Workability Characteristics Research Articles

Effect of polymer dispersion characteristics and incorporation methodology on properties of cement asphalt mortar for high-speed rail slab track system

This study investigates the impact of polymer dispersion characteristics and incorporation methods on the polymer modified asphalt emulsion (PMAE) characteristics and, consequently, on the properties of Cement Asphalt Mortar (CAM) for high-speed rail tracks. The results showed that latex-form polymer dispersions with anionic charge and coagulation values below 1 % after 30 minutes provided stable mortars with shorter flow times. Mortar with PMAE produced through terminal blending (TB) method exhibited superior workability characteristics compared to those produced via soap pre-batch (S) and co-milling (C) methods. Differential Scanning Calorimetry (DSC) studies indicated improved polymer integrity in the CAM when produced with PMAE:TB. Mortar containing PMAE:C found to have the highest compressive strengths, with values of 1.49 MPa at 7 days and 2.32 MPa at 28 days, followed by PMAE:S, PMAE:TB, and the control asphalt emulsion (AE). Thermogravimetric Analysis (TGA) results on hydrated CA paste were consistent with the compressive strength trend, and Field Emission Scanning Electron Microscopy (FESEM) analysis revealed a more uniform polymer distribution in TB method. The study concludes that anionic polymer dispersions having low coagulation values introduced through terminal blending are most suitable for CAM production.

Influence of Manufactured Sand on Fresh Properties, Strength Properties and Morphological Characteristics of Self-Compacting Coconut Shell Concrete

This research examines the fresh properties, strength performance, and morphological analysis of self-compacting coconut shell concrete (SCCSC) blended with crushed coconut shell and manufactured sand (M-sand). Crushed coconut shell (CS) was used as a coarse aggregate (CA), and M-sand replaced river sand (R-sand) at 25%, 50%, 75%, and 100%. The study focused on the workability characteristics, mechanical behavior, and microstructural analysis of SCCSC. Experiments were performed on fresh and mechanical characteristics, including slump flow diameter, T500 slump flow time, L-Box blocking ratio, V-funnel and a wet sieving stability test. Mechanical characteristics include compressive, split tensile, flexural, impact resistance and bond strength. Utilizing M-sand develops the mechanical performance of SCCSC. The morphological characteristics, using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) and the X-ray diffraction (XRD) technique, were studied in this research work. The findings show that the addition of M-sand increases the concrete strength. The microstructural analysis demonstrates that adding different amounts of M-sand to SCCSC reduced the porosity and anhydrous cement percentage, although it increased calcium hydroxide and hydration products. The substitution of 100% M-sand at 28 days increased compressive strength by 3.79% relative to the reference SCCSC. Based on the findings, the mechanical strength of SCCSC containing M-sand significantly improved compared to the concrete with river sand.

Comparative analysis of polyacrylate latex modified cement grout for water blocking and rock reinforcement with six alternative materials

Grouting plays a crucial role in mitigating water inrush disasters and reinforcing weak surrounding rock formations, and the effectiveness of grouting operations is heavily dependent on the choice of grouting materials. This study undertakes an assessment of the feasibility of deploying polyacrylate latex modified cement grouting material (PLMC) for the purposes of water obstruction and surrounding rock reinforcement, achieved through a comparative analysis against six alternative grouting materials, each of which has been applied in practical engineering. The experimental results demonstrate that the initial setting time and fluidity of PLMC fall within the range of other grouting materials, meeting the project requirements. PLMC achieves the highest filling rate at 77.42%, while the filling rates of other grouting materials range from 39.69% to 74.13%. PLMC exhibits good performance in bleeding ratio (2.77%) and resilience against dynamic scouring (retention rate is 72.95%), ranking as the third highest among the seven compared materials for both indexes. Additionally, the uniaxial compressive strengths of PLMC grout stone body and grouting-reinforced body reached 11.94 MPa and 22.74 MPa, respectively, representing the best performances. In comparison, the highest levels of these two indexes for other grouting materials are 8.78 MPa and 21.46 MPa, respectively. Compared with other grouting materials, the porosity of PLMC grout stone body is the lowest, and the interface between rock and grout in PLMC-reinforced body exhibits no significant gaps. The findings suggest that polyacrylate latex modified cement grouting material exhibits exceptional workability characteristics, positioning it as a promising candidate for practical applications.

Influence of production technology of thick plate rolled from shipbuilding steel of strength level 500 on structure parameters and workability characteristics at low temperatures

The influence of manufacturing technology of low-alloy steel with yield strength not less than 500 MPa on structure parameters has been studied. Under industrial conditions, two 50 mm thick sheets were produced by different technologies: 1) hot rolling followed by furnace quenching and high-temperature tempering; 2) quenching from rolling heating followed by high-temperature tempering. By means of optical, scanning and transmission electron microscopy the structural features of steel were revealed. Standard mechanical properties and low-temperature serviceability characteristics were determined.

Experimental investigation on fresh and hardened properties of high strength fibre reinforced concrete using GGBFS and micro silica

The use of High Strength Concrete (HSC) has increased now a days. The concrete is one of the most useful construction materials, but the major defects of concretes are brittle in nature, low workability and low tensile strength. Experimental study is carried out to assess fresh and hardened properties of high strength fibre reinforced concrete (HSFRC) of grade M70. In addition to normal materials, silica fume and GGBS are added to achieve higher strength and poly propylene fibres are added to improve its ductility. The content of silica fume and GGBS is 5% and 25% respectively by weight of cement. Water to cementitious material ratio is 0.31. Mixes with different percentages of poly propylene fibres such as 0.5%, 0.1%, and 1.5% by the weight of cementitious content are denoted as HSFRC 1, HSFRC 2, and HSFRC 3, respectively. To improve the workability characteristics of the low water-binder ratio HSC mix, the Poly Carboxylate Ethylene-based chemical admixtures are used. The fresh properties were investigated in terms of slump flow and mechanical performances of the HSFRC over HSC are evaluated in terms of compressive, flexural, split tensile strength.

Properties of High-Content Micro-Steel Fiber Self-Compacting Concrete Incorporating Fly Ash and Slag Powder Performance Study

The addition or substitution of various gel materials in cement-based composites has been proven to be an effective approach in enhancing the performance of concrete. Current research focuses mainly on enhancing the toughness of concrete, but lacks discussion on the performance of alternative gel materials. Therefore, this study aims to explore the effects of partially substituting cement with fly ash and slag powder as gel materials, while incorporating a high volume fraction of micro-steel fibers (6%), on the workability and mechanical properties of self-compacting concrete. By means of rigorous experimental investigation and meticulous analysis, we comprehensively assessed the workability characteristics of self-compacting concrete, encompassing critical aspects such as filling ability, cohesion, and permeability. Additionally, we conducted an extensive evaluation of the mechanical attributes of self-compacting concrete, encompassing vital parameters, such as compressive strength, axial compressive strength, splitting tensile strength, and flexural strength. Last but not least, through a holistic integration of workability and mechanical properties, we conducted a comprehensive performance evaluation of self-compacting concrete incorporating a synergistic blend of fly ash, slag powder, and micro steel fibers. The experimental results indicate that the composite addition of fly ash and slag powder in self-compacting concrete, while compatible with up to 6% micro-steel fibers, leads to a decrease in concrete workability and an increase in cohesiveness due to the addition of micro-steel fibers. Moreover, fly ash predominantly influences the tensile properties of concrete, while the addition of slag powder significantly affects the compressive and flexural properties of concrete. Additionally, the addition of micro-steel fibers significantly improves the overall mechanical properties of concrete.

Prediction of self-consolidating concrete properties using XGBoost machine learning algorithm: Part 1–Workability

The interest in implementing self-consolidating concrete (SCC) in major construction projects has increased significantly in recent years. This paper reports the results of an extensive survey of experimental data of more than 1700 SCC mixtures from over 100 studies published in the last decade. The survey included the SCC mixture proportioning, key fresh properties including flowability, passing ability, and segregation resistance, as well as some of the derived properties (e.g., paste volume). The statistical analysis of the reported parameters showed wide variations in values. The outcome of the survey indicates that SCC mixture design and workability properties do not systematically lie within the recommendations reported in various guidelines. A wide range of workability tests is used; however, only 22 % of the studies reported values for segregation resistance. The slump flow test was the most tested fresh property and the most reported values are in range of 591–760 mm (X¯ = 679 mm). The V-funnel time was the second most reported test, and the most of reported values are in range of 4.0–20 s (X¯ = 11 s). The study devised and evaluated the efficacy of using machine learning (ML) models, namely Extreme Gradient Boosting (XGBoost), to predict the two most reported workability characteristics of SCC, namely slump flow and V-funnel flow time. The model was formulated to predict slump flow and V-funnel time using a refined sub-database of 852 tests (the extreme data i.e., 5 % from each side, for the both properties and the empty data was deleted). The findings revealed that the XGBoost model can provide an accurate prediction for the slump flow and V-funnel values, thus indicating its potential as a powerful tool for SCC optimization. The findings provide valuable insights into the application of ML in SCC research and contribute to the development of more efficient and sustainable construction practices.

EFFECT OF DAIRY INDUSTRIAL EFFLUENT AND KITCHEN WASTE WATER AS MIXING WATER ON THE PROPERTIES OF CONCRETE

Water resources are the greatest blessing that nature has bestowed upon mankind. This non-renewable resource is becoming scarcer day by the day, and predictions say that the third world war for water could break out. So there is a lot of scope for the conservation of water and recycle of wastewater. As per the literature review an attempt can be made to divert the wastewater into the construction industry as mixing and curing water for concrete. With this attempt one can save consumption of potable water in the construction industry, reduce the cost of treatment of wastewater and minimize the wastewater disposal problems. Construction industry uses plenty of water for all its construction purposes. Hence an attempt can be made to use industrial effluents and domestic effluents in mixing of concrete and there by save potable water resources. The main objective of this research is to study the effects of using the domestic effluents and industrial effluents as mixing water on the properties of concrete and thereby saving the potable water in construction industry. The effect will be studied on the workability characteristics of concrete with domestic effluent and industrial effluent, as mixing water. Key Words: workability characteristics, setting time characteristics, domestic effluent and industrial effluent, mixing water.

Workability Assessment of Pumpable Structural-Grade Heavy-Weight Concrete Using Novel Coaxial Cylinder Method

The mixture proportioning of heavy-weight concrete (HWC), as seen from the literature, is primarily based on a trial-and-error approach; even so, data from the literature indicate that obtaining high-slump mixtures for high density levels (more than 3.1 g/cm3) is difficult. Because heavy-density aggregates are prone to segregation at high slump, a low water to cement ratio is generally used for HWCs, and full-scale pumping trials are needed for checking pumping placement. For structural-grade HWCs used in nuclear facilities and specific infrastructure such as tunnel cross-rail floating slabs, rheological properties are needed to quantify the workability for pumping placement. Because use of rheological assessment methods using sophisticated rheometers cannot be realized easily onsite, a novel coaxial cylinder method is proposed in this study for determining the yield stress of HWCs delivering 3,800 to 3,900 kg/m3 density. The device proposed in this study is portable and can be used also onsite. Four structural-grade hematite aggregate HWCs, with design strengths varying from 40 to 70 MPa, were designed with ordinary portland cement. To understand the effect of fly ash addition on rheological behavior, one of the structural-grade HWC with three different levels (15%, 25%, and 35%) of fly ash was investigated. For referring the initial workability and workability retention properties of HWCs used in jobsite pumping, the conventional slump test values of the mixture were compared with yield stress measurements. Experimental investigations suggested that the method proposed in this study are able to adequately capture the workability characteristics required for pumpable mixtures. Further, it was seen that 35% partial replacement of fly ash resulted in 100% reduction in yield stress of HWC mixtures. Fly ash replacement (15% to 35%) did not significantly alter the hardened concrete density (3,800 kg/m3); however, attainment of the specified compressive strength depended on the replacement level of fly ash and extended curing period.

Impact analysis of ceramic tile powder aggregates on self-compacting concrete

Waste ceramic tile (CT) powders are used to improve the workability, mechanical properties, and durability of self-compacting concrete (SCC). The waste CT powder is prepared by mixing construction tiles, sanitary fittings, and electrical insulators, with different weight percentages mixed into the SCC. Experiments have been conducted to evaluate the workability, mechanical, and durability of SCC. The optimum compressive, flexural, and tensile strengths were predicted to be 52.5 MPa, 8.5 MPa, and 7.8 MPa. SCC’s durability and workability characteristics are achieved by mixing 50% CT powder, which increases interlocking properties and meets EFNARC standards. It is concluded that CT powder can be substituted for conventional fine aggregate in concrete, increasing compressive, flexural, and split tensile strengths by 12.5%, 9.33%, and 28.76% compared to conventional SCC. The 50% CT powder mixed SCC is the optimum value for achieving optimal mechanical, durability, and workability characteristics. Samples of 50% CT powder-mixed SCC with 7, 28, and 90 days of curing processes and microstructure are also illustrated.

Bond strength characteristics of high strength alkali activated slag concrete mixes

Bond characteristics are influenced by several factors such as concrete compressive strength, type, diameter, and embedment length of the bar and confinement of concrete. Herein, an attempt has been made to evaluate the bond strength characteristics of a new class of high-strength, flowable, alkali activated slag concrete mixes made using the industrial by-products from iron and steel industries. Such evaluations are made using the results of direct pull out tests where again, the bond stress – slip behaviour of the trial mixes at different ages are also studied. GGBFS was used as the principal binder along with fine amorphous quartz powder in the development of the present class of high strength, flowable AASC mixes. While mixtures of steel slag sand and quartz sand were used as the fine aggregates, 12.5 mm down electric-arc furnace slag aggregates constituted the coarse aggregate fractions in all these mixes. The alkaline solutions used consisted of mixtures of specified amounts of sodium hydroxide flakes dissolved in the calculated quantity of water pre-mixed with the liquid sodium silicate solution. The experimental study was planned based on Taguchi’s design of experiments methodology. A set of AASC mixes were developed and evaluated for their workability characteristics along with compressive strengths at the ages of 3, 28, 56 and 90 days. Bond strength characteristics of a set of nine of such mixes were evaluated in an initial calibration phase. Strength prediction equations were then derived based on those initial results, the predictive capability of which were then assessed and ascertained with actual results of experiments on a set of six new mixes, in the prediction phase. Further better bond stress-slip behavior, with higher bond strength values, varying in the range of 12–14 MPa as compared to control OPC based reference concrete mix were obtained for the AASC mixes.

RILEM TC 266-MRP: round-robin rheological tests on high performance mortar and concrete with adapted rheology—rheometers, mixtures and procedures

Recent developments in understanding the rheology of mortar and concrete as well as applying this understanding in the practice of construction necessitate an accurate assessment of materials’ rheological properties. It is well known that different rheometers for mortar and concrete deliver different results, as this was shown over 15 years ago in two measuring campaigns comparing concrete rheometers. Considering newly developed rheometers, including those to evaluate interface rheology and structural build-up at rest, as well as additional measurement procedures and data interpretation techniques, a new comparison campaign was carried out in 2018 at the Université d’Artois, in Bethune, France. This new campaign focused on measuring workability characteristics, flow curves, static yield stress values, interface properties and tribological data. A total of 14 different devices capable of measuring one or more of the above-mentioned characteristics were employed. These devices included four ICAR rheometers, the Viskomat XL, the eBT-V, the RheoCAD (two geometries), the 4SCC rheometer (two geometries), the plate test, the sliding pipe rheometer, a tribometer and an interface tool for the ICAR rheometer. This paper describes the mixture design and rationale of the five investigated concrete and three investigated mortar mixtures, design and analysis of the experiments, and comparison of test results. The findings confirmed some of the conclusions from two previous testing campaigns and expanded the findings to more modern concrete mixtures and more diversified sets of rheological devices. The investigated rheometers yielded different absolute values for material parameters, but they all were able to similarly distinguish between mixtures qualitatively. For static yield stress and interface rheology measurements, similar conclusions were obtained as for flow curves.

Recycling prestressed concrete pile waste to produce green self-compacting concrete

Construction and demolition waste is produced in large quantities and constitutes an overlooked resource with significant potential for recycling and reuse. In fact, recycled concrete aggregate (RCA) has a high resource value, although it is also the case that RCA has characteristics that complicate its reuse. This research study looks at the efficacy of producing green self-compacting concrete (SCC) using uniform in-situ prestressed concrete pile waste (RCA) as a replacement for natural aggregate and fly ash (FA) as a replacement for Type 1 Portland cement (OPC). In accordance with the European standard, the workability characteristics of the SCC mixtures were assessed using slump flow, T500 time, J-ring flow, L-box, and V-funnel tests. The hardened properties of compressive strength at 7, 28, and 91 days as well as pulse velocity, Young's modulus, and surface resistivity were also tested. Based on this study, it is possible to produce SCC with both RCA and FA that has better workability and hardened properties than does RCA and also to reduce the negative effects of the latter. SCC produced without coarse natural aggregates showed compressive strength above 50 MPa and maximum compressive strength above 74 MPa at 91 days. SCC produced in this way is, therefore, viable for industrial use.

A brief review on workability characteristics of iron slag concrete

The population growth, industrial development, housing demand & infrastructure upgradation are increasing the need for concrete day by day, consequently exerting an enormous burden on natural resources. Sustainability in the construction industry is of great importance these days as the rate of exploiting natural resources for extracting aggregates and cement is greater than the rate of self-renewal of these natural resources. The practice of recycling the industrial waste in concrete as an approach to preserving finite natural resources is common these days. Also, the use of waste materials decreases the carbon footprints & shows sustainability in the construction industry as an alternative to conventional materials. Iron slag (IS) is one such industrial by-product derived from the iron and steel industries. IS can be processed to resemble the size of natural fine aggregate (NFA) in concrete. The physical characteristics of IS alter the fresh as well as hardened properties of concrete. The workability of concrete is an important aspect while designing any type of blended concrete. This paper briefly reviews some of the workability properties indicating the fresh-state performance of iron/steel slag concrete. The effects of different tests due to slag content are also examined. The present paper encompasses the existing literature on the workability characteristics of concrete made with IS as an NFA supplant. The literature reveals the enhancement in the workability in the concrete when the incorporation of IS with NFA supersede. The contradictory results along with the research gaps and future scopes have also been presented in the present study to provide an in-depth analysis of the effect of IS as an NFA substitution on the fresh-state properties of concrete.

Effect of dosage of superplasticizer on earth concrete

The environmental load put forth by the construction industry is tremendous. Being a major contributor to the present-day environmental situation, the construction industry must embrace the necessary changes. Sustainable development, effective utilization of resources and responsible engineering are of utmost priority. There are several alternative construction materials on the rise, adhering to such new requirements, in addition to the benefits of the materials that are already being employed. Earth concrete is one such emerging construction material. In earth concrete soil along with other constituents are made into a flowable form that can be cast into various shapes using forms and cured to attain certain desired strength characteristics. Binders, coarse aggregates and admixtures for earth concrete are selected on the basis of the characteristic requirements of the resulting matrix. In the present study, laterite soil is used to produce earth concrete, cement acts as binder, crushed stone as coarse aggregate and a naphthalene-based admixture helps in achieving the required workability characteristics. By the incorporation of Ceraplast 300, a naphthalene-based super plasticizer, the density, workability and the compressive strength of earth concrete have been enhanced. The paper considers the effect of dosage of super plasticizer on the workability, density and strength characteristics of earth concrete. Through parametric experimental study of earth concrete specimens, the optimum dosage of the naphthalene based super plasticizer has been determined. 1 % dosage of the super plasticizer with earth concrete exhibited the best results for the selected matrix. In the experimental program, earth concrete capable of sustaining 47.7 MPa stress at failure was achieved, which accentuates the possibilities and need for further studies on earth concrete.

An investigation on the hot workability and microstructural evolution of a novel dual-phase Mg–Li alloy by using 3D processing maps

Hot compression tests of a novel dual-phase Mg–Li alloy were performed in temperature range of 200–400 °C and strain rate range of 0.01–10s−1. 2D and 3D processing maps were established using Prasad's and Murty's instability criteria (methods) based on the dynamic materials model. It was found that one instability region obtained based on Prasad's instability criterion exist in the domain of power dissipation efficiency at a strain of 0.7. Prasad's and Murty's instability criteria are difficult to accurately characterize the instability characteristics of the alloy. The accuracy processing map rectified was obtained by means of Murty's and Prasad's instability criteria and microstructural analysis. On the basis of the processing map rectified, the optimum hot working parameters were obtained to be the temperature range of 320–400 °C and strain rate range of 0.01–0.4s−1 with the peak power dissipation efficiency. In this domain, the α phase undergone dynamic recrystallization (DRX) and dynamic recovery (DRV). The β-phase occurred DRX during the hot deformation. The instability regions lie in the temperature range of 200–250 °C with strain rate range of 0.01–1s−1 and the temperature range of 200–312 °C with strain rate range of 1–10s−1. Microstructural observations indicate that characteristics of the flow instabilities were flow localization, deformation twinning, the adiabatic shear bands and macro/micro cracking. The rectified processing map was successfully verified by the hot rolling test. The rectified processing map could accurately characterize workability characteristics of a novel dual-phase Mg–Li alloy and could be used for the optimization of hot working process parameters.

Rheological behavior and key properties of metakaolin and nano-SiO2 blended fibrous self-compacting concretes

The basic aim of the study herein is to experimentally determine and evaluate the influences of nano-SiO2 and metakaolin incorporation on the rheological and workability characteristics as well as mechanical properties of fibrous self-compacting concretes (SCCs). For that purpose, two SCC series were designed at a constant total binder content of 550 kg/m3 and a water-to-binder (w/b) ratio of 0.37. The first SCC series were manufactured as nonfibrous while the second series was produced as a steel fiber reinforced at a volume fraction of 0.5 %. In all SCC mixtures, 30 % of the total binder content was fly ash by weight. In both series, the cement (70 % of the total binder content) was partially replaced with metakaolin (0 % and 10 %) and nano-SiO2 (0 %, 2 %, and 4 %) by weight. In this way, a total of 12 SCC mixtures were designed and manufactured. The ICAR rheometer was employed to carry out the rheology measurements of the mixtures and the modified Bingham model was applied to describe the rheological behavior. Fresh characteristics of mixtures were investigated in terms of slump flow diameter, T50 slump flow time, V-funnel flow time, and l-box height ratio and flow times. In addition, the fundamental mechanical properties like compressive strength, elastic modulus, and splitting tensile strength were determined at the ages of 28 and 90 days. The plain SCC mixture had the slump flow diameter, T50 slump flow time, V-funnel flow time, and l-box height ratio of 750 mm, 2.29 s, 8.3 s, and 0.96, respectively. Metakaolin and nano-SiO2 replacements and steel fiber addition resulted in lower self-compactibility with up to 7% reduction in slump flow diameters. Especially the steel fiber particles played a blocking role and, thereby, caused a decrease in the flowability and passing ability of the mixtures by about 8–10 %. A similar effect was observed in the rheology measurement. The mixtures involving nano-SiO2, metakaolin, and/or steel fiber behaved more cohesively and viscously. On the other hand, the 28-day (90-day) compressive and splitting tensile strengths and modulus of elasticity of plain SCC mixture were respectively 67.5 (76.4) MPa, 3.95 (4.32) MPa, and 37.9 (39.4) GPa. Both metakaolin and nano-SiO2 replacements led to a significant increase in the strength performance of the mixtures, especially at a later age. However, it is hard to state whether steel fiber addition has a distinct and systematic effect on the compressive strength and modulus of elasticity. In contrast, it was clearly observed that steel fiber incorporation remarkably enhanced the mixtures’ tensile performance, resulting in more than 20 % and about 17–24 % increases in 28- and 90-day splitting tensile strengths, respectively.

Pineapple fibre as an additive to self-compacting concrete

As concrete being widely used in the field of construction, the demand for the materials used is increased ­rapidly. To meet the growing demand it is necessary to use alternative materials to meet the requirements. The Pineapple leaf fibre (PALF) is a highly available material in larger quantity with lesser water content and higher fiber content which makes it as a desirable material as natural fibre. The workability characteristics of Self ­compaction Concrete (SCC) like flowability, filling ability, passing ability, resistance to segregation and bleeding of concrete were out by using slump cone, U-box, L-box, V- Funnel and J-ring test. The test result shows satisfactory results on the workability of SCC. The fresh and hardened properties of concrete were found at the ages 7 days, 14 days and 28 days for various addition of PALF and various replacements of granite powder with the fine aggregate. The addition of PALF has achieved maximum compressive strength and split tensile strength in all ages of concrete at PALF0.2. The replacement of granite powder with fine aggregate seems to be promising in achieving the maximum compressive strength and split tensile strength at the 10% of replacement.

Hot workability characteristics of two A335 P92 steels for power plant application: A comparative study

The article reports on the workability of two P92 steels having a chromium content of 8.29 and 9.48 wt%. Constitutive equations were used to calculate material parameters describing the hot deformation flow stress. Hot deformation tests were conducted using the Gleeble® 3500 thermomechanical facility. Test conditions were: temperature of 850-1000°C and strain rate of 0.1-10s-1 to a strain of 0.5. The flow stress curve results show that dynamic recovery was the only softening mechanism. A comparative study of the two steels revealed that Cr content had a marginal significance on the flow stress behaviour. Constitutive analysis results of the material parameters were: a stress exponent of 9.0 (P92-A), and 11.0 (P92-B), while the activation energy was 369 kJmol-1 (P92-A), and 472 kJmol-1 (P92-B). A brief explanation of the material parameter results is in this article. A flow stress model was developed to predict the flow stress behaviour of the two P92 steels investigated. The results show that the model accurately predicts the flow stress at all the deformation conditions applied. The statistical parameters showed a good correlation between the predicted and the experimental data. Therefore, this model can be used to develop metal forming schedules for industrial applications.

Strength and workability characteristics of hybrid bamboo and steel fiber reinforced concrete

Strength and workability characteristics of hybrid bamboo and steel fiber reinforced concrete