Optimal Strength Research Articles

Preparation and Characterization of Waste Cotton Fabric Reinforced Polylactic Acid Green Composites with Multifunctional Properties in a Low-Carbon Process

The development and design of eco-friendly materials prove crucial for promoting the recycling of waste cotton textiles and reducing environmental pollution. In this study, waste cotton fabric (WCF) and polylactic acid (PLA) serve to produce cotton fabric-reinforced PLA composite material (CF/P). The CF/P is then integrated with traditional porous sound-absorbing materials to create a novel composite plate. This research highlights the potential of WCF reinforced plates for sound absorption and thermal insulation applications in the construction field of construction and reports the effects of variables such as hot pressing temperature, WCF mass fraction, and WCF layer alignment angle on the material properties. The optimum tensile strength, water absorption, and thermal conductivity of the prepared CF/P are 64.2 ± 1.8MPa, 1.98% ± 0.04%, and 0.03W/(m·K), respectively. By combining with porous sound-absorbing materials and modifying the layering structure of composite plates, its acoustic performance can be adjusted. The highest Sound Absorption Average (SAA) of plates with a multilayer composite structure is 0.67. Direct shaping through hot pressing diminishes the use of adhesives, thereby reducing costs and health hazards. This approach offers a practical and efficient solution for the recycling and repurposing of natural fibers.

Optimization of Alkali-Activated Ladle Slag-Fly Ash Composites Using a Taguchi-TOPSIS Hybrid Algorithm

The effect of multiple mix design factors on the properties of ladle slag-fly ash alkali-activated composites was investigated. Taguchi-TOPSIS hybrid algorithm was adopted to optimize mix design parameters, including ladle slag replacement by fly ash (LSR), sodium hydroxide molarity (SHM), the ratio of sodium silicate to sodium hydroxide (NS/NH), the ratio of alkaline activator solution to binder (AAS/B), and crushed stone replacement by desert dune sand (CSR). The results revealed that the mix proportions of the optimum strength response comprised LSR, AAS/B, SHM, NS/NH, and CSR of 10%, 0.5, 8 M, 2, and 75%, respectively, with a compressive strength of 21 MPa. Conversely, the mixture proportions for superior fresh properties had a flow of 240 mm and entailed LSR, AAS/B, SHM, NS/NH, and CSR of 40%, 0.5, 8 M, 2.5, and 75%, respectively. Additionally, the hybrid method prediction model proved to be robust, with the ability to predict strength and workability at 93 and 100% accuracy. The optimum mixes comprised an intermix of calcium aluminosilicate hydrate and sodium aluminosilicate hydrate gels, with traces of calcium silicate hydrate gel, as identified by microstructure analysis and using ternary diagram system of Ca/Si-Na/Si-Al/Si ratios.

Analisa Pemanfaatan Limbah Plastik Sebagai Bahan Baku Pembuatan Paving Block

Plastic waste is most commonly found around us and is a source of pollution in the environment, both on land and in water. paving is formed into a rectangle with a press made manually. This paving can be used as a path in the plantation or at home because it is made from recycled waste that pollutes the environment. Methods used Experimental method. The optimum compressive strength value is obtained in sample 2 of LDPE plastic type and decreases in sample 1 of PET type The decrease in compressive strength value occurs because PET plastic type dries quickly. The optimum compressive strength value in LDPE plastic type of 3.341 MPa can also be caused because it is easy to fuse when heated and dries long so that it can be molded easily. The compressive strength value in the 33% variation decreased because the plastic shreds overlapped with other plastic shreds, reducing its compressive strength. The type of waste plastic pet compressive strength produced is smaller than other types and dries easily so it is difficult to mold, the average weight of 1.089 gr / cm3 is heavier than other types of plastic, for specific gravity in water heavier mixed variation 33% with an average of 0.266 gr / cm3 and for the smallest weight type HDPE with an average of 0, 181 gr/cm3, For all types of testing does not meet the minimum requirements of SNI 03-0691-1996 as a paving block with quality D with the required average compressive strength of 10 Mpa and a minimum compressive strength of 8.5 Mpa, in this test the highest compressive strength is in the type of LDPE sample 2 of 3.341 Mpa and for the lowest in the type of PET sample 1 of 0.248 Mpa.

One-pot preparation of strong, tough, frost-resistant and recyclable organohydrogels via Hofmeister effect and its application for electronic devices

Conductive hydrogels have shown a great potential in the field of flexible electronics. However, it is difficult to combine high strength and high toughness in conductive hydrogels prepared by conventional methods, which limits their applications in various fields. In this work, we pioneered a facile and cost-effective strategy to prepare soy protein isolate/poly(vinyl alcohol) (SPI/PVA) conductive hydrogels with high strength, toughness, low-temperature resistance, and recyclability by introducing all the salts into the prescuor solution directly. To solve the problem of unable to directly introducing high concentration Na3Cit into the soy protein isolate/PVA solution, MgCl2 was used to alleviate the strong salting-out effect of Na3Cit. Thus the stable SPI/PVA/EG/MgCl2/Na3Cit complex solution was obtained and the SPI/PVA/EG/MgCl2/Na3Cit (SPEMS) organohydrogel was prepared by the freezing/thawing process. The optimum tensile strength of the SPEMS organohydrogel was 1.1±0.07 MPa, and the elongation at break was 701.3±23.67 %, respectively. Meanwhile, the ionic conductivity of the organohydrogel was as high as 1.7±0.01 S/m. Finally, the EG/H2O binary solvent system endowed the organohydrogel with excellent low-temperature resistance (freezing point of −19.4 °C). The strain sensors assembled with SPEMS organohydrogels were characterized by high sensitivity (GF = 3.2, strain range from 20 %–500 %) and long-term stability. The flexible all-solid-state supercapacitor assembled with SPEMS organohydrogel as the electrolyte and activated carbon as the electrodes has a high area specific capacitance (113.76 mF/cm2) and good cycling stability (capacitance retention of 81.62 % after 1,000 charging and discharging cycles) at room temperature.

Evaluating the mechanical and environmental impact of PEF plastic waste incorporated with graphene nano-platelets in concrete

There has been a significant surge in the yearly use of plastics, leading to a notable rise in plastic waste generation. Consequently, the recycling of plastic garbage has emerged as a prominent concern around the world. This research explores the feasibility of using polyethylene furanoate (PEF) plastic waste as a substitute for coarse aggregate (CA) in concrete. Graphene nano-platelets (GNPs) were added to the concrete mix in different quantities to improve its structural reliability. The research study used an experimental research design in conducting its investigation. PEF waste plastic was added in concrete in varying proportions of 0%, 5%, 15%, 20%, and 25% as a supplementary material to gravel, and GNPs were added in different percentages of 0%, 0.03%, 0.05%, 0.08%, and 0.1% by weight of cement. Mechanical tests were conducted, which includes compressive strength (CS), split tensile strength (STS), flexural strength (FS), modulus of elasticity (MoE), and ultrasonic pulse velocity (UPV), and the environmental assessment of concrete was done by assessing carbon in concrete and concrete’s eco efficiency (ESE). It was found that 5% addition of PEF as the substitute to CA and 0.1% of GNPs gives the optimum strength, enhancing CS, STS, and FS by 9.10%, 18.18%, and 4.45%, respectively. Response surface technique (RSM) models were created to provide mathematical equations for predicting the predicted outcomes. All models were optimized using a multi-objective optimization approach and then validated.

EXPERIMENTAL APPROACH FOR DEVELOPMENT OF SUSTAINABLE HYBRID GRADED FIBER REINFORCED CONCRETE BY CONSUMING LATHE WASTE STEEL FIBERS WITH GLASS FIBERS FOR ENHANCED MECHANICAL PROPERTIES

Local workshops generate large quantities of industrial lathe waste steel fibers, which the steel manufacturing industries find difficult to recycle because of their sharp edges. The utilization of lathe waste steel fibers as fiber reinforcement is sustainable in concrete because these fibers have the same properties as steel fibers. Furthermore, using combinations of ductile and elastic fibers improves strain capacity and resistance to pre- and post-cracking. This research employs hybrid fiber reinforcement technology, utilizing industrial lathe waste steel fibers and glass fibers in varying proportions, to bridge the micro and macro cracks in concrete specimens. This research was done to examine the physical (workability) and mechanical properties (compressive and flexural strength) of hybrid fiber-reinforced concrete. In this research different mixtures of hybrid fiber-reinforced concrete were cast and designated as M0, M1, M2, M3, M4, M5, and M6. The mixtures included lathe waste steel fibers at 0%, 0.50%, 1%, 1.5%, 2%, 2.5%, and 3%, and glass fibers at 0%, 0.15%, 0.25%, 0.45%, 0.60%, 0.75%, and 0.90%, respectively. The ASTM-standardised protocols were followed for all laboratory testing. The physical property results showed a decrease in the workability of concrete mixes as the percentage of lathe waste steel and glass fiber increased. This suggests that a higher percentage of lathe waste steel and glass fibers leads to a lower slump value. Consequently, the mechanical property results showed a gradual enhancement in the compressive and flexural strengths of hybrid fiber-reinforced concrete up to 2.5% lathe waste steel fibers and 0.75% (M5). Further incorporation causes a reduction in strength. The physical examination of fractured samples of hybrid fiber-reinforced concrete confirms that the lathe waste steel fibers yield a maximum strain before breaking down in the concrete matrix. Furthermore, lathe waste steel fibers broke rather than being pulled out, indicating a good bond with the concrete. It is recommended that up to 2.5% lathe waste steel fibers and 0.75% of glass fibers by the total weight of the concrete can be used as hybrid fiber reinforcement for optimum strength achievement.

Development of sustainable alkali activated composite incorporated with sugarcane bagasse ash and polyvinyl alcohol fibers.

The infrastructure boom has driven up cement demand to 30 billion tons annually. To address this and promote sustainable construction, researchers are developing solutions for carbon-neutral building practices, aiming to transform industrial waste into an eco-friendly alternative. This study aims to develop and enhance the mechanical and durability properties of alkali-activated composites (AACs) by incorporating varying amounts (5, 10, 15, and 20%) of finely ground bagasse ash (GBA) and polyvinyl alcohol (PVA) fibers. Results indicate that higher GBA content initially reduces the 7th and 14th-day strength but results in increased strength at later ages. The optimum 28-day strength is achieved with a 10% GBA content, leading to a 10% increase in compressive strength, 8% increase in tensile strength, and 12% increase in flexural strength. Additionally, the incorporation of GBA enhanced the resistance of the composite to chloride ingress, thus reducing its conductance and increasing the overall durability. This study demonstrated the potential of GBA as an eco-friendly material, emphasizing the significance of tailored AACs formulations for durable and sustainable construction practices.

Towards sustainable construction: Harnessing potential of pumice powder for eco-friendly concrete, augmented by hybrid fiber integration to elevate concrete performance

This study investigates the innovative use of industrial waste pozzolana, specifically pumice powder (PP), as a partial replacement for cement, combined with hybrid fibers in concrete. Seven formulations varying PP content from 10 % to 35 % were tested, identifying 15 % PP as optimal. PP improved porosity due to its fineness, leading to better homogeneity, a refined microstructure, and an optimum compressive strength of 28.8 MPa with reduced permeability, enhancing durability. Hybrid fibers, including steel fibers (SF) from waste tires and polypropylene fibers (PF), improved toughness, ductility, and resistance to brittle failure. Tests on hybrid fiber-reinforced concrete (HyFRC) mixes with 1 % and 2 % hybrid fibers showed up to an 18.09 % increase in compressive, tensile, and flexural strengths. Energy dissipation in compressive response improved by 544.20 %, while flexural and splitting responses increased by up to 299.65 % and 208.57 %. Durability assessments in hydrochloric (HCl) and sulfuric acid (H2SO4) exposure revealed the synergy of fibers and PP enhanced resistance to chemical degradation, with high PF mixes losing as little as 0.04 % strength. Scanning electron microscopy (SEM) confirmed a dense, well-bonded matrix with reduced porosity. Analytical characterizations of mixtures such as energy dispersive x-ray spectroscopy (EDX) were studied. Regression models developed using Popovic’s and Mander’s models, accurately predicted HyFRC stress-strain behavior, closely aligning with experimental results. The integration of PP and hybrid fibers not only improved mechanical properties but also extended service life in harsh environments, offering a cost-effective, sustainable concrete solution.

Utilization of quarry dust and periwinkle shell ash in concrete production.

The usage of plentiful raw discarded resources in the manufacturing of concrete has proven to be a sustainable and environmentally beneficial method of making concrete for a variety of purposes. In this study, the physical and mechanical properties of concrete made by partially and fully substituting fine aggregates and ordinary Portland cement with periwinkle shell ash and quarry dust (5%, 10%, 15%, 20%, and 100%), respectively, were examined. The ratio of water to cement utilized for the concrete mixture, 1:2:4, was 0.60. Fresh concrete underwent a slump test, and then 150-mm cubes of cured concrete were subjected to density, compressive strength tests, and morphological and structural property characterizations. The concrete without the waste materials gave an optimum compressive strength of 22.9 N/mm2 as opposed to those that were partially replaced, having 18.8-15.1 N/mm2. The concrete samples with full replacements of periwinkle shell ash and quarry dust have compressive strengths lower than 13.8 N/mm2. All the concrete samples produced with partial and full replacements are in the class of normal concrete, but only those with partial replacements of up to 20% can be utilized for load-bearing and non-load-bearing applications. Opting for these alternative waste materials implies taking steps towards creating a cleaner and healthier planet for now and the future.

Flexural strength and viscosity of dental luting composite reinforced with zirconia and alumina

Objectives Optimum flexural strength and viscosity are essential for longevity while efficiently handling dental luting composite. This study aims to investigate the effects of zirconia and alumina on the flexural strength (FS)and viscosity of dental cement made of silica rice husk. Materials and Methods Study groups with different percentages of weight (wt.): Group 1 (3 wt.% zirconia), Group 2 (3 wt.% alumina), and Group 3 (3 wt.% zirconia and 2 wt.% alumina), negative control specimen (0 wt.% zirconia/ alumina) and Rely-X U200 (3M ESPE). A universal testing machine and a rheometer were used to test FS and viscosity, respectively. One-way ANOVA and post-hoc Bonferonni test were used for data analyses. Results and Discussion FS and viscosity for Group 3 (3 wt.% zirconia and 2 wt.% alumina) were significantly higher compared to the negative control (p<0.05). Conclusion: Adding zirconia and alumina improved flexural strength without compromising the viscosity of dental luting composite. This experimental dental luting cement using hybrid fillers could be an alternative to resin luting cement. Bangladesh Journal of Medical Science Vol. 23 No. 04 October’24 Page : 1048-1053

Effect Of Post-Curing Treatment Temperature On The Tensile Strength And Impact Resistance Of Coconut Fiber-Reinforced Polyester Composites

Composite material is an engineered material created by combining two or more materials to produce enhanced mechanical properties compared to its constituent materials. This study focuses on natural fiber composites using coconut fiber as reinforcement with a polyester matrix. Post-curing treatment is applied to improve the mechanical strength of the composite. Post-curing is a heating process at a specific temperature aimed at enhancing the properties of the composite. The purpose of this research is to determine the effect of post-curing temperature on the impact strength of polyester-coconut fiber composites. The specimens were fabricated using the mixing method for material blending and hand lay-up for composite formation, following the standards of ASTM D638-02 Type I and ASTM D256 for impact testing. The specimens were heated in an oven at various temperatures: non-post curing, 110°C, 120°C, and 130°C, each for one hour. Impact testing was conducted using a Mory Testing Machine. The results showed that the composite with a post-curing temperature of 120°C achieved optimum tensile strength of 9.2 N/mm² and impact strength of 0.1663 J/mm². Based on these findings, the polyester-coconut fiber composite can be used as material for particleboard type 100 and meets the SNI 03-2105- 1996 standards for tensile and impact strength. Additionally, this composite has the potential to be used as an alternative material for manufacturing SNI-standard helmet

Biodegradable packaging paper derived from chitosan-based composite barrier coating for agricultural products preservation

Development of green packaging materials is essential to replace traditional plastics in fresh agricultural products preservation. Herein, a coated paper was designed by applying chitosan-based composite coating on paper substrate through a facile automatic coating method. The hydroxypropyl trimethyl ammonium chloride chitosan (HACC) was obtained by direct quaternization via the introduction of hydroxypropyl trimethyl ammonium chloride into the amino group of chitosan, then mixed with polyvinyl alcohol (PVA) to prepare the HACC/PVA coating. Accordingly, the key performance of coated paper were improved ascribed to the synergy effect of HACC/PVA coating and paper substrate. In particular, the minimum oxygen permeability of the coated paper could reach to 0.87 × 10−13 cm3·cm/cm2·s·Pa, and the optimum water vapor permeability and tensile strength of HACC/PVA coated paper was 0.75 × 10−12 g·cm/cm2·s·Pa and 6.88 kN/m, respectively. The coated paper used as packaging material not only reduced weight loss ratio of strawberry and greengrocery, but also exhibited lower chromatic aberration and better sensory evaluation, indicating a favorable effect on fruit and vegetable storage. Taken together, the designed eco-friendly coated paper has shown tremendous potential for green and biodegradable packaging material in agricultural products preservation.

Valorization of ashes from different wood species in cementitious materials

The aim of this study is to evaluate the potential use of wood ash as a cement additive. Four wood specimens from Yaoundé city of (Cameroon) were used namely: Sapelli, Iroko, Movingui and Padouk. Five mortar were produced, with cement substitutions of 0%, 5%, 10%, 15% and 20%. The fresh rheological, mechanical and hardened durability properties of various mortar were obtained after 7, 14, 28 and 56 days. The results showed that cement paste consistency and the cuing time increases with the addition of ash. At 28 days, the mortars obtained from the 5% and 15% Padouk and Movingui ash substitutes, respectively, showed optimum compressive strength (9%, 6%) and flexural strength (5%, 3%) compared with the control mortar. Due to continuous pozzolanic activity, this flexural gain is multiplied by 3 for Movingui mortar (9%) at 56 days. Compared with the 28-day and 56-day compressive strength results, there were increases of 5% and 4% respectively for the 5% and 15% ash substitutions in Padouk and Movingui mortars. Durability results were evaluated through absorption, which showed relatively identical rates in mortars containing ash from Padouk and Movingui wood, due to their water content for normal consistency. Chemical attack with H2SO2 and NaCl proved that the incorporation of ash improved the mortars' resistance to chemical attack. Thermal analyses and microscopic observations were performed with the optimum.

SIFAT MEKANIS KOMPOSIT MATRIKS ALUMINIUM BERPENGUAT ABU JERAMI DENGAN METODE METALURGI SERBUK

The powder metallurgy method is one method for making metal matrix composite products. This method provides researchers with material engineering.This study aims to determine how the effect of variations in mixing time and sintering holding time affects the hardness and compressive strength of composites made of aluminum powder and straw ash. The composition of this composite is 90%wt Aluminum and 10%wt straw ash. Preparation of specimens using powder metallurgy method. Mixing time variations were applied for 120, 150 and 180 minutes with the dry mixing method. Variation of sintering holding time was applied for 60, 120 and 180 minutes at 550°C.The mechanical test carried out are hardness test and compression test. The results showed that the optimum hardness value was found in the specimens with a mixing time of 150 minutes and sintering holding time of 180 minutes with an average hardness of 96 HRF. The optimum compressive strength is found in specimens with a mixing time of 150 minutes and sintering holding time of 120 minutes with an average compressive strength of 101.28 MPa. It can be concluded that mixing time and sintering holding time affect the hardness and compressive strength of the metal matrix composite.

Optimization of Flexural Strength of Sawdust Ash Blended Geopolymer Concrete

release of greenhouse gases linked to the manufacture of cement. Geopolymer as a binder for making concrete consists of two (2) main components; (1) the alkaline liquid consisting of sodium or potassium silicate and sodium or potassium hydroxide and (2) source material of geological origin or by-products rich in silica and alumina. The combination proportions utilised in this investigation were formulated utilising Scheffe's (5,2) basic lattice mix design approach with the intent to create the trial mix and the control mix. A total of thirty (30) geopolymers concrete sample mixes were made in the laboratory, with fifteen samples for trial mixes and fifteen mixtures for control mixes. These mixtures were used to appraise the performance of the sawdust ash geopolymer concrete in term of its flexural strength property. The study used sawdust ash as the source material and investigation revealed that subjecting sawdust ash to pyrolysis without oxygen has a notable impact on the pozzolanic characteristics of the constituent. Consequently, this also affects the flexural qualities of the concrete. Furthermore, it has been shown that softwood sawdust exhibits superior pozzolanic properties when compared to hardwood sawdust. The study revealed that the optimum flexural strength of sawdust ash blended geopolymer concrete is 3.3002 MPa and the corresponding mix deign obtained. Computer programs were created using Matlab and used for the optimization and prediction of the flexural strength of sawdust ash based geopolymer concrete.

Mechanical durability and degradation characteristics of long kenaf-reinforced PLA composites fabricated using an eco-friendly method

The research has focused on evaluating the mechanical strength of long unidirectional kenaf-PLA composite and the degradation effect after accelerated weathering exposure. The composite was fabricated using a green traditional method of hot-pressing method with different compositions of non-chemically treated kenaf fiber to PLA with the ratio of 30:70, 40:60, 50:50, and 60:40. The finding of this work demonstrated fiber weight-matrix ratio of 50:50 gain a remarkable optimum strength with 224 % and 239 % enhancement for tensile and flexural strength respectively. The applied enhanced Rule of Mixture (E-ROM) model used in this study was reliable in predicting the experimental results whereby the composites reached an optimum value. Despite the successful enhancement of fiber–matrix compatibility and composite strength, the presence of fiber misalignment, structural imperfections, and voids observed in scanning electron microscopy (SEM) images still has some detrimental effects on its degradability. Nevertheless, a noteworthy strength reduction of PLA (80 %) as compared to the PLA-kenaf composite demonstrated better resistivity of weathering for the composite after 508 h. Hence, this study suggests deeper insights into the viability of eco-friendly combed methods as fiber treatments for kenaf as PLA reinforcement. It is proven that even without any chemical treatment, the composite demonstrated a remarkable mechanical resilience suitable for indoor non-structural applications.

Pengaruh Penambahan Serat Ampas Tebu Sebagai Tulangan Micro pada Beton

Based on this research, concrete has high compressive strength but low flexural strength. There-fore, the addition of sugarcane bagasse fibers is carried out as an additive to overcome the low flexural strength issue in concrete. This study aims to determine the effect of adding sugarcane bagasse fibers on the characteristics of concrete, including compressive and flexural strength. Fiber-reinforced concrete is a composite material consisting of regular concrete and other mate-rials, such as natural or artificial fibers. The method used in this research is an experimental method, adding 1% of sugarcane bagasse fibers by weight of cement to the normal concrete with a target strength of F'c 19.3 MPa and fiber length of 5 cm. The samples used in this research are concrete cylinders and beams tested using a Universal Testing Machine. The research results show that the optimum compressive strength of normal concrete is 20.36 MPa at 28 days of age. Meanwhile, for fiber-reinforced concrete BSTC and BSTH, the compressive strengths are 17.83 MPa and 16.49 MPa, respectively, indicating a decrease compared to the normal concrete. This decrease is attributed to the addition of sugarcane bagasse fibers, which are lightweight addi-tives and not solid aggregates, resulting in some voids in the sugarcane bagasse fibers. The re-sults of the flexural strength testing show that the optimum flexural strength of BSTC is 4.44 MPa, and for BSTH, it is 4.09 MPa, while the normal concrete (BN) only achieves 3.61 MPa. This is due to the increased bonding effect in concrete caused by the addition of fibers, which helps to resist the occurrence of cracks during flexural testing

Strength development and durability requirement in recycled aggregate concrete: effect of drying and post curing

Present research critically investigates drying sensitivity and cement hydration resumption in recycled aggregate concrete (RAC). To determine minimum post-curing time for optimum strength resumption in RAC, a curing ratio (δ) is introduced. Curing ratio is defined as the ratio between post-curing duration and delay time before curing. Drying sensitivity of RAC is observed significantly lower than NAC. The maximum strength loss under drying conditions is 25.9% in RAC (OPC) and 23.2% in RAC (PPC). Strength criteria determine the curing ratios of RAC (OPC) and RAC (PPC) as 2.22 and 0.30. The maximum delay time for RAC (OPC) and RAC (PPC) is determined at 8 days and 21 days with a minimum post-curing for 17.76 and 6.63 days. The longest allowable delay produces ion penetration less than 1000 Coulombs, resistivity greater than 208 ohm-m, superior structural integrity and internal compactness, and sorptivity comparable to RACs cured after a shorter delay.

Experimental Investigation on Effect of Cementitious Materials on Strength of Sandy Soils

Abstract Weak soil characteristics pose a significant challenge for geotechnical engineers when designing the foundations of a structure. Consequently, researchers resort to improving the properties of weak sandy soil by mixing it with pozzolanic or chemical additives. This study aims to assess the effects of using cementitious materials to enhance the strength and stiffness of loose sand soils. To achieve this goal, experimental work was conducted, involving several laboratory tests to determine the soil properties. Three different curing times were utilized (one day, three days, and seven days), and four various percentages of the added cementitious material were employed (5%, 10%, 15%, and 20%) as a replacement by the weight of the treated soil. The results revealed that 15% is optimum gp content must be added to the mixture for optimum strength and stiffness. And three days is the optimum curing time.

Impact of the partial substitution of cement and sand by ash from several types of wood species in cementitious materials manufacture: valorization in the industrial field

The main objective of this article is to evaluate the potential use of wood ash as a substitute for cement and sand in mortars. Three types of wood were selected: Ayous, Sapelli and Fraké, all of which were sourced from carpentry in Cameroon. The sawdust was dried and combusted to obtain ash, then ground and sieved. Six types of mortar were produced, with cement substitution at 0%, 5%, 10%, 15%, 20% and 25%. The physico-mechanical properties of these substitutions were determined after 7, 28 and 56 days. The results of the cement paste consistency show that it increases with the addition of ash, due to the fact that sawdust ash requires a large quantity of water. The addition of ash caused an increase in setting time due to the fact that sawdust ash is less reactive than Ordinary Portland cement, resulting in a delay in the rate of cement hydration. Apparent density values decreased with the addition of sawdust ash, probably due to the hygroscopic behavior of type of ash in mortar specimens. The highest pozzolanic index is that of 5% replacement by ash and almost identical absorption for all mortars at this substitution percentage. Acid attack results revealed a higher durability of mortar specimens with the higher percentage of ash substitution. Optimum compressive strengths for the different substitution percentages were observed at 5%, 15% and 10% respectively for Ayous, Sapelli and Fraké. The best wood ash is Sapelli because of its chemical composition and resistance to compression in mortars. At 56 days, compressive strength values exceed those of the reference composition. This may be due to pozzolanic reactions in the mortars of ash.