Papers by Keyword: Compressive Strength

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.

Abstract: This study evaluates the impact of replacing natural sand (NS) with quarry waste sand (QWS) or recycled concrete sand (RCS) at varying substitution rates (0%, 25%, 50%, 75%, and 100%). The analyzed properties include Abrams cone slump, superplasticizer demand (SP), rheological and tribological parameters, mechanical strength, capillary water absorption, and shrinkage. The results show that QWS-based concrete exhibits better workability and requires less superplasticizer, whereas RCS-based concrete necessitates a higher admixture dosage. Both QWS sand and RCS sand significantly enhance the rheological and tribological properties of concrete Moreover, QWS sand provides higher mechanical strength than NS sand, with a strength gain of up to 16% at full replacement (100% QWS sand) at 90 days. Conversely, RCS sand reduces compressive strength by 28.6% at 28 days. and negatively affects porosity and capillary water absorption. However, these negative effects are mitigated when the RCS sand replacement is limited to 25%. QWS sand-based concrete exhibits slower shrinkage and reduced deformability compared to NS sand-based concrete. Predictive strength models were established based on experimental parameters, displaying a high correlation coefficient and a low root mean square error. Replacing NS sand with QWS sand or RCS sand reduced production costs, lowered carbon emissions, minimized waste, and preserved natural resources, offering a sustainable approach for concrete applications.

Abstract: The article provides some information about gypsum concrete, its applications, and the advantage of using organic fillers compared to mineral ones. The optimal technology for the production of gypsum concrete mix was determined, and an economically attractive type of organic filler in the form of chopped corn stalks was established. The compressive strength of the resulting material was studied depending on the fraction of crushed stone used. Effective methods for combating shrinkage cracks at the stage of manufacturing prototypes have been identified, which allows increasing the bearing capacity of the samples by 2.5 times. The water resistance and water absorption of the material, as well as their effect on strength, were investigated. As a result of experimental studies, it was found that the optimal concrete compositions with filler fractions of 3-5 and 5-10 mm should be considered 1:1 and 1:1.5 by volume (binder: filler), which can provide sufficient compressive strength (13-23 MPa) for blocks and slabs of internal partitions and good water resistance (0.91-1.0), while having good sound-absorbing properties.

Abstract: The assessment of compressive strength, and air-dry density constitutes essential parameters for evaluating the quality and performance of earthen construction materials. To ascertain these properties, this study investigates the potential application of ultrasonic testing as a non-destructive evaluation technique for earthen materials, including specimens, elements, or structures. The methodology is predicated on the measurement of ultrasonic pulse velocity (UPV), which is affected by various factors such as density, elasticity, and the curing process. By examining the propagation of ultrasonic waves through earthen samples, significant insights can be obtained regarding their drying duration, compressive strength, and density. Compressive strength is a pivotal factor in evaluating the structural integrity of earthen materials. The UPV method provides a non-destructive means to ascertain the compressive strength of earthen samples, thereby serving as a valuable instrument for quality control and assessment of earthen construction materials. Density, another critical property influencing the performance of earthen materials, can also be evaluated using the UPV method. By measuring ultrasonic pulse velocity and analyzing its correlation with density, this non-destructive approach enables rapid and efficient estimation of the compactness and quality of earthen mixtures. The ultrasonic method presents a non-destructive and efficient strategy for determining the compressive strength, and density of various soil compositions. By quantifying pulse velocity and examining its relationship with these properties, substantial insights can be garnered regarding the quality and performance of earthen construction materials. This technique holds the potential to enhance assessment and quality control processes in earthen construction, ultimately contributing to the development of more sustainable and reliable structures utilizing earthen techniques.

Abstract: Sustainable concrete has become more popular due to supplementary cementitious materials (SCMs) that help achieve sustainability. Despite the well-established benefits of these SCMs, the search for substitute materials continues as they become harder to find and adapt to changes with the industry. Concrete performance may be enhanced using bentonite, a commercially available clay mineral that shows promise as an SCM. In the present work, an Artificial Neural Network (ANN) model was developed to predict the compressive strength of cement-based mortar incorporating bentonite as a SCM, by training it on existing data, allowing for better performance and mix design improvement. A comprehensive experimental database comprising test specimens was established. A critical assessment of the collected experimental data suggested that there are several key parameters governing compressive strength gains. The proposed model's parameters, such as weights, biases, and transfer functions, were effectively transformed into a mathematical model that correlates the compressive strength with the key input parameters. An experimental investigation measuring the impact of treating bentonite at various temperatures on compressive strength was also included in the study.The statistical evaluation results indicated that a three-layered Artificial Neural Network model with different hidden neurons could precisely estimate the compressive strength of mortar mixtures modified with bentonite, showing strong agreement with the experimental results. The mortar's compressive strength may be increased by partially replacing cement with calcined bentonite, especially in the initial stages. The type of bentonite and the intended performance determine the appropriate replacement rate and calcination temperature.

Abstract: The aim of this study was to investigate the feasibility of manufacturing typha-based materials with a lime-based binder. For this purpose, three types of lime with different compositions were tested to produce lime-based typha concretes. The mechanical performance (compressive strength and apparent modulus of elasticity) of the materials developed was evaluated as a function of binder content and binder type. Two types of formulations were studied: one with a binder/aggregate ratio of 3, called F3, and the other with a binder/aggregate ratio of 2, called F2. Water absorption kinetics and typha particle size analysis were also studied. The dry density, compressive strength and apparent modulus of elasticity of typha concretes were determined. The results showed a reduction of mechanical performance as the binder/aggregate ratio decreased. The density of typha concretes range from 520 kg/m3to 396 kg/m3. The best mechanical performances were obtained with Thermo Tradical and Earasy binders. When the binder/aggregate ratio was reduced from 3 to 2, stress at 10% strain ranged from 0.6 MPa to 012 MPa and apparent modulus of elasticity from 31.5 MPa to 3.57 MPa. This study showed that binder composition has a significant impact on the mechanical performance of plant-based concretes.