforced concrete

To investigate the relationship of hybrid fiber volume friction on the mechanical properties and failure mechanisms of steel-polypropylene hybrid fiber reinforced concrete (HFRC), the study constructs a three-dimensional, five-phase mesoscale model using the Discrete Element Method (DEM), which consists of mortar, coarse aggregate, polypropylene fibers (PPF), steel fibers (SF), and the interfacial transition zone (ITZ). The axial compression test results of twelve cubic specimens with four different hybrid fiber combinations (0.5 % SF + 0.05 % PPF, 0.5 % SF + 0.1 % PPF, 1.0 % SF + 0.05 % PPF, 1.0 % SF + 0.1 % PPF) were used to validate the model’s accuracy, examining the influence of fiber content on the mechanical performance and cracking features of HFRC. Directed by experimental mix proportions, the model employed cluster particle modules with realistic aggregate geometries and randomly distributed SFs to simulate concrete microstructure. Utilizing the Flat-Joint Model (FJM) in DEM software (PFC3D), two contact models are developed: one FJM with bi-nonlinear softening segments to describe the ITZ between steel fibers and PPF-reinforced mortar (PFRM); another FJM considering the volume fraction effect of SF to describe the ITZ between coarse aggregate and FRM. Both models were experimentally validated, proving their accuracy. The results indicate that the established DEM model can accurately simulate the stress-strain relationship and failure modes of HFRC under compression. The hybrid fibers increased the compressive strength by 2.13–17.33 % and reduced the cracking strain by 5.25–9.33 %. Furthermore, the computational findings reveal that PPF primarily affects the crack initiation phase, while SF plays a significant role in the overall crack propagation stage. This discovery holds significant importance for understanding and optimizing the structural performance of HFRC.

Experimental study of rock fracture behavior under direct tension using three-dimensional digital image correlation

Understanding the mechanical characteristics of rocks when subjected to direct tension is crucial for assessing the stability of rock formations. Within the scope of this research, a series of tests was conducted using Tage tuff to assess the deformation behavior and crack extension of rock under direct tension. The axial, lateral, and shear strain fields as well as crack propagation, localized deformation behavior, and failure mode of the rocks were analyzed using three-dimensional digital image correlation method. The results showed that the axial strain fields on the specimen surface were heterogeneous, with different locations and localization occurring in the pre-peak stage, which was similar to the evolution of shear strain, whereas the lateral strain only showed slight changes. The crack extension direction was inferred, indicating that both tensile and shear stress occurred in the tests. Furthermore, different stress–strain responses were observed for the inside and outside of the localized bands. Then, the surface patterns of specimen failure were scanned and analyzed to assess the failure mode and residual strength of the specimen under direct tensile stress. Finally, the results of direct tension, uniaxial compression, and Brazilian split tests for Tage tuff were compared, and the complete stress–strain curve of uniaxial tension (UT) was simulated using a nonlinear-variable-compliance constitutive equation. This study provides a deeper understanding into the damage behavior of rocks under direct tension.

PENGARUH PEMANFAATAN AIR KELAPA SEBAGAI BAHAN SUBSTITUSI CAMPURAN BETON PRACETAK METODE SELF COMPACTING CONCRETE (SCC)

Concrete mixtures are usually made with drinking water or pure water. However, if we are in a difficult condition to get clean water, we must try to use additional materials or waste around us. This is also a difficulty in the construction industry; one of the challenges is how to develop new ideas, such as high-quality and durable concrete (sustainability), from existing materials, such as coconut water. The data collection strategy for this study is laboratory-based. Given that the variables studied in this study include the composition of coconut water used to determine the quality of the concrete mixture, its compressive strength, and its comparison with ordinary water. The compressive strength of self-compacting concrete (SCC) made with 100% coconut water varies. The average compressive strength of SCC concrete with 100% coconut water is 41 kg/cm2 after 3 days, 88.67 kg/cm2 after 7 days, 242.67 kg/cm2 after 14 days, and 364 kg/cm2 after 21 and 28 days. 550.67 kg/cm2. The results of the normal compressive strength test showed growth; the average compressive strength was 284 kg/cm2 at 3 days, 511 kg/cm2 at 7 days, and 1386 kg/cm2 at 14 days. 21 days = 2226; 28 days equals 3098.67.

Effect of Nano Α-Mno2 Addition on Thermal Decomposition and Compressive Properties of Epoxy

The ability of a nanocomposite material to withstand high temperatures and maintain strength is crucial for the design of products and processes. This research examined the thermal decompositionand compressive properties of α-MnO2/epoxy polymer nanocomposites. The samples were created using a simple, inexpensive solution technique. The scanning electron microscope, X-ray diffraction, and energy-dispersive X-ray analysis indicated the formation of α-MnO2 nanosheets. The thermal analysis revealed that the addition of α-MnO2 increased the glass transition temperature of the epoxy. Thermogravimetric analysis showed that the residue was left at 550°C for a sample of pure epoxy with a loading of 0.1 wt.%. 0.2 wt.%, 0.3 wt.%, and 0.5 wt.% of α-MnO2 were 9.55%, 11.05%, 16.78%, 17.37%, and 21.20%, respectively. As a result, the nanocomposites were more thermally stable than pure epoxy. The compressive characteristics were tested using a universal testing machine. Compression test results showed that the addition of α-MnO2decreased the compressive properties of the epoxy matrix. However, the brittleness of nanocomposites increased. Images captured at the microscopic level showed that the sample cracked and fractured during testing. The reduced compressive property values was associated with reduced α-MnO2dispersion in the epoxy, the shape of α-MnO2nanosheets, and the generation of air voids during the synthesis process. As a result, the α-MnO2 nanosheets reduce the compressive properties of the nanocomposites by acting as stress enhancers. The nanocomposite can be used as a thermal heat-resistant material.

Pemanfaatan Abu Cangkang Kopi Sebagai Substitusi Semen Untuk Bahan Beton Ringan Menggunakan Bahan Tambah Sikament NN

The chemical reaction of cement and water produces compounds that are alkaline and react with various acids so that they can reduce the quality of concrete. To minimize this effect, pozzolanic materials need to be added. Organic pozzolan materials such as coffee shell ash waste can be used as material for making lightweight foam concrete which can be applied to non-structural buildings such as lightweight bricks. This research was conducted to see the effect of coffee shell ash substitution for cement on the properties of fresh concrete and the mechanical properties of lightweight foam concrete and to find the most optimal substitution composition for coffee shell ash for cement as well as lightweight foam concrete with FAS 0.5. Substitution of coffee shell ash for cement weight was carried out with variations of 0% BBN, 5% BBAAK1, 10% BBAAK2, and 15% BBAAK3 using 1% superplasticizer additive. The test object used is a cylinder with dimensions of 15 cm x 30 cm. The number of test objects used was 24 pieces. Tests for compressive strength and split tensile strength were carried out at the age of 28 days. The results of compressive strength tests carried out at 28 days for the lightweight foam concrete variations BBN, BBAAK 1, BBAAK 2 and BBAAK 3 were respectively 15.29 MPa, 12.21 MPa, 18.29 MPa and 19.52 MPa. The greater showing variation in the percentage of coffee shell ash substitution used, the greater the resulting compressive strength and split tensile strength values. This is because Sikament NN also plays a role in increasing the compressive strength of concrete