Split Tensile Research Articles

Workability, strength, and microstructure of high strength sustainable concrete incorporating recycled clay brick aggregate and calcined clay

Abstract This study examines the workability, strength, and microstructure of high strength eco-concrete incorporating recycled clay brick aggregate and calcined clay. The study adopted a design mixes proportioning of 1:1:2 by weight at a constant water/binder ratio of 0.25. The waste bricks were crushed, then used to partially substitute sand at levels of 0, 10, 20, 30, 40, and 50%, while calcined clay was used as a pozzolanic supplement was blended with cement at a constant replacement dosage of 10%. The workability was determined using the slump apparatus. The compressive, split tensile and flexural strengths of the hardened samples were evaluated using cubes, cylinders and beams of dimension 100 mm3, 100 × 200 mm and 100 x 100 × 550 mm, respectively. Scanning electron microscopy (SEM) coupled with energy dispersive x-ray (EDX) was conducted on selected samples. Results from the tests indicated a decreasing trend in the workability as the recycled clay brick content increases. Results on the mechanical properties show some levels of improvement in the strength performance and microstructure of the hardened samples containing recycled clay brick aggregate, not beyond 30% at constant calcined clay content. Concrete mix with 10% recycled clay brick aggregate and 10% calcined clay achieved a higher strength compared to the control. This implies that recycled clay brick aggregate can be utilize in the production of structural concrete.

SIMILAR MATERIALS FOR QUASI-STATIC SCALED TESTS OF FAULT-CROSSING TUNNELS

The design of similar materials is one of the key links to ensure the matching of the physic-mechanical properties between the prototype and the test specimens. Based on the prototype of the Xianglu mountain tunnel of the water diversion project in the central Yunnan province, China, the scaling relationship of the physical quantities in the quasi-static scaled test of a fault-crossing tunnel is derived in this study according to the similarity theory and dimensional analyses. The similar materials of concrete and rock mass used in the test are developed with barite powder and sand as the aggregates and with gypsum and lime as the cementing material. The effects of each component on the physic-mechanical properties of the similar materials are investigated through orthogonal tests. The test results indicate that the strength, elasticity modulus and density of the similar materials can be significantly changed by the overall content of the high-strength gypsum and water-gypsum ratio. Small variation of the strength of the similar material is found when the sand-gypsum ratio is between 0.8 and 1.2, but the strength significantly decreases when the sand-gypsum ratio is between 3 and 12. The elastoplastic performance and the brittle failure mode of Grade C30 concrete can be well simulated by the similar material made of high strength gypsum, low strength gypsum, barite powder and sand. The tensile splitting and the diagonal shear failure modes of rock mass of Grade IV and V can be well simulated by the proposed similar material made of high strength gypsum, lime and sand. The development process and ratios of similar materials can provide important reference for model test and numerical simulation.

Effect on Fresh and Harden Properties by using Fly Ash and GGBS with Fibers of High Performance Self Compacting Concrete

The study of cementations materials of supplementary on High Performance Concrete with Self Compacting is studied in this work. The High Performance Self-Compacting Concrete makes it suitable for placing in difficult sections and conditions in members with congested reinforcement the properties of fresh concrete and Harden properties in Special concrete of High Performance Self Compacting Concrete (HPSCC) studied in this work. Effect of fibers with fly ash & GGBS behavior of combined fibers sections subjected to load. The work studied has been focused on the Fly ash and GGBS effect with fibers on mix proportion and concrete in harden state Strength in Ultimate with replacement of Polypropylene fibers range 0%-1.5% in 0.5 interval and also the focusing of work with various percentage of fly Ash and GGBS combination and behavior of fiber under loading, compression strength, Split Tensile Strength & Flexural Strength. The obtained values from this study are to be useful in determining design charterstic of HPSCC with fiber (polypropylene) sections. It gets helps the mix proportion, analysis and designing of specimens with high performance to resist various loading.

MECHANICAL PROPERTIES OF RECYCLED COARSE AGGREGATE CONCRETE REINFORCED WITH STEEL FIBERS

This paper presents the combined influence of natural aggregates (NA) replacement with recycled concrete aggregates (RCA) and incorporating steel fiber reinforcement on the mechanical properties of normal-strength (30 MPa) concrete mixes. Hooked-end steel fibers were added in a 2% volumetric fraction to promote 100% RCA replacement. Fine aggregates were in the form of locally-abundant desert dune sand. Mechanical properties of 28-day concrete samples were assessed, including compression strength, tensile splitting strength, elastic modulus, flexural stress, and flexural toughness. For plain concrete mixes, the replacement of NA by RCA resulted in 18, 27, and 5% reductions in the respective design compression strength, elastic modulus, and tensile splitting strength. Nevertheless, the addition of steel fibers could restore the aforementioned properties by up to 90, 77, and 164%. Compared to the control mix made with NA, the flexural strength of the plain RCA-based concrete mix decreased by 33%, while the flexural toughness increased by 100%. In turn, the corresponding flexural properties of RCA concrete mix reinforced with steel fibers were 2 and 56 times those of the control made with NA. Findings provide evidence of the ability to produce concrete made with 100% RCA and reinforced with steel fibers with comparable compression properties and improved tensile and flexural performance compared to those of NA-based concrete.

Reduction of cement content using graded aggregates in concrete production

The aim of this project was to reduce cement content in concrete mixtures by changing the aggregate grading. For this purpose, concrete mixtures were made with aggregates having different shapes, textures, and grading. However, the workability of concrete mix depends on its paste volume, paste composition, and the type of aggregate used. Concrete testing was performed, and concrete properties including slump, compressive strength, and tensile splitting test were tested. The effect of aggregate shape on workability was evaluated by comparing one aggregate combination to another. It was found that the aggregate combination with S/A= 0.4 GR-B-CA+NA-A-FA had optimum workability properties and generally, GR-B-CA+NA-A-FA consistently had the highest workability, as well as the highest paste volume demand. This can be attributed to its poor grading as a result of the gaps in GR-B-CA content. Compared with NA-A-CA + NA-A-FA, it resulted in concrete mixtures with lower paste volume demand.

Effect of Design Parameters on Compressive and Split Tensile Strength of Self-Compacting Concrete with Recycled Aggregate: An Overview

One of the prime objectives of this review is to understand the role of design parameters on the mechanical properties (Compressive and split tensile strength) of Self-Compacting Concrete (SCC) with recycled aggregates (Recycled Coarse Aggregates (RCA) and Recycled Fine Aggregates (RFA)). The design parameters considered for review are Water to Cement (W/C) ratio, Water to Binder (W/B) ratio, Total Aggregates to Cement (TA/C) ratio, Fine Aggregate to Coarse Aggregate (FA/CA) ratio, Water to Solid (W/S) ratio in percentage, superplasticizer (SP) content (kg/cu.m), replacement percentage of RCA, and replacement percentage of RFA. It is observed that with respect to different grades of SCC, designed parameters affect the mechanical properties of SCC with recycled aggregates.

Concrete Modular Pavement Structures with Optimized Thickness Based on Characteristics of High Performance Concrete Mixtures with Fibers and Silica Fume.

Usually, C30/37 strength class concrete is used to construct concrete pavements on a rigid, semi-rigid or flexible base. Concrete with such a strength delivers essential design characteristics: flexural strength and tensile splitting strength are between 4.5–5.4 MPa and 2.8–3.7 MPa, respectively. Design characteristics can be significantly increased by densifying the concrete mixture, i.e., adding silica fume, steel or polypropylene macro fibers. As high-performance concrete characteristics are 20–60% higher than those for standard concrete (C30/37), new possibilities to reduce the thickness of concrete pavement slabs appear. The theoretical analysis of concrete pavement structures with high-performance concrete mixtures (C40/50, C45/55 and C50/60) showed that slab thickness could be reduced by 6–39% compared to a standard concrete pavement structure depending on the concrete properties and design method. From all those pavement structures, three concrete mixtures were determined as the most rational ones in terms of PCP thickness reduction and total pavement cost: (i) with 49.5 kg/m3 of steel fibers and 25.2 kg/m3 of silica fume; (ii) with 10.0 kg/m3 of polypropylene fibers (type A); (iii) with 49.5 kg/m3 of steel fibers.

Development of self-compacting concrete using Bailey aggregate grading technique in comparison with Indian standard code of practice

Purpose This study aims to present the results of an experimental evaluation of low (M30), mid (M40) and high (M50) grade self-compacting concrete (SCC) with three nominal maximum aggregate sizes (NMAS), namely, 20 mm, 16 mm and 12.5 mm, with Bailey gradation (BG) in comparison with Indian standard gradation (ISG). Design/methodology/approach This study was conducted in a laboratory by testing the characteristics of fresh and hardened properties of self-compacting concrete. Findings Rheological and mechanical properties of SCC were evaluated in detail and according to the results, a concrete sample containing lower NMAS with BG demonstrated improvement in modulus of elasticity and compressive strength, while improving the rheological properties as well. Meanwhile, SCC demonstrated poor performance in split tensile and flexural strengths with lower NMAS gradations and a direct correlation was evident as the increase in NMAS caused an increase in the strength and vice-versa. Originality/value Upon comparison of BG with ISG, it was revealed that BG mixes succeeded to demonstrate superior performance. From the material optimization, rheological and mechanical performance study, it is recommended that BG with NMAS 16 mm can be used for conventional SCC.

Role of mineral admixtures on strength and durability of high strength self compacting concrete: An experimental study

This research reports the experimental investigation about the role of mineral admixtures on strength and durability properties of self compacting concrete (SCC) with a view to decrease cement consumption. For this experimentation nine mixes are prepared, using alccofine and ground granulated blast furnace slag (GGBS) as mineral admixtures for M60, M80 and M100 grade SCC. The fresh and hardened properties of these mixes are examined by varying both water-binder ratio and admixtures. Fresh properties of SCC like, filling ability flowability and passing ability are investigated by using slump flow, T500 mm, V-funnel, J-ring, U-box & L-box tests as per EFNARC standards. Hardened properties of SCC like compressive, split tensile and flexural strengths are investigated as per Indian standard IS-516:1959. This study also reports the durability properties of SCC, like creep and shrinkage. Test results indicate that, use of GGBS and alccofine as mineral admixture enhances fresh and hardened properties for all the mixes and helps in reducing the cement consumption and thus advantageous in lowering the cost of construction using SCC. Literature lacks regarding studies, on creep and shrinkage in context to high grade SCC; authors believe that their investigation will add value to the body of knowledge and will be beneficial for both practitioners and researchers.

Impact of carbon Nano tubes on fresh and hardned properties of conventional concrete

Carbon Nano Tubes are strongest known materials known till now which can be ideally used in conventional concrete to tailor its functionalities. As water cement ratio governs the strength, serviceability and durability of concrete so its important to know the effect of Carbon Nano Tubes on basic properties of concrete. In order to analyze fresh and hardened properties of conventional concrete 0.5% Carbon Nano Tubes by weight of cement was incorporated in concrete mixes having water cement ratio 0.40, 0.45, 0.48.0.50 and 0.50. It was observed at 0.45 water cement ratio compressive, split tensile and Moment of resistance was greater by 8.89%, 28.9% and 5.33% respectively in comparison to Reference mixes while workability diminued by 38.40% and water absorption decreased by 0.03%. Also Coefficient of relationship R2 for water absorption and water-cement ratio of Carbon Nano Tube reinforced concrete was found as high as 0.97. Scanning electron microscopic analysis revealed dispersion of Carbon Nano Tubes and their bridging effect.

Experimental study on mechanical properties of polypropylene fiber reinforced concrete with silica fume

In this research, the mechanical properties of polypropylene and silica fume are examined with the 0.40% water-cement ratio of M40 grade concrete. The synthetic polypropylene fibers of length 12mm short fibers. in this study, the polypropylene fibers are used up to 0.3% (0%, 0.1%, 0.2%, 0.3%). And the silica fume is being utilized as a substitute for cement with a 4% mass of cement in all the mix proportions. The addition of silica fume to the cementitious matrix strengthened fiber scattering, resulting in a substantial decrease in the absorbency of the polypropylene fiber reinforced concrete(PPFRC). Superplasticizer is also added to these concrete mixes to increase workability. The concrete samples are prepared and cured for 7, 28 days. After completing the curing duration, samples were tested. After That finally, the mechanical properties, as comp. strength, split tensile, bending strength and mode of failure and ultimate load are determined and all proportions of the mix are compared to traditional concrete.

Strength and Durability Characteristics of Coir, Kenaf and Polypropylene Fibers Reinforced High Performance Concrete

ABSTRACT Cement concrete is used in small structure to big multi-storied buildings. It is noteworthy to concentrate on concrete elements and mix ratio to achieve desirable strength with feasible cost of raw material. In this investigation, fibers reinforced concrete specimens (M50 grade) were prepared. The strength and durability were tested and compared with the properties of plain concrete (PC). The fibers such as coir, kenaf, and Polypropylene (PP) were used as reinforcement and the compressive, split tensile, flexural, and durability analysis were performed. The compressive test resulted that the natural fiber-based PC/Coir & PC/PP-Coir specimens displayed the maximum compressive strength of 64.5 and 66 MPa owing to the small density and slighter water up taking properties of coir and PP fiber. The split tensile test showed that the PC/kenaf specimen exhibited the higher split tensile strength of 7.3 MPa due to the presence of kenaf fiber with high young’s modulus. Flexural test reported that the PC/PP-Coir/Kenaf specimen exhibited the higher flexural strength of 7.6 MPa because of reinforcing effect offered by coir, kenaf, and PP fibers. Durability study showed that the PC/PP and PC/PP-coir specimens displayed the minimum weight loss of 1.05 and 2.1% and the minimum loss in compressive strength of 3.4 and 4.6%, respectively, in alkaline medium. It was concluded from this study that the coir fiber could be a suitable candidate to improve the strength and durability of concrete.

Improving of Lightweight Concrete Properties Produced with Pumice Aggregate of Nevşehir Region with Fly Ash Substitution

In this study, it was aimed to determine the effects of industrial waste fly ash substitution on physical and mechanical properties of lightweight concrete. In this respect, lightweight concrete samples were produced by the use of fly ash as a cement replacement material in different proportions (1%, 3% and 5%). In lightweight concrete production, the Nevşehir region acidic pumice has been used as aggregate. The physical and mechanical properties of these lightweight concrete samples were investigated and microstructural analysis was carried out. To determine the physical differences, dry unit volume weight, capillary water absorption, porosity, compactness and freeze-thaw experiments were conducted. For the determination of mechanical properties, tensile splitting strength and compressive strength tests were applied. SEM images have been interpreted to examine the structural differences occurring within the material. As a result of the study, it was determined that the physical and mechanical properties of the ligtweight concrete were improved with the increase in the amount of fly ash. The best results were obtained from sample with 5% fly ash substitution. The use of industrial waste in a large sector such as construction, which adversely affects the ecological balance, will be an opportunity to dispose of waste.

Mechanical properties on light weight aggregate concrete using high density polyethylene granules

This present research and explores the properties of concrete's structural and durability High-density polyethylene granules (HDPE) are partly replaced by the coarse aggregate. Five separate concrete mixtures of grade M30 have been built to partially replace the coarse aggregate from 1% to 5%. The properties of strength and durability such as compressive strength, split tensile test, flexural test and durability test such as rapid chloride permeability test, acid test, alkaline test, sulphate test assault. In the acids, the samples will equate with control concrete after 190 days for durability test cubes. The experiment is conducted to evaluate how much the acid attacks on the concrete. The loads are determined by an average of 3 for the compressive strength, split tensile, flexural test.

Effect of Metal Lathe Waste Addition on the Mechanical and Thermal Properties of Concrete.

The amount of steel chips generated by lathes and CNC machines is 1200 million tons per year, and they are difficult to recycle. The effect of adding steel chips without pre-cleaning (covered with production lubricants and cooling oils) on the properties of concrete was investigated. Steel waste was added as a replacement for fine aggregate in the amounts of 5%, 10% and 15% of the cement weight, which correspond with 1.1%, 2.2% and 3.3% mass of all ingredients and 0.33%, 0.66% and 0.99% volume of concrete mix, respectively. The slump cone, air content, pH value, density, compressive strength, tensile strength, tensile splitting strength, elastic modulus, Poisson’s ratio and thermal parameters were tested. It was observed that with the addition of lathe waste, the density decreased, but mechanical properties increased. With the addition of 5%, 10% and 15% metal chips, compressive strength increased by 13.9%, 20.8% and 36.3% respectively compared to plain concrete; flexural strength by 7.1%, 12.7% and 18.2%; and tensile splitting strength by 4.2%, 33.2% and 38.4%. Moreover, it was determined that with addition of steel chips, thermal diffusivity was reduced and specific heat capacity increased. With the addition of 15% metal chips, thermal diffusivity was 25.2% lower than in the reference sample, while specific heat was 23.0% higher. No effect was observed on thermal conductivity.

Influence of aggregates, glass fibre reinforcement and recycled aggregates on polyester mortar

As the performances of unsaturated polyester mortar are related to its composition, this research is focused on the influence of the grain size distribution of the aggregates, glass fibres reinforcement and the use of recycled aggregates on its mechanical and physical properties and microstructure. It revealed that a higher fraction of coarse sand caused a decrease in compressive (2 to 3%), tensile splitting (10 till 14%) and flexural tensile (5 to 9%) strength since the interlocking effects decrease, while microstructure analysis reveals more cracks and air voids when the filler fraction is substituted. Moreover, the addition of a small amount of glass fibres, i.e. 0.20 vol%, resulted in a decrease of 0.9, 3.4 and 4.6%, respectively, in compressive, tensile splitting and flexural tensile strength, whereas the impact toughness doubled. The properties related to the microstructure indicate that this mixture is less compacted compared to a mixture without fibre reinforcement, although the ultrasonic pulse velocity increased with 2.5%. Furthermore, the study highlights the potential of recycled polymer mortar as aggregates since enhanced tensile (18.5 and 3.9% respectively, for tensile splitting and flexural tensile strength) and impact properties (an improvement of 41.8%) were observed, while the additional tests indicate that the mixture with recycled aggregates has a less dense structure compared to the reference mixture.

Fresh and mechanical properties of concrete made of binary substitution of millet husk ash and wheat straw ash for cement and fine aggregate

Abstract Now-a-days, many researchers use priceless industrial or agricultural products as the main raw material for the construction industry. However, these wastes are inexpensive and easily available everywhere to utilize for commercial purpose and also helpful in reducing the environmental pollution. This experimental study aimed to evaluate fresh (workability) and mechanical properties (density, permeability and split tensile strength, compressive and flexural strength) of concrete with 0%, 5%, 10%, 15% and 20% of millet husk ash (MHA) and 10%, 20%, 30% and 40% of wheat straw ash (WSA) to replace Ordinary Portland Cement (OPC) and sand respectively at conditions: a) concrete with MHA; b) concrete with WSA; and c) concrete with MHA and WSA. 525 concrete specimens were prepared with 1:1:2 mix proportions with 0.55 water/cement ratio and cured at 28 days. The increase of combined MHA and WSA contents to produce concrete decreased the workability of fresh concrete and decreased density and permeability of hardened concrete. Compressive strength, split tensile and flexural strength are increased with addition up to 15% of MHA and 30% of WSA combined. Same behavior is observed to compressive strength after chloride attack. Those results were better when compared to those of conditions a) and b). Therefore, it is possible to produce eco-friendly concrete with MHA replacing OPC and WSA replacing sand, individually or combined, which contributes to less environmental impact.

Properties of Sustainable Concrete Containing Red Mud: A Review

Concrete is an essential construction material and major component of concrete is cement. There is a huge amount of carbon dioxide emission into the atmosphere during manufacturing process of cement which has negative impact on the environment. Thus it become necessary to discover a substitute material for cement in concrete. Rapid industrialization generates a significant quantity of waste material which are causing negative effect on environment. These wastes can be a replacement for traditional material which are used in concrete like cement or fine aggregate. Red mud is waste material which generated from bauxite ore at the time of production of aluminium by the Bayer process. In this review paper, the effort is made to present the properties of concrete with red mud after studying several research papers. This paper discusses the properties of red mud concrete such as workability, compressive strength, split tensile strength, flexural strength, water absorption and modulus of elasticity. This paper shows the feasibility of partial substitution of cement in concrete by red mud. The study shows that incorporating red mud resulted increase in strengths of concrete such as compressive, split tensile and flexural strength. The water absorption of concrete decrease as increase in red mud content, it can be established that there is a possibility for using red mud in concrete as a binder ingredient for sustainable construction.

The effect of rice husk ash and gilsonite on the properties of concrete pavement

ABSTRCT Abrasion susceptibility of roadway pavements has a significant effect on the skid resistance, and consequently accident rate. In this study, the mechanical properties of concrete pavement were investigated in 10 mixing designs containing Rice Husk Ass (RHA) and gilsonite. For this purpose, by modifying the concrete cement by 10, 15, and 20 percent with RHA and 5, 7, and 9 percent of gilsonite by the weight of the concrete cement as filler, the mechanical properties of the modified concrete pavement is improved, leading to changed mechanical strength and abrasion resistance. Flexural strength, tensile splitting strength, compressive strength, and abrasion tests were performed on the specimens. The results showed that the combination of RHA and gilsonite did not affect the concrete’s specific gravity. The results showed that the combination of two additives reduced the compressive strength of the mixture. However, in some compounds, the concrete’s tensile splitting and flexural strength increased by about 4 and 7 percent. Finally, the abrasion test results showed that the mixture containing 10% RHA and 5% gilsonite had increased abrasion by about 15%; therefore, this mixture is in the category of class 1 and can be used in light pedestrian and vehicular areas.

Strength Performance of Oil Palm Shell Lightweight Aggregate Concrete

The concrete consumption that is high in the construction industry had resulted in uncontrolled aggregates exploitation. The extraction of these natural resources has raised great environment concerns that the use of waste materials as replacement of aggregates is proposed. Oil palm shell lightweight aggregate concrete (OPS LWAC) is produced by full replacement of oil palm shell (OPS) to coarse aggregate. OPS is the lightweight aggregates that potentially produce lightweight aggregate concrete (LWAC). Palm oil fuel ash (POFA) is also the byproduct of the palm oil industry that can be utilized to partially replace the fine aggregates. The objective of this study is to investigate the effect of POFA as partial fine aggregates replacement on density, compressive and tensile strength of OPS LWAC and to determine the optimum replacement percentage of fine aggregates with POFA. The control mixes were prepared with 100% OPC in the concrete while modified mixes contained various percentages of POFA, which were 5%, 10%, 15% and 20% as the replacement of fine aggregate. The specimens of cubes sizes 100 mm x 100 mm x 100 mm and cylindrical specimens with diameter of 100 mm and height of 200 mm were prepared and tested. The concrete mixtures were mixed according to the Department of Environment (DoE) method followed by the trial mixed. Mixes with 10% replacement of POFA to fine aggregate obtained the highest compressive strength and tensile splitting tensile strength which were 26.3 MPa and 2.37 MPa respectively. The property of POFA plays a role in the concrete strength determination. The higher replacement percentages resulted in lower density of OPS LWAC.