Cube Specimens Research Articles

Experimental and numerical characterization of EPS using elastoplastic response in ABAQUS

Expanded polystyrene (EPS) is an attractive research area in the field of construction engineering. Its ultra-lightweight properties, high compressibility, and environmental-friendly characteristics make it ideal for the use as a compressible backfilling material for embankments, a filling material behind retaining walls and many other applications. Consequently, the compressive strength is one of the important properties for engineers. To this end, this paper aims to create a simplified elastoplastic model for the uniaxial unconfined compressive behavior of EPS. The developed model can predict the plastic stress–strain behavior of EPS using only its elastic modulus. A mathematical curve fitting model was developed by testing several 50 × 50 × 50 mm cube specimens under the test setup of a 50 kN uniaxial loading machine. Then, the proposed model was validated through the elastoplastic behavior in ABAQUS, by creating a finite element model for the described test setup. It was found that the proposed experimental test setup resulted in reasonable stress–strain behavior for EPS, similar to that indicated in the literature. Also, the presented mathematical model can accurately predict the stress–strain behavior of EPS, which was validated using the elastoplastic response in ABAQUS.

Strength and Acoustics Properties of Lightweight Foamed Concrete Incorporating of Bio-Based Aggregate

This paper investigates the incorporation of bio-based aggregate in lightweight foam concrete (LWFC). The aim of this research is to determine the strength and acoustics properties of lightweight foamed concrete incorporating 5% bio-based aggregate (LWFC-OPS5). A targeted density of 1100 +/- 100 kg/m3 of LWFC-OPS5 is produced and achieved a compressive strength of 3 MPa. A total of six mixes containing different water to cement (w/c) ratios 0.52, 0.56 and 0.60 with 0% and 5% of OPS replacement were designed. From the result, LWFC-OPS5-0.52 had showed the highest strength properties at 28 days, which are recorded at 3.59 MPa and 1.75 MPa respectively. It also showed the highest density among the LWFC-OPS5 mix design which is 1180 kg/m3 under fresh density conditions. LWFC-OPS5-0.56 has showed the most significant increase in compressive strength and flexural strength at 28 days, which have an increment of 30 - 40% from 7 days’ results. On the other hand, LWFC-OPS5-0.60 has increased about 36.81%, 32.73% and 63.83% compared to LWFC-CTR. All cube specimens have achieved above 3 MPa of compressive strength except LWFC-OPS5-0.60 due to its lowest fresh density. From the acoustics properties test results, LWFC-OPS5-0.56 had showed the maximum sound absorption coefficient. Thus, this research proved that LWFC-OPS5 can be used for different applications such as wall panels, roof tiles, sound barriers and etc.

Experimental study on similar materials for tunnel lining concrete in geomechanical model tests

In geomechanical model tests, a reasonable proportioning of similar materials is one of the keys to ensuring that the physical and mechanical properties of the model match those of the prototype. Using gypsum, white cement, barite powder, quartz sand, and water as raw materials, a similar material of tunnel lining concrete was developed by orthogonal design. The density, compressive strength, elastic modulus, and tensile strength of the similar material were measured, which were evaluated using range analysis. Meanwhile, the mechanical parameter relationship was studied between the similar material specimens with different sizes. The results show that the similar material has a large range of physical and mechanical parameters, and can be used in the model test with a large unit weight; its ratio of compressive strength to tensile strength is 8.31–16.12, which conforms to the mechanical properties of concrete. The aggregates/cementing materials ratio has the largest impact on the material density, while the water/cementing materials ratio has the greatest influence on the strength and elastic modulus of the material. There is a good fitting relationship between the mechanical parameters of cylinder specimens and the mechanical parameters of cube and prism specimens, so cylinder specimens can be prepared for mix proportioning tests during trial preparation of the similar material. The physical and mechanical performance of grade-C25 concrete and grade-C40 concrete can be well simulated by the developed similar material. The research can provide a reference for the selection of similar materials for lining concrete in similar model tests.

Effect of Cooling Conditions, Retrofitting on Strength of Concrete Subjected to Elevated Temperature

Concrete has a high degree of fire resistance at moderate temperatures. High temperatures, however, cause concrete to lose its stiffness and strength. The effects of cooling techniques and retrofitting on the strength of concrete exposed to high temperatures have not been synchronized in previous studies. This experimental research aims to evaluate the effect of cooling conditions and the effectiveness of retrofitting concrete subjected to elevated temperatures. Four types of concrete: M 20 normal concrete (NC); M 20 metakaolin concrete (MC); M 40 standard concrete (SC); and M 40 self-compacting concrete (SCC) are considered in this study. A total of 864 samples consisting of cube, beam, and cylinder specimens are subjected to sustained elevated temperatures of 400oC, 600oC, and 800oC for 2 hours rating. The weight and strength of half of the heat-damaged samples are assessed following natural air cooling (NAC) and water jet cooling (WJC). The remaining 50% of samples retrofitted with carbon fiber reinforced polymer (CFRP) are tested to evaluate the upgraded strength. The experimental findings demonstrate that water jet cooling (WJC) causes more strength degradation, and CFRP proves to be effective in restoring the strength of heat-deteriorated specimens. Overall, self-compacting concrete (SCC) has shown high resistance to elevated temperatures. Doi: 10.28991/CEJ-2023-09-07-013 Full Text: PDF

An Experimental Study on Partial Replacement of GGBS with Cement and Utilizing Demolished Coarse Aggregate in Concrete

bstract: The majority of municipal solid wastes are made up of debris from construction and demolition projects, including recycled construction aggregate (RCA). This paper presents the findings of an experimental and analytical examination of the creation of environmentally friendly concrete. It is a good idea to replace natural material with aggregate from old, demolished structures to reduce debris and preserve the environment. To reduce consumption, recycled aggregate can be utilized in place of natural aggregate. To address these issues, an attempt is undertaken in the current experimental work to substitute GGBS in varied proportions for cement. The purpose of this research is to demonstrate the findings of an investigation into the applicability of GGBS in the manufacturing of concrete by using construction and demolition debris as a recycled resource. Ground granulated blast furnace slag (GGBS) and recycled concrete aggregates are the recycled materials employed in this study. A concrete mix of grade M25 was created through the mix design process. GGBS was partially replaced with wastedestroyed aggregate in the amounts of 0, 10, 20, 30, and 40% to create the mixes. Cubes of 150x150x150mm3 were poured. The compressive strength of the concrete cube specimens was measured by smashing the cube after 7, 14, 28, 60, and 90 days of curing for various curing intervals. The compression test results on the cubes show that strength increases with the amount of slag added up to the maximum value. Compressive strength was seen to grow when GGBS content increased up to 30%, but after the replacement level was above 30%, strength began to deteriorate. The outcomes of GGBS with conventional concrete and concrete made entirely of demolished aggregate without GGBS are compared to the outcomes of GGBS with concrete containing demolished aggregate

A novel method of predicting shear strength of fiber-reinforced high-strength concrete based on cube specimens: part-1

A novel method of predicting shear strength of fiber-reinforced high-strength concrete based on cube specimens: part-1

Mechanical Behavior of Nano Clay on Cement Mortar at Ambient Temperature

The Experimental studies prove that the use of cement as a partial replacement with Nano clay and polypropylene fibres along with Ground Granulated Blast Furnace Slag improves the strength properties like compressive strength of cement mortar at ambient temperature. These Nano clay has been successfully recognized as promising advanced materials used for construction purpose due to their enhanced mechanical properties. The primary focus and purpose of this study is to investigate the effect of Nano Clay and its properties on cube specimens. The test specimens consist of cubes (70.6 mm) as per IS specifications, the specimens were casted for 3 days and 7 days and tested with cement mortar mix 1:3, and polypropylene fibres (0.25% by weight of cement) all the test specimens are subjected to ambient temperature then, and strength properties at normal temperature were studied. The test result shows there is a significant improvement in 3 days and 7 days strength as compared to the conventional mortar. The inclusion of Nano clay will have significant improvement and high boning properties when it is added to the cement.

Influence of elevated temperature on compressive strength of LD slag aggregate concrete

PurposeThis study aims to investigate the compressive strength of concretes incorporating Linz-Donawitz slag (LD slag) as partial replacement for natural fine and coarse aggregates and compare them with traditional concrete.Design/methodology/approachThe natural fine and coarse aggregates were replaced by weight simultaneously up to 100% with LD slag aggregates at an incremental increase of 20%. Concrete of grades M20, M25, M30, M35 and M40 were cast, cured and tested with standard cube specimens to study the density and compressive strength of reference and LD slag aggregate concretes (LDSACs). The concrete specimens were exposed to elevated temperatures, i.e. 100 to 900 °C at an equal interval of 100 °C and tested to study the variation in density and residual compressive strength.FindingsThe results from the experiments reveal that the LDSAC yields a higher density than that of the reference concrete and also undergo less density variation when exposed to elevated temperatures. In addition, the residual compressive strength of LDSAC specimens was significantly higher than that of the reference concrete.Research limitations/implicationsLD slag is believed to be stronger and more durable than locally available limestone aggregates or blast furnace slag. Moreover, it is necessary to study its strength and other properties to determine whether it can be successfully used as an aggregate in concrete universally.Practical implicationsUse of LD slag as aggregates in concrete will convert LD slag into a value added product and as an alternative to the existing natural aggregates which will help in maintaining ecological balance and save valuable lands.Social implicationsThe economically weaker section of the society may now use LDSAC as waste utilization will bring down the overall cost and hence it will benefit people on large scale.Originality/valueUse of LD slag as aggregate in concrete can help find an alternative to the existing natural aggregates which will save the ecosystem and at the same time help in reducing the industrial waste on a large scale.

Mechanical Properties of Concrete Containing Ferronickel Slag as Fine Aggregate Substitute Using Digital Image Correlation Analysis

This study aimed to analyze the mechanical, displacement, and strain properties of concrete with Ferronickel Slag (FNS) fine aggregate substitute (0%, 50%, and 100%, by mass, later called FNS-0, FNS-50, and FNS-100, respectively) experimentally using the Digital Image Correlation (DIC) method and the Ultrasonic Pulse Velocity (UPV) test. The FNS used in this study is a by-product that came from a Ferronickel smelter in Indonesia coupled with manufactured sand (M-sand) as the fine aggregate control. A D10 × 20 cm3 cylinder and 15 × 15 × 15 cm3 cube specimens were used to analyze the density, compressive strength, and UPV. Additionally, the cube specimens were tested using the DIC method to analyze the displacement and strain properties. The test results show the highest compressive strength was obtained by FNS-50, followed by FNS-100 and FNS-50. The highest pulse velocity was obtained by FNS-100, followed by FNS-50 and FNS-0. The load–displacement response and strain behavior indicate the specimen that had the most load resistance was FNS-50, followed by FNS-100 and FNS-0. Poisson’s ratio obtained using DIC and strain gauges showed consistent results where FNS-0 had the highest values, followed by FNS-50 and FNS-100. Overall, concrete with FNS substitute showed higher density, compressive strength, pulse velocity, and stiffness, as well as lower Poisson’s ratio compared to control concrete (FNS-0).

Strength performance of reinforced concrete beam containing waste tire rubber and local waste material

The strength of Reinforced Concrete (RC) structure is one of the concerns for construction development. In this study, waste tire rubber has been used to replace fine aggregate and the local waste material, Rise Husk Ash (RHA) as a cement replacement. Three groups of specimens with the same percentage of RHA about 10% and different percentages of waste crumb rubber (CR), 0%, 6% and 10% have been produced. Cube specimen and cylinder specimen are tested under compressive strength test and splitting tensile test. Besides, RC beam is tested under four points bending test. It is observed that by replacing 10% of RHA as cement replacement in addition to 0%, 6% and 10% of CR into concrete specimen, it can produce the compressive strength of 52.3 MPa, 34.3MPa and 28.6MPa respectively. Meanwhile, splitting tensile test gives a result of 2.80 MPa, 2.17 MPa and 1.84 MPa, respectively, based on the different CR percentages. For four points bending test, 6% of CR with 10% RHA gain 81.3 kN maximum load with 4.98 mm deflection while 10% of CR with 10% of RHA generate 79.5 kN of maximum load with 5.86 mm deflection compared with control specimen. Overall, 6% of CR with 10% of RHA in the reinforced concrete beam manage to withstand maximum load compare with control specimen.

Stress Analysis and Spalling Failure Simulation on Surrounding Rock of Deep Arch Tunnel

To study the stress distribution characteristics of surrounding rock and the spalling mechanism of deep hard rock tunnels with different arch heights, the complex variable function and angle-preserving transformation method in elasticity theory were applied to the analytic solution of tangential stress distribution of arch tunnels during stress adjustment. In addition, true triaxial tests were conducted on granite cube specimens (100 mm × 100 mm × 100 mm) containing holes with three arch heights (including the 25 mm semi-circular arch, 16.7 mm three-centered arch, 12.5 mm three-centered arch) to simulate the spalling process under different initial ground stresses. The stress distribution solution and experimental results show that the initial failure stress of arch holes is 0.39–0.48 times the uniaxial compressive strength (UCS) of the rock. The initial failure location occurs at the arch foot, where tangential stress maximizes. When the lateral pressure coefficient is in the range of 0.38–0.50, the tangential stress is 3.2–3.5 times the UCS. The rock debris of the hole wall are in thin flake shapes. Symmetrical V-shaped or curved failure zones occurred on hole sidewalls. The stress distribution resolution of the surrounding rock of tunnels with different arch heights shows that with the increasing burial depth, the bearing performance of the semi-circular arch tunnel is optimal. In addition, the maximum tangential stress increases as the height of the arch decreases or the lateral stress increases, making it easier for the initial failure to occur at the foot of the arch.

Study on the Influence of Specimen Size and Aggregate Size on the Compressive Strength of Rock-Filled Concrete

Rock-filled concrete (RFC) technology is a new type of mass concrete construction technology, which consists of two basic components: the force transfer frame formed by large-size rock accumulation and the matrix formed by self-compacting concrete (SCC) filling. Its unique construction method also distinguishes RFC from ordinary concrete in terms of its force characteristics. In this paper, RFC is considered as a composite material consisting of aggregate and SCC; based on the realistic failure process analysis (RFPA) method, the effects of specimen size and aggregate size on the compressive strength of RFC were studied. Firstly, RFC cube specimens were prepared and uniaxial compression tests were conducted. During the preparation process, in order to eliminate the influence of factors such as shape, spatial distribution state, and volume share of aggregates on the compressive strength, aggregates of different sizes were set as spheres and arranged in simple cubic stacking; then a numerical model of RFC with different specimen sizes and different aggregate sizes was established for uniaxial compression numerical simulation experiments to analyze the variation law and failure pattern of the RFC compressive strength. The results indicate that the compressive strength of RFC exhibits a significant size effect and follows a negative exponential function distribution law; with the same volume fraction of aggregate, the smaller the aggregate size, the higher the compressive strength of the RFC will be, and this increasing trend gradually levels off. Based on the findings of this study, it is recommended that the size effect and the reduction of aggregate size on dam strength be taken into account in the design of RFC dams.

A combined experimental–numerical modelling approach for self-crack monitoring in conductive cementitious materials

This study proposes an innovative methodology by combining experimental testing and numerical modelling for self-evaluating the crack development of conductive cementitious materials based on piezoresistivity. Cube specimens enhanced with carbon black nanoparticles were subjected to cyclic and uniaxial compression loads individually for evaluating their piezoresistivity behaviour and analysing the crack sensing mechanism. A discrete element model (DEM) was utilised to extract crack development information which was correlated with resistivity variation in experiments for damage quantification. Acoustic emission was also utilised for the validation of resistivity-based crack monitoring. It was found that electrical resistivity started to rise at a relatively early stage of compression process, followed by an increasing rise before the specimen reached its peak strength and then a rapid surge when the specimen started to lose its load-bearing capacity. The results prove that the proposed approach can monitor crack development of conductive cementitious materials from a micro scale through resistivity variation and more precisely describe the damage accumulation. The study also demonstrates that DEM is capable of capturing failure mechanism of cementitious materials.

Effect of partial replacement of aggregate with granulated polyethylene terephthalate (pet) on compressive strength of concrete

This paper is aimed at the development of appropriate combination of composite materials such as cement, aggregates and inclusion of Polyethylene Terephthalate (PET) in varying proportion in order to determine the optimal measure for the optimal strength. The study also, investigated the effect of PET aggregate on the compressive strength of concrete. Mix design targeting grade 25 concrete strength, using the Department of Environment (DOE) approach was adopted. Five different concrete samples were prepared accordingly, using natural aggregate as control mix and four others which consist of PET aggregate as partial replacement of fine aggregate at 5%, 10%, 15%, and 20% ratios respectively. The recycled fine aggregate (PET) was processed from bottle water waste, it was crushed, pressed and processed into finely material having river sand resemblance i.e., well distributed within sieve sizes of 0.075 and 2.00. The batching was done by weight. Cubes specimens were prepared, cured for 7, 14, and 28days and tested for compression. The results of the tests were analyzed statistically using regression method (Mintab) to establish optimal strength require mixture. The results and analysis established that there were reduction in compressive strength of the concrete containing PET aggregate and reduction rates increased with increase in the amount of PET inclusion in the concrete. The compressive strength values for 5%, 10%, 15% and 20% replacement of sand with PET at 28-day were 29.70N/mm2 , 25.95N/mm2 , 24.28N/mm2 and 23.23N/mm2 respectively. When compared with the control concrete specimens with an average value of 33.08N/mm2 gave 11.38%, 27.48%, 36.24% and 42.40% reduction in strength respectively. It was recommended that, though, the use of PET aggregate in the production of concrete does not have significant appreciable effect on the concrete strength, its use will protect the environment and as well help to conserve natural resources used as materials in production of concrete elements which currently undergo excessive depletion.

Experimental Investigation and Flexural behavior of Reinforced Geo polymer Concrete Beam by RCA

This research report presents the study on material characteristics of GPC by using natural aggregate and Recycled Coarse Aggregate. Experiments were conducted on the effect of variation of alkaline solution and different molarities on the mechanical properties of GPC. The alkaline liquid used for the present study was sodium silicate and sodium hydroxide solution with varying ratios of 2, 2.5 and 3. The molarities chosen for the sodiumhydroxidesolutionwere8M, 10Mand14M.Thetestspecimenswere150mmsizecubesand100x200mmcylindersheat-cured at 60 Cinanoven. The compressive strength was about 18to39 MP a and split tensile strength was in the range of3to3.8MParespectively.In this investigation on GPC using RCA, a total of 9 mixes were cast and tested, out of which three were conventional concrete mixes and six GPC mixes having varying combinations of fly ash, GGBS and RCA. The test specimens were 100mm size cubesand100x200mmcylinderscuredat90°Cinanovenfor18hours.Furthsize 150mm GPC cube specimens were cured at ambient temperature conditions. The studies showed that the compressive strength and spilt tensile strength of different mixes decreased with the increase in the percentage of recycled coarse aggregates.

Influence of early age loading on compressive strength of M25 fly ash concrete

In this study, the influence of early age loading on compressive strength of fly ash concrete is investigated. M25 grade fly ash concrete with w/c of 0.45 and 30% replacement of cement by class ‘F’ fly ash is considered. Early age loads of nearly about 70%, 80% and 90% of compressive strengths corresponding to 1-day, 3-day and 7-day aged specimens are determined by testing a set of nine cube specimens initially. Later these loads are applied on a total of thirty six cube specimens of respective ages to find out the effect on 28-day compressive strength. From the obtained results it is observed that the 28-day compressive strength of 1-day, 3-day and 7-day aged fly ash concrete specimens increased for 70% and 80% early loading in comparison to the non-early loaded specimens. However reduction of strength is noticed in the case of 90% early loaded specimens irrespective of age.

A Study On the Hardened Properties of M25 Grade Concrete Using Carbon Fibers and Its Evaluation by NDT

Concrete is a mixture of cement, fine aggregate, coarse aggregate and water. concrete plays a vital role in the development of infrastructure buildings, industrial structures, bridges and highways etc. Leading to utilization of large quantity of concrete.The present project focuses on investigating characteristics of M25 grade concrete is choosen and aggregate mean size of 20mm is adopted Carbon fibers are added by 1% to the weight of cement.. It leads to examine the admixtures to improve the performance of concrete. The cubes, beams and cylinders are tested for both compressive, flexural, Concrete Core test, youngs-modulus strength tests were conducted for 7, 28, 56, 90 days and the results are compared to the conventional concrete. ND-Tests like rebound hammer and ultra-sonic pulse velocity were conducted. Cube specimens of size 150 mm, cylinder specimens of diameter 150,100 mm and height 300,150 mm respectively, beam specimens of size 100 mm and length 500 mm were casted.

Damage identification in concrete under impact loading at varying temperatures using voltage strain relations technique: an experimental and numerical study

Impact-loaded concrete structures cause severe and rapid damage, resulting in significant property and human life loss. As the temperature rises, the damage caused by impact loading becomes increasingly severe. Concrete structures need structural health monitoring (SHM) to avoid this damage and loss. In this study, the voltage strain relation technique was used to identify the damaged state of concrete under impact loads at various temperature conditions experimentally and numerically. For this purpose, an experimental study was performed on concrete cube specimens in which different piezo configurations (surface bonded, non-bonded, and jacketed) were installed to acquire the voltage data. Before applying an impact load to the top surface of the concrete specimen, it was preheated at 50 °C, 100 °C, and 150 °C to provide the temperature effect, and then a free-falling iron ball was dropped from 3 m heights on the top of the specimens. Furthermore, finite element analysis has been carried out to validate the experimental results with analytical results. The experimental results show that the voltage strain relation technique is well capable of detecting the damage in concrete under the temperature and impact loading conditions. The maximum absolute voltage value (Vp) of 17.11 V was recorded for the jacketed sensors under an impact height of 3 m at 100 °C. All the piezo sensor configurations are capable of finding the damage. Jacketed sensors are more efficient in the health assessment of concrete in terms of voltage strain relations. In terms of strain values, the analytical results are in good agreement with the experimental results.

Evaluation of Early Concrete Damage Caused by Chloride-Induced Steel Corrosion Using a Deep Learning Approach Based on RNN for Ultrasonic Pulse Waves.

The objective of this study is to explore the feasibility of using ultrasonic pulse wave measurements as an early detection method for corrosion-induced concrete damages. A series of experiments are conducted using concrete cube specimens, at a size of 200 mm, with a reinforcing steel bar (rebar) embedded in the center. The main variables include the water-to-cement ratio of the concrete (0.4, 0.5, and 0.6), the diameter of the rebar (10 mm, 13 mm, 19 mm, and 22 mm), and the corrosion level (ranging from 0% to 20% depending on rebar diameter). The impressed current technique is used to accelerate corrosion of rebars in concrete immersed in a 3% NaCl solution. Ultrasonic pulse waves are collected from the concrete specimens using a pair of 50 kHz P-wave transducers in the through-transmission configuration before and after the accelerated corrosion test. Deep learning techniques, specifically three recurrent neural network (RNN) models (long short-term memory, gated recurrent unit, and bidirectional long short-term memory), are utilized to develop a classification model for early detection of concrete damage due to rebar corrosion. The performance of the RNN models is compared to conventional ultrasonic testing parameters, namely ultrasonic pulse velocity and signal consistency. The results demonstrate that the RNN method outperforms the other two methods. Among the RNN methods, the bidirectional long short-term memory RNN model had the best performance, achieving an accuracy of 74% and a Cohen's kappa coefficient of 0.48. This study establishes the potentiality of utilizing deep learning of ultrasonic pulse waves with RNN models for early detection of concrete damage associated with steel corrosion.

Effect of Using Glass Fiber Reinforced Polymer (GFRP) and Deformed Steel Bars on the Bonding Behavior of Lightweight Foamed Concrete

The study aims to conduct a direct pull-out test on fifty-four cube specimens considering different variables, including the type of reinforcement (sand-coated glass fiber-reinforced polymer (GFRP) and ribbed steel bars); the type of concrete (normal weight concrete NWC and lightweight foamed concrete LWFC); the diameter of the reinforcing bars (10 mm; 12 mm; and 16 mm) and the bonded length (3∅, 4∅, and 5∅). The hybrid fiber hooked-end steel (0.4% by volume) and polypropylene (0.2% by volume), respectively were used to improve the properties of LWFC by converting the brittle failure to ductile. The results showed that in the case of strengthened foamed concrete (FC), the bond strength with steel bars was greater compared to that with the GFRP bars. The bond strength ratio between the GFRP and steel bars of the FC specimens was found to vary between 37.8–89.3%. Additionally, in all specimens of FC, pull-out failure was witnessed with narrower crack width compared to NWC. Furthermore, mathematical equations have been proposed for predicting the bond strength of FC with steel and GFRP bars and showed good correlation with the experimental results.