Compressive Strength Values Research Articles

Influence of Grinding Aids on the Grinding Performance and Rheological Properties of Cementitious Systems

The cement industry is of great importance in terms of raw materials consumed, energy consumed, and greenhouse gases emitted. Grinding aids (GA) are used to reduce energy consumption and costs, as well as to reduce the amount of CO2 released into the environment. In this study, the effect of GA-polycarboxylate ether-based water-reducing admixture (PCE) compatibility on some fresh, rheological and hardened state properties of cementitious systems was investigated. In order to investigate the rheological properties and thixotropic behavior of the mixtures, a total of 51 cement paste mixtures were prepared, containing 4 different types (molasses, MEG, DEA and ethanol) and ratios (0.025, 0.05, 0.75 and 0.1) of GAs and 2 different ratios (0.08% and 0.16%) of PCE in addition to the control mixture. In addition, the effect of the used GAs on the grinding efficiency and compressive strength value was investigated. Additionally, the predictability of the type of GA, dosage and cure time using the Taguchi method was investigated. It was determined that the highest grinding performance was obtained in mixtures containing MEG. It was determined that in cement paste mixtures containing GAs, the dynamic yield stress and viscosity values generally decrease with the increase in PCE usage rate up to a certain value, and these values may increase if the PCE usage increases further. It was determined that such behavior is not present in cement paste mixtures containing GAs and that the structural build-up value of the mixtures generally increases with the increase in the PCE admixture usage rate. It was determined that the use of GAs had a positive effect on 28-day compressive strength.

Heritage clay brick characterization and assessment with compatible contemporary bricks for retrofitting of heritage monuments

Various mughal architecture clay brick masonry monuments were built in the Punjab state of northern India from the late 14th to late 19th centuries. Nanakshahi monuments (era of 1st Sikh Guru-Guru Nanak Dev Ji) are gigantic clay brick masonry structures constructed of lime and lime surkhi mortar (a powdered form of red burnt clay brick). Currently, this study is focused on identifying a suitable material for repairing and strengthening heritage clay brick monuments. Using the mineralogical composition of heritage Nanakshahi clay bricks (NSCB), the study compares them with contemporary clay bricks (CCB) from the same region, and then compares them to newly prepared clay bricks (NPCB), which have similar composition and dimensions to NSCB. The X-ray fluorescence confirms that the NSCB samples of southeast Punjab have an elemental composition consisting of filler SiO2 and binding elements like Al2O3, Fe2O3, CaO, K2O and MgO. The average density of ancient NSCB and CCB has been found to be similar; the ancient NSCB has a lower water absorption rate and porosity in contrast to the present-day clay bricks. The Initial rate of absorption of an ancient NSCB is quite higher. In comparison to the heritage NSCB, the CCB's compressive strength value is lower and uniaxial compression strength of newly prepared clay bricks (NPCB) of similar mineralogical composition and dimensions is comparable to that of the heritage NSCB from Punjab districts. The significance of the study is to suggest a compatible material for strengthening of heritage clay brick monuments of northern India.

Role of Ti3AlC2 MAX phase in regulating biodegradation and improving electrical properties of calcium silicate ceramic for bone repair applications

Calcium silicate ceramic is a promising bioceramic for various biomedical applications, but its high biodegradation rate and low strength restrict its clinical utility. As a result, the study devised an innovative solution to address these issues by utilizing the titanium aluminum carbide phase, potentially for the first time in biological applications, in conjugation with hydroxyapatite. Then, using powder metallurgy technology, they added these phases to calcium silicate to create nanocomposites. After soaking in simulated body fluid for ten days, the produced nanocomposites were assessed for bioactivity and biodegradability using scanning electron microscopy, inductively coupled plasma-atomic emission spectroscopy, and weight loss assays. Their electrical and dielectric properties were also measured before and after soaking in the simulated body fluid solution. Furthermore, the tribo-mechanical properties of all sintered samples were measured. Interestingly, adding 40% hydroxyapatite nanoparticles to calcium silicate reduced the porosity from 12 to 6%. However, adding five vol% of the titanium aluminum carbide phase to the same sample increased the porosity to 8%. Importantly, these recorded percentages of porosity were comparable to those of compact bone porosity, which range from 5 to 13%. The addition of hydroxyapatite and titanium aluminum carbide phase significantly improved the rapid biodegradation of calcium silicate, albeit with a slight decrease in its bioactive properties, as evidenced by the incomplete surface coverage of the samples with the hydroxyapatite layer in the scanning electron microscopy images. The electrical properties of the nanocomposites were better with the addition of hydroxyapatite and titanium aluminum carbide phase, which helped the bone heal faster. The addition of a titanium aluminum carbide phase significantly improved the mechanical properties of the resulting nanocomposites. For example, the calculated values for compressive strength of all examined samples were 131, 115, 105, 147, and 135 MPa. Based on the results, the prepared samples can be used in orthopaedic and dental applications.

Predictive modeling of compressive strength in silica fume‐modified self‐compacted concrete: A soft computing approach

AbstractSelf‐compacting concrete (SCC) is a specialized type of concrete that features excellent fresh properties, enabling it to flow uniformly and compact under its weight without vibration. SCC has been one of the most significant advancements in concrete technology over the past two decades. In efforts to reduce the environmental impact of cement production, a major source of CO2 emissions, silica fume (SF) is often used as a partial replacement for cement. SF‐modified SCC has become a common choice in construction. This study explores the effectiveness of soft computing models in predicting the compressive strength (CS) of SCC modified with varying amounts of silica fume. To achieve this, a comprehensive database was compiled from previous experimental studies, containing 240 data points related to CS. The compressive strength values in the database range from 21.1 to 106.6 MPa. The database includes seven independent variables: cement content (359.0–600.0 kg/m3), water‐to‐binder ratio (0.22–0.51), silica fume content (0.0–150.0 kg/m3), fine aggregate content (680.0–1166.0 kg/m3), coarse aggregate content (595.0–1000.0 kg/m3), superplasticizer content (1.5–15.0 kg/m3), and curing time (1–180 days). Four predictive models were developed based on this database: linear regression (LR), multi‐linear regression (MLR), full‐quadratic (FQ), and M5P‐tree models. The data were split, with two‐thirds used for training (160 data points) and one‐third for testing (80 data points). The performance of each model was evaluated using various statistical metrics, including the coefficient of determination (R2), root mean square error (RMSE), mean absolute error (MAE), objective value (OBJ), scatter index (SI), and a‐20 index. The results revealed that the M5P‐tree model was the most accurate and reliable in predicting the compressive strength of SF‐based SCC across a wide range of strength values. Additionally, sensitivity analysis indicated that curing time had the most significant impact on the mixture's properties.

Finite Element Analysis of Two-Way Reinforced Concrete Slabs Strengthened with FRP Under Flexural Loading

This paper presents a finite element (FE) model of reinforced concrete two-way slab strengthened using fiber-reinforced polymer (FRP) sheets. This model was validated against experimental data from the literature and it showed acceptable prediction accuracy. Although carbon-FRP (CFRP) is the most commonly used composite in repairing and strengthening reinforced concrete structures, it is important to consider other types of FRP composites such as the eco-friendly basalt-FRP (BFRP) and the newly developed polyethylene terephthalate-FRP (PET-FRP). Therefore, the validated FE model was utilized to perform a parametric study for slabs having different values of concrete compressive strength (ranging from 20 to 80 MPa) and strengthened with other types of FRP. The results show that CFRP provides the highest strength enhancement with a 34.5% increase in the ultimate load, while PET-FRP provides the lowest improvement with an increase of 11.2%, compared with unstrengthened slab. The results also show that the concrete compressive strength (fc’) has moderate influence on the ultimate load. For example, increasing fc’ from 20 MPa to 80 MPa increased the predicted ultimate load for CFRP-strengthened slab from 15% to 62%. The FE model provides a suitable prediction for the ultimate strength and deformability of the strengthened two-way slabs that helps in better understanding of the performance of strengthened slabs and allows engineers to optimize design parameters.

Sustainable concrete production: Partial aggregate replacement with electric arc furnace slag

Abstract The pursuit of sustainability in the construction industry has stimulated interest in seeking environmentally friendly alternatives to natural aggregates in concrete production. This study evaluates the behavior of concrete when electric arc furnace (EAF) slag is used as aggregates in its production. The primary research gap filled by this study is to deduce the blend of the fine and coarse EAF slag aggregates that would produce concrete of comparative strengths to concrete made with natural aggregates. Concrete mixtures were formulated using varied EAF slag content in the proportions of 0, 10, 15, 25, and 50%, respectively. The compressive strength values increased as the EAF slag content increased. However, this trend was not evident for the density and tensile strength values. The concrete mixture containing 25% EAF slag with 15% fine and 20% coarse EAF slag aggregates had the greatest density value of 2550.00 kg/m3 and the tensile strength value of 4.8 Pa respectively. This could be due to the distribution of the fine and coarse aggregate grains in the mixture. Since the percentage of fine and coarse aggregate grains were 10 and 15%, respectively, it was a close enough range for the fines to fill in the void spaces. This made the mixture more compact which resulted in a higher density and tensile strength values.

Effect of costus lucanius bagasse fibre on fresh and hardened concrete using RSM modelling

This investigation purposes to use the recycling waste materials in concrete to produce a sustainable environment for construction. The Costus lucanius bagasse fiber (CLBF) was utilized as supplementary cementitious material (SCM) to analyse the workability and mechanical properties of blended cement concrete. The concrete samples were made with the inclusion of 5–20% of CLBF at several w/c ratio by applying RSM modelling and optimization. Moreover, the cubical specimens were cast to study the compressive strength (CS), while beams were used to investigate the flexural strength (FS) on 28th days correspondingly. The outcomes show that the compressive and flexural strengths were decreased with rise in proportion replacement in concrete at various w/c ratio. The highest flexural and compressive strengths was attained at 5% of CLBF at 28 days respectively. Across the tested specimens, the values of compressive strength and flexural strength ranged from 30.20 to 53.92 N/mm2 and 2.15–8.81 N/mm2 for CLBF correspondingly. Besides, the workability and water absorption of concrete is getting decreased as the content of CLBF increases while it is recorded increasing as w/c ratio increases from 0.20 to 0.40. Furthermore, response model predictions were constructed and verified applying ANOVA at an acceptable level of significance of 95%. The coefficients of R2 for the mathematical models ranged from 98 to 99.99%. The research study also indicated that cement can be substituted by CLBF in the production of concrete for various construction purposes.

Compressive behavior of additively manufactured lightweight structures: Infill density optimization based on energy absorption diagrams

The use of 3D-printed components as load-bearing structures is widely studied, while their use as energy absorbers constitutes a gap in the additive manufacturing (AM) field. Most of the reported works address the compressive behavior of AM parts up to low strains (<15%), thus omitting many important properties. Therefore, this paper presents the compression characterization of Polylactic Acid (PLA) samples with different infill densities-IDs (10–100% range, with a step of 10%) fabricated by material extrusion (MEX) AM process. The physical (dimensional accuracy, printing time and sample mass) and mechanical (elastic, strength, strain and energy absorption) properties are determined and discussed in detail, along with the failure mechanisms that occur in the samples. Moreover, an ID optimization is performed based on the energy absorption diagrams (EAD), a unique approach in the AM field. The highest values of compressive strength (81 MPa) and modulus (1306.6 MPa) are found for 90%-ID, over 2.2% higher than those obtained for 100%-ID. On the other hand, based on three different approaches, EAD identified 30%-ID as optimal. The 30%-ID samples absorb the largest amount of energy (12 MJ/m3) at the lowest (ideal) peak stress value (23.57 MPa), which is 69.1% lower than that for 100%-ID. At low IDs (<30%), the samples exhibit a brittle behavior, changing to a ductile one with the increase of ID (≥40%). The MEX-printed PLA samples show a dimensional relative error below 0.15%, and the optimization process reduces the amount of filament material by 54.3% and the printing time by 42.7%.

In-situ sol-gel process for the formulation of Bis-GMA/TEGDMA/silica dental nanocomposite

A novel dental composite based on Bis-GMA/TEGDMA resin incorporating silica nanoparticles was developed using an innovative in situ sol-gel process. This method ensures a homogeneous dispersion of fillers, effectively preventing their agglomeration during preparation. It results in an interpenetrating network in which polymer chains and silica particles are intimately mixed, thereby enhancing the structural and mechanical properties and minimizing the volumetric shrinkage of the dental restorative material.The formation of organic and inorganic network was confirmed by infrared spectroscopy. The in situ synthesis enabled uniform dispersion of silica nanoparticles within the material as evidenced by transmission electron microscopy, scanning electron microscopy and energy dispersive spectroscopy.The results showed that the prepared composite containing 50 wt% fillers achieved hardness, modulus of elasticity, compressive strength and flexural strength values of 72 HV, 10 GPa, 240 MPa, and 110 MPa, respectively. These properties are comparable to those of the commercial “Nt Premium” composite containing 75 % preformed silica nanoparticles, which has hardness, modulus of elasticity, compressive strength and flexural strength values of 68 HV, 10 GPa, 220 MPa and 95 MPa, respectively. Additionally, the study revealed a significantly reduced volumetric shrinkage of 0.5 % for our composite, compared with over 2.2 % for Nt Premium. This groundbreaking approach holds substantial promise for developing advanced dental materials, offering superior performance and enhanced longevity in clinical applications.

Compressive strength of nano concrete materials under elevated temperatures using machine learning

In this study, four Artificial intelligence (AI) - based machine learning models were developed to estimate the Residual compressive strength (RCS) value of concrete supported with nano additives of Nanocarbon tubes (NCTs) and Nano alumina (NAl), after exposure to elevated temperatures ranging from 200 to 800 degrees. These models were developed via adapting meta- heuristic models including the Water cycle algorithm (WCA), Genetic algorithm (GA), and classical AI models of Artificial neural networks (ANNs), Fuzzy logic models (FLM), in addition to the statistical method of Multiple linear regression (MLR). 156 post heating experimental results available as a literature data (represents four input parameters of temperature change, heat exposure duration, nanomaterial type, and replacement proportion) are used to achieve the study’s objective. Results of the developed models demonstrated that ANN and FLM have strong potential in predicting RCS. However, it is often infeasible to generate practical equations that relate input and output variables from these models. Upon analysing the results of the WCA and GA, it was found that WCA yielded the most accurate predictions based on all performance indicators. Furthermore, RCS prediction equations with superior accuracy were derived utilizing the meta-heuristic AI models of WCA and GA, with Mean absolute errors (MAEs) of 3.09 kg/cm² and 3.53 kg/cm² for the training, 1.91 kg/cm² and 2.72 kg/cm² for the validation, and 1.91 kg/cm² and 2.72 kg/cm² for the testing data sets, respectively. Additionally, sensitivity analysis via neural networks weights and SHAP investigation were performed to reveals the impact and relationship of the input variables with the output variables. Both techniques reveal that temperature degree and time of exposure had the highest positive impact on RCS value, followed by NAl and NCTs, in order.

Performance and mechanism of triethanolamine-triisopropanolamine corrosion inhibitor to deterioration of reinforced concrete under the coupling effect of freeze-thaw cycles and chloride attack

The purpose of this study is to propose an efficient and economical organic triethanolamine-triisopropanolamine corrosion inhibitor (OTTCI) to reduce the corrosion of steel in reinforced concrete. The influence of OTTCI on corrosion of steel in reinforced concrete under the coupling effect of freeze-thaw cycles and chloride attack (FTCs-CA) were characterized by electrochemical impedance spectroscopy (EIS), dynamic electrode potential (PDP), mechanical properties (mass loss rate (M), compressive strength (fn) and relative dynamic elastic modulus value (Pi)), capillary water absorption (CWA), bubble spacing coefficient (BSC) and scanning electron microscope (SEM). The inhibition mechanism of OTTCI was also analyzed and summarized. The results displayed that the dosage of OTTCI delayed the degradation of reinforced concrete under FTCs-CA. After 150 cycles, the M value of specimens with 1.0 % OTTCI reduced by 66.31 % compared to that of specimens without OTTCI, the Pi value increased by 51.9 %, and the polarization resistance and corrosion inhibition efficiency reached 2744.19 Ω cm2 and 92.88 %, respectively. In addition, OTTCI significantly reduced the CWA value and porosity. After 150 cycles, the CWA and porosity with 1.0 % OTTCI decreased by 60.1 % and 54.54 % respectively. The capillary water absorption coefficient increased linearly with the increase of FTCs-CA. SEM tests illustrated that OTTCI inhibited the development of internal cracks and macropores in concrete and promoted the formation of hydrated calcium silicate gels and calcite. The application of this study not only provides a new method to alleviate the deterioration of reinforced concrete, but also offers theoretical and technical support for further investigate on the deterioration characteristics of reinforced concrete in harsh environments.

Synergistic Effects of Polypropylene Fibers and Silica Fume on Structural Lightweight Concrete: Analysis of Workability, Thermal Conductivity, and Strength Properties

Structural lightweight concrete (SLWC) is crucial for reducing building weight, reducing structural loads, and enhancing energy efficiency through lower thermal conductivity. This study explores the effects of incorporating silica fume (SF), micro-polypropylene (micro-PP), and macro-PP fibers on the workability, thermal properties, and strength of SLWC. SF was added to all mixtures, substituting 10% of the Portland cement (PC), except for the control mixture. Macro-PP fibers were introduced alone or in combination with micro-PP fibers at volumetric ratios of 0.3% and 0.6%. The study evaluated various parameters, including slump, Vebe time, density, water absorption (WA), ultrasonic pulse velocity (UPV), thermal conductivity coefficients (k), compressive strength (CS), and splitting tensile strength (STS) across six different SLWC formulations. The results indicate that while SF negatively impacted the workability of SLWC mortars, it improved CS and STS due to the formation of calcium silicate hydrate (C-S-H) gels from SF’s high pozzolanic activity. Additionally, using micro-PP fibers in combination with macro-PP fibers rather than solely macro-PP fibers enhanced the workability, CS, and STS of the SLWC samples. Although SF had a minor effect on reducing thermal conductivity, the use of macro-PP fibers alone was more effective for improving thermal properties by creating a more porous structure compared to the hybrid use of micro-PP fibers. Moreover, increasing the ratio of micro- and macro-PP fibers from 0.3% to 0.6% resulted in lower CS values but a significant increase in STS values.

Study on the properties of recycled concrete mixed with coal gangue: Mechanics, workability and microstructure

Coal gangue is a by-product in the process of coal mining. Calcined coal gangue powder and coal gangue aggregate are used to prepare concrete, which can not only enhance the utilization rate of coal gangue, but also improve the performance of coal gangue concrete. In this study, calcined coal gangue powder (CCGP) was employed as an auxiliary cementation material, and coal gangue was employed as coarse concrete aggregate (CCA). Different mix proportions were designed to prepare 180 concrete specimens, and slump, cube compressive strength, splitting tensile strength and SEM test were carried out, respectively. The results show that after standing for 120min, the slump of CP0CA0 group is 53 mm, while the slump of CP30CA0 group is only 48 mm. CCGP can reduce the slump loss of concrete over time. The incorporation of CCGP into coal gangue concrete (CGC) can improve the late strength of concrete. When the substitution rate of CCA is constant, the CGC whose substitution rate of CCGP is 20 % will have the best mechanical properties: the compressive strength values are 49.67 MPa, 39.22 MPa and 27.35 MPa; the splitting tensile strength values are 2.92 MPa, 2.59 MPa and 1.92 MPa. In addition, how CCGP affects the mechanical properties of CGC was analyzed from the microscopic level in this paper. Through the regression analysis of the test data, the conversion relationship between the compressive strength and the splitting tensile strength of the concrete mixed with CCGP and CCA was obtained, which can be used to predict the splitting tensile strength. The results of this study can provide a new research idea for the efficient utilization of coal gangue.

Physical and Mechanical Properties of Autoclaved Aerated Concrete (AAC) with Ceramic and Gypsum Waste (CGW) Addition Before and After Exposure to Direct Fire at Temperatures up to 920°C

This research endeavors to comprehensively explore the physical and mechanical properties of Autoclaved Aerated Concrete (AAC) with ceramic and gypsum waste (CGW) addition before and after exposure to direct fire at temperatures up to 920°C. The investigation focuses on determining the effects of CGW addition on AAC properties before and after exposure to direct fire at temperatures reaching 920℃ for 300 seconds. The main objective of this research was to determine the work density and compressive strength of AAC-CGW on the surface of direct fire exposure. In pursuit of this goal, various compositions of AAC with CGW, ranging from 5% to 30% wt/wt, were accurately prepared. The physical and mechanical were conducted before and after subjecting to direct fire testing. Important parameters such as work density, ranging from 593.71kg/m3 to 672.70kg/m3, and compressive strength from 1.64MPa to 2.39MPa, were analyzed. The findings demonstrated that the compressive strength exhibited an increase with CGW addition, particularly within the 5% wt/wt. The high point compressive strength value recorded was 2.39MPa for a 5% wt/wt CGW addition, reflecting a 45.73% increase in compressive strength compared to the reference sample (RS). The study also revealed convincing fire resistance results. Indicating for the reference sample (RS), the samples exhibited surfaces devoid of cracks, burns, or melting during direct fire exposure exceeding 920℃ for 300 seconds. Furthermore, CGW addition contributed to a remarkable 20.1% improvement in thermal insulation compared to the RS. Direct fire resistance testing had a positive influence on the physical and mechanical characteristics of AAC-CGW samples. The average work density experienced a 9.9% reduction, while compressive strength exhibited an 18.8% increase. Direct fire exposure led to an outstanding 53.30% enhancement in compressive strength compared to the sample.

Investigation of thermal, acoustic, mechanical, and radiation shielding performance of waste and natural fibers

It is crucial to address two pressing global issues, energy shortage and environmental pollution, when producing building insulation materials. Using waste and natural fiber groups can be part of the solution. The insulation material was produced using pumpkin fiber, chicken fiber, cotton waste, vermiculite, and epoxy as binders. The samples were tested for thermal conductivity coefficient, ultrasonic sound transmission rate, density, water absorption rate, compressive and bending strength, and fire resistance at temperatures of 75, 100, 125, and 150C. The samples produced using natural and waste materials yielded a thermal conductivity value of 0.041 W/mK, an ultrasonic sound transmission speed of 0.25 km/s, a compressive strength value of 1.57 MPa, and bending strength values of 0.91 MPa. It has been clearly demonstrated that, with its low volume loss, it can serve as an alternative to the EPS-XPS types available in the market. Furthermore, the linear attenuation coefficients (LAC) were examined to obtain radiation shielding properties of the samples at 1173 and 133 keV energies using a 60Co gamma source. Also, LAC values determined between 0,1167 ± 0,0452 cm−1-0,2315 ± 0,0065 cm−1 for 1173 keV and 0,1042 ± 0,0488 cm−1 - 0,2141 ± 0,0062 cm−1 for 1333 keV. Accordingly, it has been revealed that waste compositions are effective in protecting against radiation.

Fresh and Hardened Properties of Alkali-Activated POFA-GGBFS Pastes Cured in Ambient Temperature – An Initial Mix Design

Weak soils are characterised by their high compressibility and low shear strength, which requires stabilisation to improve their compaction and strength characteristics before being used for construction projects. Recent trends in soil stabilisation show an increased interest in the application of waste-derived geopolymers as low-carbon materials to address the carbon emission problem related to cement production. This paper presents the preliminary findings of using Palm Oil Fuel Ash (POFA) and Ground Granulated Blast Furnace Slag (GGBFS) binary blends as geopolymer precursor materials. These binary waste material blends were activated using alkaline solutions, namely Sodium Hydroxide (NH) and Sodium Silicate (NS), to synthesise geopolymers at ambient temperatures. Three main factors were considered for the optimisation of the geopolymer mix design, as recommended by past research: alkali equivalent (8-11.5%), activator modulus (0-0.7), and slag replacement (fixed at 30%). Alkali equivalent and activator modulus parameters were varied and tested to establish its initial and final setting times, workability and strength properties, while the slag replacement percentage was set at 30%. This study aimed to determine the most influential parameters to produce the geopolymer material with the highest compressive strength and satisfactory setting times and workability. Single-source alkali activators (NH only) used on POFA-GGBFS produced specimens with smaller flow diameters, longer initial and final setting times, and lower compressive strength than specimens activated with NH and NS. Geopolymer specimens synthesised with NH and NS produce stiffer compounds possessing higher compressive strength values and explosive-type failure modes due to their higher silica content. At ambient temperatures, TM-Mix 2 (7% alkali equivalent and 0.7 activator modulus) produced the highest compressive strength value of 67.3 MPa at 28 days curing, flow diameter of 227 mm, with the initial and final setting time of 25 minutes and 45 minutes, respectively. Consequently, the results show that the preliminary POFA-GGBFS geopolymer mix design could produce sustainably sourced geopolymer compounds with adequate strength and acceptable setting time and workability. This study is part of a current investigation to further optimise the POFA-GGBFS mix design for the purpose of weak soil stabilisation.

Effect of Compressive Strength and Tensile Strength Value on Fiber Concrete Using Bendrat Wire Fibers

Concrete is a material used in modern construction and is a very important component in the manufacture of structures. Concrete has advantages, but also disadvantages, namely low tensile strength. To increase the tensile strength of concrete, fibers are added to the mix. One of the efforts made to increase the tensile strength of concrete is the addition of fibers to the fiber-concrete mixture. The purpose of this study is to examine the compressive strength and tensile strength values in fiber concrete if added with variations in fiber addition. An innovation in increasing the value of mechanical quantities in concrete is the use of bent wire fibers as a mixture in fiber concrete. This material is taken from former pieces in construction projects to connect steel reinforcement with Sengkang reinforcement and is also widely found in building shops. The fibers were also analyzed for microstructure using SEM (Scanning Electron Microstructure) tools. The length of this bent wire fiber is 13 mm with a diameter of 0.82 mm and has a minimum tensile strength value of 334.5 MPa. The variations in the addition of these bent wire fibers are 0%, 3%, 6%, and 9% of the total weight of the steel fiber. The soaking life of concrete is 7 days, 14 days, and 28 days. The results of this study show that the more variations in the addition of bent wire fibers, the compressive strength value of concrete and the tensile strength value of concrete will also increase. It can be seen that fiber concrete with an immersion life of 28 days with a variation of 9% added bent wire fiber has a maximum compressive strength value of concrete which is 63,645 MPa and a maximum value of tensile strength of 3,294 MP.

Environmentally Friendly Paving Block Based on Wood Waste: The Effect of Rubber Wood Waste Content on the Physical-Mechanical Properties of Paving Block

The wood sawing industry generates significant waste, consisting of wood chips, wood scraps, and sawdust. This research aims to evaluate the effect of rubber wood sawdust addition on the moisture content, water absorption capacity, and compressive strength of paving blocks. The study was conducted in August–September 2023, starting with preparing raw materials, composition planning, and test specimen fabrication. The parameters in this study included density testing, moisture content, water absorption capacity, and compressive strength. The density test results for treatments P0 were 1.11 g/cm3, P1 1.09 g/cm3, P2 1.07 g/cm3, P3 1.08 g/cm3, and P4 1.09 g/cm3. The moisture content test yielded values of 11.38% for P0, 12.56% for P1, 12.94% for P2, 13.24% for P3, and 13.80% for P4. The water absorption capacity values obtained were, for P0, 5.17%; P1, 5.40%; P2, 6.36%; P3, 8.11%; and P4, 9.27%. Compressive strength tests produced values for P0 at 7.19 N/mm2, P1 at 5.67 N/mm2, P2 at 4.22 N/mm2, P3 at 3.48 N/mm2, and P4 at 3.07 N/mm2. The addition of rubber wood sawdust to paving blocks significantly influences density, moisture content, water absorption capacity, and compressive strength values. Keywords: Composition, Compressive strength, Paving block, Sawdust waste.

Optimizing damage resistance and structural evolution in CaO-modified Li2O-Al2O3-B2O3-TiO2-P2O5 glass-ceramics

Aluminoborate glass, recognized for its remarkable crack resistance, presents significant potential as a cover material for portable electronic devices. Nevertheless, its relatively low hardness has been a limiting factor. This study synthesized a series of 11 Li2O-30 Al2O3-(55-x) B2O3-2 TiO2-2 P2O5-xCaO (wt%), with x varying from 0 to 10, employing the melt-cast method. The resultant glass-ceramics were produced via heat treatment at 590 °C for 2 h, followed by a systematic examination of their structural and mechanical properties. The investigation demonstrated that an increase in CaO content diminishes crystallization and induces a morphological transition in the crystalline phases from granular and short rod-like structures to lath-like formations, which subsequently impacts the coordination environment of Al and B atoms. With a CaO content of 2 %, the GC2 sample precipitated Li(Al7B4O17) and Li2AlB5O10 phases, achieving a compressive strength (CR) value of 15.0 N, a hardness of 7.51 GPa, and a fracture toughness of 1.50 MPa m0.5. This glass-ceramic exhibited optimal scratch resistance and visible light transmittance exceeding 85 %, underscoring its considerable promise for application as smartphone cover glass due to its impressive overall damage resistance.

Soft Soil Stabilization using Co-Pyrolytic Biochars from Sewage Sludge and Nymphaeale, an Invasive Plant Biomass

This research addresses a significant gap in current literature by proposing an alternative to traditional carbon positive soil stabilizers by utilizing sewage sludge in conjugation with Nymphaeale, an invasive plant biomass derived co-pyrolytic biochars to stabilize the soft soil, with a focus on understanding strength gaining mechanism. Various combinations of sewage sludge and Nymphaeale biomass underwent thermogravimetric analysis in a nitrogen environment, suggesting 450⁰C as pyrolysis temperature for biochar synthesis. Soft soil, which is considered problematic for construction, was blended with five distinct dosages (0%, 5%, 7.5%, 10%, and 12.5%) of biochars (BC75:25, BC50:50, BC25:75) by weight and unconfined compressive strength values were examined over curing periods of 1, 7, 14, and 28 days. The stress-strain and failure behaviour of soil-biochar mixes varied depending on the type of biochar used. SBC25:75 mixes exhibited ductile behaviour, whereas SBC75:25 mixes showed brittle failure. Furthermore, unconfined compressive strength values of soil-biochar mixes increased 4-5 times with maximum strength achieved at 10% dosage of BC50:50. Biochar dosages led to a reduction in moisture content and an increase in alkalinity and conductivity of the mixes, facilitating the initiation of pozzolanic reactions. The combined findings from the various analysis suggested that the presence of free oxides of calcium in biochars disrupted the laminated structure of the soil and reacted with silica and other aluminum silicates, resulting in the densification of the structure and the formation of cementing mineral phases in the mixes. Overall, the research-work emphasizes the idea of creating novel environmentally friendly binders for soil stabilization through the utilization of waste materials.