Engineered Cementitious Composites Specimens Research Articles

Effects of silica fume and zeolite on the durability of engineered cementitious composite containing limestone powder and blast furnace slag in a magnesium sulphate medium

ABSTRACT Engineered cementitious composite (ECC) is a highly ductile high-performance fibre-reinforced cementitious composite whose design, mixing ratios and other important parameters can be optimised using the theory of micromechanics. This study investigated the effects of different quantities of silica fume and zeolite on the mechanical properties and durability of ECC specimens containing lime stone powder and blast furnace slag when treated in the 5% magnesium sulphate solution at 28, 150, 180 and 210 days of age. The results obtained showed that the compression strengths in lab environment were enhanced up to 25% at the age of 150 days by increasing the silica fume content of the ECC, whereas the modulus of rupture (MOR) and mid-span deflection (MSD) were decreased in all the specimens tested. Meanwhile, a 17% increment in blast furnace slag content was observed to enhance both MSD and MOR at all ages, e.g. it causes 23% increase in MSD and 9% increase in MOR at the age of 28 days. In addition, a 46% increase in lime stone powder content was found to increase compressive strength but to reduce MOR by 7% and 8% at the age of 28 days, respectively.

Experimental study on bond durability of GFRP bar/engineered cementitious composite exposed to freeze-thaw environments

Glass fiber reinforced polymer (GFRP) bars and engineered cementitious composites (ECC) present better structural performance as compared to conventional concrete with reinforcing steel bars. However, the bond behavior of the GFRP bar to ECC matrix under freeze-thaw (FT) cycles in cold climates remains underexplored. Therefore, this study aims to investigate the bond durability of GFRP bars and ECC under FT conditions. An experiment was conducted with 33 pullout specimens, categorized according to concrete types (normal concrete and ECC), compressive strengths (30 MPa and 50 MPa) and the number of FT cycles (0, 100, 150, and 200 cycles). Assessment parameters included surface degradation, failure modes, mean bond strength, weight loss, and the relative dynamic modulus of elasticity. Results indicated ECC specimens exhibited greater durability compared to normal concrete specimens, with no significant improvement in durability observed with increased compressive strength. Specifically, the mean bond strengths of N30 (30 MPa normal concrete) specimens, E30 (30 MPa ECC) specimens, and E50 (50 MPa ECC) specimens decreased by 88.41 %, 38.86 %, and 58.21 % after 150 FT cycles, respectively. Failure modes correlated strongly with concrete type and the number of FT cycles. SEM and composition analyses revealed the effects of FT cycles on the concrete matrix, the bond interface, and the GFRP bars. The ascending branches in the bond stress-slip curves of specimens subjected to FT cycles were effectively modeled using Malvar's model. Based on the declining relative dynamic modulus of elasticity and the correlation between laboratory and natural FT cycles, the estimated fatigue lives for GFRP bar/E30 specimens subjected to 250 FT cycles are 35.7, 71.4, and 46.2 years in Beijing, Detroit, and Vancouver, respectively. This research provides insights on GFRP bar/ECC's longevity in practical engineering contexts.

Shear behavior of low-cost and sustainable bio-fiber based engineered cementitious composite beams –experimental and theoretical studies

The design of reinforced concrete (RC) members subjected to shear dominant loading is complex due to their quasi-brittle failure nature. Hence, a highly ductile material as a replacement for conventional concrete is essential to perform well under shear loading. Engineered Cementitious Composite (ECC) is one such material designed based on micromechanical theory for achieving a high strain capacity of about 3%. The objective of the proposed research work is to develop a cost-effective ECC using bio-based natural fibers such as flax, hemp, kenaf, and pineapple for achieving a large strain levels under shear dominant loading. The test program consists of different ECC specimens with (a) 2.0% flax fiber, (b) 2.0% hemp fiber, (c) 2.0% kenaf fiber, and (d) 2.0% pineapple fiber. In addition, the ultimate shear capacity of natural fiber-based ECC beams are estimated theoretically using the AIJ method and the results are compared with the tests and FE predictions. Test results revealed that the use of flax fibers in ECC beams was highly effective in enhancing the ultimate load through an excellent crack-bridging mechanism when compared to the other natural fiber types. Also, the ultimate load predictions from analytical calculations matched well with the test results.

Peridynamic study of fatigue failure of engineered cementitious composites

Fatigue crack propagation is crucial in studying fatigue in engineered cementitious composites (ECC). This paper established a peridynamics (PD)-based fatigue crack propagation model for ECC, incorporating the “cycle broken bonds number” to enhance calculation efficiency. First, the PD fatigue crack propagation model was constructed, and the validity of the model was verified by simulating the fatigue crack propagation path of an inclined edge crack in the plate. Secondly, an improved PMB model considering the strain softening stage was used to model the ECC cement matrix, and the fibers were modeled as one-dimensional cyclic dynamic rods to establish a PD fully discrete model of ECC. At the same time, an interface exponential friction attenuation model was introduced. Then, the effectiveness and validness of the fully discrete model were verified by simulating single fiber pull-out tests and uniaxial tensile tests of ECC specimens. Finally, the fatigue crack propagation forms of ECC beams with mid span Type I cracks under three-point bending fatigue loads were studied, and the effects of fiber volume fraction, stress level, and fiber length on the crack propagation forms and structural deflection of ECC beams under four-point bending fatigue loads were investigated.

Bond behavior between steel-FRP composite bars and engineered cementitious composites in pullout conditions

Steel-FRP composite bar (SFCB) reinforced engineered cementitious composites (ECC) members are promising to apply in structural engineering due to their excellent mechanical properties and durability. The bond behavior between SFCB and ECC was investigated by direct pullout tests. The experimental variables included the diameter of SFCB, bond length, type of matrix, compressive and tensile strengths of ECC, and type of reinforcement. All ECC specimens failed in a ductile manner with ECC keys being crushed and sheared off. The bond strength and bond toughness of ECC specimens were higher than those of concrete specimens possessing similar compressive strengths. An interfacial bond-slip model was proposed to predict the bond behavior of SFCB embedded in ECC. An iteration procedure was performed utilizing the developed bond-slip model to analyze the distributions of bond stresses and slips. Notably, an increase in bond length and the yielding of SFCB led to heightened non-uniformity in bond stress and slip distributions. Furthermore, equations were derived to predict the embedment lengths of SFCB applicable to various scenarios.

Influence of Fiber Orientation on the Water and Ions Transportation of Engineered Cementitious Composite (ECC).

An engineered cementitious composite (ECC) belongs to a type of high-performance fiber-reinforced materials. Fiber alignment causes the anisotropy of such materials. Herein, the influence of the fiber orientation on water and ion penetration into an ECC was studied. Fiber alignment was achieved using an extrusion approach. Water absorption, sorptivity, chloride penetration resistance, sulfate attack resistance, and freezing-thawing resistance of specimens with fiber aligned horizontally (AH), vertically (AV), and randomly (R), corresponding to the direction of the exposure surface that was studied. The results showed that fibers oriented perpendicular to the water path delayed water migration into the ECC matrix. The sorptivity was significantly affected by the fiber direction. The sorptivity of the AH specimens was 35% and 13% lower than that of the AV and R specimens, respectively. After 180 days of exposure, the chloride penetration depth of the AH specimens was 5.7 mm, which is 13.6% and 20.8% lower than that of the AV and R specimens, respectively. The sulfate ingress profile indicates that the fiber-matrix interface oriented perpendicular to the penetration path can effectively delay sulfate migration. The fiber orientation also influences the compressive strength gain under immersion conditions (Na2SO4 solution, Na2SO4 + NaCl solution, and water). Compared with the AH and R specimens, the AV specimens are more sensitive to the immersion condition. In contrast, the fiber orientation has no significant effect on ECC specimens under freeze-thaw cycles. These findings indicate that controlling the fiber alignment and orientation in an ECC can improve its durability under certain exposure conditions.

Impact of low temperature and NaCl attack on the fracture properties of engineered cementitious composites (ECC)

Engineered cementitious composites (ECC) is a potential reinforcement and repair material for hydraulic structures due to its excellent mechanical properties. However, the fracture properties of ECC under the coupling effect of low temperature and chloride ions attack are still unclear. In this study, fracture experiments were performed on ECC specimens under different working conditions (immersed in water and NaCl solutions for different time (0, 30, 60, and 90d) and undergoing different freeze-thaw cycles (0, 25, 50, and 100 cycles) in NaCl solution) at experimental temperatures of 20 °C and −20 °C. The relationship between the depth of chloride ions erosion and the nominal fracture energy was analyzed. The effect of the coupled of temperature and chloride ions attack on the fracture performance of ECC under different working conditions was investigated. The results showed that: Under the loading condition of −20 °C, the fracture parameters of ECC under NaCl solution immersion were all lower than those of the water immersion group, indicating that extravasated chloride ions negatively impacted ECC's fracture properties. When ECC was loaded at −20 °C, the initiation fracture toughness and unstable fracture toughness of ECC under NaCl solution immersion were lower than those of the water immersion group, but the fracture energy was larger than that of the water immersion group, and when the specimens were immersed for 90 days, the drop in the fracture energy of ECC loaded at −20 °C compared to 20 °C for the NaCl solution immersion group was 59.1% less than 62.7% for the water immersion group; While loading at 20 °C revealed a linearly declining relationship between erosion depth and fracture energy, loading at −20 °C revealed no discernible pattern. The crack initiation fracture toughness of ECC gradually decreased with the increase of the freeze-thaw cycles, but the specimens' crack initiation fracture toughness following NaCl freezing at −20 °C was consistently larger than that at 20 °C. Following 100 freeze-thaw cycles on the specimens, the increase in initiation fracture toughness at −20 °C compared to 20 °C for the water freeze-thaw group was 128.4% less than that of the salt freeze-thaw group, which was 135.8%, while the decrease in fracture energy was 19.9% less than that of the salt freeze-thaw group, which was 46.3%. It shows that the repair effect of ice on ECC after NaCl freeze-thaw cycles is stronger than that of water freezing at the low temperature.

Pullout performance of headed anchor studs in Engineered Cementitious Composites (ECC) with Polyvinyl Alcohol fibers

To study the pull-out resistance of headed anchor studs in Engineered Cementitious Composites (ECC) for steel-ECC composite structures, pull-out tests were carried out on 9 scenarios of ECC specimens. The failure modes, load–displacement curves, peak load (Nu), initial stiffness (K0.3), and ultimate displacement (Du) of studs in Polyvinyl Alcohol fiber (PVA)-ECC under different stud sizes (d = 13 mm and 16 mm), stud embedment depths (hef = 40 mm, 60 mm, and 80 mm) and fiber content (Vf = 2.0% and 2.5%) were obtained. Failure modes include (ductile) concrete cone failure, cone-splitting combined failure, and steel failure. For the specimens with concrete cone, either increasing d or hef increases K0.3, Nu, and Du, and Nu shows the greatest improvement. Increasing fiber content (Vf) exerts a significant enhancing effect on Nu, but exerts little effect on K0.3 and Du. Through the comparisons to the pull-out resistance of studs in high-strength concrete (HSC), the studs in ECC show evident advantages in ductility, toughness, and Nu. Based on the experimental results, the applicability of the original CCD model and two modified CCD models from literature to studs in ECC is discussed. The modified CCD model including the effect of stud size and specimen size presents the best accuracy in predicting Nu of studs in ECC. Overall, ECC is a promising material for steel–concrete composite structures, considering it evidently improves the pull-out performance of studs, thus the anchorage between steel and ECC.

Engineering properties of sustainable engineered cementitious composites with recycled tyre polymer fibres

To lower the material cost and environmental impact of polyvinyl alcohol (PVA) fibre reinforced engineered cementitious composite (ECC), recycled tyre polymer (RTP) fibres were adopted to partially replace PVA fibres in ECC in this study, with an overall aim to develop sustainable ECC with RTP fibres without significantly affecting the engineering properties. A series of tests were conducted to investigate the effect of RTP fibre content on the engineering properties of ECC, with special focus on tensile strain-hardening behaviour and dynamic compressive behaviour. Results indicate that the incorporation of RTP fibres can improve the drying shrinkage resistance of PVA fibre reinforced ECC by 5–13% at 28 d while no positive influences are found on the workability and quasi-static compressive properties. There exists clear strain-hardening behaviour for all studied ECC mixes even when 50% of PVA fibre is substituted with RTP fibre. Based on the results of the micromechanical investigation, all mixtures satisfy the criteria for achieving a robust strain-hardening behaviour. All ECC specimens are characterised by a pronounced strain rate effect under dynamic compression and ECC incorporating RTP fibres shows a stronger sensitivity as opposed to ECC with 2.0% PVA fibre. The material cost and energy consumption of ECC are reduced by about 11–45% and 5–18%, respectively, when RTP fibres are present. This study proves the feasibility of utilising RTP fibres in ECC to improve its sustainability and maintain acceptable static and dynamic mechanical properties while the incorporated fibre volume fraction should be limited to 0.5%.

Micromechanics-based model of single crack propagation in Engineered cementitious composites (ECC)

Engineered Cementitious Composites (ECC) are composites exhibiting strain-hardening behavior accompanied by the formation of multiple cracks. A special feature of ECC is the ability to tune the material composition to meet the different needs of various structural components, which benefits from the special micromechanics-based design theory of ECC. However, these existing micromechanics-based design theories are specific to the case of direct tension and has not been fully discussed and developed for the case where the ECC is subjected to bending load. In this study, a micromechanics-based crack propagation model for ECC under bending load is developed to guide the design of flexural performance of ECC. The entire crack propagation process is simulated by considering the microstructure of ECC and the crack propagation criterion. For ECCs with different types of fiber, the simulated load-crack mouth opening displacement curves agree well with experimental results and the dispersion of the ECC specimens can be captured by imparting randomness to the model. Based on this model, parametric studies of several representative parameters are performed to illustrate the applicability of the model. The results indicate that the material has a higher ultimate flexural bearing capacity near a fiber aspect ratio of 448 for the given material property parameters; and the fiber/matrix bonding should not be excessively strong. Insights from this model can facilitate the design of ECC members with excellent bending properties through fiber tailoring and surface treatment.

SHRINKAGE BEHAVIOR OF AN ECO-FRIENDLY ENGINEERED CEMENTITIOUS COMPOSITE

The purpose of the present research is to assess the impact of foundry sand (FS) and cement kiln dust (CKD) on the autogenous shrinkage, drying and total shrinkage of engineered cementitious composites (ECCs) over 100 d. Additionally, the pore sizes and their distribution in the developed ECC system were assessed through the BJH adsorption technique. The findings showed that the pore structure was refined continuously over time. This indicates that the CKD-modified ECC mixes demonstrated decreased autogenous shrinkage at the early and later ages of the 100-d period, although the total shrinkage, developed during the later stages, was comparable to the CKD/FS mixes and conventional ECCs. Specimens with 30 % FS and 15 % CKD inclusions showed significantly fewer medium capillary holes and more gel pores. As the pores in a CKD-modified ECC system are smaller than in the traditional ECC, the modified ECC specimens are denser and show a lower loss of water.

Experimental Study on Toughness of Engineered Cementitious Composites with Desert Sand.

In this paper, engineered cementitious composites (ECCs) were prepared with desert sand instead of ordinary sand, and the toughness properties of the ECCs were studied. The particle size of the desert sand was 0.075-0.3 mm, which is defined as ultrafine sand. The ordinary sand was sieved into one control group with a size of 0.075-0.3 mm and three other reference groups. Together with the desert sand group, a total of five groups of ECC specimens were created. Through a uniaxial tensile test, three-point bending test and single-seam tensile test on the ECC specimens, the influence of aggregate particle size and sand type on the ECC tensile strength, deformation capacity, initial crack strength, cement-matrix-fracture toughness, multiple cracking characteristics and strain-hardening properties were studied. The experimental results show that the 28d tensile strain of the four groups of the ordinary sand specimens was 8.13%, 4.37%, 4.51% and 4.23%, respectively, which exceeded 2% and satisfied the requirements for the minimum strain of the ECCs. It is easier to achieve the ECC strain hardening with sand with a fine particle size; thus, a particle size below 0.3 mm is preferred when preparing the ECCs to achieve a high toughness. The multiple cracking performance (MCP) and the pseudostrain hardening (PSH) of desert sand and ordinary sand with a 0.075-0.3 mm grain size were 2.88 and 2.33, and 8.76 and 8.17, respectively, all of which meet the strength criteria and energy criteria and have similar properties. The tensile strength and tensile deformation of the desert sand group were 4.97 MPa and 6.78%, respectively, and the deformation capacity and strain-strengthening performance were outstanding. It is verified that it is feasible to use desert sand instead of ordinary sand to prepare the ECCs.

The effect of graphene nanoplatelet addition on the mechanical, durability and self-healing properties of engineered cementitious composites

Nanomaterial usage is an effective method to enhance the mechanical and durability properties of cementitious materials. Graphene Nanoplatelets (GNPs) are cost-efficient graphene-based nanomaterials that can exhibit graphene-like features. Although GNPs have been found to improve mechanical and durability properties, their effect on the self-healing behavior of cementitious materials, particularly Engineered Cementitious Composites (ECC), has not been examined in the literature studies. Therefore, this study aims to investigate the effects of GNP addition on mechanical, durability and self-healing behavior of ECC. During the study, the mechanical, durability, and self-healing characteristics of ECC with and without GNP were observed by using various mechanical and non-destructive test methods. Compression test, four-point bending test, resonance frequency test, ultrasonic pulse velocity test, sorptivity test, electrical impedance test and microscopic inspection were conducted. According to the test results, 0.05% GNP addition increased the compressive strength of ECC specimens. With the effect of GNP, first cracking strength, ultimate flexural strength and deformation values increased both for virgin and preloaded ECC specimens. The preloaded specimens with GNP performed similarly to virgin specimens under bending. The cracks of preloaded GNP specimens were either closed completely or extensively compared to control specimens. The crack numbers of GNP specimens after failure were also greater than that of control specimens. Accordingly, the flexural and self-healing behavior of the specimens improved with GNP addition. The effect of improvement by GNP addition was also evident in nondestructive tests. A considerable increment occurred in electrical resistance with GNP addition.

Behavior of Engineered Cementitious Composites (ECCs) Subjected to Coupled Sustained Flexural Load and Salt Frost

The performance of engineered cementitious composites (ECCs) under coupled salt freezing and loaded conditions is important for its application on the transportation infrastructure. However, in most of the studies, the specimens were generally loaded prior to the freezing. The influence of sustained load was merely considered. To this end, four sustained deflection levels, i.e., 0%, 10%, 30% and 50% of the deflection at the ultimate flexural strength, and three salt concentrations (1%, 3% and 5%) were applied. Prior to the salt frost resistance test, the fluid absorption of ECC specimens under various conditions were measured. The changes in relative dynamic elastic modulus (RDEM) during the freeze-thaw cycles were captured. The depth and the content profile of free chloride were measured after the coupled sustained load and freezing and thawing cycles. It is shown that 3% NaCl solution leads to the largest deterioration in all cases. There is no visible flaking or damage occurring on the surface. The relationships between locally sustained flexural stress and RDEM loss and also locally sustained flexural stress and free chloride penetration depth were proposed and showed satisfactory results. It is concluded that when ECC is subjected to the FTCs under 1% de-ice salt solution, no depassivation of the steel is expected even under a large deflection level. In terms of 3% and 5% salt solution, the thickness of cover should be no less than 20 mm when a deflection level of 0.5 is applied.

Performance of cost effective engineered cementitious composite in exterior beam‐column connections under cyclic loading

AbstractThe present research examines the structural performance of exterior beam‐column connections made with the hybrid use of fibers and stone waste in engineered cementitious composite (ECC). The polyvinyl alcohol (PVA), recron 3 s polyester (PET) and micro steel fiber (MSE) were dispersed in various ECC mixtures to analyze the impact of fiber hybridization. The stone waste (SW) was utilized in different ECC mixtures as replacement of silica sand (SS). The performance of ECC beam‐column connection specimens was judged in terms of hysteresis load–deflection behavior, energy dissipation, ductility, and cracking pattern. The recorded results of ECC reinforced specimens were compared with specimens made with normal concrete (NC). Recorded results revealed that the connections made with ECCs exhibited better performance in terms of ductility and various parameters as compared to NC connections. The hybrid dispersion of fibers and addition of SW also contributed in improving the behavior of ECC specimens. The higher deformation, loading response, energy dissipation and ductility indicated that structures made with ECC can withstand strong ground earthquake motions.

NUMERICAL SIMULATION ON THE TENSILE STRAIN HARDENING BEHAVIOUR OF ENGINEERED CEMENTITIOUS COMPOSITES (ECC)

Numerical simulation for evaluating tensile strain hardening behaviour of engineered cementitious composites (ECC) materials are extremely limited. This paper presents a finite element (FE) model developed to determine the multiple-cracking and strain hardening behaviour of ECC under uniaxial tension. A nonlinear FE program, ATENA was used in this study. A constitutive law based on individual crack-based model derived by the traction-separation relationship, or also known as tensile function was implemented in the model. Model calibration with parameter modifications were illustrated. The final simulation result predicts accurately the experiment tensile stress strain curves, including the tensile strain hardening response, ultimate tensile strength and tensile strain capacity. This includes validation from ECC specimens tested by various researchers. It has found that accuracy of the model is improved by lowering the crack opening displacement corresponds to the first cracking. The finding from this study would be useful in the future for further parametric analyses and structural optimization design of ECC members.

Experimental investigation on reinforcing effects of engineered cementitious composites (ECC) on improving progressive collapse performance of planar frame structure

This paper experimentally investigates the progressive collapse performance of planar frame structure with engineered cementitious composites (ECC) under middle column removal scenario. One normal concrete specimen and two ECC specimens were used for experiments. Quasi-static vertical loading was imposed onto the middle column, and structural response was analyzed for the specimens with different concrete and reinforcement ratio. Furthermore, the impact of ECC on the behavior of planar frame structure to resist progressive collapse was evaluated. Experimental results indicated that ECC specimens exhibited multi-cracking behavior with limited crack width, and their progressive collapse performance including ductility, horizontal reaction, bending moment and rotation capacity of plastic hinge can be improved significantly in three stages of resisting mechanisms. The resistance force and energy absorption can be reinforced over several times in elastic stages while the reinforcing effects can not continue in compressive arch stage and catenary stage. The ultimate resistance in catenary stage is largely determined by the reinforcement ratio. Finally, the ECC is proved to be highly effective in reinforcing progressive collapse resistance, which provides a basic insight into the application of ECC building structure in engineering.

Mechanical strength model of engineered cementitious composites with freeze–thaw damage based on pore structure evolution

A freeze-thaw cycle test, nuclear magnetic resonance (NMR) T2 spectrum test, uniaxial tensile test, and uniaxial compression test were designed to study the service conditions of engineered cementitious composites (ECC) in a freeze-thaw (FT) environment in cold areas. The degradation law of the mechanical properties and damage characteristics of the pore structure of ECC with three water-binder ratios (M1: W/B = 0.24, M2: W/B = 028, and M3: W/B = 0.32) are discussed. The results demonstrate that the number of micropores and mesopores in the ECC specimens increases with an increase in the number of freeze-thaw cycles (FTs), thus gradually increasing the porosity. The uniaxial tensile strength (UTS) and uniaxial compressive strength (UCS) decrease gradually with increasing number of FTs. After FTs300, the porosity of the three groups increases by 43.83%, 59.39%, and 59.16%; the loss ratios of UTS are 26.16%, 24.47%, and 19.63%; and the loss ratios of UCS are 31.52%, 27.98%, and 27.30%, respectively. Based on the mechanical properties and pore structure test results of ECC, relation models of the UTS and UCS of freeze-thaw damaged (FTD) ECC with porosity were constructed according to the simplified center hole model of ECC and the elastic mechanics theory. To further disclose the FT evolution laws of uniaxial tensile/compressive strengths (UT/CS), the relationship models of UT/CS and number of FTs with the degree of FTD were deduced. The constructed models and test results were compared with those of some classical porosity-strength models. It was found that the constructed models met the requirements of satisfactory reliability and applications.

Time and Crack Width Dependent Model of Chloride Transportation in Engineered Cementitious Composites (ECC).

This paper aims to develop a chloride transport model of engineered cementitious composites (ECC) that can consider the influence of both exposure time and crack width. ECC specimens with crack widths of 0.1 mm, 0.2 mm and 0.3 mm were soaked into NaCl solution with periods of 30, 60, 90 and 120 days. The free chloride content profile was measured and used for the development of the transport model. Regression analysis was applied to build the time and crack width dependent models of apparent diffusion coefficient and surface chloride content. The results show that the crack width has significant influence on the free chloride concentration profile when it is above 0.2 mm and the time-dependent constant n decreases linearly with the crack width. The chloride transport model was obtained by subscribing the models of apparent diffusion coefficient and surface chloride content into the analytical solution of Fick’s second law. The model was further validated with the experimental results, showing a deviation within 20%. The findings of the presented study can enhance the current understanding on the chloride transportation in ECC.

Durability study on engineered cementitious composites with hybrid fibers under sulfate and chloride environments

Engineered cementitious composite (ECC) is an exclusive type of cement mixture composite which imparts high ductility and high tensile strength. Over the decades, enormous strides have been made in creating ECC with extreme tensile ductility, on the order of several hundred times than that of normal concrete or fiber reinforced concrete. The experimental behaviour of ECC which is combined with polyvinyl alcohol (PVA) and steel fibers has been investigated in this research. The main aim of the research is to study the durability of ECC through compressive strength for long-term exposure condition under chloride, sulfate and combined sulfate–chloride environmental conditions experimentally. In the present work, six different ECC mixtures with constant water-cement ratio were prepared with the total volume fiber fraction (Vf) of 2%. ECC mechanical properties such as compressive strength, flexure strength and uni-axial tensile strength have been experimentally determined. The test results emphasize that the flexural strength and uni-tensile strength of the ECC specimens with the combination of 1.5% PVA and 0.5% steel fibers were improved as supposed to conventional ECCs. The durability property has been carried out only for the optimized dosage of fibers after exposed to aggressive solutions. The performance of optimized dosage of ECC mixture with hybrid fibers was barely affected by the aggressive solutions of chloride and sulfate–chloride when compared the same with water.