Compressive Strength Properties Research Articles

Reinforcement effects on the tensile properties of seawater sea-sand engineered cementitious composites reinforced with multi-scale hybrid fibers

The preparation of seawater sea-sand engineered cementitious composites (SS-ECC) holds great potential for development in coastal and marine infrastructure. To improve its compressive strength and tensile properties, this study investigated the crack characteristics, micro-mechanics, fibers reinforcement index, and micro-structure of SS-ECC using a multi-scale hybrid fibers system consisting of CaCO3 whiskers, PE fibers, and stainless steel fibers (SSF). The aim was to gain an in-depth understanding of the reinforcement effects of multi-scale hybrid fibers. The results showed that CaCO3 whiskers increased the number of cracks and the stability of crack evolution in SS-ECC during the ultimate tensile state by bridging the matrix micro-cracks, improving the matrix micro-structure, and filling the interfacial transition zones between the macroscopic fibers (PE fibers and SSF) and the matrix. Additionally, it reduced the crack width and spacing. These combined effects increased the compressive strength, tensile strength, and tensile strain capacity of SS-ECC by 12.8%, 15.7%, and 11.9%, respectively. Finally, the reinforcement effects of multi-scale hybrid fibers were analyzed based on the pseudo-strain hardening performance indices, fibers reinforcement index, and hybrid coefficient. This analysis provides reference and insight for the design of multi-scale hybrid fibers SS-ECC with a high comprehensive performance (σcσtε/w) index.

Sandy soil based foam concrete with ultra-small pore structure through in-situ mechanical frothing

During the manufacturing of foam concrete, conventional chemical and physical foaming methods are still inadequate for regulating and stabilizing the bubble properties. In this work, a one-pot method, denoted as in-situ mechanical frothing, was proposed preparing foam concrete by vigorously stirring the mixture of water, cement, sandy soil, and foaming agent. Sandy soil (SS) was used in the content range of 25–75 % as cement replacement to decrease the binder consumption and reduce costs. The influence of in-situ mechanical frothing technology and SS dosage on the properties of paste rheology, pore structure, compressive strength, and thermal properties was investigated. The results showed that the average pore size of foam concrete prepared by this method is between 45.73 and 74.58 μm. The compressive strength of the formed foam concrete at dry density of 600–1000 kg/cm3 was 2.78–16.37 MPa, which was 85%–231 % higher than that the standard values. The incorporation of SS resulted in smaller and homogeneous pore structure in foam concrete. Moreover, foam concrete with 25–75 % SS dosage showed 7–40 % decrease in thermal conductivity. The overall analysis showed that the 25–50 % SS-incorporated foam concrete enabled achieving higher standard properties through in-situ mechanical frothing.

Experimental Investigation on Durability Properties of Slurry Infiltrated Fiber Concrete

Slurry infiltrated fibrous concrete (SIFCON) can be considered as a special and advanced type of steel fiber reinforced concrete composite. SIFCON is produced by infiltrating rich flow able cement slurry into the bed of preplaced fibers in the mold. In this paper, an attempt has been made to investigate the durability study of SIFCON. An ordinary Portland cement is used with fiber contents of (5%, 7.5%, 10%, and 12%). This study also presents the effect of incorporating Metakaolin (MK) on the mechanical and durability properties of SIFCON for a constant water/cement ratio of 0.5. The physical properties include the specific gravity, density, fineness modulus, water absorption, consistency. The above properties are studied for materials used like cement, fly ash, coarse aggregate, ceramic, sand and laterite. Mechanical properties of the hardened concrete such as compressive strength, tensile strength, flexural strength, and durability properties like water absorption, sorptivity, acid test, marine environment are tested and the values are validated. Metakaolin is a waste/non-conventional material which can be utilized beneficially in the construction industry. From the literature survey, Metakaolin inclusion increases the compressive, tensile, flexural and bend strength and modulus of elasticity of mortar considerably; however, the workability is slightly compromised.

A comparative analysis of compressive and wear failure of laser-powder bed fused Stainless Steel 316L produced with different hatch spacing in stripe and contour patterns

The selection of hatch spacing is crucial in additive manufacturing processes to produce a defect free Stainless Steel 316L (SS) components, especially in laser powder bed fusion (LPBF) process. Improper selection of hatch spacing could lead to various failure regimes (like vertical cracking, porosity, and un-melted particles) in Stainless Steel 316L (SS) component produced through laser powder bed fusion (LPBF). Further, the failure regimes have a direct impact on the hardness, compression strength, friction, and wear properties of LPBF SS components. The present study has taken substantial efforts to analyse the impact of various hatch spacing (0.08 mm, 0.10 mm. and 0.12 mm) in stripe and contour patterns, in terms of morphology, mechanical, and tribological properties of LPBF SS components. Also, the present study elucidates how variations in hatch spacing influences the features like particle fusion, crack formation, density, hardness, surface roughness, compression, and wear properties. The stripe pattern with low hatch spacing of 0.08 mm showed better particle fusion and high surface roughness; whereas the high hatch spacing has produced voids, un-melted powder particles, and cracks in the stripe and contour pattern. High densities and hardness values were attributed to the stripe patterns with more effective melting and fusing of powder particles. XRD analysis revealed the stable phase compositions across various hatch spacing with a predominant FCC crystal structure. Residual stress distribution was significantly influenced by the hatch spacing for both stripe and contour patterns. Importantly, the low hatch space leads has promoted the tensile residual stress formation and vice versa for the higher hatch spacing. Stripe patterns showed higher compression strengths with buckling and shear mode as a compression failure. The stripe pattern demonstrated a low specific wear rate (SWR) and coefficient of friction (COF) compared to the contour pattern, with respect to the various hatch spacing. Furthermore, the simulated body fluid (SBF) lubrication regime played a significant role in reducing the COF. Patches, groves, furrows, and craters demonstrated the abrasive and adhesive failure for both stripe and contour pattern, which is further detailed in the article.

Preparation of geopolymers from thermally activated lithium slag as sole precursor: Mechanical properties and microstructure

Lithium slag (LS) is a waste residue generated during lithium extraction, posing significant environmental challenge due to its extensive accumulation. This study proposes a method of utilizing thermally activated LS as the sole precursor for geopolymer synthesis. The thermal activation mechanism of LS was investigated using XRD, FTIR, ICP, and SEM techniques, while exploring the optimal composition for LS geopolymers(LSG). The research revealed that heating at 700 °C increased the amorphous content of LS from 15.9 % to 48.1 %, altering the chemical structure of its aluminosilicates and enhancing its leaching capacity in alkaline environments, thereby boosting its reactivity. The activator modulus and alkali equivalent were found to significantly influence the strength and microstructure of LSG. As the modulus increased from 1.0 to 1.4, geopolymer strength initially rose before declining, whereas strength progressively increased with alkali equivalent from 0.10 to 0.16. The geopolymer synthesized with a modulus of 1.2 and alkali equivalent of 0.16 exhibited the highest compressive strength of 53.1 MPa after 28 days. Test results indicated that the internal structure of LSG primarily comprised unreacted particles, N(C)-A-S-H gel, and microcracks. The increased alkali equivalent facilitated the dissolution of Si4+ and Al3+ within LS, intensifying geopolymerization to produce more N(C)-A-S-H gel, thereby densifying the structure and significantly enhancing compressive strength. This study elucidates the mechanism by which high-temperature calcination enhances LS reactivity, as well as the impact of activator on compressive strength and microstructural properties of LSG, offering new insights into the engineering applications of LS in high-performance cementitious materials.

Catalyst-free construction of biomass-based robust and flame-retardant polyurethane foams

This study introduces a green synthesis method for the preparation of flame-retardant biobased polyurethane foams (PUFs) without the use of catalysts. The approach involves the design and utilization of two cardanol-based hydroxyalkyl benzoxazines (CHBzs) capable of self-catalytic foaming through the action of their oxazine rings. Additionally, tris(hydroxymethyl)phosphine oxide (THPO) is incorporated as both a crosslinking agent and a flame-retardant additive during the foaming process to enhance the physical properties and flame retardancy of the resulting PUFs. The thermodynamic performance, compressive strength, and flame-retardant properties of the synthesized foams are analyzed. Furthermore, the morphology of the combustion residues is investigated to understand the combustion process. The results demonstrate that the addition of THPO significantly improves the flame-retardant performance and thermal degradation characteristics of bio-based flame-retardant PUFs. This green synthesis approach offers a promising strategy for the development of sustainable and flame-retardant PUF materials.

Utilization of phosphogypsum from industrial dumps as an element of environmentally safe energy- and resource-conserving technologies

The paper discusses the problem of disposal and processing of phosphogypsum dumps as an element of environmentally safe energy- and resource-conserving technologies. The process of impact and possibility of phosphogypsum pre-treatment with weak electric fields to improve its physical and mechanical properties was studied. Two samples of different origin phosphogypsum, which are located in dumps on the territory of the Kamianske City (Ukraine), were used as research material. The research was conducted on samples of the following fractions: 1.0–2.0, 0.4–1.0, 0.1–0.4 mm. Further, balls were formed from the treated phosphogypsum and raw materials to study their compressive strength. The experiment was performed on a pellet strength meter, which operates in the range of 0–2.5 kgf/grain. Phosphogypsum balls, treated with electric current, did not collapse with the maximum values of the device. According to the research results, it was established that preliminary treatment with a low electric current leads to a decrease in the dehydration temperature of phosphogypsum, and the subsequent hydration allows to obtain a material with higher compressive strength properties. This substantiates the potential possibility of involving research results to obtain a cheaper product and will allow to liquidate multi-ton deposits of phosphogypsum.

Radiation shielding properties of heavy-weight concrete and heavy-weight geopolymer concrete incorporating nano-ZnS

The population growth and the subsequent increase in energy demand for buildings require the widespread use of sustainable materials in the construction industry. Therefore, geopolymer concretes (GPC) are expanding with the ability to emit less greenhouse gases (GHG) compared to conventional concrete. In this study, the effect of adding different content of Zinc sulfide nanoparticle (nano-ZnS) 0, 1.5, 3, 4.5, and 6 % by weight of cement on density (ρ), compressive strength, gamma ray radiation protection characteristics, and microstructure based on scanning electron microscope (SEM) is investigated in heavy-weight concrete (HWC) and heavy-weight geopolymer concrete (HGC). The results have shown that nano-ZnS nanoparticles improve the strength and gamma ray shielding properties of HWC and HGC by modifying the microstructure so that by adding the optimal amount of 6 % nano-ZnS, the maximum compressive strength for HWC and HGC was obtained by 57.4 and 41.5 %, respectively. In addition, the highest linear attenuation coefficient (µ)was obtained with the addition of 4.5 % nano-ZnS for HWC and HGC, 12.8 and 8.9 %, respectively.Furthermore, the life cycle assessment (LCA) of the three phases of raw material production, transportation and concrete production has revealed that HGC has emitted 41.5 % less CO2 compared to HWC. In general, HGC in the presence of the optimal amount of nanoparticles has shown a more visible improvement in compressive strength and gamma ray shielding properties. In addition, HGC as an environmentally friendly material, has significantly reduced the emission of CO2.

A multistimuli‐responsive recyclable poly(vinyl alcohol)/perylene imide hydrogel of high‐performance piezoresistive sensors for human wearable devices

AbstractMultiple factors stimulate human beings in their daily lives, but uniformly collecting these signals is challenging. This study proposes a physically cross‐linked method that employs hydrogen bonding interactions to prepare poly(vinyl alcohol)/perylene imide (PVA/PI) hydrogels. The prepared PVA/PI hydrogels demonstrate favorable compressive strength (45–75 kPa) and adhesion properties. At room temperature, elongation reaches approximately 400%. Additionally, the PVA/PI hydrogels exhibit strong mechanical properties, with a maximum elongation of 200%, and high ionic‐electronic conductivity of 29.6 S m−1, even after being soaked in a 2 M HCl solution for 24 h. The water‐soluble PI in the PVA/PI hydrogels is environmentally responsive, resulting in a current response time of 100 ms under 365 nm irradiation, as well as reversible fluorescence changes across different pH levels. Both the PVA5/PI1 and PVA5/PI1/HCl2 (the concentrations were 5 wt%, 1 mg mL−1 and 2 mol L−1, respectively) hydrogels demonstrate high sensitivity (0.49 and 7.88 kPa−1) and a wide pressure monitoring range (0.088–30.67 kPa and 0.088–18.67 kPa, respectively) as pressure sensors. The first developed recyclable PVA/PI hydrogel shows promise for use in wearable sensing devices and is expected to be applied in complex environments.

Synergetic enhancement of ultimate strength and damping properties by pore structure in novel porous Cu-Al-Mn shape memory alloy

To meet the higher device vibration reduction requirements, novel porous Cu71Al18Mn11 shape memory alloys (SMAs) with controllable porosity were prepared using Cu, Al, and Mn elemental powders as raw materials. To further enhance the strength and damping performance of SMAs, a low-temperature reactive synthesis combined with spark plasma sintering (LTRS+SPS) process was used. In this paper, the effects of LTRS+SPS process on pore structure and texture, compressive strength, and damping properties of porous Cu71Al18Mn11 alloy were studied. The outcomes indicated that LTRS+SPS process can effectively improve both compressive strength and damping properties. The associated closed pore structure caused by this process and the second phase γ2 phase formed by element diffusion result in a variety in compressive strength from 324.6 MPa to 617.9 MPa, which were 3.9 times that of the comparable porosity alloy with alloy powder as raw material by vacuum sintering. Meanwhile, the damping value changed from 0.27 to 0.10, which was 4.5 times that of the homogeneous dense alloy. The increase in damping property is caused by the increase of motionable interfaces in the matrix for the introduction of pores, which leads to the increase of energy dissipation. Besides. the interaction between the second phase γ2 and dislocation contributes to the improvement of damping, as well as the compressive strength. These findings in this paper provide new insights and references for the structural design and microstructure design of high-performance Cu-based alloys.

Perlite incorporation for sedimentation reduction and improved properties of high-density geopolymer cement for oil well cementing

Portland cement (PC) is known for its environmental and technical concerns and massive energy consumption during manufacturing. Geopolymer cement is a promising technology to totally replace the use of PC in the oil and gas industry. Although geopolymers are widely used in the construction industry, it is yet to see a full-scale application in the petroleum industry. High-density geopolymer cement development is essential to substitute heavy-weight Portland cement slurries for high pressure well cementing applications. Sedimentation issue is associated with high-density cement slurries which use high specific gravity solids such as weighting materials. This problem causes heterogeneity and density variation along the cemented sections. The main target of this work is to evaluate the use of perlite powder to address the sedimentation issue in the heavy weight geopolymer systems. Hematite-based Class F fly ash (FFA) geopolymer cement slurries with perlite concentrations of 0, 1.5, and 3% by weight of binder (BWOB) were prepared. The sedimentation problem was investigated using three techniques: API method, nuclear magnetic resonance (NMR), and computed tomography (CT) scan. The perlite effects on different geopolymer properties such as unconfined compressive strength (UCS), porosity, elastic and rheological properties were assessed. The results proved that perlite incorporation in high-density hematite-based FFA geopolymer significantly reduced sedimentation issue by increasing yield point and gel strength. NMR and CT scan showed that perlite decreases porosity and density variation across the geopolymer samples. The UCS increased with increasing perlite percentage from 0 to 3%. The measured Young’s moduli (YM) and Poisson’s ratios (PR) showed that the developed perlite based geopolymer systems are considered more flexible than Class G cement systems. It was found that the optimum perlite concentration is 3% BWOB for tackling sedimentation and developing a slurry with acceptable mixability and rheological properties.

High‐Strength Wear‐Resistant Cu/Tungsten Carbide/Diamond Composites Fabricated by Powder Metallurgy

Copper‐based diamond composites are widely used for thermal management and wear‐resistant materials. In this work, Cu/diamond, Cu/tungsten carbide (WC)/diamond, and Cu–0.92Cr/WC/diamond composites are fabricated by high‐energy ball milling and rapid hot‐pressing sintering. Physical characteristics, compressive strength, and tribological properties of the studied composites are investigated. The compressive strength of Cu/7wt%WC/diamond composites is 102% higher than the Cu/diamond composites, reaching 415 MPa. Compression fractures extend from the interface due to compression cracks, consistent with the compression curves from molecular dynamics (MD) simulations. The crack propagates from the interface during the compression experiment, which is consistent with the result of MD simulation. The Cu/7wt%WC/diamond composites exhibit a wear rate of 0.6 × 10−6 mm3 (N m)−1 and a friction coefficient of 0.37 at 50 N. The addition of WC and diamond improves the compressive strength and wear resistance. These findings are helpful in the development of copper composites with high compression strength and wear resistance.

Relationship between mechanical properties and height-diameter ratio of moso bamboo

Systematic tests of longitudinal compression, bending, longitudinal shear, and longitudinal tensile strength of bamboo were conducted to study the variation of mechanical properties and the height-diameter ratio of bamboo. The predictive relations of mechanical properties and height-diameter ratio were fitted by linear regression analysis. The results showed that the mechanical properties of longitudinal compression, bending, longitudinal shear, and longitudinal tensile strength of bamboo increased with the increase of the height-diameter ratio. In this paper, the method of deducing the relationship between mechanical properties and height-diameter ratio of bamboo through the linear fitting relationship between mechanical properties and height-diameter ratio was shown to have high applicability and accuracy for bamboo. This paper has a certain reference value for the evaluation of mechanical properties of bamboo and has a certain practical value for reducing the testing cost.

The Influence of Materials on the Mechanical Properties of Ultra-High-Performance Concrete (UHPC): A Literature Review.

Ultra-high-performance concrete (UHPC) is a cementitious composite combining high-strength concrete matrix and fiber reinforcement. Standing out for its excellent mechanical properties and durability, this material has been widely recognized as a viable choice for highly complex engineering projects. This paper proposes (i) the review of the influence exerted by the constituent materials on the mechanical properties of compressive strength, flexural tensile strength, and elastic modulus of UHPC and (ii) the determination of optimal quantities of the constituent materials based on simplified statistical analyses of the developed database. The data search was restricted to papers that produced UHPC with straight steel fibers at a content of 2% by volume. UHPC mixture models were proposed based on graphical analyses of the relationship of constituent materials versus mechanical properties, aiming to optimize the material's performance for each mechanical property. The results proved to be in accordance with the specifications present in the literature, characterized by high cement consumption, significant presence of fine materials, and low water-to-binder ratio. The divergences identified between the mixtures reflect how the constituent materials uniquely impact each mechanical property of the concrete. In general, fine materials were shown to play a significant role in increasing the compressive strength and flexural tensile strength of UHPC, while water and superplasticizers stood out for their influence on the material's workability.

Clinkering and hydration of alite-belite-ye'elimite cement with increasing ye'elimite percentage

Alite-belite-ye'elimite (ABY) cement is considered to be eco-cements with adequate mechanical properties and fewer CO2 emissions. The phase assemblage and ye’elimite content of ABY cement play a very important role in cement properties. In this study, ABY clinkers with increasing ye'elimite percentage (0.3 wt%-36.4 wt%) were prepared at 1300 °C and the phase composition was characterized by Rietveld Quantitative Phase Analysis combined with energy dispersive X-ray spectrometry. The ye'elimite formed with a calculated composition of Ca3.92Mg0.02Al2.81Fe0.05Si0.04S1.16, incorporating additional sulfur compared to the theoretical value. In addition, the hydration properties of heat evolution, hydration products and compressive strength of ABY cement are studied. The result shows that the increase of ye'elimite content leads to a more intense initial heat release and a higher cumulative heat release. The presence of ye'elimite inhibits the hydration of alite at early ages. ABY mortars with increasing ye'elimite (15.8 wt%) exhibited a higher strength (29.6 MPa) at 3 days by the contribution of ye'elimite hydration, and an increase (47.4 MPa) at 28 days. An adequate proportion of ye'elimite (<15 wt%) is favorable to the performance of ABY cement, and releases 12% less CO2.

Influence of recycled coarse aggregate on properties of fly ash and slag-based geopolymer concrete cured under oven and ambient temperature

Purpose The purpose of this paper is to investigate the effect of the replacement of natural coarse aggregate (NCA) with different percentages of recycled coarse aggregate (RCA) on properties of low calcium fly ash (FA)-based geopolymer concrete (GPC) cured at oven temperature. Further, this paper aims to study the effect of partial replacement of FA by ground granulated blast slag (GGBS) in GPC made with both NCA and RCA cured under ambient temperature curing. Design/methodology/approach M25 grade of ordinary Portland cement (OPC) concrete was designed according to IS: 10262-2019 with 100% NCA as control concrete. Since no standard guidelines are available in the literature for GPC, the same mix proportion was adopted for the GPC by replacing the OPC with 100% FA and W/C ratio by alkalinity/binder ratio. All FA-based GPC mixes were prepared with 12 M of sodium hydroxide (NaOH) and an alkalinity ratio, i.e. sodium hydroxide to sodium silicate (NaOH:Na2SiO3) of 1:1.5, subjected to 90°C temperature for 48 h of curing. The NCA were replaced with 50% and 100% RCA in both OPC and GPC mixes. Further, FA was partially replaced with 15% GGBS in GPC made with the above percentages of NCA and RCA, and they were given ambient temperature curing with the same molarity of NaOH and alkalinity ratio. Findings The workability, compressive strength, split tensile strength, flexural strength, water absorption, density, volume of voids and rebound hammer value of all the mixes were studied. Further, the relationship between compressive strength and other mechanical properties of GPC mixes were established and compared with the well-established relationships available for conventional concrete. From the experimental results, it is found that the compressive strength of GPC under ambient curing condition at 28 days with 100% NCA, 50% RCA and 100% RCA were, respectively, 14.8%, 12.85% and 17.76% higher than those of OPC concrete. Further, it is found that 85% FA and 15% GGBS-based GPC with RCA under ambient curing shown superior performance than OPC concrete and FA-based GPC cured under oven curing. Research limitations/implications The scope of the present paper is limited to replace the FA by 15% GGBS. Further, only 50% and 100% RCA are used in place of natural aggregate. However, in future study, the replacement of FA by different amounts of GGBS (20%, 25%, 30% and 35%) may be tried to decide the optimum utilisation of GGBS so that the applications of GPC can be widely used in cast in situ applications, i.e. under ambient curing condition. Further, in the present study, the natural aggregate is replaced with only 50% and 100% RCA in GPC. However, further investigations may be carried out by considering different percentages between 50 and 100 with the optimum compositions of FA and GGBS to enhance the use of RCA in GPC applications. The present study is further limited to only the mechanical properties and a few other properties of GPC. For wider use of GPC under ambient curing conditions, the structural performance of GPC needs to be understood. Therefore, the structural performance of GPC subjected to different loadings under ambient curing with RCA to be investigated in future study. Originality/value The replacement percentage of natural aggregate by RCA may be further enhanced to 50% in GPC under ambient curing condition without compromising on the mechanical properties of concrete. This may be a good alternative for OPC and natural aggregate to reduce pollution and leads sustainability in the construction.

Compaction Delay and Temperature Effects on Early-Age Properties of Roller-Compacted Concrete

The lower water content of roller-compacted concrete (RCC) coupled with climatic conditions (e.g., higher air temperature, increased wind speed, and lower relative humidity) and compaction delay factors (e.g., traffic delay, plant location, and paving speed) can significantly affect the in situ density and hardened properties of RCC pavements. In this study, a control RCC mix was batched and maintained at standard (21°C) and elevated (35°C) temperatures and then compacted at increasing delay times for up to 180 min. The elevated mix temperature and compaction delay times greater than 90 min prevented the RCC mix from achieving 98% of the initial wet density from the modified Proctor test. Two additional RCC mixes were batched to determine if they could maintain a longer compaction window, one containing a rheology-modifying and retarding admixture and the other incorporating saturated fine lightweight aggregates. The RCC with admixture was the most effective at maintaining moisture content, density, compressive strength, and fracture properties at all compaction delay times. For example, at 180 min of delay, the RCC mixture with admixture still maintained 98.2% of the initial wet density, 81% of the compressive strength, and approximately the same fracture toughness and energy. The addition of fine lightweight aggregates did not extend the compaction window relative to standard RCC mix. The gyratory compacted specimens were more sensitive to the effects of temperature and compaction delay on RCC mixes than the vibratory hammer prepared specimens.

Testing the effect of UHPFRC jacket thickness and steel fiber volume fraction on NSC‐UHPFRC column compressive behavior

AbstractSeveral efficient applications of ultrahigh‐performance fiber‐reinforced concrete (UHPFRC). Among them are UHPFRC jackets utilized for strengthening or permanent formworks of the steel reinforcing normal strength concrete (NSC) columns since UHPFRC jackets could enhance the compressive strength and other properties of the NSC column. However, the efficiency of a UHPFRC jacket simultaneously depends on its thickness and the added steel fiber volume fraction. The paper aims to explore the interaction effect of UHPFRC jacket thickness and steel fiber volume fraction on the behavior of UHPFRC jackets confining the NSC core under compressive load. The circular ultrahigh performance concrete jacket filled inside with the normal strength concrete, named NSC‐UHPFRC column specimen, is tested under loading on the NSC core. UHPFRC jacket thickness of 18‐49 mm with three adding steel fiber volume fractions was conducted for the experimental study. The investigation and analysis of the effect of the UHPFRC jacket and the steel fiber volume fraction on compression behaviors of NSC‐UHPFRC columns proceeded after the compressive strength test results were validated using Richart's model. This comprised a review of various parameters such as specimen failure pattern, stress–strain relationship, and ductile indices. The Weibull distribution was employed to explain the interaction effect on the variation in the experimental results. Finally, an interaction model was proposed and used to discuss the interaction effect of UHPFRC jacket thickness and steel fiber volume fraction and the optimum condition of the compressive strength of the NSC‐UHPFRC columns.

Review on Investigating Soil Stabilized Mud Blocks with Combined C&amp;D Waste

Buildings built by ancient civilizations like the Mesopotamians and Egyptians were made of clay and other materials, and the use of stabilized soil for construction dates to those times. On the other hand, the scientific underpinnings of soil stabilization were not established until the early 1900s. In comparison to conventional building materials, the use of stabilized soil-based construction materials, such as soil stabilized mud blocks, can offer several advantages, such as improved strength and durability, less of an adverse effect on the environment, and lower costs. The world is facing an issue that calls for the disposal of inorganic solid waste to be addressed right away. This solid waste that is produced when old buildings are demolished is frequently classified as industrial waste or C&amp;D waste. In India alone, enormous amounts of waste are produced, very little of which is recycled. When modifying the properties of stabilized soil, this C&amp;D waste can be used in place of soil or quarry sand. This work explores the use of a stabilizing agent in conjunction with combined C&amp;D waste for soil sampling. The studies use combined C&amp;D waste and soil stabilized mud blocks to test the hollow blocks' water absorption capacity and strength for various replacements. The materials needed for the study came from nearby structures that had been demolished. Using mortar, cylindrical samples for 32 different ratios of mixed construction and demolition waste with a 9% cement content were cast for various compositions. To determine whether the stabilized samples were suitable for use in construction, tests were conducted on their compressive strength and water absorption properties. Based on the least compressive values found in cylindrical samples, the C&amp;D waste was used in ratios ranging from 0% to 100% in place of soil. Mud blocks stabilized by soil were poured and examined for durability, strength, and mechanical qualities. In this study, an effort was made to use C&amp;D waste—that is, brick and concrete waste—in varying amounts to create cylindrical samples that could be used to create concrete and stabilized mud blocks. In order to create cylindrical samples, different ratios of brick waste, concrete waste, and brick-concrete waste were used for 23 mix proportions. Cylindrical samples were manufactured using a cement content of 9 and 12%. These samples' mechanical and physical characteristics, such as their compressive strength, water absorption capacity, and initial rate of absorption, were investigated.

Environmentally friendly binders from calcium carbide residue and silica fume and feasibility for soft clay stabilization

This investigation elucidates the development of an innovative, sustainable binder derived from calcium carbide residue and silica fume, aimed at enhancing soft clay stabilization with minimal environmental impact. Various mixtures were examined, focusing on the CaO to SiO2 molar ratio (Ca/Si), which varied from 1.85 to 0.65. Comprehensive analyses of the raw materials and pastes, including chemical composition, phase evolution, and microstructure, were conducted using techniques like Energy dispersive X-ray fluorescence, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. Results indicate a significant impact of raw material fractions on the compressive strength and cementitious properties. The mixture with a Ca/Si of 1.55 demonstrated the highest long-term strength, attributed to increased C–S–H content. A mixture of 30 wt% calcium carbide residue and silica fume was found to improve the unconfined compressive strength of soft Bangkok clay by 84% compared to 10 wt% ordinary Portland cement, demonstrating its efficacy and potential for widespread application in green construction initiatives. This research not only promotes the recycling of industrial by-products, reducing environmental impact, but also represents a significant advancement in sustainable construction materials.