Papers by Keyword: Compressive Strength

Abstract: This study explores the variation of compressive stress-strain behavior of concrete incorporating waste tire aggregates as a partial replacement for conventional coarse aggregates, addressing the global challenge of tire waste management. Concrete mixes with 0%, 10%, and 20% rubber replacement were tested under varying loading conditions after curing for 28 days. The research aims to provide insights into the trade-offs between strength and flexibility in rubberized concrete to support sustainable construction practices. Experimental results demonstrated that the control mix (0% rubber) exhibited the highest compressive strength but showed brittle behavior with minimal strain tolerance. The 10% rubber mix achieved a balance, retaining substantial strength while improving strain capacity and energy absorption, making it suitable for applications requiring both strength and ductility. The 20% rubber mix had the greatest strain tolerance and energy absorption but the lowest compressive strength, indicating its potential for impact-resistant and flexible structures. These findings align with existing literature, emphasizing the material's suitability for applications in seismic zones, noise barriers, and vibration-dampening structures. This study highlights the potential of rubberized concrete as a sustainable alternative, offering environmental benefits by reusing waste tires and reducing dependence on natural aggregates. However, challenges such as reduced strength with higher rubber content need to be addressed through optimized mix designs and pretreatment methods. Rubberized concrete provides a promising pathway for balancing sustainability with structural performance, particularly for dynamic and non-load-bearing applications.

Abstract: This study investigates the mechanical and durability properties of Self-Compacting Concrete (SCC) incorporating bentonite clay and marble dust as partial cement replacements. Bentonite clay, a natural pozzolanic material sourced from Jehengirah (Swabi district), was evaluated for its physical properties, including specific gravity, setting time, and soundness. Results indicate that bentonite has a lower specific gravity and shorter initial setting time compared to Ordinary Portland Cement (OPC), though the final setting time remains similar. A total of nine SCC mix designs were prepared, replacing cement with up to 20% marble dust and 20% bentonite clay by weight. The study focuses on assessing compressive strength, split tensile strength, and durability characteristics compared to conventional SCC. Findings reveal that exceeding 20% cement replacement with pozzolanic materials leads to a notable reduction in compressive strength. However, while the modulus of rupture at 28 days is lower than conventional concrete, the flexural strength relative to compressive strength shows improvement.

Abstract: The escalating global demand for energy efficient infrastructure has intensified interest in Phase Change Materials (PCMs) for thermal regulation in buildings. PCMs, owing to their high latent heat storage capacity, can significantly reduce operational energy demands when integrated into construction materials. However, for structural applications, the mechanical integrity of concrete remains paramount, requiring careful evaluation of how PCM incorporation affects its strength characteristics over time. In concrete technology, the introduction of secondary functional materials often alters the internal microstructure, influencing both load bearing capacity and durability. For PCMs, this balance between thermal enhancement and mechanical performance remains a pertinent research frontier in sustainable construction. However, in recent past, focus of the research in construction sector has not brought this aspect to the limelight for practical integration of these materials into concrete especially in Pakistan. Therefore, this study has attempted to instroduce this technology in construction sector of Pakistan by investigating the influence of two distinct microencapsulation shell materials, Melamine Formaldehyde (MF) and Polyurethane (PU), on the compressive strength of PCM modified concrete. Fine aggregates were partially substituted with microencapsulated n-octadecane paraffin PCMs by mass to observe performance trends. Experimental results demonstrated a consistent and progressive reduction in compressive strength with increasing PCM content, with MFPCM mixtures exhibiting comparatively lower strength loss than PUPCM mixtures throughout the curing period. The observed deviations ranged from 7.73% at the lowest replacement level to a maximum of 24% at the highest level, emphasizing the decisive role of shell material stiffness and composition in preserving structural performance while enabling thermal benefits. Through these results, this research has paved a way for construction sector in Pakistan to incorporate the PCM technology in concrete by conducting more research on PCM properties.

Abstract: The present study evaluated the mechanical behavior of adobe when incorporating crushed barley straw as a natural stabilizer. Specimens were prepared with three different stabilizer proportions: 0, 1, and 2%. These were used to compare their compressive and flexural strength. The results showed an average 10% increase in compressive strength and a 43% increase in flexural strength in adobes incorporating 2% stabilizer compared to the control units. This increase demonstrates the potential of crushed barley straw to improve the load-bearing capacity and ductility of adobe, thus contributing to the creation of sustainable material for construction in rural areas.

Abstract: The partial substitution of cement with ground blast furnace slag (GGBS) and silica fume (HS) in the concrete mix has the potential to reduce the carbon footprint associated with cement production. The objective of this study is to evaluate the feasibility of this partial replacement as a strategy to promote greater sustainability in construction. The research looks at four replacement percentages with different ratios: 10% HS, 10% GGBS, a combination of 10% GGBS and 10% HS, and 13% GGBS with 10% HS. The results indicate that the mixtures obtained not only reach but exceed the required strength of f´c=280 kg/cm² and have a reduced carbon footprint compared to conventional concrete. This highlights the environmental benefits of using industrial by-products as partial replacements in concrete manufacturing, helping to mitigate the negative impacts of cement production.

Abstract: Earth has been used as a construction material for centuries, starting with sun-dried mud and straw bricks, which had limited strength and durability. This evolved into fired clay bricks, which enabled large-scale production. However, with the building industry now accounting for 35% of global energy consumption, there is an urgent need to reduce energy use, construction costs, and reliance on nonrenewable resources—particularly in energy-scarce developing nations. This study explores Unstabilized Earth Bricks (UEBs) as a sustainable alternative, requiring 98% less energy than conventional bricks. The addition of straw as an eco-friendly additive not only addresses the disposal of 200 million tons of agricultural straw waste but also improves brick strength. Tests on 230 mm x 100 mm x 90 mm bricks with 1% and 2% straw content showed increased compressive strength, though strength declined in recycled samples. Both straw-reinforced and recycled UEBs demonstrated high durability in wire brush tests, underscoring their potential as cost-effective, sustainable building materials. However, recycled clay bricks exhibited significantly lower strength and are less suitable for structural applications.

Abstract: Rapid growth in infrastructure projects in Nigeria has led to indiscriminate river sand mining, causing river bank erosion, bed degradation, biodiversity loss, and poor water quality. Researchers have explored laterite as a substitute for river sand in concrete production. This study investigated use of lateritic soil from Akure (Lat. A), Ondo (Lat. B), and Ile-Oluji (Lat. C) for replacing fine aggregate with replacement levels of 0%, 10%, 20%, and 30% used in concrete cubes (150 × 150 × 150 mm). The physical, chemical, and mineralogical properties of the laterite, and the strength and durability of the resulting concrete, were investigated through Atterberg limits, X-Ray fluorescence, compressive strength, splitting tensile strength and sorptivity tests. Results revealed that concrete with 10% Lat. C achieved the highest compressive strength of 11.45 N/mm², while 20% Lat. B and 10% Lat. A attained strengths of 8.5 N/mm² and 10.77 N/mm², respectively. The optimal sorptivity values were 3.18 ×10⁻⁴ mm/min⁰^.⁵ for 10% Lat. A, 4.73 ×10⁻⁴ mm/min⁰^.⁵ for 20% Lat. B, and 5.66 ×10⁻⁴ mm/min⁰^.⁵ for 10% Lat. C. This suggests that laterite with predominantly silty fines is comparatively better in achieving satisfactory strength and durability than laterite with predominantly clayey fines. The laterite index properties showed a good relationship with the compressive strength models, but did not fit well with the sorptivity models. Hence, while the laterite index properties contribute to the compressive strength of lateritic concrete, they may not essentially affect its sorptivity.

Abstract: To produce functional cups by press forming, clad cups with a corrugated structure with voids like the cross section of corrugated cardboard were formed. Deep drawing, which is one type of press forming, is a plastic processing technology that forms thin sheets into three-dimensional containers. In the experiment, pure titanium TP270 and ultra-low carbon steel SPCC were used as test materials. The blank sheet thickness was 0.3 mm and the diameter was 80 mm to 90 mm. To form the corrugated cup, the roller ball die with steel balls installed on the shoulder of the die was prototyped. The steel balls were made of bearing steel JIS-SUJ2 and had diameters of 6.4 mm and 7.5 mm. The corrugated clad cup was formed by the composite die combined with a conventional die. Three conventional dies and two roller ball dies were used to obtain two corrugated layers with voids. The lubricant was a tool oil containing molybdenum disulfide powder. The sheet thickness strain distribution and residual stress distribution of the cup were evaluated. No destruction of the cup occurred during deep drawing. A regular wavy structure was observed in the cross section of the cup. The maximum reduction in the cup thickness was approximately 10 %. The residual stress on the outside of the cup was tensile stress from the bottom to the opening of the cup. The composite die made it possible to form a functional cup.

Abstract: Sugarcane bagasse ash (SCBA) is a by-product of the ethanol and sugar industry. SCBA is generally used as fertilizer or dumped in landfill, which has led to increasing environmental problems. In the recent years, SCBA has been investigated in the field of construction materials due to its pozzolanic character. This research aims at examining some physical and mechanical properties of mortars with partial replacement of sugarcane bagasse ash from sugar cane refineries. In the present case, the cement substitution was made with SCBA at 0%, 15%, and 30% of the binder (Cement + ash). The physical and mechanical testing of the mortar was carried out to determine the effect of ash addition on porosity, density, flexural and compressive strengths of the mortar. In general, the findings revealed that the mechanical and physical behavior of the mortar mixtures improved over time because of pozzolanic effects. On one hand, the physical changes were relatively restricted and do not show a well-established trend. On the other hand, reduction of mechanical strength was observed with the addition of SCBA, and with a 15% cement replacement percentage, it is possible to obtain a material with favorable physical and mechanical properties.

Abstract: The structural response of materials under dynamic impact loads is crucial in protective design, particularly in applications where energy absorption is a primary concern. This study presents a comprehensive experimental investigation into the energy storage potential of additively manufactured polymeric axial members subjected to high-speed and low-speed impact tests. These axial members were fabricated using additive manufacturing techniques, emphasizing optimizing their structural performance under deformation. The study focuses on assessing the performance of various internal infill geometries to enhance energy dissipation during impact loading. A series of tests was conducted to evaluate the members' capacity to absorb impact energy and to compare their performance under varied strain rates. The findings indicate that specific infill patterns significantly improve energy absorption capabilities, making them suitable for applications involving blast and impact-resistant designs. Furthermore, the results demonstrate that careful optimization of the internal structure of 3D-printed elements can effectively reduce the adverse effects of dynamic loads, making them a promising option for protective structures. The findings contribute to a broader understanding of material behavior at high strain rates, provide valuable guidance for designing lightweight, impact-resistant components, and provide new perspectives on utilizing innovative materials and manufacturing techniques to enhance structural resilience in demanding environments.