Compressive Strength Behavior Research Articles

GRANULATED BLAST FURNACE SLAG AS A SUPPLEMENT ENHANCING FIRE RESISTANCE OF PORTLAND CEMENT MORTAR

Using steel slag in the cement industry has been considered a green recycling solution to the solid waste problem. Granulated blast furnace slag (GBFS), in fact, is used as an additive to counteract the sulfate attack of Portland cement; however, its ability to undergo fire or heat exposure has not been highlighted yet. Therefore, this study focuses on compressive strength behaviour at high temperature along with workability of cement paste of cement containing GBFS. Here, a set of blended mixture prepared with OPC was replaced by GBFS at 10, 20, 30, 40 wt.%. Setting time of pure OPC and blended OPC and GBFS was carried out to evaluate workability of all mixtures. After 28 days of curing, compressive strength of samples exposed to heat at 200, 400 and 600 °C was measured. Along with that, the mass loss of the sample to predict thermal resistance was analyzed by thermogravimetric analysis (TGA); moreover, microstructure of hardened samples in terms of mineral composition, distribution was analyzed by X-ray diffraction (XRD) and Scanning electron microscopy (SEM). Results of the conducted study showed that GBFS addition into OPC could enhance fire resistance through the slight increase in compressive strength compared to the OPC one at 600 °C and the mass loss; moreover, the blended cement containing different amount of GBFS maintain workability of cement paste.

Improving nonlinear behavior and tensile and compressive strengths of sustainable lightweight concrete using waste glass powder, nanosilica, and recycled polypropylene fiber

Abstract Concrete is one of the most extensively utilized building materials that can be produced, and has the potential to release a significant quantity of CO2 into the environment. In this research, through studying lightweight (LW) concrete, attempts are made to produce environmentally friendly LW concrete with high strength using nanosilica rather than part of the cement and waste glass powder instead of aggregates. Recycled polypropylene fibers are used to increase the concrete’s compressive strength and nonlinear behavior. The use of glass powder was 20, 25, and 30% of the weight of aggregates, the consumption of nanosilica was 1, 2, and 3% of the weight of cement, and the consumption of recycled fibers (FORTA Ferro-Green) was 0.5, 1, and 1.5% of the weight of cement. Leca is also utilized as a LW aggregate. According to 7- and 28-day experimentation results and field emission scanning electron microscope analysis, the best sample had 1.5% fiber, 3% nanosilica, and 25% waste glass powder, and had a compressive and tensile strengths of roughly 1.7 and 1.6 times, respectively, those of the control specimen after 28 days. Also, using 3% nanosilica instead of cement can reduce greenhouse gas emissions by about 3%.

PROPERTIES OF NORMAL STRENGTH CONCRETE WITH TREATED CRUSHED BRICK AND RECYCLED CONCRETE AS COARSE AGGREGATE

The results of a research program conducted at the University of Mustansiriayah in Iraq to analyze the qualities of concrete created with crushed bricks and crush concrete are presented in this paper. To make a suitable aggregate, these materials were crushed. Some aggregates were treated, while others were not. The properties investigated were the workability and the density of fresh the aggregates of crushed bricks and crush concrete were treated in some mixtures and others were not treated. The properties investigated were the workability and the density of fresh concrete, and the compressive strength and tensile splitting strength behavior of hardened concrete. Different replacement ratios (0, 50%, and 100%) were investigated. The concrete rustles produced with recycled aggregates were compared with a reference concrete produced with natural coarse aggregates currently used in Iraq. Using surface treatment with silicate solution, when comparison to RCA50 and RCA100 samples, TRCA50 and TRCA100 compressive strength improved by roughly 5.05 percent and 5.9 percent after 28 days, respectively. And came closer to concrete with natural aggregate R, and improved 3.25% and 4.6% in TBR100 and TBR50, respectively compared. With the BR100 and BR50 respectively, they added a cross resistance of R for TRAC100% when silica fume was added, approaching R at TBR100%. Aggregates indicate that this type of concrete can be used in various precast applications.

Comparative study of mechanical properties between irradiated and regular plastic waste as a replacement of cement and fine aggregate for manufacturing of green concrete

Concrete and plastic are a major source of environmental contamination and unsustainability. This study has been employed to come up with the eco-friendly concrete by using the plastic waste to promote the sustainability. Gamma radiations were used to enhance the micro-structure of plastic waste to increase the mechanical properties of resulting concrete. The crystallinity and chemical properties of regular and irradiated plastic were studied using x-ray diffraction (Xrd) and x-ray fluorescence (Xrf), respectively. Enhancement in the crystallinity and chemical properties were observed in the irradiated plastic. Different compositions by weight were opted for replacement of cement and fine aggregate for both regular and irradiated plastic waste with silica fume and superplasticizers. A set of experiments were performed on concrete and the effect of plastic waste on the compressive strength and split tensile strength of concrete was examined. Untreated replacement of plastic waste has shown to decrease the compressive strength and anomalous behavior was observed in case of split tensile strength. Both the mechanical properties were enhanced by replacing the cement and fine aggregates with irradiated plastic waste including silica fume and superplasticizers. This study contributes towards sustainable development of green concrete by lowering the carbon emissions and overcoming the fine aggregate scarcity problem. Moreover, as plastic is ductile and inclusion of plastic in concrete lowers the overall weight of the structure; impact of an earthquake is reduced.

A novel technique to improve the compressive strength and ductility of glass fiber reinforced polymer (GFRP) composite bars

Glass fiber reinforced polymer (GFRP) composite bars have excellent durability compared to traditional steel reinforcements but their strength contribution in the design of compression members is generally neglected. The non-homogeneous and anisotropic nature of GFRP bars including their complex behavior in compression and the lack of standard testing procedure have hindered their use as compressive reinforcements. To improve their behavior and strength in compression, a novel technique has been developed by winding additional GFRP layers around the longitudinal fibers. One, two and three winding layers with a thickness of 1.5 mm for each layer and a winding angle of ± 83.3° have been used. Compressive strength tests have then been conducted on 20 mm and 30 mm high GFRP bars with a core diameter of 20 mm to determine the improvement in compressive strength, ductility, and failure behavior. Test results showed that the 20 mm core diameter GFRP bars have shown promising improvement in the compressive strength and ductility with the increased number of winding layers wherein the compressive strength of the 20 mm and 30 mm high bars increased by 74% and 63%, respectively for bars with three winding layers. Comparison of the mechanical properties in compression and tension showed that the optimum strength and ductility improvement can be achieved with two winding layers. A simple theoretical strength model has been developed which can reliably predict the compressive strength of the winded GFRP bars.

Microstructure, mechanical and wear behavior of LM24/SiC/MoS2 hybrid composites produced via liquid metallurgy process

Silicon carbide (SiC) and Molybdenum disulphide (MoS2) has been expected broad contemplation is a potential strengthening particulate for metal matrix composites (MMCs) to enhance the mechanical and wear behaviors. The purpose of this study is to process and investigate the mechanical characteristics of LM 24/SiC/MoS2 composites. These composites were fabricated via the stir casting process from the prepared arrangements of LM 24/SiC/MoS2 with various weight proportions. The following proportions are pure LM 24, LM24-3wt%SiC-1wt%MoS2, LM24-6wt%SiC-1wt%MoS2 and LM24-9wtSiC-1wt%MoS2. The scanning electron microscope (SEM) utilized to inspect the micrographs on processed composites. The SEM micrographs interpret identical dispersion of SiC with LM 24. The influence of SiC weight percentage on the physical properties like density, relative density & porosity and mechanical properties like tensile, compression, hardness, impact and flexural strength and tribological behavior were investigated. The processed LM24-9wt%SiC-1wt%MoS2 composites compose the enhanced mechanical properties. The wear performance was studied throughout the pin on disc device with various wear process parameters. These parameters are load, Sliding velocity and distance. Finally, these parameters are framed via the L16 orthogonal array and to attain the minimum wear rate and coefficient of friction from the optimal process parameters by Grey Relational Analysis (GRA). The optimal parameters for wear rate and coefficient of friction are LM24-9wt%SiC-1wt%MoS2 and followed by the wear parameters namely load 15N, sliding velocity 2 m s−1 and sliding distance 1600 m, respectively. The ANOVA outcomes uncovers that the load is the most significant parameter for wear rate and coefficient of friction.

Water absorption behavior of hydrophobized concrete using silane emulsion as admixture

Influences of silane emulsion as hydrophobic agent on pore structure of hardened cement paste (hcp), compressive strength and water absorption behavior of concrete were studied through pore structure analysis, water contact angle test and water/isopropanol absorption measurement. Results indicate that silane slightly inhibits early cement hydration and slightly reduces the 28-d compressive strength of concretes. The incorporation of silane significantly decreases the water sorptivity of concretes ascribed to the hydrophobization of capillary walls in hcps, whereas isopropanol absorption is not visibly affected by the addition of silane. The absolute water sorptivity decreases along with increasing water absorption amount for each group of concrete, which is believed to originate from swelling of C-S-H gel upon water absorption. However, the relative water sorptivity of the silane-modified concretes to the plain concrete remains constant during water absorption. A predicting method for long-term water absorption behavior of the silane-modified concrete is proposed.

Effect of drilling-induced defects on progressive damage of open-hole composite laminates under compression

In this study, the effect of drilling-induced defects on open-hole compression progressive failure and buckling and post-buckling behavior of composite laminates was investigated numerically. First, drilling-induced defects were identified from X-ray computed tomography data using image processing software, from which delamination and fiber pull-out defects were quantified on the specimen. These defects were then incorporated into finite element mesh, and numerical analyses simulating ASTM open-hole compression tests were performed in Abaqus. Hashin failure criterion and energy-based linear softening law were employed to determine in-plane failure initiation and evolution. Interlaminar failure was accounted for by cohesive zone modelling inserting cohesive elements at delaminated interfaces. The numerical model with defects was validated against experimental results and very good agreement was obtained. Next, simulations were performed on both defect-free and defective open-hole composite laminate models to study the effect of drilling-induced defects on compressive strength and progressive failure behavior. Finally, analyses were performed with buckling deformation allowed and the effect of buckling and post-buckling on compression failure behavior was investigated.

Failure-mode dependence of the strengthening effect in Ti3AlC2/10 vol.% Al2O3 composite

Abstract The high-temperature mechanical properties of both Ti3AlC2 and Ti3AlC2/10 vol.%Al2O3 composite, including compressive strength, bending strength, and fracture behavior, were investigated. The strengthening effect caused by Al2O3 strongly depended on the mode of failure: significant enhancement in strength was only observed under the brittle mode of failure; whereas under the ductile mode of failure the strengthening effect was impaired due to Ti3AlC2 matrix softening and stress relaxation.

The Effect of Elevated Temperature on Engineered Cementitious Composite Microstructural Behavior: An Overview

This paper discusses the quantitative bibliographic data derived from scientific publications on Engineered Cementitious Composites (ECC) subjected to elevated temperature, the influence of elevated temperature on the mechanical properties, particularly the compressive strength and microstructure behavior of Engineered Cementitious Composites (ECC) mixtures based on the review of previous pieces of literature. Systematic literature reviews were employed as the methodology in this study. The age of related publications selected to be reviewed was limited to publications for the past ten years, 2010 to December 2020. It was found from available research that exposure of the ECC specimen at the elevated temperature starting from 200oC significantly reduced the compressive strength when the temperature increases, melting of fiber and increase of porosity causes the dramatically increase micro-cracks.

Residual Impact Performance of ECC Subjected to Sub-High Temperatures.

Despite the fact that the mechanical properties of Engineered Cementitious Composites (ECC) after high-temperature exposure are well investigated in the literature, the repeated impact response of ECC is not yet explored. Aiming to evaluate the residual impact response of ECC subjected to sub-high temperatures under repeated drop weight blows, the ACI 544-2R repeated impact test was utilized in this study. Disk impact specimens (150 mm diameter and 64 mm thickness) were prepared from the M45 ECC mixture but using polypropylene fibers, while similar 100 mm cube specimens and 100 × 100 × 400 mm prism specimens were used to evaluate the compressive and flexural strengths. The specimens were all cast, cured, heated, cooled, and tested under the same conditions and at the same age. The specimens were subjected to three temperatures of 100, 200 and 300 °C, while a group of specimens was tested without heating as a reference group. The test results showed that heating to 100 and 200 °C did not affect the impact resistance noticeably, where the retained cracking and failure impact numbers and ductility were higher or slightly lower than those of unheated specimens. On the other hand, exposure to 300 °C led to a serious deterioration in the impact resistance and ductility. The retained failure impact numbers after exposure to 100, 200, and 300 °C were 313, 257, and 45, respectively, while that of the reference specimens was 259. The results also revealed that the impact resistance at this range of temperature showed a degree of dependency on the compressive strength behavior with temperature.

An experimental investigation on improvement of concrete serviceability by using ferro sialate based bacterial concrete development

GPBC (Geo-Polymer Bacterial Concrete) is a recent developing green concrete which over comes the drawback of emission of carbon-di-oxide and the crack damage in the concrete structures. This project describes the compressive strength and flexural properties of GPBC. The purpose is to incorporate the healing agents into the geo-polymer concrete which makes the cracks heal from inside. Sodium silicate and sodium hydroxide are the alkaline solutions which activates the cementitious materials for the process of geo-polymerization. The bacillus megaterium and bacillus subtilis are the two species which is selected with a 0gm/l, 100gm/1, 200gm/1 as a varying proportion in this study to act as the healing agent and calcium lactate acts as organic precursor, incorporated into the concrete by the direct mixing technique. The mechanical properties such as compressive strength and Flexural behavior of reinforced concrete slab specimens are planned. The 28 days of compressive strength for cubes is done to indicate the strength property of geo-polymer concrete in which the GGBS and Fly ash acts as the strength governing factor. These experimental results of deflection values are compared with corresponding load vs deflection curves are plotted for the experimental studies.

Experimental and Numerical Study of Strength and Failure Behavior of Precracked Marble under True Triaxial Compression

Cracks play an important role in evaluating the strength and failure behavior of engineering rock mass. In order to increase the understanding of strength and failure mechanism of precracked rock, crack propagation and coalescence from preexisting cracks under true triaxial compression are investigated using true triaxial compression tests and Cellular Automata Software for engineering Rockmass fracturing process (CASRock). Three types of specimens were studied experimentally and numerically. Experimental and numerical results show that both the preferential angle and areal intensity of preexisting cracks can affect the compressive strength and failure behavior of the specimens. The peak strength firstly decreases and then increases with increase of the preferential angle. Also, the peak strength nonlinearly decreases with the increase of cracks’ areal intensity. The numerical results show that the crack initiation and coalescence are observed and characterized from the inner and outer tips of preexisting cracks in specimens containing single crack and multiple parallel cracks. The main shear failure in the specimen containing multiple unparallel preexisting cracks initiate and propagate from one of the macroscopic preexisting cracks, and other preexisting cracks do not initiate, propagate, and coalesce until reaching the peak strength.

Interface behavior and oxidation consolidation mechanism of titanium-bearing iron sand particles with ball-milling pretreatment

The titanium-bearing iron sand (TIS) riches Fe, Ti and V elements and exhibits great value in ironmaking. The agglomeration of TIS is difficult due to complex mineralogical characteristics. In this study, the ball-milling pretreatment was conducted to improve the particle interface characteristics and promote the oxidation-consolidation behavior of TIS. The results show that the transition of TIS from spherical to polyhedral structure could disaggregate the interlocked gangue and iron oxide and produce large amounts powders adhering on the TIS surface, which promotes the interface behavior and increase the molten slag formation in oxidation-roasting. Besides, the introduced lattice defects of titanium hematite accelerate the oxidation and recrystallization behaviors, thereby strengthening consolidation and increasing the TIS pellet compressive strength with lowering bentonite addition. After ball-milling pretreatment and preparation parameters optimization, the TIS pellet exhibits favorable compressive strength, reducibility and softening-melting behavior, fully meeting the BF smelting requirements.

Mechanical, physical and thermoacoustic properties of lightweight composite geopolymers

This research evaluates the physical and mechanical properties of particulate composites, produced from geopolymer paste with the incorporation of different organic type wastes as expanded polystyrene (EP), corkwood (CK), tire rubber (RB); in percentages by volume of 2, 4, and 6%. Metakaolin was used as a precursor of the geopolymer produced by alkali activation from NaOH and sodium silicate. The geopolymer composites were cured at room temperature. Properties as density, porosity, absorption, compressive strength, thermal conductivity, and acoustic behavior were evaluated. As complementary techniques, light and scanning electron microscopy were used. It was observed that the high alkalinity of the geopolymer mixture causes deterioration of the CK particles. Composites with the incorporation of 4% of the EP and RB particles reported compressive strength of 32 and 45 MPa at 28 days, and apparent density of 1853 and 1922 kg/m3, respectively, which represents a reduction of 6.08% and 2.58% in comparison to the GP reference. The thermal conductivity for composites with 4% of EP and RB was 0.316 and 0.344 W/m.K and the sound absorption coefficient was evaluated at frequencies of 500 Hz, 0.70, and 0.50 respectively. The evaluated performance properties show the feasibility of using 4% of EP and RB for the manufacture of geopolymer composites for applications in thermal and sound insulating panels.

Development of Eco-Friendly Mortars Produced with Kaolin Processing Waste: Durability Behavior Viewpoint

This study presents the development of new eco-friendly mortar compositions containing kaolin residues (KR) and assesses their durability behavior. Firstly, the natural and calcinated kaolin residues (600 °C, 650 °C, 700 °C, 750 °C, and 800 °C) were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), granulometric analysis, and surface area. The kaolin residue calcinated at 800 °C was chosen to be added to new compositions of mortar because it presented the best pozzolanic performance. The aging tests accomplished in internal (Ei) and external (Ee) environments were applied in mortars with a mass proportion of 1:2:6 (cement + KR: lime: sand), in which the KR, calcinated at 800 °C, replaced the cement in the mass fraction of 0%, 5%, 10%, 15%, 20%, and 30%. The Ei was performed for 30, 60, 90, 180, and 360 days, and the Ee for 90; 210; 360; and 512 days. After the aging tests were completed, the mortar compositions containing KR were evaluated to determine their mineralogical phases (XRD), compressive strength (CS), and thermal behavior (DTA and thermogravimetry). In summary, the KR addition to the mortar compositions decreases the mechanical resistance to compression; however, mortars with a substitution of 10% and 20% presented resistance values within the minimum limit of 2.4 MPa established by ASTM C 270.

Mechanical Properties of Alkali-Activated Ground Waste Glass–Carbide Lime Blends for Geotechnical Uses

The present research aims to evaluate the potential of combining two wastes, finely ground waste glass (GWG) and carbide lime (CL), together with a sodium hydroxide solution (SHS) to form a new material which, when compacted, can develop cementitious properties over time. Such blends have potential application in the construction of stabilized rammed walls, as well as in earthworks such as beds of pipelines, spread footings, fill materials, and generally, as a new material for replacement of geomaterials of inadequate specifications in localized geotechnical works. Blends compacted exclusively with water were also produced in order to understand and differentiate, in a comparative manner, the effects of the addition of SHS on the mechanical, mineralogical, and microstructural properties resulting from alkaline reactions. The effects of the CL content, degree of compaction, and inclusion of a SHS on the evolution of strength and stiffness at 7 and 28 days under controlled curing conditions (23°C±2°C and 95% relative humidity) were determined. An original parameter, called the porosity/lime index (η/Liv), was used to normalize the behavior of unconfined compressive strength (qu) and shear modulus in small strains (G0) of the blends. The results have shown that the GWG-CL blends (compacted with water and SHS) developed an evolution of the mechanical properties over time with increasing CL content and degree of compaction. This results from the reaction between the dissolved aluminosilicates present in the GWG and the calcium (Ca2+) in CL, as a product of the pozzolanic and geopolymerization reactions in a high-alkalinity medium by the addition of CL and SHS, respectively. The formation of stable compounds, hydrated calcium silicate (C─ S─ H) type, analogous to those produced in the hydration processes of portland cement after 28 days of curing in alkali-activated blends with SHS, has been verified. Additionally, correlation equations were established between the mechanical response of the blends and the η/Liv index, as a function of the curing time and the type of activating solution, which can be considered as dosage curves for the prediction of a required mechanical response.

Workability and Compressive Strength Behavior of a Cemented High-Porosity Backfill Material

A full understanding of the workability and unconfined compressive strength (UCS) of the cemented high-porosity (CHPB) material, made of surface sand, widely distributed in the western mining area, foam, and cementing materials, is important for applying in ecologically fragile mining areas of western China. In this article, the influence of solid content, density grade, sand/binder ratio, and silica fume dosage in binder on workability and strength development of CHPB samples in different curing ages is studied. Test results show that the fresh CHPB mix has good workability, due to the existence of a large number of bubbles. With the increase of density grade, the UCS of the CHPB sample increases exponentially. Workability of fresh CHPB samples significantly decreases with increasing solid content due to the reduction of interparticle distance. For a given mix proportion, the optimal solid content of CHPB samples is 83.7%. The variation of the sand/binder ratio from 3 to 4.5 results in a slight increase of workability and a significant increase of the UCS. Silica fume demonstrates improvement on workability and strength behavior, and the optimal dosage in the binder should not exceed 10%.

Effects of thermal shock on the microstructure, mechanical and thermophysical properties of ZrC-C composites

To explore the effects of thermal shock cycles on ZrC-C composites, their microstructure, coefficient of thermal expansion (CTE), compressive strength and internal friction behavior after different thermal shock cycles were studied. As the thermal shock cycle between 1500 ℃ and room temperature increased from 0 to 30, the CTE of the ZrC-C composites with the ZrC/PyC (Pyrolytic carbon) weight ratio of 1.7 first increased and then decreased, and its compressive strength increased by 35.8 % (295.4 ± 10.1 MPa) after 10 thermal shock cycles and could still be maintained above 85 % of its original strength after 30 thermal shock cycles. The changed interface bonding strength between ZrC skeleton and PyC resulted in the first decrease and then increase of their internal friction. This work provides an effective strategy for optimizing the thermal shock resistance of ultra-high temperature composites by regulating the component contents.

Synthesis of brushite/polyethylene glycol cement for filler in bone tissue injuries

The objective of this work was to produce brushite cement for orthopedic applications, based on the system wollastonite/phosphoric acid with the incorporation of polyethylene glycol (PEG) as a setting and processing additive. Brushite/PEG cement was obtained by the dissolution-precipitation method and its physicochemical properties were characterized by X-ray diffraction, compressive strength, porosimetry, and biological behavior (cell adhesion and bioactivity tests). The results indicated the formation of brushite cement with 21.4 MPa of compressive strength and 30% porosity, similar to human trabecular bone. The surface was shown to be adequate for cell adhesion and growth and bioactive with the formation of apatite layers. The incorporation of PEG improved working conditions without causing undesirable changes in the physicochemical properties and biological behavior of developed cement, thus promising for the repair of bone tissue injuries.