Dynamic Properties Of Concrete Research Articles

Effect of Graphene Quantum Dots (GQDs) on the mechanical, dynamic, and durability properties of concrete

Addressing ecological concerns stemming from concrete usage is paramount, prompting exploration into additives for mitigation. Graphene quantum dots (GQDs) have been recognized for their potential to improve the mechanical attributes of cement composites. Additionally, the electrochemical reduction of a saturated solution of carbon dioxide (CO2) and monoethanolamine (CO2-MEA) effectively removes CO2 from the atmosphere. This study delves into the influence of GQDs on the mechanical and durability aspects of concrete. It is noted that the control mix of concrete without GQDs was specifically designed for concrete railway sleepers. Varied proportions of GQDs, ranging from 0.3 % to 1.2 % at 0.3 % increments, were incorporated to assess their impact on fresh and hardened concrete properties. Mechanical properties such as compressive strength, splitting tensile strength, flexural strength, and dynamic properties were evaluated. Durability assessments encompassing water absorption and chloride ion penetration were conducted. Microstructural analysis via Field Emission Scanning Electron Microscopy (FESEM) imaging and Energy-dispersive X-ray spectroscopy (EDS) elucidated the concrete's internal composition. Notably, an optimal GQDs percentage of 0.3 % was observed, signifying its efficacy in enhancing the performance of concrete. When 0.3 % of GQDs was added to concrete, compressive strength, split tensile strength, and flexural strength were enhanced by 10.8 %, 23 %, and 11 % respectively. The incorporation of GQDs resulted in a notable improvement in the fundamental frequencies and dynamic modulus of elasticity. Concurrently, a decrease in the damping ratio was observed for specimens containing GQDs. Additionally, the porosity and chloride penetration depth were lower by 6 % and 30 % for specimens with 0.3 % GQDs. The improvement in workability, mechanical, and dynamic properties of concrete, along with reducing CO2 from the atmosphere, makes GQDs an ideal eco-friendly material. This study is the first to open new pathways for the development of construction materials that are not only structurally superior but also environmentally responsible, marking a significant step forward in the field of civil engineering materials, especially in railway applications.

Overview of the Influence of Static Water Saturation on The Mechanical Properties of Concrete

This paper reviews a series of experimental and theoretical research results on the influence of existing pore water on the static and dynamic properties of concrete. This paper summarizes the current experimental research methods and conclusions, analyzes the influence mechanism of moisture content and loading speed on the elastic modulus and strength of concrete, and points out that the influence of pore water on concrete properties should be the result of the joint action of multiple factors.

Study on the Dynamic Properties of Concrete under Freeze-Thaw Cycles and CT Fine View Damage

In order to study the dynamic mechanical properties of concrete under freeze-thaw cycles, uniaxial impact compression tests were conducted on concrete specimens with different number of freeze-thaw cycles (0, 25, 50, 75, and 100) using a 50 mm diameter split Hopkinson pressure bar (SHPB) test device at an impact air pressure of 0.4 MPa and combined with a CT scanning system to analyze the internal fissures of concrete specimens before and after freeze-thaw cycles. The results showed the following. (1) The concrete specimens were divided into linear elastic stage, plastic stage, and damage stage under the freeze-thaw cycle, and the macroscopic mechanical parameters of the specimens were weakened with the increase of the number of freeze-thaw cycles. (2) Freeze-thaw intensified the expansion and penetration of the internal fracture of the specimens, and the CT scan results showed that the internal fracture parameters of the concrete specimens were increased with the increase of the number of freeze-thaw cycles, and the structural characteristics of the internal fracture show gradually complex expansion and evolution characteristics. (3) The degree of damage was defined at the fine level, which increased with the number of freeze-thaw cycles, establishing an intrinsic link between the fine deterioration of concrete specimens and the loss of macroscopic parameters under freeze-thaw cycles. The results are of great significance to further elucidate the internal structural characteristics of concrete material damage under freeze-thaw conditions and to reveal the damage deterioration mechanism.

Effects of Coating Aggregates on Dynamic Properties of Concrete by Impact Resonance Method

Concrete structures may be subjected to dynamic loadings like earthquakes, impact, and vehicular loads. These loads may cause considerable damage to infrastructures and shorten their life span. To reduce the effects, improving concrete’s dynamic properties is important. This can be done using granular elastic components and fibers in the production of concrete. This research explores the influence of using coated aggregates on the physical, mechanical, and dynamic properties of concrete. Experimental investigation on concrete with epoxy, epoxy-sand, and epoxy-crumb rubber as a partial replacement of coarse aggregates at different volume fractions ranging from 5% to 20% was conducted. Furthermore, the dynamic modulus of elasticity of concrete with coated aggregate was determined by measuring the resonant frequencies of flexural vibrations in a prismatic beam using an impactor (hammer). Results indicate that partial replacement of epoxy-crumb rubber coated aggregates in concrete shows a reduction in mechanical proprieties. However, significant improvements in the mechanical and dynamic properties of concrete were observed by the partial replacement of coarse aggregates with epoxy and epoxy-sand coated aggregates. Compressive strength and dynamic elastic modulus were enhanced by 12% and 10%, respectively, when concrete with 15% epoxy-sand coated was used. The results showed that concrete specimens using epoxy and epoxy-sand coated as a partial replacement for coarse aggregate have higher mechanical properties as compared to those of concrete specimens with epoxy-crumb rubber-coated aggregates. Moreover, the results showed that the calculated values of the dynamic modulus of concrete using the empirical relations proposed by Popovics and Hansen were overestimated as compared to the experimental values.

Investigation of the dynamic compressive mechanical properties of concrete under the combined effects of freeze–thaw and salt erosion

The objective of this study is to investigate the dynamic compressive mechanical properties of concrete under the combined effects of freeze–thaw (F-T) and salt erosion. The Split Hopkinson Pressure Bar (SHPB) test system was employed to conduct dynamic compression tests on concrete specimens subjected to 0 ∼ 250 cycles of F-T in NaCl solutions with concentrations ranging from 0 % to 8 %. The influence of strain rate, F-T cycles, and chloride concentration on the dynamic properties of concrete were analyzed, and a constitutive model considering rate-dependency was developed to describe its compressive mechanical response. The research findings suggest that the dynamic compressive strength of concrete gradually increases with an increase in strain rate, indicating a strengthening effect due to higher strain rates. Additionally, the dynamic growth factor exhibits an exponential relationship with the logarithm of strain rate. Moreover, an increase in the number of F-T cycles results in a gradual reduction in the dynamic compressive strength of concrete and an accompanying increase in specimen fracture. Furthermore, the dynamic compressive strength of concrete exhibits a non-linear trend concerning chloride solution concentration: initially decreasing and subsequently increasing. The minimum compressive strength is observed at a concentration of 3.5 %, indicating the most severe damage to the concrete. However, it should be noted that a higher strain rate mitigates the influence of chloride solution concentration on specimen breakage. To comprehensively understand the mechanical behavior of concrete under combined F-T and salt erosion effects, we propose a dynamic constitutive model based on established mechanical and damage theories relevant to composite materials. The experimental results demonstrate that the proposed model effectively captures the mechanical response of concrete subjected to the combined influence of F-T and salt erosion.

PROPERTIES OF CONCRETE WITH COATED AGGREGATES UNDER DIFFERENT LOADING CONDITIONS

Properties of concrete can be improved using different coating materials and chemicals. Some of the materials, however, are not effective as there is a weak bond between the coarse aggregate and the cement mortar. Hence, in this research, the mechanical and dynamic properties of concrete with epoxy resin, epoxy-sand and silicon coated aggregates at different volume fractions ranging from 5 to 15 percent were experimentally investigated. The test results indicate that there are improvements in compressive strength of concrete ranging from 10 % to 18 %, in which a maximum strength was achieved by using 15 percent epoxy-sand coating. Furthermore, a 5 % epoxy resin coating, resulting in an increase in compressive and tensile strengths of concrete by 5% and there are enhancements in static and dynamic modulus of elasticity by 2.7 %. In general, concrete specimens made with aggregates coated with epoxy-sand have higher performance in compressive strength as compared to using aggregates epoxy and silicon coated aggregates. Based on the findings of this study, it is recommended that coating of coarse aggregates with epoxy and epoxy-sand can be used as an alternative building and construction material to enhance the mechanical and dynamic properties of concrete.

Effect of nano-SiO2 and nano-CaCO3 on the static and dynamic properties of concrete

Three kinds of nano-concrete, i.e., 2.0% nano-SiO2 doped, 2.0% nano-CaCO3 doped and 1.0% nano-SiO2-1.0% nano-CaCO3 co-doped concretes (NS, NC, NSC) were prepared for a study on static property and dynamic property under different strain rates (50–130 s−1) using HYY series hydraulic servo test system and Φ100 mm split Hopkinson pressure bar test system, and a comparison with plain concrete (PC) as well. The results have shown that under static load, as compared with PC, NC has both strength and elastic modulus increased obviously, while NS has strength decreased and elastic modulus increased, and under dynamic load, there is an obvious strain rate effect for the dynamic compressive strength, impact toughness, energy dissipation and impact failure mode of concrete. Under the same strain rate, the dynamic compressive strength, peak strain, impact toughness and energy dissipation of NC are significantly increased, while its dynamic elastic modulus is decreased. Compared with PC, NS has dynamic compressive strength, peak strain, impact toughness and energy dissipation decreased, and dynamic elastic modulus increased, NC has static and dynamic mechanical properties improved, NS has static and dynamic mechanical properties weakened, and NSC is between PC and NC in static and dynamic mechanical properties, but generally improved. Doped with nano-CaCO3, NC has compactness improved, weak areas reduced, and pore size distribution optimized, while doped with nano-SiO2, NS has obvious internal weak areas, with pore structure degraded.

Influence of boron carbide and calcium carbonate on static and dynamic properties of concrete

Static and dynamic characteristics of 3 sort of nano-concrete, 2.0 % nano-B4C, 2.0 % nano-CaCO3, and 2.0 % nano-B4C –1.0 % nano-CaCO3 co-doped concretes, were studied using a 100-mm split Hopkinson pressure bar (SHPB) testing system. There is a clear strain rate consequence for concrete's dynamic compressive strength (DCS) and impact toughness (IT) and energy dissipation (ED) as well as affect failure mode, as shown by the results, which reveal that NC is stronger and has a greater elastic modulus than PC under static load. Even though NC's dynamic elastic modulus increases while its dynamic compressive properties and peak strain all reduction at the same strain rate. There are no significant differences between NS and PC in terms of DCS, peak strain (PS), IT and ED. But whereas NC's static and dynamic mechanical characteristics declined, NSC's are roughly in the middle between PC's and NC, but it has seen an uptick. Nano-CaCO3 has enhanced compactness, decreased weak areas and optimized pore size distribution, whereas nano-B4C has evident internal weak areas and destroyed pore structure.

Calculating Dynamic Strengths of Concrete Subjected to Impact Load

The objective of this paper is to calculate the influential properties of concrete. These are the dynamic properties of sustainable concrete in the situation in which metal waste can found within its components. Growing the rate of pollution in the world, a fast decrease of the original resource, the requirement for utilization more areas of natural land, and increase the price of the newly available area are the reasons that make the researchers give great attention to the new concrete (green concrete) and destruction of unwanted material in the green mix. The concept of reuse aimed at sustainable structures was implemented within the current paper through consuming metal waste of cans and bottle caps in concrete. The waste materials were consumed in two modes; at 1stmode, it was applied in the role of fibres and mixed using 15% by weight of cement. On the 2ndmode, it was applied as coarse aggregate with 25% replaced by volume. The procedure includes testing 4 concrete mixes. The estimated properties were the flexural and compressive strengths, besides modulus of elasticity. Adding bottle caps (waste materials fibres) in concrete led to enhancement in strengths. The use of walls of cans (waste materials fibres) in concrete reduced the strengths. While in the case of compacted bottle caps plus pull-tab of cans (waste materials aggregate), concrete mechanical properties a little below the reference mix. The dynamic properties of concrete contain these types of waste under impact load were determined. As known, the dynamic properties are so helpful in the strategy that deals with civil constructions put in danger of impact loads like runways, gas explosion, etc. CEB-FIP (2010) code provides wide-ranging formulas to predict the strain change of concrete. The dynamic properties are determined by this code with consideration strain level between (10-2-100). In this range, dynamic loads in the civil constructions at the level of quasi-static strain were predicted.

Effects of Saturation Levels on the Ultrasonic Pulse Velocities and Mechanical Properties of Concrete.

The main objective of this research is to investigate the effect of water content in concrete on the velocities of ultrasonic waves (P- and S-waves) and mechanical properties (elastic modulus and compressive strength) of concrete. For this study, concrete specimens (100 mm × 200 mm cylinders) were fabricated with three different water-to-binder ratios (0.52, 0.35, and 0.26). These cylinders were then submerged in water to be saturated in different degrees from 25% to 100% with an interval of 25% saturation. Another set of cylinders was also oven-dried to represent the dry condition. The dynamic properties of concrete were then assessed using a measurement of elastic wave accordance with ASTM C597-16 and using resonance tests following ASTM C215-19, before and after immersion in water. The static properties of saturated concrete were also assessed by the uniaxial compressive testing according to ASTM C39/C39M-20 and ASTM C469/C469M-14. It was observed that the saturation level of concrete affected the two ultrasonic wave velocities and the two static mechanical properties of concrete in various ways. The relationship between P-wave velocity and compressive strength of concrete was highly sensitive to saturation condition of concrete. In contrast, S-wave velocity of concrete was closely correlated with compressive strength of concrete, which was much less sensitive to water saturation level compared to P-wave velocity of concrete. Finally, it was noticed that water saturation condition only little affects the relationship between the dynamic and elastic moduli of elasticity of concrete studies in this study.

Effect of Jute Fibre Orientation and Percentage on Strength of Jute Fibre Reinforced Concrete

The demerits of plain concrete are its lesser tensile strength, not significant ductility and poor resistance to cracking. Due to propagation of internal micro cracks in plain concrete causes decrease in tensile strength, hence leads concrete to brittle fracture. Addition of fibres behaves like crack arrester and enhances the dynamic properties of concrete. In India natural fibres such as bamboo, coir, jute, sisal, pineapple, banana, ramie etc are high available. Jute is a useful natural fibre for concrete reinforcement due to its easy availability and low cost. In this research, the experiments related to Jute fibre reinforced concrete (JFRC) are done by taking different fibre percentage and the compressive strength and modulus of rapture value observed. This JFRC can replace plain concrete and wood in many cases for example in door and window panels, inclined roof slabs, partition walls etc

Evolution of the dynamic properties of concrete in a sulfate environment

The effects of sulfate solution concentrations, erosion form, and erosion age on the dynamic properties of concrete were investigated. A novel methodology for determining the damping ratio of concrete was proposed based on the enveloping curve of the waveform amplitude. Moreover, variations in the dynamic properties of concrete attacked by sulfate were analysed. The results indicated that the sulfate solution concentration, erosion form, and erosion age had significant effects on the dynamic properties of concrete. With an increase in the sulfate solution concentration, the dynamic elasticity modulus of concrete first increased and then decreased, until it finally stabilized. Although the change trends in the relative dynamic elasticity modulus of concrete specimens with different strengths attacked by sulfate were similar, the corresponding degree of variation decreased with an increase in the strength of the concrete. With the partial immersion form in which the sulfate attacked, the dynamic elasticity modulus of the concrete increased with an increasing sulfate solution concentration but decreased with an increase in the concrete strength. The vibration of waves in concrete gradually decayed until it disappeared, and the wave curve could be represented by a cosine function. The damping ratio of concrete was deduced from the different forms of segmented time or the difference in the accumulations of initial time, which was caused by varying decay rates. The attenuation coefficient of the waveform in concrete increased with an increase in the sulfate solution concentration and erosion age and decreased with an increase in the concrete strength.

Influence of silica fume on the dynamic properties of concrete

Ultrasonic pulse velocity and resonance frequency methods are non-destructive tests that allow the evaluation and control of building materials. They have been used to determine the dynamic properties of concrete, which are used in the design and control of structures and which are the key elements of the dynamics of materials. In this study, we chose a non-destructive approach to quantify -in laboratory-, the influence of adding “silica fume” on ordinary concrete’s dynamic characteristics. However, several concrete mixtures have been prepared with limestone aggregates. The experimental plan used, allowed us to determine the dynamic elasticity modulus and the dynamic rigidity modulus of different formulated concretes.

Influence of silica fume on the dynamic properties of concrete

Ultrasonic pulse velocity and resonance frequency methods are non-destructive tests that allow the evaluation and control of building materials. They have been used to determine the dynamic properties of concrete, which are used in the design and control of structures and which are the key elements of the dynamics of materials. In this study, we chose a non-destructive approach to quantify -in laboratory- the influence of adding silica fume on ordinary concrete’s dynamic characteristics. However, several concrete mixtures have been prepared with limestone aggregates. The experimental plan used, allowed us to determine the dynamic elasticity modulus and the dynamic rigidity modulus of different formulated concretes.

Experimental Assessment Techniques for the Dynamic Properties of Concrete

Recent progress in measurement techniques have given rise to increasing interest in non-destructive testing. Incorporating non-conventional, recycled materials in concrete (i.e. rubber crumbs from discarded tires), the heterogeneity is increased. Based on this, it is of importance to determine to what degree the accepted protocols, valid for traditional materials, are applicable to newly developed construction materials with particular interest to rubberized concrete. Several tests, including parameters missing from the standardized measurement techniques, such as the increasing rate of the frequency during the sweep for finding the resonant frequency of the specimen, were conducted on two types of concrete: traditional and rubberized concrete. The assessment of the dynamic properties was done by means of the forced vibration method and the impact method. The obtained results indicate the fact that current procedures should be applied with care when considering aggregate replacement in traditional concrete by other recycled materials.

Dynamic Properties of Concrete at Moderately Elevated Temperatures

Reinforced concrete is widely used to not only provide structural support but also to mitigate the effects of radiation, malevolent attacks, and dynamic accidents. Dynamic tests were performed on 102 x 203 mm (4 x 8 in.) normal weight concrete (NWC) and fiber-reinforced concrete (FRC) cylinders using a drop hammer. Dynamic splitting tension and dynamic compression tests were performed at room temperature and at 204°C (400°F). The dynamic increase factor (DIF), which is the ratio of dynamic to quasi-static strength, and the strain rate were compared to existing models. The DIF for tension and compression increased with strain rate. For compression, a DIF up to 3.2 was recorded for strain rates up to 12 s⁻¹. For tension, a DIF up to 4.1 was recorded for strain rates up to 1.8 s⁻¹. Heated NWC and FRC specimens had lower DIFs compared to room-temperature specimens for dynamic compression and tension. The experimental DIFs followed closely the Modified Comite Euro-International du Beton (CEB) model for tension.

Influence of the Supplementary Cementitious Materials on the Dynamic Properties of Concrete

The resonance frequency method is one of many non-destructive tests which allow us to evaluate construction materials. It was used to determine the dynamic properties of concrete, required in structures design and control, also considered as the key elements for materials dynamic. In this study, we chose a non-destructive approach to quantify-in laboratory-, the influence of adding “crushed limestone” and “natural pozzolan” on local concrete’s dynamic characteristics. However, several concrete mixtures have been prepared with limestone aggregates. The experimental used plan, allowed us to determine the dynamic modulus of elasticity, the dynamic modulus of rigidity of different formulated concretes.

Relationships between Resonant Frequency and some Dynamic Properties of Marble and Brick Waste-Substituted Concrete

The present research determines the relationships between resonant frequency and some dynamic properties of concrete. Based on the research, new relationship equations are offered. The resonant frequency method is used to measure the resonant frequency of concrete samples from which a dynamic module of elasticity, a dynamic ratio of Poisson, and a dynamic module of shear are computed. Marble or brick waste substituted concrete in samples with water-cement ratios of 0.60 and 0.70 are cured in water and measured at 90 days.

The influence of sulfate attack on the dynamic properties of concrete column

Concrete structures in service may be suffer from sulfate attack, which may lead to the deterioration of both static and dynamic properties of concrete, and therefore jeopardize their performance in earthquake events. To predict the seismic performance of sulfate-damaged concrete structures, the rate-dependent strength, deformation behavior and energy absorption capacity of concrete specimens under sulfate attack were investigated. First, half of the specimens were initially cured under sulfate attack for 4 months and the other half of the specimens were cured in a room environment for comparison. Then axial compressive experiments for concrete specimens with different strain rates were carried out. Experimental results show that sulfate attack had a significant impact on the dynamic properties of concrete. Sulfate attack makes concrete strength more sensitive to strain rate. With increasing strain rates, the peak strain and energy absorption capacity of control and sulfate attacked concrete tend to increase, but they are greatly decreased by disruptive expansion and chemical deterioration induced by sulfate attack. Finally, the failure phenomenon was shown and the damage mechanism of specimens was discussed.

Effect of steel and carbon fiber additions on the dynamic properties of concrete containing silica fume

Fiber reinforced concretes (FRC) are technologically important due to their combination of good structural properties, durability and multifunctional properties. The behavior of a structure under dynamic actions is determined by its dynamic mechanical properties and its total overall damping. In this work the influence of the steel fiber (SF) and carbon fiber (CF) additions on the mechanical properties of concrete containing silica fume has been studied, focusing on its passive material damping ability (damping ratio) and dynamic properties. According to the obtained results, under dynamic loads of low magnitude and high frequency, CF additions are more effective than SF additions for reducing vibrations, as they increase the damping ratio of concrete. In all cases, the dynamic elastic properties of concrete present higher values than their static counterparts. Both CF and SF additions lead to slight decreases of the compressive strength of concrete. For the same volumetric fraction, this fact is more significant in the concrete types containing SF.