Ultimate Tensile Capacity Research Articles

Study on fracture behaviour of pipeline girth welds based on curved wide plate specimens: Experimental and numerical analysis

Understanding the fracture characteristics and strain capacity of pipelines with girth welds under external loads is crucial for evaluating pipeline safety. The use of curved wide plate (CWP) specimens closely resembling full-scale (FS) pipelines in geometry provides a more realistic representation of crack tip constraint states compared to small-size fracture toughness test specimens in laboratory settings. This study aims to investigate the ductile fracture characteristics of center cracks on the outer surface of girth welds in high-grade steel pipelines under external loads through large-scale CWP tensile tests and advanced numerical simulations. Tensile tests were conducted on CWP specimens using a kiloton tensile testing machine, with double crack opening displacement (COD) gauge monitoring crack mouth opening displacement (CMOD), and high-precision displacement sensors and strain gauges tracking deformation and strains at various positions. The study yielded significant experimental results, and a finite element (FE) model of the CWP was developed using the nonlinear finite element method (FEM) to validate the experimental data against simulation results. The FE model was then used to investigate the influence of material properties on crack propagation resistance and driving force curves. A method for determining the ultimate tensile strain capacity (UTSC) of pipelines based on actual material fracture toughness was proposed. This research contributes valuable experimental data for further exploration of fracture behaviour in large-scale pipeline girth welds and offers insights for safety evaluations of such welds.

Rehabilitation and reinforcement of cracked pavements using crack sealers and composite patches

Cracking is a significant concern for pavements and should be appropriately treated during road, highway, and runway rehabilitation. This study investigates the behavior of asphaltic materials under tensile and shear loading modes in intact, fractured, and repaired conditions. With this aim, several methods and materials are utilized for repairs, such as poring adhesive into the crack (using bitumen, neat epoxy resin, and polymer concrete adhesives) and patching the crack with textile (by glass fiber and epoxy resin or bitumen). These tests were conducted at +10 °C, with a three-point bending loading configuration, the same as the actual loading configuration of pavements. Criteria such as failure load, failure work, and post-failure work, as well as failure patterns, were assessed to assess the effectiveness of repairs. Numerical analysis was also performed, and a constitutive model was presented. The ultimate tensile capacity of the cracked specimen is measured at 63 % lower than the intact condition (778 N). The ultimate tensile load of the bitumen-repaired specimen is higher than that of the cracked specimen, but it is still 11 % lower than that of the intact condition. The ultimate tensile capacity of epoxy resin repaired and polymer concrete repaired specimens are 88 % and 79 % higher than the intact specimen (about 1400 N). The ultimate tensile load of the fabric patch reinforced specimen that used bitumen as the adhesive is 38 % higher than the intact specimen (1075 N), while for the case of using the epoxy resin adhesive, this value is 258 % (2788 N). Observations of tensile failure patterns show that, because bitumen is viscoelastic, failure in bitumen-repaired specimens happens in bitumen necking mode and starts at the repaired crack tip. In other cases, the failure occurred far from the pre-crack plane.

The first engineering application of 10MN CFRP cables in cable-stayed bridge in China

Existing engineering applications typically involve carbon fiber reinforced polymers (CFRP) cables with relatively small ultimate tensile forces (less than 10MN). This study presents the engineering application of China's first thousand-ton-grade CFRP cable-stayed bridge. The optimal steel and CFRP hybrid cable system was determined through a comparative analysis of structural behavior and life cycle cost. Thereafter, the CFRP cable, consisting of 121 strands of φ7 CFRP tendons, along with its anchoring system, was designed and manufactured with a theoretical ultimate tensile strength of 10,710 kN (Pb). Subsequently, the mechanical properties of 7–121 CFRP cable were investigated and experimentally verified. The tensile test revealed a satisfied ultimate tensile bearing capacity of 10,805 kN. Furthermore, after two million fatigue cycles, the CFRP cables retained approximately 90 % of their theoretical ultimate force, highlighting their excellent fatigue resistance. Besides, no damage occurred with a maintained tension force of 0.45 Pb at a temperature of 150 °C for a duration of at least 30 min, meeting the requirements of specification. Moreover, the key procedures of CFRP cable installation were also claimed. This study aims to further promote the application and development of CFRP cables in larger span and even super-long span bridges.

Theoretical and FEA investigation of the mechanical behaviour for offshore LCO2 floating hose

Injecting liquid CO2 (LCO2) into the seabed for storage utilizing an offshore platform to achieve offshore storage of CO2 is one of the effective measures to realize the reduction of CO2 emissions. To solve the difference in motion characteristics between the LCO2 carrier and the receiving platform due to wind and wave currents, floating hoses can be employed as the pipeline in the CO2 transportation. In this study, an LCO2 floating hose based on the structural form of steel wire reinforced thermoplastic composite pipe is proposed. A mechanical model for this hose is developed to analyze the tensile mechanical properties. It is verified that the method is reliable by comparing with the published experimental results of composite hose containing 4 layers of aramid fiber reinforced layers with a maximum error of 11.48%. A comparative analysis was also carried out by finite element analysis (FEA) with a maximum error of 10.67%. On this basis, the damage states of the hose under internal pressure, tension, bending and torsion load were investigated to analyze mechanical properties. The ultimate tensile load capacity, ultimate bending radius and ultimate unit torsion angle are 463 kN, 1.64m and 14°/m, respectively. The components most prone to failure under different loads were clarified. This study can provide technical reference for the design of floating hoses for offshore LCO2 storage and transportation.

Tensile analysis of loop joints with different overlap lengths

ABSTRACT In order to achieve rapid bridge construction, on-site wet joint joining techniques for prefabricated bridge decks are commonly used. The primary method involves mainly lap welding, but this form poses some drawbacks such as difficult lap jointing of two steel bars and a hefty welding workload. To address these issues, this study conducts model experiments on the unwelded structure of loop joints. We compare and analyze the displacement, crack distribution, crack development process, and strain variability of loop joints across three different overlap lengths, along with one type of straight bar lap-welded wet joints. It is observed that, despite the comparable ultimate tensile capacity of loop joints with the main rib to that of the welded wet joint with the main rib, the failure mode varies, and the crack direction changes with the overlap length. From a structural stress perspective, if the U-bar of the loop joint meets a specific overlap length, the wet joint adequately fulfills stress requirements and can be applied in practical engineering.

High-strength high-ductility seawater sea-sand Engineered Cementitious Composites: Mechanical properties, cracking behavior and micro-mechanics

This study developed strain-hardening seawater sea-sand engineered cementitious composites (SS-ECC) with both high-strength and ultra-high tensile ductility for the first time using CaCO3 whiskers (CW). The developed SS-ECC exhibited a compressive strength of 132.7 MPa and successfully pushed the ultimate tensile strain capacity over 10 %. Investigations into crack characteristics and micro-mechanics were conducted to analyze in depth the obtained tensile performance. The results showed that the incorporation of 0.3 vol% CW increased the degree of crack saturation and decreased the crack width, leading to a further increase in the ultimate tensile strain capacity. With CW dosage increasing from 0.3 vol% to 0.8 vol%, the compressive strength increased significantly, but the ultimate tensile ductility decreased. In addition, this study took into account the effects of CW and PE fibers in the micro-mechanical model and theoretically explained the synergistic effect of CW and PE fibers on the enhancement of tensile performance of SS-ECC through the obtained PSH indices. The finding provides new insights into the production of high-cost efficiency and high overall performance index (fcftε/w) for ultra-high ductility SS-ECC, with promising applications in sustainable marine infrastructures.

The Effect of Polyethylene Fiber Addition and Fiber Length on the Behavior of Tensile Loaded Ferrofoam Concrete Plates

This study investigates the influence of adding polyethylene fibers and varying their lengths on the behavior of ferrofoam concrete plates under tensile loading. Test specimens of ferrofoam concrete plates with three different matrix variations were prepared: plain foam concrete, foam concrete with 10 mm fibers, and foam concrete with 15 mm fibers. Tensile tests were conducted to evaluate the cracking capacity of the plates for each variation. The results show that the addition of polyethylene fibers improves the ductility and tensile strength of the foam concrete. The 15 mm fibers exhibited a split tensile strength ratio of 13.84% to the compressive strength of the concrete. Additionally, the use of fibers increased the average cracking capacity of the ferrofoam concrete plates, with the highest value reaching 1.5 MPa. However, the ultimate tensile capacity of the plates was not significantly affected by the addition of fibers.

Ultimate tensile capacity of hot-dip galvanized ultra-high-strength steel cut edges and welded joints

AbstractTensile tests of 6-mm-thick hot-dip galvanized (HDG) S960 specimens were performed. The study focused on room temperature but also − 40 °C cold temperature tests were performed to ensure material behavior and reliability. Microstructural characterization using a scanning electron microscopy was performed to evaluate the influence of HDG. The results showed that HDG slightly decreased the tensile strength of plain S960 specimens whereas its effect on welded joints was not significant in both room and cold temperatures.

A UNIFIED MACHINE LEARNING MODEL TO PREDICT ULTIMATE TENSILE AND BOND CAPACITY OF FRCM

Fiber-reinforced cementitious matrix (FRCM) is a new-era material for strengthening concrete and masonry structures. Unlike Fiber reinforced polymer (FRP), it has excellent substrate bond properties. However, FRCM shows intra-fiber slip and Fiber-matrix debonding as its major failure modes, effectively reducing its ultimate load-carrying capacity. It has led to broad research scope, and researchers have used permutations and combinations of various types of fibers, matrices, coatings, and substrates to improve the tensile and bond properties of the FRCM composites. Additionally, other experimental parameters, such as rate of loading and experimental setup (clevis, hydraulic or mechanical), affect the tensile and bond properties of FRCM composites. Complex failure modes and parameters make tensile and bond capacity prediction very difficult. Previous attempts by researchers showed the effectiveness of machine learning in predicting the bond capacity of the FRCM composites. Artificial neural network (ANN) based models have also been used successfully to predict the flexural capacity of FRCM-strengthened masonry panels. This study develops a unified machine learning-based model to predict bond and tensile capacity using complex tree-based algorithms such as extra tree regressor, categorically boosted trees, extreme Gradient boosted trees, etc. The authors extracted 603 data points from the literature to develop and validate the model; this includes 345 data points from tensile testing and 258 data points from FRCM-concrete bond testing. It is found that the developed tree-based model predicts the ultimate tensile and bond capacity with about 93% and 95% overall accuracy, respectively.

A UNIFIED MACHINE LEARNING MODEL TO PREDICT ULTIMATE TENSILE AND BOND CAPACITY OF FRCM

Fiber-reinforced cementitious matrix (FRCM) is a new-era material for strengthening concrete and masonry structures. Unlike Fiber reinforced polymer (FRP), it has excellent substrate bond properties. However, FRCM shows intra-fiber slip and Fiber-matrix debonding as its major failure modes, effectively reducing its ultimate load-carrying capacity. It has led to broad research scope, and researchers have used permutations and combinations of various types of fibers, matrices, coatings, and substrates to improve the tensile and bond properties of the FRCM composites. Additionally, other experimental parameters, such as rate of loading and experimental setup (clevis, hydraulic or mechanical), affect the tensile and bond properties of FRCM composites. Complex failure modes and parameters make tensile and bond capacity prediction very difficult. Previous attempts by researchers showed the effectiveness of machine learning in predicting the bond capacity of the FRCM composites. Artificial neural network (ANN) based models have also been used successfully to predict the flexural capacity of FRCM-strengthened masonry panels. This study develops a unified machine learning-based model to predict bond and tensile capacity using complex tree-based algorithms such as extra tree regressor, categorically boosted trees, extreme Gradient boosted trees, etc. The authors extracted 603 data points from the literature to develop and validate the model; this includes 345 data points from tensile testing and 258 data points from FRCM-concrete bond testing. It is found that the developed tree-based model predicts the ultimate tensile and bond capacity with about 93% and 95% overall accuracy, respectively.

A macro element of demountable bolted steel-concrete composite connections for a novel prefabricated concrete sandwich wall panel structure

A novel prefabricated concrete sandwich wall panel structure (PCSWPS) system has been proposed for low-rise buildings in rural areas in China. The wall panels are jointed using high-strength bolts and steel plates through bolted steel-concrete composite connections (BSCCs). Despite published experimental results showing promising seismic performance of the structural system, the mechanics governing the interaction between the bolts, steel plates, and concrete at the connections still need to be clarified. To this end, we carried out full-scale connection experiments and finite element (FE) analysis to investigate the uniaxial tensile characteristics of the connections to simulate their working conditions in seismically loaded structures. It is shown that the tensile load-transfer mechanism through a BSCC is closely related to two frictional sliding responses and a compressive contact behavior. Based on the experimental data and FE results, a macro element was proposed to simulate the mechanical behavior of BSCCs. The macro element is able to model the interactions between the bolts, steel plates, and concrete separately using springs, assembled in series and/or in parallel in a composite manner. In particular, the loss of bolt clamping forces and ultimate tensile capacity of the connection are well captured by the macro element. Finally, the macro element was validated against existing experimental data on bolt-connected shear walls using OpenSees. It is believed that the clear load-transfer mechanism can be beneficial for the design of PCSWPS, and the proposed macro element can facilitate seismic analysis of PCSWPS without the need of a detailed connection FE model.

A novel plug-in self-locking inter-module connection for modular steel buildings

The inter-module connection of modular steel building components is key to ensuring the integrity and stability of modular steel buildings. To tackle the existing technical problems of the inter-module connection, especially those related to the complex on-site installation process, and ensure installation quality, this study presents a novel plug-in self-locking connection involving a lock cylinder consisting of two horizontal locking blocks, a locking plate, and an inner insert plate. A series of axial tensile tests were conducted on plug-in self-locking inter-module connections by changing the processing and the thickness ratio of different components of the locking cylinder (i.e. hP: hC: hI). In addition, mechanical tests were performed to study the axial tensile load capacity, axial tensile ductility factor, and failure modes of the locking cylinder of the plug-in self-locking inter-module connection with different configurations. The results show that the weld fracture of the locking plate and the inner insert plate can result in brittle damage to the connection, when the locking plate and the inner insert plate are manufactured as a whole, and the self-locking connection is rendered ineffective by shear fracture of the horizontal locking block. Among all the specimens, the ultimate tensile load capacity of the lock cylinder of Specimen R70NCB40 can reach around 293 kN with a tensile ductility factor of around 4, showing better mechanical properties. In addition, the thickness ratio of different components of a lock cylinder (i.e. hP: hC: hI) plays an important role in governing the mechanical capacity of the lock cylinder due to its relatively low tensile strength achieved through reducing the thickness of the inner insert plate (i.e., R70NCB40). This demonstrates a better mechanical performance of the cylinder through fully utilizing the plastic deformation capacity of different components of the locking cylinder. The recommended thickness ratio of different components of the lock cylinder (i.e. hP: hC: hI) is 1:1:0.68. Finally, based on the experimental and FEM results, an empirical theoretical model for the lock cylinder of a plug-in self-locking connection was proposed for the design of plug-in self-locking connections in engineering practice.

Experimental and numerical study on tensile performance of GFRP bar reinforced UHPC members

Glass fiber reinforced polymer (GFRP) bar reinforced ultra-high performance concrete (UHPC) (GFRP-UHPC) members’ tensile performance should be significantly different from that of steel-UHPC members due to differences between GFRP and steel bars in mechanical and bond properties. In this paper, six dog-bone shaped specimens with different types of reinforcement materials, rebar diameters, and quantities of rebars were fabricated and tested under axial tension, and their failure modes, load-displacement curves, and cracking behavior were recorded and investigated. Furthermore, an extensive nonlinear finite element analysis considering the bond behavior between rebars and UHPC was conducted. Finally, formulas were proposed to predict the tensile stiffness and ultimate tensile capacity of GFRP-UHPC members. Results confirmed that bond shear strength (τcs) and stiffness (K) of the GFRP and UHPC interface were the key factors that affected GFRP-UHPC members’ tensile performance: τcs mainly determined the failure mode; increasing K and the reinforcement ratio can improve the post-cracking stiffness and obtain tension hardening behavior; the wedging effect caused the post-cracking curve of the tension member in bond failure mode re-ascend periodically. The proposed formulas could produce accurate and safe predictions after comparing predicted results with experimental and simulation results. This study provides the underlying insights needed to guide the design of GFRP-UHPC members.

Failure envelope considering the ultimate tensile capacity of suction caissons in sand

Little analytical work has been done to elucidate the ultimate capacity of suction caissons under vertical tensile (V), lateral (H), and moment (M) loads in soils. In this paper, in order to reveal the effect of vertical tensile, lateral, and moment loads on the ultimate capacity of suction caissons in sand, an analytical investigation was made using a traditional bearing capacity theory. Taking account of the vertical equilibrium of an annular element of a skirt, through the vertical tractions inside and outside the skirt of a suction caisson when a vertical tensile load is applied, the vertical displacement of the soils adjacent to the skirt of the suction caisson was presented. The most appropriate bearing capacity equation for predicting the experimental results was shown for suction caissons having an embedment larger than a diameter in sand. For the deformation-load responses of suction caissons with various embedment ratios in sand, subjected to inclined tensile loads, there was a good agreement between the results obtained from laboratory tests and those predicted by the present method. The failure surfaces, considering the ultimate tensile capacity in the H-M, H-V, and M−V planes, and in the H-M−V space, for suction caissons in sand, were presented.

Tensile behavior of UHPC wet joints for precast bridge deck panels

Precast bridge deck panels (PBDPs) have been widely used in bridge engineering in the past decade. However, as the crucial part of connecting adjacent precast members, wet joints are often regarded as the weakest link in the bridge superstructure. To narrow the width of wet joints and reduce the assembling accuracy of U-bars, a total of five full-scale bridge deck panels (BDPs) were designed, which included four precast bridge deck panels with wet joints and one monolithic cast-in-place bridge deck panel (MCIPBDP). The major design variables included reinforcement types (straight bar and U-bar), U-bar lap details (non-contact lap and contact lap) and wet joint filling materials (NC and UHPC). The axial tensile loading tests were conducted to evaluate the tensile behavior of five BDPs. The experimental results demonstrated that all specimens experienced ductile failure, and finally failed due to the yielding of reinforcements. However, due to the insufficient lap length of 150 mm for the specimen P-NS-U200, bond slip appeared, and its ultimate tensile capacity decreased by 23.2% compared to the specimen P-NU-U200. Regarding the specimens P-NU-U200 and P-CU-U200, the difference in ultimate strength between non-contact lap and contact lap was within 3%. In addition, compared with the 500-mm-width normal concrete (NC) wet joint, the tensile capacity of the 200-mm-width UHPC wet joint was increased by 8.8%. Finally, based on the strut-and-tie model and failure mode, a modified calculation formula was proposed for estimating the tensile capacity of PBDPs. The predicted tensile capacity agrees well with the experimental results. The research provides a reference for engineers to guide the project’s construction and apply UHPC wet joints in practical engineering.

Synergistic effects of silica fume and slag on the microstructure and mechanical behaviors of ultra-high-strength and high-ductility cementitious composites

This work evaluated the synergistic effects of silica fume (SF) and ground granulated blast furnace slag (GGBS) binders on the microstructure and mechanical behavior of Ultra-High-Strength and High-Ductility Cementitious Composites (UHS-HDCC). The potential mechanisms of the synergistic effects of GGBS and SF on the fresh flow, mechanical properties, and microstructure of UHS-HDCC were investigated. The results indicated that the use of GGBS instead of SF could effectively improve the flowability of fresh mortar and UHS-HDCC mixtures. The hydration process of cement and the heat of hydration were delayed and reduced when the content of GGBS was below 25 %. Moreover, reducing the SF while increasing the GGBS reduced the compressive strength of the composites but had little effect on the flexural strength. The compressive strength of all specimens remained above 120 MPa. All specimens achieved strain-hardening behavior after the initial cracking of the matrix in uniaxial tension and four-point bending, and had a variety of cracking characteristics. Furthermore, the range of ultimate tensile strain capacity and mid-span deflection were 3.26 %–5.79 % and 16.73 mm–33.05 mm, respectively. The S10G30 specimen reached a maximum tensile strain energy of 414.6 kJ/m3. As the level of GGBS replacing SF increased, the number of cracks in the tensile region or the compressive bending surface of UHS-HDCC specimens increased, while the crack width and crack spacing decreased. The relatively smooth sidewalls of the fiber tunnels and fiber exit points meant that matrix fragments attached to the fiber surfaces were caused by matrix fragments generated throughout the matrix cracking process. Besides, the interfacial frictional stress and slip hardening coefficient acquired from the single fiber pullout test reduced with increasing levels of GGBS replacing SF.

Flexural Capacity of Cross-Shaped Concrete-Filled Steel Tubular Column–Steel Beam Joints with Side-Plate Connections

The application of connection joints between a cross-shaped concrete filled steel tubular column and a steel beam can improve the seismic performance, which also provides an effective way for saving building space. In this paper, models and flexural capacity of the connection joint with and without side plates were designed and evaluated, respectively. A refined mechanical analysis model of a joint subjected to low-cycle reciprocating loading was established using the finite element software ABAQUS. The failure characteristics of the joints with and without side plates were compared. The influence of axial compression ratio, side plate height, and side plate thickness on the flexural capacity of joints with side plates was studied. Moreover, the failure mode and force transfer mechanisms of these joints were analyzed. Based on the results of the finite element analysis (FEA), the ultimate tensile capacity of the steel tube column flange to the steel beam was calculated according to the yield line theory; the tension transmitted by the side plate was simplified for calculation via the static equilibrium method. Subsequently, the formula for calculating the flexural capacity of the joint with side plates is established. The results show that the ultimate bearing capacity of the joint was increased by 41.5% due to side plates effect, which decreased with an increasing axial compression ratio. Moreover, the ultimate bearing capacity of the joints increase slightly with an increase of height and thickness of the side plate, and the maximum increase was only 6.2%. In addition, the calculated results obtained by the proposed formula of ultimate flexural capacity are consistent with the results of the FEA.

Ultra-low cycle fatigue performance of grid structure with bolted spherical joints

This study aimed to investigate the effect of the specification of each grid structure component on the ultra-low cycle fatigue performance of the rod element of a grid structure with bolted spherical joints. Thus, an ultra-low cycle fatigue test of three identical composite steel tube and bolted sphere specimens was performed. The test was performed under three kinds of constant amplitude loading regimes for large axial cyclic plastic strain loads. Based on steel ductility damage and initial geometric defects, a finite element simulation of the test was then conducted using Abaqus/Explicit, which was calibrated according to the test results. In addition, parametric numerical simulations were performed to analyze the effects of different steel tube slenderness ratios, bolt diameters, and steel tube wall thicknesses on the seismic performances of the composite steel tube and bolted sphere specimens. The results indicated that the specimen dissipated energy mainly through material damage in the plastic hinge region in the middle of the steel tube. The steel tube slenderness ratio mainly affected the fatigue life and energy dissipation capacity of the specimen. Further, the ultimate tensile and compressive bearing capacity as well as deformation capacity of the specimen both increased with increasing steel tube wall thickness. Finally, the energy dissipation pattern of the specimen was most sensitive to the bolt diameter; thus, the energy dissipation capacity of the steel tube can be fully utilized only by selecting the bolt specification that matches the rod element.

Short- and Long-Term Prestress Losses in Basalt FRP Prestressed Concrete Beams under Sustained Loading

The favorable mechanical properties of basalt fiber–reinforced polymer (BFRP) bars, such as their excellent strength-to-weight ratio, resistance to corrosion, lower environmental impact, and electromagnetic neutrality, make them attractive for internal reinforcement of concrete elements with specific service requirements. Prestressing has emerged as a possible method for limiting the deflections and cracking of BFRP-reinforced flexural RC elements. However, long-term behavior of such structural members has not yet been investigated extensively. Therefore, this paper aims to give information on long-term behavior and prestress losses of pretensioned BFRP-reinforced concrete beams based on the collected experimental data. The testing program includes long-term analysis of six BFRP concrete beams pretensioned to different prestress levels—namely, 20%, 30%, and 40% of the ultimate tensile capacity of the bars. The monitored testing stages included initial tensioning of the bars, casting and curing of concrete, transfer of prestressing force to the concrete, long-term unloaded phase after transfer, sustained-loading application, long-term sustained loading phase, unloading, and final destructive testing, conducted in a controlled indoor environment. During all phases of the testing, strain levels in the BFRP bars and deflections were continuously monitored. The results of continuous strain monitoring show that the average loss of strain over the period of initial 90 days of unloaded monitoring was 7% of the initial strain. During the following 6 months of monitoring under sustained loading, an additional 0.3% reduction was recorded on average. The loss was dependent on the initial strain.

Optimization of matrix viscosity improves polypropylene fiber dispersion and properties of engineered cementitious composites

• PP fiber dispersion can be improved by tailoring ECC matrix viscosity using VMA. • At optimal state, PP-ECC attains 7 % tensile strain and 3.5 MPa tensile strength. • Adding VMA beyond optimal state lowers ECC’s tensile strength and ductility. Engineered cementitious composites (ECC) is a durable cementitious material with high tensile ductility and strain-hardening characteristics. Although considered as a cost-effective fiber for ECC, polypropylene (PP) fiber is reportedly difficult to disperse in mortar matrix due to its high aspect ratio and hydrophobicity. In this study, the matrix viscosity of a low-carbon ECC based on limestone calcined clay cement was tailored as a variable to improve PP fiber dispersion under a pre-determined mixing protocol. The effect of matrix viscosity on the composite fresh and hardened properties was investigated experimentally. Results suggested an optimal range of matrix viscosity (10.3–11.5 Pa‧s) favors the composite tensile strength and strain capacity at 28 days. At the optimal state with a 0.1 % viscosity modifying admixture (VMA)-to-binder mass ratio, PP-ECC achieved 7.0 % tensile strain capacity and 3.5 MPa ultimate tensile strength. When matrix viscosity falls outside the desired range, both ultimate tensile strength and strain capacity were diminished. By tailoring the VMA dosage, the matrix viscosity can be adjusted for desired fiber dispersion, workability, and mechanical properties. The findings of this study provide a technical reference for the practical design and application of PP-ECC.