Compressive Strength Research Articles

INNOVATIVE BLENDS OF GGBFS, METAKAOLIN, AND ALCCOFINE FOR ENHANCED MECHANICAL PROPERTIES IN GREEN CONCRETE

This research aims to improve the sustainability and mechanical properties of concrete by using partial replacement of cement with Ground Granulated Blast Furnace Slag (GGBFS), Alccofine (AL), and Metakaolin (MK). The study compares the effects of different proportions of GGBFS (0-50%), Alccofine (0-20%), and Metakaolin (0-15%) on the compressive, tensile, and flexural strength and at curing ages of 7th, 28th, 56th, and 90th days. The effective proportions of the replacements were determined to be 30% GGBFS, 15 % Alccofine, and 10% Metakaolin in ratios, which considerably improved the structural characteristics of conventional concrete. A ternary blend of these optimal levels was subsequently studied to determine its synergistic effect on the mechanical properties and microstructure. The ternary blend of these optimal levels demonstrated a 67.1% increase in compressive strength at 28 days and a 51.2% increase at 90 days compared to the control mix. Scanning Electron Microscopy (SEM) analysis suggested that increased pozzolanic activities, an increase in densities of the microstructure, and packing densities of the particles were the key factors for the improved performance. The results highlight that through the application of supplemental cementitious materials (SCMs), there exist promising opportunities in attaining high performance at the same time as a low environmental footprint that could help in concrete innovation for more sustainable solutions.

Study on mechanical properties and mechanism of soda residue-fly ash stabilised marine clay based on orthogonal matrix method

Improving the engineering and mechanical properties of marine clay (MC) by modifying it with soda residue (SR) and fly ash (FA), and stabilising with cement and /or lime to create Soda residue-Fly ash stabilised soil (SRFSS). Using the orthogonal design, the mechanical properties of SRFSS were analyzed, recommending a basic proportion of 70% SR + 20% FA + 10% MC. Results showed SR significantly impacted optimum water content (OWC), unconfined compressive strength (UCS), and water absorption quality. FA influenced the maximum dry density (MDD), while cohesion (c) was mainly affected by lime and cement. Cement had a higher unit contribution rate to mechanical indices than lime, except for MDD and OWC. The excellent properties of SRFSS were derived from good gradation and the cementation action of the materials. This research provides a solution for improving MC properties and promoting solid waste reutilisation.

Enhancing Sustainable Road Construction: Evaluation of the Mechanical and Durability Properties of Stabilized Earth-Based Pavement Materials

The materials traditionally used in the construction of flexible and rigid pavements in modern road infrastructure present challenges in achieving sustainable development goals. Advances in technology have introduced the use of different pavement material mixes, leading to the introduction of earth-based alternatives. These materials are environmentally friendly, cost-effective, recyclable, and offer excellent insulation properties. Stabilization of earth-based materials improves their mechanical properties, reducing road construction costs and increasing durability. The present study investigates the mechanical and durability properties of earth-based materials stabilized with various additives, including cement, lime, polymer, and biopolymer, over 28 and 56 days. Fresh properties are assessed using unit volume weight, flow table, air content, and fall cone tests, while hardened properties are assessed using flexural strength, compressive strength, and water absorption. Microstructural analysis is carried out using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The cement-stabilized samples show improved strength and durability, with the 5% cement group showing a 67% increase in compressive strength over the control group and the 10% cement group showing over 200% higher compressive strength. These results suggest that stabilized earth-based materials could provide a cost-effective and sustainable alternative to conventional pavements for low-traffic roads.

Influence of nanomaterials on properties and durability of ultra-high-performance geopolymer concrete

Abstract This study examines the effect of adding different dosages of nontitanium (NT) and nano-silica (NS) ranging from 0.5 to 4% by weight of binder materials on ultra-high-performance geopolymer concrete (UHPGC). The material’s feasibility was evaluated using slump flow measurements. A detailed analysis of its compressive strength (CS), transport properties, and sulfate attack was conducted. The addition of 2.5% NS and 4% NT improved the CS and transport properties of UHPGC compositions, creating a denser and more durable microstructure with enhanced interfacial bonding, as confirmed by the microstructure study. According to this study, the most effective doses for enhancing UHPGC performance in various aspects are 2.5% NS and 4% NT. The CS was recorded at 198.7 MPa for 2.5% NS mixes and 197.6 MPa for 4% NT mixes for ages test 28 days. These findings provide valuable insights into developing and utilizing advanced, high-efficiency UHPGC for sustainable and sturdy construction techniques.

Influence of water saturation on mechanical characteristics and fracture evolution of coal rock assemblage with rough interfaces

To comprehensively investigate the influence of water content on the mechanical and crack propagation characteristics of coal rock assemblage (CRA) with a rough interface, uniaxial compression tests were conducted on specimens with varying water content. Nuclear magnetic resonance (NMR) and acoustic emission (AE) techniques were employed to monitor the water content and AE signals throughout the experiment. The physical and mechanical properties, as well as the extent of crack development and acoustic emission (AE) parameters, were comprehensively investigated under conditions of water erosion. The results demonstrate that a rough interface contributes to an enhancement in the compressive strength of the composite material. Moreover, the moisture content exerts a significant influence on various aspects of the composite specimen, including its compressive strength, time b value, crack development, and crack propagation. With the increase in water content, the initial single slope shear failure of the composite specimen gradually transitions into a multi-section shear failure mechanism. Under the influence of water-rock interaction, sandstone within the formation undergoes a metamorphosis from a densely cemented structure to an irregular honeycomb-like configuration. This transformative process engenders novel porosity and fractures, ultimately compromising the rock’s mechanical strength. The analysis focuses on the relationship between the AE parameter b and uniaxial stress and water content, with emphasis on its relevance to damage theory. A damage model based on water immersion rate was established to elucidate the correlation between damage variables and water content. This was achieved by considering the characteristics of water-rock coupling AE and constructing a structural model of the water absorption process in different pore throats, thereby providing valuable insights for stability design and evaluation of roadway rock masses.

Sustainable Stabilization of Brown and Green Clays Using Industrial By-products

Background The disposal of industrial by-products and the rising cost of construction materials are critical issues globally, particularly in developing nations such as Jordan. Brown and green clay are considered problematic types of soft clay, as they fail to meet the necessary specifications for use in construction. Objective This study aims to assess the efficiency of Cement Kiln Dust (CKD) and Silica Fume (S.F.) as stabilizing agents for brown and green clays. The research explores how CKD and S.F. can be used as cost-efficient and eco-friendly alternatives to enhance the mechanical properties of soft clays, improving their viability for construction. Methods An experimental approach was used to investigate the impact of CKD and S.F. on brown and green clay stabilization. The study examines the effect of varying CKD and S.F. concentrations on the clays' plasticity, compaction, unconfined compressive strength, and consolidation properties. CKD was tested at four different levels (0%, 5%, 10%, and 15%), as was S.F. (0%, 5%, 10%, and 15%). Results The findings revealed a notable enhancement in the engineering properties and behavior of both brown and green clay, with reductions observed in the plasticity index (P.I.), compression index (Cc), compressive strength (qc), and maximum dry density (γd). Conclusion Adding 15% CKD to brown clay resulted in the most significant improvements after a curing period of 7 days based on the unconfined compressive strength test results.

Effect of Alumina Proportion on the Microstructure and Technical and Mechanical Characteristics of Zirconia-Based Porous Ceramics

The current study investigates the process of preparing and analysing porous-structured ceramics made from zirconium, aluminium, and magnesium ceramic oxides. The starch consolidation casting (SCC) technique, with different types of starches (potato and tapioca), was used for this purpose. Our objective was to methodically examine the impact of different processing factors, such as the temperature at which pre-sintering and sintering occur, and the proportions of ceramic powders, on the microstructure, mechanical characteristics, and porosity of the resultant composites. Pre-sintering effectively reduced the rate of shrinkage during the final sintering stage; this resulted in more controlled and predictable shrinkage, leading to better dimensional stability and reduced risk of defects in the final product. A higher alumina content was associated with an increase in apparent porosity and a reduction in volume shrinkage and apparent densities. The mercury intrusion porosimetry (MIP) findings concluded that the prepared porous ceramics have a multi-modal pore structure. The highest calculated compressive strength was 76.89 MPa for a sample with a porous structure, which was manufactured using 20 wt.% tapioca starch and 30 wt.% alumina content. The main advantage of alumina is its ability to improve compressive strength by refining the grain structure and serving as a barrier against fracture development.

Analysis of engineering performance of concrete comprising recycled crushed plastic waste and fly ash

This study investigated the attributes of blending of recycled crushed polypropylene plastic coarse aggregates (PPCA) and fly ash (FA) towards the fresh and hardened properties of concrete. Natural coarse aggregate was partially replaced with PPCA at volumetric replacement levels up to 30% and cement was replaced with FA up to 20%. Initially, the performance of PPCA and FA in concrete was investigated distinctly. The incorporation of 30% of PPCA in concrete rather impaired the workability (from 95 mm – 50 mm: 47%) and the compressive strength (from 44.6 MPa to 31.4 MPa: 29.7%). By appropriate using of a superplasticizer, the loss in the workability could be recovered. Microstructural investigation was conducted employing scanning electron microscope analysis; it showed that the formation of a weak interfacial transition zone between PPCA and cement paste to be the reason for strength reduction in PPCA concrete. In contrast, the addition of 10 – 20% of FA in concrete improved the workability by 63.2% – 100%, but yet again, the 28-day compressive strength reduced by 15.8 – 35.6%. Meanwhile, thermal conductivity results and constitutive relationships proved that the use of PPCA enhanced the thermal insulation property and ductility of PPCA concrete, respectively. Eventually, a total of six concrete batches with binary blended PPCA and FA were cast to find the optimum replacement levels. The optimum binary combination with reasonable strength and workability at a minimal cost was achieved to be 10% PPCA and 20% FA.

Structural Behavior of Reinforced Fibrous Concrete Beams Incorporating Nano Silicon Dioxide Powder

ABSTRACTThis research investigated the combined effect of nano‐silicon dioxide (NSD) and steel fibers (SF) on the structural behavior of reinforced concrete beams. Eight specimens were tested: four without SF and four with SF, with varying NSD percentages (1%, 2%, and 3%) replacing cement. The study examined the mechanical properties of concrete and structural behavior outputs, including load‐deflection, ductility, and damage patterns. Results indicate that NSD significantly enhances compressive strength, with increases of 8.7%, 25.2%, and 32.5% for 1%, 2%, and 3% NSD, respectively. Combined with SF, there are additional improvements in tensile and flexural strengths, leading to higher load capacity and reduced deflection. Beams with 1% steel fibers showed a 30% higher load capacity compared with those without fibers. The ACI code was found to underestimate the load capacity of beams with NSD and SF, indicating the need for updated equations. While NSD increased concrete brittleness, SF enhanced ductility and energy absorption. Future research should focus on optimizing NSD and SF dosages, studying long‐term durability, and validating findings through large‐scale tests.

The Influence of Planning and Architectural Styles on the Sustainability of the City of Kumasi, Ghana

The city of Kumasi that was once dubbed the ‘Garden City of West Africa’ was founded in the late 17th century and served as the seat of government for the medieval Greater Asante Union. It later served as a commercial hub for the British Colony after undergoing massive transformation in the first two decades of the 19th century. Post-independence, the city went through various urban planning projects that mostly targeted social development. The architecture of Kumasi has also been changing through different periods of its history. This article examines the relationship between the evolution of the city of Kumasi through urban planning and architecture and the general sustainability in construction. The results show that there is massive depletion of the green belt in Kumasi. Moreover, contemporary architecture uses fewer passive designs for indoor climate control and less local materials for construction. Use of technology for improvement of local materials compressive strength and integration of renewable energy sources in architecture are recommended as course of action.

A hierarchically porous and SLIT3-releasing scaffold for bone tissue engineering applications

AbstractOne of the most fundamental characteristics of a biomaterial tailored for bone repair and regeneration is its ability to promote bone regeneration and healing of large defects. This work reports producing a functionalized and hieratically porous bone scaffold that significantly supports cell adhesion and proliferation by providing bone mimicry structure and controlled release of protein. The Slit Guidance Ligand 3 (SLIT3) protein was previously tested to promote bone formation and control the resorption process in natural bone healing. In this study, our goal was to design a nanocomposite bone scaffold to be functionalized with SLIT3 protein and then evaluate the uptake and release profile from surface into culture media to support bone marrow-derived mesenchymal stem cells (MSC) 3D culture. Indirect 3D printing of a polylactic-co-glycolic acid (PLGA), hydroxyapatite nanoparticles, and polydopamine coated (PLGA-HANPs-PDA) was utilized to obtain a hierarchically porous and SLIT3 protein-releasing scaffold. The produced scaffold was evaluated and optimized using chemical, architectural, mechanical, and biological characterization techniques. Optimal physicochemical properties resulted in a unique microstructure with an average pore size of 178.06 ± 45 µm, 63% porosity, and stable and homogenous chemical composition. Mechanical testing demonstrated a compression strength up to 1.5 MPa at 75% strain, with a compression modulus of 0.58 ± 0.05 MPa. Preliminary biological experiments showed that the scaffold exhibited gradual SLIT3 protein release, biodegradability, and reliable biocompatibility for MSC cell culture. Finally, we showed for first time the bioactivity of SLIT3 protein within PLGA-HANPs-PDA scaffold to promote attachment and growth of mesenchymal stem cell (MSCs) seeded in bone mimicry scaffold matrix. The collected findings will serve as a bedrock for thorough and targeted in vitro studies to evaluate anticipated osteogenesis the MSCs.

Interpretable machine learning models for concrete compressive strength prediction

Interpretable machine learning models for concrete compressive strength prediction

Research on broadband vibration reduction performance of high-damping stainless steel fiberboard

This study investigates the application of stainless steel fiberboards (SFBs) for effective vibration reduction in the head section of autonomous underwater vehicles (AUVs). SFBs offer a compelling combination of lightweight design, high static load capacity, and broad-band vibration reduction. To understand their effectiveness, we analyzed the mechanisms behind SFBs’ superior compressive strength and high-damping properties. Furthermore, a finite element model (FEM) of the AUV head section was created using COMSOL software. The model’s accuracy was validated by comparing simulation results with experimental data. This validated model was then employed to calculate the energy consumption of the bearing plate within the AUV’s head section, providing valuable insights for optimizing SFB design for specific vibration reduction applications. The results demonstrate that SFBs of various thicknesses exhibited higher energy consumption ratios compared to the aluminum plates. This finding reinforces the effectiveness of the SFB’s damping mechanism. Additionally, across the 0–6 kHz frequency range, SFBs significantly outperform the aluminum plates, achieving an average improvement of approximately 18 dB in vibration level difference (VLD). These results highlight the excellent vibration reduction performance of SFBs.

Development and microstructural characterization of ultra-lightweight aggregate concrete incorporating different sizes of polypropylene fibers

In this study, ultra-lightweight concrete with an oven-dry density of 800 kg/m3 was produced using expanded glass as the lightweight aggregate. Polypropylene fibers of different sizes were incorporated into the specimens to examine their effects on the material properties, such as drying shrinkage and flexural strength. The target dry density was achieved by applying the packing density concept to optimize the mix grading and calculate the content of each concrete component. Specimens with different ratios of short and long fibers were produced. Their fresh state, mechanical performance, and physical properties were extensively analyzed using various methods, including X-ray micro-computed tomography to examine the microstructure. The experimental results indicated a significant reduction in drying shrinkage for the fiber incorporated specimens, dependent on the fiber length and content. The compressive strength of the specimens exceeded 12 MPa. Moreover, the inclusion of polypropylene fibers notably enhanced the flexural strength by approximately 60%, while the lower density contributed to substantially reduced thermal conductivity by up to 26%, which is beneficial for thermal insulation. These results confirm that polypropylene fibers can be used to produce ultra-lightweight concrete with self-leveling properties, without compromising mechanical and physical performance.

Residual flexural performance of large-scale ferronickel slag alkali-activated concrete slabs after fire exposure

Background This study explores the flexural behavior of unfired and fired one-way slabs constructed from reinforced ferronickel slag-based alkali-activated concrete (AAC). Despite growing interest in AAC as a sustainable alternative to ordinary Portland cement (OPC), limited research exists on large-scale structural elements, particularly under post-fire conditions. Methods Four slabs (2.1 × 0.9 × 0.18 m3) were tested: two made of AAC and two of OPC concrete with comparable compressive strengths. In each group, one slab served as a reference and was tested under monotonic four-point bending in its original state. The other was exposed to a standard fire curve on the tensioned side, then cooled to ambient conditions before mechanical testing. Additional analyses, including mercury intrusion porosity (MIP) and scanning electron microscopy (SEM), were conducted to evaluate fire-induced microstructural changes in the AAC slabs. Results The AAC slabs demonstrated a load capacity 6% lower than OPC slabs. However, AAC slabs exhibited better post-fire retention of stiffness and ductility. Microstructural analysis revealed increased porosity and microcracking in AAC after fire exposure, which influenced its mechanical performance. Conclusions The results suggest that ferronickel slag-based AAC can provide comparable performance to OPC concrete in flexural applications, with enhanced retention of stiffness and ductility after fire exposure. These findings support the viability of AAC for structural applications while highlighting its resilience under post-fire conditions.

Eco-Friendly Brake Pad Formulation Using Agro-Waste Derived Fillers: Bush Mango Nutshell and Palm Fruit Fiber Reinforced Composites

The increasing demand for eco-friendly automotive materials necessitates the replacement of carcinogenic asbestos in brake pads. This study investigates the development of asbestos-free brake pads using bush mango shells (Irvingia gabonensis) and palm fruit fibre (PFF) as sustainable fillers. Response Surface Methodology (RSM) optimized the formulation, focusing on wear rate, compressive strength, and hardness. The optimal brake pad composition, containing 30% BMS/PFF with a 300 µm particle size, exhibited competitive mechanical and wear properties: wear rate (2.97-3.96 mg/m), compressive strength (74.66-148 MPa), and hardness (94-104 HRB). Thermal stability was maintained between 200°C and 550°C. This eco-friendly formulation presents a viable alternative to asbestos, supporting sustainable automotive manufacturing.

Expandable Microspheres Transform 2D Electrospun Mats Into 3D Composite Scaffolds.

Electrospun nanofibers have proven versatile across numerous fields, including environmental, energy, and biomedical applications. Typically, however, electrospun nanofiber materials are fabricated as two-dimensionalsheets, membranes, or mats. In this study, a straightforward and adaptable foaming method is presented to create three-dimensionalmicrosphere-nanofiber composite structures. This approach involves incorporating expandable microspheres within the nanofiber mats during electrospinning, followed by thermal treatment to achieve the 3D morphology. The expansion ratio and compressive strength increase with higher concentrations of expandable microspheres. In addition, the compressive strength of the 3D composite structures significantly surpasses that of 3D nanofiber scaffolds expanded with subcritical CO2 fluids. This approach presents a promising pathway for fabricating 3D microsphere-nanofiber composite scaffolds with broad potential applications.

Reuse of sheep wool fibers in the production of ultralightweight foamed concrete: effect of fiber treatment, length, and content on the mechanical properties

Concrete is one of the most widely used materials in the world. Still, its production processes, energy consumption, and high use of raw materials make it one of the most environmentally harmful materials. This study aims to enhance the sustainability of concrete by reducing the amount of binder and incorporating secondary materials into the cementitious matrix. The binder reduction is achieved by using a foaming agent that creates a microporous matrix, significantly decreasing the volume of cement in the material. Additionally, reinforcing the material with sheep wool fiber not only improves its mechanical properties but also gives a new purpose to a commonly discarded secondary material. The research specifically seeks to identify the most effective treatments for sheep wool fiber (including non-treated, salt-treated, lime-treated, NaOH-treated, and surfactant-treated fibers), as well as the optimal fiber length (6, 12, and 20 mm) and content (4.5, 9, and 15 kg/m³) for ultralightweight foamed concrete in terms of mechanical strength. The findings demonstrate excellent compatibility between wool fibers and ultralightweight foamed concrete, with fiber-reinforced samples showing up to a 60% increase in flexural strength and up to a 50% increase in compressive strength. Among the various fiber treatments evaluated, surfactant-treated fibers yielded the best results.

Use of Granular Aerogel in Lightweight Blend Brick: On Thermal Properties and Compressive Strenght

Blended bricks can be defined as the ancestor of the fabricated bricks used today, although they are not preferred much today. The development of technology has led to changes in the properties and form of blended bricks. The use of blended bricks, which we frequently encounter in architectural applications, continues, albeit less than in the past. Today, it continues its activities in many areas, especially restoration projects. In this study, it was aimed to produce blended bricks with improved thermal insulation, low unit weight and compressive strength accordance to TS standards by substituting granular aerogel, which is a nanomaterial, into the blended brick body. In the study, brick samples containing 0%, 2.5%, 5%, 7.5% and 10% granulated aerogel were produced. Acidic pumice used for lightweight brick production was kept constant at 50%. Lightweight blended brick samples were fired at 900 oC and 1000 oC. As a result of the study, blended brick samples with improved thermal insulation properties, low unit weight and compressive strength in accordance to the required standards were produced.

Influence of metakaolin on physical and mechanical properties of cement stone heat-resistant binder from mineral-technogenic raw materials of the Aral region

The results of studies of the influence of metakaolin obtained from kaolin of the Khodzhakul deposit on the process of formation of cement stone based on heat-resistant binder from mineral-technogenic raw materials of the Aral Sea region are presented. It has been established that metakaolin allows one to control the processes of hydration, setting and hardening of the cement mass. The high degree of hydration of aluminous cement in the presence of metakaolin provides porosity and sufficiently high compressive strength of the cement stone in the last 14‒28 days of hardening. Increasing the concentration of metakaolin in the cement mixture to 15 % affects not only the process of liquefying the cement mortar, reducing the setting and hardening time of the cement mass, but also increases the compressive strength of the cement stone. New formations of hydration products have been studied.