Performance Of Ultra-high Performance Concrete Research Articles

Influence of Modified PVA Fiber on Ultra-High Performance Concrete and Its Enhancing Mechanism.

In this study, the properties of ultra-high-performance concrete (UHPC) were enhanced by adding modified polyvinyl alcohol (PVA) fibers. The specimens with different curing ages were evaluated in various aspects to investigate the effects of different dosages, lengths, and surface treatments of PVA fibers on the performance of UHPC. The performance was compared with that of steel fiber-reinforced UHPC with the same ratio and multiple dosages. At the same time, the distribution of fibers and the morphology of fibers were observed by a scanning electron microscope, and the mechanism of fiber reinforcement was discussed. The results showed that the mechanical properties were significantly affected by the fiber dosage, length, and surface treatment. Based on the test results, the optimum PVA fiber addition can increase the compressive strength and flexural strength by 12.0% and 6.0% compared to the control UHPC without fibers. A comprehensive evaluation was carried out and indicated that the optimum PVA fiber addition has the potential to replace 0.5% steel fiber in certain conditions.

Influence of fibre surface treatment on the performance of ultra high-performance concrete with metallic and non-metallic fibres

Influence of fibre surface treatment on the performance of ultra high-performance concrete with metallic and non-metallic fibres

Incorporating geranium plant waste into ultra-high performance concrete prepared with crumb rubber as fine aggregate in the presence of polypropylene fibers

Abstract This research examines the efficiency of ultra-high-performance concrete (UHPC) when utilizing geranium plant (GP) ash, which is subjected to different curing temperatures ranging from 300 to 900°C for 3 h of burning time. The GP ash is used as a replacement for cement in varying amounts (10, 20, 30, 40, and 50 wt%). Crumb rubber powder is utilized as a substitute for fine aggregate. Polypropylene fibers have been used to improve concrete performance. The performance of UHPC is evaluated by assessing its mechanical qualities, such as flexural strength, splitting tensile strength, and compressive strength. The sorptivity test is also evaluated as a component of it. Scanning electron microscopy is used to analyze UHPC after exposure to temperatures as high as 900°C. The findings demonstrated a notable enhancement in the mechanical characteristics of all mixtures. The most favorable mixtures were achieved with proportions of 50, 40, 40, and 20% for mixtures including GP waste incinerated at temperatures ranging from 300 to 900°C. Furthermore, the optimal outcome is achieved when 40% substitution is performed at a temperature of 700°C, resulting in notable enhancements of 14% in compressive strength, 30% in flexural strength, and 17% splitting tensile strength, respectively. At a high temperature of 700°C, the decrease in strength increased to approximately 37–40% as a result of the initial removal of carbon dioxide from calcite at temperatures ranging from 600 to 900°C and reached 56% at 900°C. Great resistance to sorptivity, as well as a dense and compact microstructure with a high content of calcium and silicon, was obtained.

Mechanical and Drying Shrinkage Performance Study of Ultra-High-Performance Concrete Prepared from Titanium Slag under Different Curing Conditions.

This research investigates the effects of various curing regimes, the incorporation of titanium slag, and the utilization of quartz sand on the strength properties and shrinkage behavior of ultra-high-performance concrete (UHPC). By using low-heat silicate cement to prepare UHPC, this study conducted standard curing and steam curing, and comprehensively analyzed the macro and micro performance of UHPC under different curing conditions. The findings indicate that the application of steam curing markedly enhances the mechanical attributes of UHPC while efficiently decreasing its drying shrinkage. In the comparative tests, we found that the compressive strength of concrete that had undergone 2 days of steam curing was 9.15% higher than that of concrete cured for 28 days under standard conditions. In addition, under the same curing conditions, titanium slag sand had higher mechanical properties than quartz sand. Under standard curing conditions, the 28-day compressive strength of UHPC using titaniferous slag aggregate was 12.64% higher than that of UHPC using standard sand. Through the data analysis of XRD, TG, and MIP, we found that the content of Ca(OH)2 in the hydration products after steam curing was reduced compared to the standard curing conditions, and the pore structure had been optimized. The UHPC prepared with titanium slag sand has greater advantages in mechanical properties and drying shrinkage, and has a smaller pore structure than the UHPC prepared with quartz sand. Moreover, the use of titanium slag sand offers ecological and economic benefits, making it a more sustainable and cost-effective option for high-performance construction applications.

Synergistic effect of nano-to-macro waste glass of various particle sizes on ultra-high-performance concrete: Tradeoff between mix design parameters and performance through a statistical design approach

Ultra-high-performance glass concrete (UHPGC) is engineered for strength, ductility, and durability, aiming to address environmental and economic concerns associated with traditional ultra-high-performance concrete (UHPC). In this approach, we individually substituted traditional UHPC components—cement (C), silica fume (SF), quartz sand (QS), and quartz powder (QP) with ground waste glass materials (GWG). Recognizing that the performance of UHPC is influenced by the chemical interactions and packing density of its constituents, which primarily depend on particle-size distribution, our current study focuses on the synergistic effects of these factors. We explored how nano to macro size GWG can simultaneously replace all traditional UHPC components and affect its properties. Employing the Design of Experiment allowed the establishment of statistical equations. Contour diagrams predicted the individual and synergetic effect of mix design parameters on UHPGC's fresh and mechanical properties, with a high correlation (R2 ≥ 0.98) and low error (≤8 %). Validation with 18 additional mixtures confirmed the models' precision. Our research established the production of a superior UHPGC with 40%–100 % lower traditional components (C, SF, QP, and QS) and 65 % less superplasticizer demand. The embodied energy, CO2 emissions, and production cost reduced by 65 %, 38 %, 36 %, and 32 %, respectively. This approach can enhance UHPGC's integrity and environmental sustainability.

Experimental Study on Flexural Resistance of UHPC Wet Joint Precast Reinforced Concrete Bridge Deck Slabs with Variable Cross-Section

With the convenient and fast requirements for construction in bridge engineering, prefabricated assembly technology is widely applied in engineering construction. Typically, prefabricated bridge decks are connected through cast-in-place wet joints. Wet joints, as the primary load-bearing parts of bridge decks, undergo complex stress and are prone to cracking and damage. Particularly in the negative bending moment region of bridges, the influence of tensile stress on wet joints is more severe, thus enhancing the mechanical performance and crack resistance of joints becomes crucial. This paper investigates the mechanical behavior of prefabricated reinforced concrete bridge deck panels with variable cross-sections under negative bending moments, focusing on the performance of Ultra High-Performance Concrete (UHPC) wet joints. Full-scale experimental tests were conducted on a 176 m steel truss composite continuous rigid bridge, employing C50 concrete panels with UHPC wet joints. Results show three distinct stages: elastic, crack initiation and propagation, and failure. The maximum failure load reached 822 kN, with a maximum displacement of 21.64 mm. Concrete strains indicate compressive stress near the wet joint and tensile stress near the loading positions. Cracks primarily develop at the wet joint interface and propagate under increasing load, ultimately leading to flexural–shear failure near the variable cross-section of the wet joint. Numerical simulations using ABAQUS/CAE (2020) corroborate experimental findings, closely matching load-displacement curves and identifying damage locations. The study demonstrates that UHPC wet joints significantly enhance crack resistance, meeting design requirements for improved mechanical performance in bridge structures subjected to negative bending moments.

Sustainable development of ultra high-performance concrete using basil plant waste: Investigation at normal and extreme conditions

This study highlights the potential of using Basil plant (BP) waste as a viable and sustainable alternative to partially replace cement in ultra-high-performance concrete (UHPC), which can contribute to developing more sustainable and eco-friendly building materials. It investigates the effect of BP waste powder as an alternative solution on the performance of UHPC under high temperatures and severe environmental conditions. The aim was to achieve environmentally friendly green UHPC by minimizing cement content. The effect of using BP as a cement replacement with different percentages of 10 %, 20 %, 30 %, and 40 % by weight, on compressive strength, splitting tensile strength, sorptivity, and microstructure was evaluated. In addition, investigation was performed at different conditions of ambient temperature, high temperatures of 300 °C and 600 °C and severe environments subjected to chlorides and sulfates. The results showed that premixing UHPC with 30 % BP waste could improve compressive strength, with a maximum increase of 10 % at 28 days, and with decreasing sorptivity by 28 %. Additionally, the microstructure analysis revealed that incorporating BP waste leads to a denser structure and a reduction in the average pore size of the UHPC, which can enhance the durability and longevity of UHPC in construction applications. The findings of this study have important implications for the construction and building materials industry, which is under increasing pressure to adopt sustainable construction practices.

Evaluation of bonding performance of ultra high-performance concrete with fly ash content as overlay on normal strength concrete.

Ultra High-Performance Concrete (UHPC) has good mechanical strength and durability, so it can be the solution for an overlay material for old materials that need to be renewed. The problem with using UHPC as a construction material is the high price and sustainability, so a partial replacement for cement is required to reduce production costs, energy consumption, and CO2 gas emissions. Bonding performance is an important parameter and must be considered when applying UHPC as an overlay material. The bonding performance test of the UHPC consists of three tests: the slant shear test, splitting tensile, and direct tensile/pull-off test. The results of this study were compared with the standards of ACI 546R-14 and M.M. Sprinkel & C. Ozyildirim. Based on the test results, replacing 40% of cement with fly ash on UHPC is good to use as an overlay because it meets applicable standards. The test results showed an increase of 27% in the slant shear test and 37% in the splitting tensile test compared to the existing standard. Replacing cement with fly ash in UHPC can also increase workability, reducing the need for superplasticizers, reducing UHPC production costs by 18.4%, energy consumption, and CO2 emission problems.

Towards greener ultra-high performance concrete based on highly-efficient utilization of calcined clay and limestone powder

In this study, greener ultra-high performance concrete (UHPC) is designed and prepared based on calcined clay-limestone powder, aiming to increase the cement substitution level while ensuring the excellent mechanical properties of UHPC. Compressive strength tests, X-ray diffraction, thermal gravity-differential thermal gravity, isothermal calorimetry, and mercury porosimetry were used to characterize the mechanical properties, hydration and microstructure development of the samples, revealing the effect of the calcined clay and limestone powder on the performance of UHPC. The results show that when the substitution level is lower than 40%, the composition of raw materials has no obvious effect on the strength at the early stage, and the early mechanical properties decrease at the higher substitution level, but the mechanical properties at 28d are still comparable to or even higher than the reference sample. Especially, when the overall substitution level is 60% and the ratio of calcined clay to limestone powder is 2:1, the compressive strength exceeds that of the reference sample at 28d. Through this study, a feasible way for the design and preparation of greener UHPC is proposed based on calcined clay and limestone powder cementitious material system.

Multiple effects of particle size distribution modulus (q) and maximum aggregate size (Dmax) on the characteristics of Ultra-High Performance concrete (UHPC): Experiments and modeling

Ultra-high Performance Concrete (UHPC) is a kind of advanced cement-based material normally designed based on particle close packing model, such as modified Andreasen and Andersen model. However, in the utilization of this model, some key parameters have not been deeply understood. Therefore, in this research, the multiple effect of typical parameters (q value and Dmax) on the properties of UHPC are clearly clarified based on mechanical property evaluation, wet packing density, low-field NMR and X-ray Computed tomography (X-CT). The obtained results show that when different maximum particle sizes are chosen, there is an optimized q value to develop UHPC (q 0.17 for Dmax 1.25 mm; q 0.23 for Dmax 2.19 mm; q 0.25 for Dmax 4.36 mm; q 0.25 for Dmax 6.61 mm) with the lowest porosity and largest strength. Comprehensively consider the performance of UHPC, the suggested Dmax should be 2.19 mm, while the chosen q value is 0.23. At last, stereological theory is employed to get the quantity distribution of aggregates, and the aggregate particles random packing model is established to visualize the real aggregate particles packing in UHPC. And a new design concept for UHPC mix proportion design is provided.

Effect of highly dispersed colloidal olivine nano-silica on early age properties of ultra-high performance concrete

Nano-silica is an important admixture for ultra-high performance concrete (UHPC). However, complex production process and agglomeration problem of conventional nano-silica significantly limit its application in UHPC. In this study, a novel highly dispersed colloidal olivine nano-silica (C-OnS) is developed. The properties of C-OnS are characterized with laser light scattering, nuclear magnetic resonance and zeta-potential. The C-OnS is applied in UHPC to enhance the cement hydration and reduce the viscosity, while a commercial sol-gel colloidal nano-silica (C-nS) is used as a reference. The effects of C-OnS and C-nS on UHPC are investigated by calorimetry, thermal gravimetry, 29Si and 27Al nuclear magnetic resonance, nitrogen physisorption and mercury intrusion porosimeter. The results show that the performance of UHPC is enhanced by C-OnS at early ages thanks to its higher silanol content, surface area and dispersibility. The advantages of highly dispersive, strong pozzolanic reactivity and tailorable particle size provide new possibilities for application of C-OnS in cement-based materials.

Experimental Study of Flexural Performance of UHPC-NC Laminated Beams Exposed to Fire.

In recent decades, reinforced-concrete bridges have experienced premature deterioration and other problems during service due to severe environmental effects such as fire and corrosion. Previous studies have shown that the use of ultra-high-performance concrete (UHPC) can improve the durability of bridge structures. In this study, four-point bending tests were conducted on twelve UHPC–NC laminated beams with different UHPC-layer heights and at different temperatures in order to evaluate their flexural performance under fire conditions. The test variables were the UHPC heights (20 mm, 50 mm, 80 mm) and temperatures (20 °C, 200 °C, 400 °C, 600 °C), and the effects on the flexural load capacity of UHPC–NC laminated beams under the influence of these factors were investigated. The test results show that the increase in temperature causes the concrete color to change from grayish blue to white and leads to a significant decrease in the flexural load capacity of the stacked beams. The height of the UHPC layer has an important effect on the stiffness of the stacked beams and delays the formation of local cracks, thus improving the durability of the stacked beams.

Influence of Glass Powder on Rheological Properties of Ultra-High Performance Concrete Paste

Replacing cement and silica fume with glass powder to prepare ultra-high performance concrete (UHPC) is beneficial to solve the ecological problem in the field of civil engineering, but the technologies of preparation, transportation, pumping, and hardening of UHPC mainly relate to its rheological property. Therefore, this paper studied the influence of glass powder on the rheological properties of UHPC paste by performing the flow and the rheological test. Experimental results showed that when the cement and silica fume partially replaced by glass powder, the UHPC paste appears shear thickening, yield stress, plastic viscosity, and area of hysteresis loop decrease. This means that mixing glass powder can somehow inhibit the problems of segregation and bleeding of UHPC during pumping. In this manner, the dosage of the superplasticizer in UHPC is appropriately reduced, the filling capacity of UHPC during pouring is improved, and the energy required for UHPC in the pumping process is weakened. Compared with replacing cement, replacing silica fume with glass powder significantly increases the shear thickening and fluidity of UHPC paste, and at the same, reduces its yield stress and plastic viscosity. This indicates that the construction performance of UHPC is greatly improved with the replacement of silica fume. The fluidity and yield stress of UHPC paste satisfy the quadratic polynomial function relationship, and the replacement of cement and silica fume with glass powder should be less than 33% and 50%, respectively. Under this condition, the rheological properties of the UHPC paste are greatly improved and result in little negative impact on the mechanical properties of UHPC.

The Role of Iron Tailing Powder in Ultra-High-Strength Concrete Subjected to Elevated Temperatures

Iron tailing powder (ITP) is considered to have the potential to replace cement to manufacture ultra-high-performance concrete (UHPC). However, the performance of UHPC with the addition of ITP after exposure to high temperatures is more complex. This investigation prepares seven UHPC formulations by introducing different contents of ITP and investigates the mechanical behavior (residual strength), bound water content, and microstructural properties (crystalline and amorphous phases, chemical structure, and morphology) of UHPC subjected to elevated temperatures. The experimental results show that the addition of ITP postpones the spalling of concrete when exposed to high temperatures. The concrete incorporating 15% ITP maintains 53.8% of its original strength at 800°C, unlike the concrete without ITP that maintains 31.6% of its original strength. The addition of ITP increases the number of micropores/cracks in concrete and helps release the vapor pressure caused by water evaporation. The findings of this investigation highlight the potential application of ITP for future UHPC design and manufacture.

Mechanical Properties and Shrinkage of Ultrahigh‐Performance Concrete Containing Lithium Carbonate and Nano‐Calcium Carbonate

Early strength generation is essential for the successful application and usage of Ultrahigh‐Performance Concrete (UHPC) in reinforcing concrete structures. The work contained in this paper focused on evaluating the effects of lithium carbonate (Li2CO3, denoted as LC) and nano‐calcium carbonate (NC) on the early mechanical properties and autogenous shrinkage of UHPC under normal temperature curing conditions. In the study, scanning electron microscope (SEM) was utilized to investigate and quantify the morphology of the early hydration products. The corresponding results indicated that the 1‐day comprehensive strength of the UHPC increased significantly with the addition of Li2CO3 and NC. Likewise, the addition of NC mitigated the loss of the 28‐day compressive strength. For the materials evaluated, the 1‐day compressive and flexural strengths reached peak values of 72.1 and 13.9 MPa, respectively, for optimum dosages of 0.075%∼0.1% Li2CO3 and 3%∼4% NC, respectively. The results also indicated that the combined LC‐NC dosage had profound effects on the early autogenous shrinkage of UHPC, which could, however, be minimized by adjusting the Li2CO3 and NC dosages. That is, the combined dosage of the two early strength enhancers shortens the hydration induction period of cement whilst concurrently accelerating the hydration rate of the cement. The early strength agent increases the number of crystals in the hydration product and the crystal grain size becomes larger. These make the microstructure of the slurry more compact after hardening and therefore improve the overall performance of UHPC.

Review of The Cement-Based Composite Ultra-High-Performance Concrete (UHPC)

Introduction: Ultra-High-Performance Concrete (UHPC) is an advanced type of concrete in the Civil Engineering industry. It is a cement-based composite which exhibits improved mechanical and durable properties showing a high compressive strength of not less than 150 MPa and high tensile strength of not less than 7 MPa. Objective: In this article, a review of the use of a different type of supplementary cementitious materials (SCMs) including fibers is made for obtaining the desired UHPC. Discussion and Conclusion: For this, it is vital to understand the principles of UHPC. UHPC has several advantages over normal strength concrete (NSC) and high strength concrete (HSC) with some commercially ready UHPC’s available, but the use of it is restricted due to the limited design codes. The influence of the curing type also plays a vital role in the overall performance of UHPC.

Investigation of Microstructural Damage in Ultrahigh‐Performance Concrete under Freezing‐Thawing Action

This work aims to investigate the damage in ultrahigh‐performance concrete (UHPC) caused by freezing‐thawing action. Freezing‐thawing tests were carried out on UHPCs with and without steel fibers. Mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and X‐ray computed tomography (X‐ray CT) were applied to detect the microstructure of the UHPC matrix before and after the freezing‐thawing tests. The results showed that UHPC possessed very excellent freezing‐thawing resistance due to its dense microstructure. After the freezing‐thawing action, cracks occurred and were prone to initiate at the sand‐paste interface in the UHPC matrix. MIP results also indicated that cracks appeared in the UHPC matrix after the freezing‐thawing action. The number of defects that can be seen by X‐ray CT increased in UHPC after the freezing‐thawing action as well. The mismatch of the thermal expansion coefficients of the aggregate and the paste is considered to be the reason for the cracking at the sand‐paste interface. The steel fibers in UHPC inhibited the propagation of cracks in the matrix and improved the freezing‐thawing performance of UHPC.

Behavior Comparison of Prestressed Channel Girders from High-Performance and Ultrahigh-Performance Concrete

In response to the demand for sustainable and improved bridge design practices, the development of emerging materials like ultrahigh-performance concrete (UHPC) is at the forefront of structural innovation. UHPC offers significant advantages to bridge superstructure design as it provides advanced mechanical and durability properties, including high compressive strength and increased tensile capacity. With the introduction of high-strength steel fibers into mixture proportions, postcracking tensile and flexural tensile capacities are increased. These increased tensile capacities provide greater ductility and reduce or possibly eliminate the need for mild steel reinforcement. The present research investigated the behavioral response of full-scale prestressed bridge girders subjected to four-point flexural loading. Two channel-shaped girders were designed to provide equal design moment capacities to facilitate comparative analyses of performance. The first of these girders was designed with high-performance concrete [HPC; 9.5 kips per square inch (ksi; 66 MPa)] and mild steel reinforcement typical of that used in New Mexico bridge designs. The second girder used nonproprietary UHPC [20 ksi (138 MPa)] mixture proportions consisting primarily of local materials, local mixing procedures, and a local curing regimen, all of which were developed at New Mexico State University, Las Cruces. Digital image correlation was used to capture deformations throughout the testing. This information creates a full field of displacements that captures tensile and compressive strain behaviors in the pure moment region. This investigation demonstrated the advantages and improved performance of UHPC and the contribution of steel fiber reinforcement to postcracking strength and flexural capacity.

Rolling Fatigue Test of Large-Sized UHPC Member for Cable Stayed Bridge

Recently, research strives to apply Ultra High Performance Concrete (UHPC) to large-sized structures owing to its remarkable mechanical performance and durability compared to normal concrete. The Korea Institute of Construction Technology proposed SuperBridge800, an edge girder type UHPC cable stayed bridge with central span of 800 m, through its detailed design. The bridge is designed to be erected through the connection of precast UHPC segments. The precast UHPC segment is monolithically composed of one ribbed deck slab and edge girders at each side. The connection between the precast segments is achieved by steel bars at the edge girders and by UHPC cast-in-place wet joint at the slab. Despite of the outstanding mechanical performance of UHPC, the fabrication of large-sized members is a difficult task since UHPC hardens faster than normal concrete and requires a special curing process. Therefore, the constructability of large-sized UHPC segment should be secured to achieve SuperBridge800. Besides, the performance of the connection between segments should also be guaranteed, especially in terms of the fatigue performance of the UHPC cast-in-place joint, which constitutes a weak point. To that goal, two half-scaled UHPC segments are manufactured and the constructability is examined by fabricating a large-sized UHPC member connected with respect to the design conditions. This study conducts rolling fatigue test on the so-fabricated large-sized UHPC member. Rolling fatigue test is carried out up to 2 million cycles considering actual vehicle load at each center and quarter points of the member. The test results confirm that the service limit state is satisfied.

Evaluation of Flexural Performance in UHPC(Ultra High Performance Concrete) According to Placement Methods

Apart from its high compressive, tensile and flexural strengths reaching approximately 200MPa, 15MPa and 35MPa, respectively, Ultra High Performance Concrete (UHPC) is characterized by its high resistance against degrading factors that can delay their penetration and diffusion speeds down to 1/20 to maximum 1/10,000 compared to ordinary concrete. UHPC also exhibits self-compaction properties with a slump flow of about 220mm. Furthermore, the most remarkable feature of UHPC is the improvement of its flexural strength and toughness through the admixing of steel fiber. Accordingly, this study evaluates the effects of the placement method on the flexural performance of UHPC. As a result, the flexural strength of UHPC appears to be extremely dependent on the placement method with variation of the maximum flexural strength up to 2 to 3 times while poor influence is observed on the initial crack strength.