Compressive Strength Behavior Research Articles

Strength Improvement Using Polypropylene Fiber as Reinforcement in Natural Pozzolana-lime-stabilized Expansive Clayey Soil Artificially Contaminated by Sulfates

This paper aims to assess the behavior of the unconfined compressive strength (UCS) of polypropylene fiber (PF) reinforced natural pozzolana-lime-stabilized expansive grey clayey soil (GS) contaminated by sulfates. Lime (0–8%), natural pozzolana (NP) (0–20%), and PF (0–3%) by dry weight of soil were used. GS was contaminated by different sulfate contents (0-6%) and UCS was assessed at various curing periods (7–120 days). Results showed that adding 8% lime alone or with 20% NP considerably improved UCS. Including 1% or 2% PF as reinforcement without sulfates in lime-stabilized GS transferred stress from GS to PF due to bonding. However, increasing PF beyond 2% formed lumps, reducing contact and friction coefficient, thus decreasing UCS. This means that the optimum PF dosage was found to be 2%. The UCS of GS increased with PF content up to 2% and then decreased. The UCS significantly increased with higher calcium sulfate content and curing period due to observed cementing agents in X-ray diffraction (XRD) and scanning electron microscopy (SEM). Adverse effect of ettringite mineral on UCS caused by sodium sulfate addition was suppressed with the combination of 20% NP and 2% PF in lime-stabilized GS. Binding forces from lime and NP resisted to ettringite expansion. Sensitivity of UCS to sulfate effect was more pronounced with sodium sulfate than calcium sulfate. In addition, NP–PF mixture in lime-stabilized GS was more effective, improving the strength of expansive soil, especially with sodium sulfate. In conclusion, reinforcement of NP-lime-stabilized expansive soils with PF is an effective method.

Fabrication and Mechanical Properties of Chitosan/FHA Scaffolds

Fluor-hydroxyapatite (FHA) is a biomaterial with dental and orthopedic potential that is highly regarded as a result of bioactivity and high biocompatibility. Chitosan is used as a growth promoting agent in the tissues of the tooth and bone. Composite scaffold from these biomaterials is used as a pattern of natural bone and tooth grafts in tissue engineering. In this study FHA was synthesized through coprecipitation method. Then chitosan/FHA composites with different amounts of FHA (15 and 30 wt%) were prepared via freeze drying way. Structural and physical characteristics of the scaffolds were determined by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) spectra, and morphological properties of the scaffolds were investigated using SEM evaluation. The compressive strength, water-uptake capacity, and biodegradation behavior of scaffolds were performed, as well. The results indicated that chitosan/30%FHA scaffold showed more compressive strength, lower biodegradation in phosphate buffer solution after 4 weeks. Therefore, it might be a suitable scaffold for tooth engineering.

Effects of K2CO3 addition on the physicochemical properties of goethite composite pellets with different basicities (CaO/SiO2)

In this study, the effects of K2CO3 addition (0, 1, 2 wt%) on the physicochemical properties (moisture content, liquid saturation, plastic deformation degree, drop number, compressive strength) of green and (crystalline phase, fraction of melt phase, morphology, compressive strength and reduction behavior) of sintered composite pellets with varying basicities (CaO/SiO2 = 0.04, 0.40, 0.83, 1.24) were examined. The moisture content of cured green pellet with higher K2CO3 addition was greater at the same basicity. The corresponding results had a positive effect on the development of capillary state, which enhance the drop number and compressive strength up to approximately 14, 28.40 N/Pellet respectively above moisture content of 12.41 wt%. However, it was also confirmed that excessive moisture content (above 13.22 wt%) induced over liquid saturation and has negative effects on physical properties. The magnetite phase predominantly observed with increasing K2CO3 addition at fixed basicity of 0.40–1.24. Intraparticle porosity (pore size = 6.4 nm to 5 μm) decreased with higher K2CO3 addition and showed below 5% at 0.40–1.24 basicity. Interparticle porosity (pore size = 5–1100 μm) showed various behavior with K2CO3 addition at a basicity 0.04–0.40 but increased up to approximately 30% at a basicity 0.83–1.24. Compressive strength of sintered pellet tends to have negative effect on porosity. However, reduction behaviors have positive effects on higher fluxed sintered pellet due to advantageous reduction condition by impurities (alkali and alkaline earth metal cations). Obtained results help elucidate the physicochemical properties of composite pellet-containing alkali metal oxides with varying basicities.

Compressive strength and corrosion behavior of steel bars embedded in concrete produced with ferronickel slag aggregate and fly ash: an experimental study

Compressive strength and corrosion behavior of steel bars embedded in concrete produced with ferronickel slag aggregate and fly ash: an experimental study

Influence of hybrid nano/micro particles on the mechanical performance of cross-ply carbon fibre fabric reinforced epoxy polymer composite materials

This study presents the flexural strength, compressive strength, and impact energy behaviour of graphene nanoplates and fly ash microparticle-loaded cement-based CFRP composites manufactured by the vacuum-assisted resin infusion method (VARIM). The composite structures consist of a fixed ratio of graphene nanoplates (2%), fly ash (2%), silica (2%), cement (2%), and sand (4%) particles filled into cross-plied carbon fibre-reinforced epoxy resin polymer composite beams and columns. Composites fabricated by hand lay-up methods because of infiltration problems. A three-point bending test through the width was used to measure the flexural strength of the graphene nanoplate (GnP)-filled CFRP composite beam. The low-velocity Izod impact and Charpy impact tests through the thickness were used to determine Charpy impact energy (3.46 J), Izod impact energy (2.5 J), and the dynamic fracture toughness of notch specimens under Charpy (28.5 KJ/m2) and Izod impact (25.0 KJ/m2). Also, the compressive test method was used to measure the compressive strength of hybrid particles and short glass fibre-reinforced epoxy resin composite square and circular columns. The results show compressive strength and flexural strength. Izod impact energy, Charpy impact energy, and dynamic fracture toughness of hybrid nano/microparticle-filled fibre composites have higher values than virgin fibre composites because of the influence of graphene nanoparticles and the perfect interface bonding between two dissimilar molecules of nano and microparticles, which improve the fracture toughness and absorb impact energy. Overall, the results show that molecules of nano/microparticle-filled carbon fibre and glass fibre-reinforced epoxy resin composites can be used in seismic wave resistance because of their improved mechanical properties compared to virgin fibre composites. In addition, SEM micrographs clearly show that nano- and microparticles are resistant to crack propagation and the debonding of matrix fibres.

Compressive strength, pore structure, and hydration products of slag foam concrete under sulfate and chloride environment

Compressive strength, pore structure, and hydration products of slag foam concrete under sulfate and chloride environment

The Effect of Ceramic Oxide Type on Compressive Strength and Abrasive Wear Behavior in Different Ceramic Oxide Reinforced Al2024 Composites

In this study, particulate tungsten trioxide (WO3), Neodymium oxide (Nd2O3), zirconium oxide(ZrO2) and aluminum oxide (Al2O3) ceramics were separately reinforced at 10% weight ratio into 2024aluminum matrix material by powder metallurgy method. Abrasive wear and compression strength testswere carried out on the composite samples. According to the data obtained, the type of ceramic oxidereinforcement in the composite structure was compared according to the wear behavior and compressivestrength. As a result of the abrasive wear tests carried, the lowest wear loss amount was obtained from theAl2O3 reinforced composite, while the highest wear loss value was obtained from the WO3 reinforcedsample. Looking at the compressive strengths, it was seen that the highest compressive stress was obtainedfrom the Al2O3 reinforced composite, while the lowest compressive stress value was obtained from theNd2O3 reinforced sample. It was understood that the hardness values of the ceramic oxides doped into theAl2024 matrix directly affect the wear loss and compressive strength values of the composite structures. Itwas concluded that WO3, Nd2O3, ZrO2 and Al2O3 reinforcement elements in the form of particles dopedinto the Al2024 matrix improve the mechanical properties of the composite structure.

Effect of superabsorbent polymer and Slag Cement on concrete properties

Effect of superabsorbent polymer and Slag Cement on concrete properties

Compressive Strength Behavior of Briquettes Produced from Manganese Ore Fines and Metal Dust: Optimization Using Response Surface Methodology

ABSTRACT Electric reduction furnaces cannot be fed fines in the production of manganese ferroalloy as they hinder gas permeability. Thus, agglomeration techniques can be used to minimize the environmental and economic impacts of storing fines. Among these techniques, briquetting is advantageous because it allows for cold agglomeration of the particles and is flexible in terms of particle sizes. Therefore, this work aimed to develop self-reductor briquettes composed of ore manganese fines, dust ferromanganese, charcoal fines, and three different binders. The compaction pressure, curing time, and % binder were optimized to enhance briquette strength through a multivariate experimental design consisting of a screening study using a 23 full factorial design followed by response surface methodology with a spherical central composite design. The results were assessed by analysis of variance, and a regression model was established. The study found that briquettes elaborated with bentonite exhibited an optimized compressive strength of 4.02 MPa, achieved with a compaction pressure of 67.55 MPa and 12.71% bentonite. For briquettes elaborated with pregelatinized starch, a compressive strength of 7.04 MPa was obtained with a compaction pressure of 67.52 MPa, a curing time of 19.51 days, and 8.07% pregelatinized starch. For briquettes agglomerated using slaked lime and molasses, an optimized compaction pressure of 27.09 MPa and a curing time of 23.27 days resulted in a compressive strength of 1.63 MPa. These results suggest that briquettes containing bentonite and pregelatinized starch are feasible substitutes for lump ore in electric furnaces.

Improvement in geotechnical properties of soft filter cake stabilized with autoclaved aerated concrete powder: Experimental evidence and micro-mechanism

Improvement in geotechnical properties of soft filter cake stabilized with autoclaved aerated concrete powder: Experimental evidence and micro-mechanism

Comparison of Different Aerogel Granules for Use as Aggregate in Concrete

In previous work of this group, a structural lightweight concrete was developed by embedding silica aerogel granules in a high-strength cement matrix. This concrete, called high-performance aerogel concrete (HPAC), is a lightweight building material characterized by its simultaneous high compressive strength and very low thermal conductivity. Besides these features, high sound absorption, diffusion permeability, water repellence and fire resistance qualify HPAC as an interesting material for the construction of single-leaf exterior walls without any further insulation. During the development of HPAC, the type of silica aerogel was found to majorly influence both fresh and hardened concrete properties. To clarify these effects, a systematic comparison of SiO2 aerogel granules with different levels of hydrophobicity as well as different synthesis methods was conducted in the present study. The granules were analyzed for their chemical and physical properties as well as their compatibility in HPAC mixtures. These experiments included determinations of pore size distribution, thermal stability, porosity, specific surface and hydrophobicity, as well as fresh/hardened concrete experiments such as measurements of compressive strength, flexural bending strength, thermal conductivity and shrinking behavior. It was found that the type of aerogel has a major influence on the fresh and hardened concrete properties of HPAC, particularly compressive strength and shrinkage behavior, whereas the effect on thermal conductivity is not very pronounced.

Experimental and numerical investigation for confined concrete elements with fabric reinforced cementitious matrix (FRCM)

Experimental and numerical investigation for confined concrete elements with fabric reinforced cementitious matrix (FRCM)

Influence of Wetting-Drying Cycles on Strength Behaviour of Cured Lime Treated Soil Contaminated with Monovalent and Divalent Sulphatic Solutions

Influence of Wetting-Drying Cycles on Strength Behaviour of Cured Lime Treated Soil Contaminated with Monovalent and Divalent Sulphatic Solutions

Optimization of Bending and Compressive Strength Behavior of Agave americana Fiber Reinforced Cementitious Composite Using Response Surface Methodology

The purpose of this research is to optimize several variables, including fiber length, volumetric fiber percentage, and sodium hydroxide (NaOH) solution concentration, which influence the bending and compression behavior of cementitious composites reinforced with plant-based fibers from Agave americana. Samples of composites based on fibers extracted from Agave americana and a cement matrix were manufactured and prepared according to a reference mortar. Box-Behnken Design (BBD) of Response Surface Methodology (RSM) was employed to build an experimental design to explore their mechanical behavior and to construct a set of mathematical models predictive of their behavior. The first stage of the work includes the extraction and processing of Agave americana fibers and the preparation of cement and Agave americana mortar specimens. The second phase aims to establish mathematical models to forecast the workability of the cement mortar and its strength at 28 days while emphasizing the correlations and interactions between the different components through the Design Expert software.

Ductility evaluation and flexural failure mode recognition of reinforced Ultra-High performance concrete flexural members

Ductility evaluation and flexural failure mode recognition of reinforced Ultra-High performance concrete flexural members

Optimizing the compressive strength behavior of iron slag and recycled aggregate concretes

Optimizing the compressive strength behavior of iron slag and recycled aggregate concretes

The Cracking Behavior of Two Dental Composite Materials Validated through Multifractal Analyzes

The aim of this in vitro study was to analyze, both experimentally and theoretically, the mechanical behavior of two types of composite materials used in restoring dental integrity. The samples of each composite resin, namely Filtek Supreme XT (3M ESPE, St. Paul, MN, USA) and Filtek Z250 (3M ESPE, St. Paul, MN, USA), were experimentally analyzed by determining their compressive strength and fracture behavior. The fractured fragments of the samples were subjected to surface evaluation by scanning electron microscopy. The compressive stress—compressive strain dependencies revealed stronger cracking of the Filtek Supreme XT composite than Filtek Z250 prior to fracture. Theoretically, the evaluation was made by means of holographic implementations of such types of composite materials. A Hooke-type equation in a differential form is presented, which links the proposed theoretical model with the experimentally obtained data.

Unconfined compressive strength and freeze-thaw behavior of silty clay soils treated with bio-enzyme

Unconfined compressive strength and freeze-thaw behavior of silty clay soils treated with bio-enzyme

Comparison of various machine learning algorithms used for compressive strength prediction of steel fiber-reinforced concrete

Adding hooked industrial steel fibers (ISF) to concrete boosts its tensile and flexural strength. However, the understanding of ISF’s influence on the compressive strength (CS) behavior of concrete is still questioned by the scientific society. The presented paper aims to use machine learning (ML) and deep learning (DL) algorithms to predict the CS of steel fiber reinforced concrete (SFRC) incorporating hooked ISF based on the data collected from the open literature. Accordingly, 176 sets of data are collected from different journals and conference papers. Based upon the initial sensitivity analysis, the most influential parameters like water-to-cement (W/C) ratio and content of fine aggregates (FA) tend to decrease the CS of SFRC. Meanwhile, the CS of SFRC could be enhanced by increasing the amount of superplasticizer (SP), fly ash, and cement (C). The least contributing factors include the maximum size of aggregates (Dmax) and the length-to-diameter ratio of hooked ISFs (L/DISF). Several statistical parameters are also used as metrics to evaluate the performance of implemented models, such as coefficient of determination (R2), mean absolute error (MAE), and mean of squared error (MSE). Among different ML algorithms, convolutional neural network (CNN) with R2 = 0.928, RMSE = 5.043, and MAE = 3.833 shows higher accuracy. On the other hand, K-nearest neighbor (KNN) algorithm with R2 = 0.881, RMSE = 6.477, and MAE = 4.648 results in the weakest performance.

The efficiency of statistical and artificial neural network techniques on evaluating and predicting compressive strength of sustainable SCC with basalt fibers

The efficiency of statistical and artificial neural network techniques on evaluating and predicting compressive strength of sustainable SCC with basalt fibers