Durability Of Ultra-high Performance Concrete Research Articles

Flexural behaviors of a novel precast hollow UHPC composite beam reinforced with inverted T-shaped steel: Experimental investigation and theoretical analysis

To fully utilize the excellent mechanical properties and durability of ultra-high performance concrete (UHPC) as well as reduce the production cost, a novel UHPC encasing inverted T-steel (PUES) composite beam with hollow section is proposed in this paper. This paper aims to study the flexural behaviors of PUES beams, a bending test program consisted of one solid PUES beam and seven hollow PUES beams is carried out. The test parameters include thickness of inverted T-shape steel flange, tensile reinforcement ratio and stud spacing. The results showed that the PUES beams failed in the typical flexural failure mode and exhibited excellent ductility without obvious drop in load. Compared to composite beam with solid section, the hollow section had negligible influence on the flexural performance of PUES beams, while it saved 26 % UHPC used compared with the one with solid section. The increasing of the thickness of inverted T-shape steel flange and the reinforcement ratio effectively improved the stiffness and the flexural capacity of PUES beams, while the larger diameter of reinforcement incurred an obvious reduction of ductility. An excessively large stud spacing resulted in a poor composite behavior and a reduction of flexural capacity. Based on the analysis of the experimental results, calculating methods considering the shear connection degree between inverted T-steel and peripheral reinforced UHPC were developed to predict the ultimate flexural capacity of the hollow PUES beams. This study provides a reference for further research and practical engineering applications of this innovation composite beam.

A Comprehensive Review of the Advances, Manufacturing, Properties, Innovations, Environmental Impact and Applications of Ultra-High-Performance Concrete (UHPC)

The article presents the progress and applications of ultra-high-performance concrete (UHPC), a revolutionary material in modern construction that offers unparalleled strength, durability, and sustainability. The overview includes the historical development of UHPC, covering its production and design aspects, including composition and design methodology. It describes the mechanical properties and durability of UHPC and highlights recent innovations and research breakthroughs. The potential integration of multifunctional properties such as self-heating, self-sensing, self-luminescence and superhydrophobicity, is explored. In addition, advances in nanotechnology related to UHPC are addressed. Beyond the actual material properties, the article presents an environmental impact assessment and a life-cycle cost analysis, providing an insight into the wider implications of using UHPC. To illustrate the environmental aspects, the determination of CO2 emissions is explained using three numerical examples. Finally, various applications of UHPC are presented, focusing on the construction of buildings and bridges. By synthesizing the above-mentioned aspects, this review paper captures the dynamic landscape of UHPC and serves as a valuable resource for researchers and engineers in the field of construction materials.

Microstructural damage characterization of NC-UHPC composite under salt freeze-thaw cycles based on ex-situ X-ray computed tomography

In the harsh environment of extreme salt-freezing conditions, concrete structures face secondary durability issues after undergoing repairs, making it a critical yet challenging topic. This paper employs a novel ex-situ X-ray computed tomography approach to explore the mechanism of damage evolution in normal concrete (NC) to ultra-high performance concrete (UHPC) composites under salt-freezing conditions. For the first time, we consider evolution in both external and internal pores to quantitatively assess the damage. Additionally, slant shear tests, Mercury Intrusion Porosimetry (MIP) were also employed to validate the damage mechanism of NC-UHPC. Finally, empirical formulas summarizing the bond strength and pore changes in NC-UHPC were derived. The results reveal a crucial factor influencing the progression of damage in the NC-UHPC composite: the presence of external pores that directly interact with the salty solution. Damage initiation primarily occurs within the NC-UHPC composite due to these external pores located in the NC region, subsequently extending into the overlay transition zone (OTZ) and UHPC sections. Remarkably, the resistance of the OTZ, previously identified as the weakest zone in the NC-UHPC composite, surpasses that of the NC. This exceptional performance can be attributed to the higher porosity of the OTZ, offering additional space for the dissipation of pressure caused by freezing. What's even more important is that this highlights the consistent origin of damage in the NC-UHPC composite, emphasizing that it always begins within the NC. Considering this perspective prompts the question of whether the exceptionally high strength and durability of UHPC may lead to an excess of repair capabilities?

Retraction notice to “Influence of eco-friendly fine aggregate on macroscopic properties, microstructure and durability of ultra-high performance concrete: A review” [J. Build. Eng. 65 (2023) 105783

Retraction notice to “Influence of eco-friendly fine aggregate on macroscopic properties, microstructure and durability of ultra-high performance concrete: A review” [J. Build. Eng. 65 (2023) 105783

Characterization of Pore Size Distribution and Water Transport of UHPC Using Low-Field NMR and MIP

Water transport is vital for the durability of ultra-high performance concrete (UHPC) in engineering, but its absorption behavior requires further comprehension. This study investigates the impact of silica fume (SF) and metakaolin (MK) on water absorption in UHPC matrix with a high volume of limestone powder (LS) under two curing temperatures, and the variation in water transport with pore size obtained by low field nuclear magnetic resonance (LF-NMR). Relations between cumulative water absorption with other properties were discussed, and the pore size distribution (PSD) measured by Mercury intrusion porosimetry (MIP) was compared with that determined by LF-NMR. Results showed that MK outperformed SF in reducing water absorption in UHPC matrix, containing 30% LS under steam curing due to the synergistic effect between MK and LS. The incorporation of LS greatly affected the water absorption process of UHPC matrix. In samples without LS, capillary and gel pores absorbed water rapidly within the first 6 h and slowly from 6 h to 48 h simultaneously. However, in samples with 30% LS, gel pore water decreased during water absorption process due to the coarsening of gel pores. MK was able to suppress gel pore deterioration caused by the addition of a large amount of LS. Compared with PSD measured by MIP, NMR performed better in detecting micropores (<10 nm).

Self-heating ultra-high performance concrete with stainless steel wires for active deicing and snow-melting of transportation infrastructures

The development of self-heating concrete composites with stable electrical conductivity and strong heating capability as well as high mechanical properties is the key for achieving active deicing and snow-melting of transportation infrastructures. Due to their microscale diameter and high aspect ratio, stainless steel wires (SSWs) can form an extensive electrically and thermally conductive as well as reinforcing network inside concrete at a low content. Together with the stainless feature of SSWs as well as high structural compactness and durability of ultra-high performance concrete (UHPC), SSWs reinforced UHPC is expected to be developed into self-heating composites with strong and stable heating capability as well as ultra-high mechanical performance and durability. Therefore, this study evaluated the self-heating capability as well as active deicing and snow-melting performances of such composites. The developed SSWs reinforced UHPC slab demonstrates stable electrical conductivity and strong self-heating capability in cycle uses as well as efficient active deicing and snow-melting properties under different environmental conditions. The electrical resistivity of SSWs reinforced UHPC is only 2.58 Ω cm and it is hardly affected by the change in temperatures, numbers of cyclic self-heating, and numbers of deicing and snow-melting. The SSWs reinforced UHPC slab can be heated from 21.4 °C to 82.4 °C in 16.18 min under the voltages of 30 V in an indoor environment at a temperature of 21.2 °C. The slab only needs 28.98 min, 15.20 min, and 27.31 min to completely melt 9 mm of ice in a freezer at a temperature of −25.6 °C, 5 cm of naturally accumulated snow and 2 cm of artificially compacted snow in an outdoor environment at a temperature of about −5 °C with the wind speed up to 5.36 m s−1. Furthermore, thanks to their characteristics of no adverse effect on vehicle tires and excellent fatigue resistance, self-heating SSWs reinforced UHPC shows promising application prospects in active deicing and snow-melting of transportation infrastructures (e.g., airport runway, pavement and bridge deck) suffering from frigid weather.

Experimental Investigation on Interface Performance of UHPC-Strengthened NC Structure through Push-Out Tests.

Strengthening concrete structures with ultra-high performance concrete (UHPC) can both improve the bearing capacity of the original normal concrete (NC) structure and prolong the service life of the structure due to the high strength and durability of UHPC. The key to the synergistic work of the UHPC-strengthened layer and the original NC structures lies in the reliable bonding of their interfaces. In this research study, the shear performance of the UHPC-NC interface was investigated by the direct shear (push-out test) test method. The effects of different interface preparation methods (smoothing, chiseling, and planting straight and hooked rebars) and different aspect ratios of planted rebars on the failure mode and shear performance of the pushed-out specimens were studied. Seven groups of push-out specimens were tested. The results show that the interface preparation method can significantly affect the failure mode of the UHPC-NC interface, which is specifically divided into interface failure, planted rebar pull-out, and NC shear failure. The critical aspect ratio for the pull-out or anchorage of planted rebars in UHPC is around 2. The interface shear strength of straight-planted rebar interface preparation is significantly improved compared with that of the chiseled and smoothened interfaces, and as the embedding length of the planted rebar becomes longer, it first increases greatly and then tends to be stable when the rebar planted in UHPC is fully anchored. The shear stiffness of UHPC-NC increases with the increase of the aspect ratio of planted rebars. A design recommendation based on the experimental results is proposed. This research study supplements the theoretical basis of the interface design of UHPC-strengthened NC structures.

Mechanical properties and durability of ultra-high-performance concrete with calcined diatomaceous earth as cement replacement

Abstract Calcined diatomaceous earth (CDE) with a maximum grain size of 143 μm was used to partially replace 5 and 10% of cement in ultra-high-performance concrete (UHPC) mixtures. The other materials used in producing the concrete include Ordinary Portland Cement, iron ore powder, and river sand with maximum grain sizes 112.5, 231, and 766.2 μm, respectively. Moreover, the UHPC specimens designed with a water–cement ratio of 0.2 and a superplasticizer of 1.5% from the cement weight were tested for flow, compressive strength, flexural strength, splitting tensile strength, durability against NaCl and Na2SO4 attack, and resistance to 400, 500, and 600°C temperatures. The results showed that the use of 5 and 10% CDE to replace cement was able to increase the compressive strength, flexural strength, splitting tensile strength, the durability of UHPC against NaCl, and Na2SO4, as well as its resistance to high temperatures but reduced the mixture flow.

RETRACTED: Influence of eco-friendly fine aggregate on macroscopic properties, microstructure and durability of ultra-high performance concrete: A review

Ultra-high performance concrete (UHPC) is considered one of the promising future building material due to its excellent performance. However, it is important to note that the production of quartz sand, the fine aggregate of traditional UHPC, causes several environmental issues, including dust and noise pollution. In addition, excessive use of river sand as a raw material causes a sharp decrease in reserves. Thus, using river sand to prepare UHPC is not a sustainable method. Considering all these undesired impacts, it becomes a necessity for UHPC to meet the increasing demands of environmental sustainability. Another major issue confronting the world is waste disposal. Numerous studies show the feasibility of using industrial by-products, municipal solid waste, and recycled materials as fine aggregates for UHPC. The current work focuses on developing environmentally friendly UHPC using waste instead of quartz sand or river sand. The macroscopic (workability, compressive strength, flexural strength, elastic modulus and shrinkage), microstructural (pore structure, interfacial transition zone), and durability properties of eco-friendly UHPC were comprehensively reviewed. This paper aims to promote the utilization of waste to produce sustainable UHPC and the large-scale use of UHPC worldwide. This development will significantly reduce waste in landfill and decrease the environmental burden of conventional UHPC.

Using mixture design method for developing and optimizing eco-friendly ultra-high performance concrete characteristics

Due to its high cement content, ultra-high performance concrete (UHPC) is not an eco-friendly material. Utilizing alternative materials as a replacement of cement could improve UHPC's sustainability and reduce environmental impact. This study intends to examine the impact of using different alternative filler materials such as quartz powder (QP), limestone powder (LP), granite powder (GP) and basalt powder (BP) along with silica fume (SF) as a cement replacement on mechanical characteristics and durability of UHPC. The total powder content composed of 60% cement, 20% SF, and 20% filler materials (QP, LP, GP, and BP). Mixture design method in Minitab program was used to design concrete mixtures. Flowability, compressive strength, water permeability, rapid chloride permeability, sulfate resistance and concrete microstructure were the tests performed on the concrete mixtures. Utilizing QP, LP, BP, and GP as a partial replacement of cement in the production of UHPC resulted in significant negative impact on concrete flowability. UHPC with low environmental impact and compressive strength more than 120 MPa with higher durability could be produced using QP, LP, BP, and GP as a replacement of cement. Mixture composed of 711 kg/m3 cement, 237 kg/m3 SF, 118.5 kg/m3 QP, 118.5 kg/m3 BP, 1017 kg/m3 sand, 142.2 kg/m3 water, 31.3 kg/m3 super plasticizer, and 156 kg/m3 steel fibers achieved the highest compressive strength at age 7, 90, 180 days, the strength were 85 MPa, 123 MPa, and 126.1 MPa respectively. The findings demonstrated the development of a strong relationship between responses and constituent materials in predicting and optimizing compressive strength of UHPC, enabling construction implementers to obtain mixture design proportion to obtain UHPC with certain desirable properties using the proposed models without resorting to making experimental mixtures using a trial-and-error method, which consume time and effort.

Changes in fractal dimension and durability of ultra-high performance concrete (UHPC) with silica fume content

Changes in fractal dimension and durability of ultra-high performance concrete (UHPC) with silica fume content

An alternative method for performance improvement of ultra-high performance concrete by internal curing: Role of physicochemical properties of saturated lightweight fine aggregate

To prepare low-shrinkage ultra-high performance concrete (UHPC) with adequate mechanical properties and durability, the role of physicochemical properties of saturated lightweight fine aggregate (LWFA) in controlling the properties development of UHPC was explored. The test results showed that the LWFA could not only mitigate autogenous shrinkage significantly but also improve compressive strength and durability of UHPC. The internal curing of LWFA mitigated the reduction of internal relative humidity and promoted the hydration of cement and pozzolanic reaction. As a result, more C-S-H gel with higher polymerization degree was formed, contributing to improved micro-mechanical properties. Meanwhile, the pores in UHPC containing LWFA were significantly refined and a dense zone was formed around LWFA. Therefore, the increased hydration and pozzolanic reaction degrees, enhanced density and polymerization degree of C-S-H gels and refined pore structure of matrix counteracted the negative effects induced by the porous LWFA, contributing to the improved properties of UHPC.

Development of hybrid UHPC-NC beams: A numerical study

The mechanical properties and durability of ultra-high performance concrete (UHPC) are superior to those of normal concrete (NC). However, because UHPC is much more expensive than NC, it must be used strategically to maximize its exceptional compressive strength and sustained post-cracking tensile strength. This study develops a finite element (FE) model that represents the behavior of UHPC beams in flexure. The model is validated using previous experimental research which included UHPC beams, both with and without steel fibers, and four different reinforcement ratios. What distinguishes this study from previous efforts is that it also leverages the validated UHPC FE model to evaluate the feasibility of a hybrid reinforced concrete beam composed of both UHPC and NC. Several methods of using UHPC and fabricating a hybrid beam are studied. For a reinforcement ratio (ρ) of 0.009, a hybrid UHPC-NC beam with only the middle 50% composed of UHPC (Lu/L = 0.5) achieves the same capacity as a beam made entirely of UHPC when the NC’s compressive strength is 30 MPa or more. Using dowel bars at the UHPC-NC interface improves beam ductility and shifts the failure location away from the interface. An outward inclination (θ) of 45° at the UHPC-NC interface also improves ductility of the Lu/L = 0.5 hybrid beam. The novel hybrid UHPC-NC beam developed in this study thus obtains strength and ductility values similar to or better than those documented in beams made completely of UHPC, but at a much lower cost. Predictive equations are proposed to evaluate the ultimate capacity of the hybrid UHPC-NC beam, and the results are compared with FE analysis results.

Physical-mechanical properties and durability of ultra-high performance concrete (UHPC)

This paper presents the results of the authors' laboratory testing of physical, mechanical and durability properties of Ultra-high Performance Concrete (UHPC). The short history of development and application of UHPC concrete is presented in the first part of this paper while the second part deals with the experimental investigation, presenting the results of material characterization obtained from physical-mechanical and durability tests. Based on the results shown in the paper, the mean value of compressive strength obtained at 28 days is 114 MPa, with the average density of 2270 kg/m3 in hardened state. The results showed that tested UHPC belongs to the highest class of water impermeability V-III, as well as the highest class MS0 (without visible damage) in a simulated freeze-thaw environment and de-icing salt attack test. Also, the highest class XM3 for abrasion resistance was achieved. Additional tests showed that the tested concrete fulfils the requirements for the highest exposure classes XC4 and XD4, in terms of resistance to carbonation and the penetration of chloride ions. Conclusions and recommendations for further development and possible application of UHPC are presented at the end of paper.

Using graphene oxide to improve the properties of ultra-high-performance concrete with fine recycled aggregate

One of the most efficient methods for recycling construction and demolition (C&D) waste is to utilise the recycled aggregate (RA) obtained from the C&D waste to manufacture recycled aggregate concrete. However, the properties of the recycled aggregate concrete are inferior compared to normal concrete, owing to the use of the RA. Accordingly, this study examines the use of graphene oxide (GO) to enhance the properties of ultra-high-performance concrete (UHPC) with fine RA. An initial mixture of UHPC with fine RA was designed based on a modified Andreasen & Andersen particle packing model, and the effects of different contents of GO on the mechanical properties, volume stability, and durability of UHPC with fine RA were investigated. It was found that (1) the mechanical properties, volume stability, and durability properties of UHPC with fine RA were comparable to or even better than those of UHPC with natural river sand; (2) the optimal amount of GO was 0.06 wt%, considering the mechanical properties, durability properties, and pore structure of the UHPC; (3) the compressive strength, tensile strength, flexural strength, and elastic modulus of UHPC increased by 2.04%–16.04%, 7.36%–30.50%, 5.83%–23.40%, and 3.62%–12.95%, respectively, owing to the addition of GO; and (4) both the chloride penetration resistance and the freezing and thawing resistance of UHPC effectively improved owing to the addition of GO. These findings are conducive to the recycling of C&D waste.

Study on durability of ultra high performances concrete with aeolian sand

Compared with ordinary concrete and high strength concrete, ultra-high performance concrete has more excellent mechanical properties and durability. It has great social and economic benefits to prepare ultra-high performance aeolian sand concrete using aeolian sand as aggregate. It is of great significance to study the durability of ultra-high performance aeolian sand concrete. The mechanical properties and durability of ultra-high performance concrete are analyzed and compared by optimizing mix ratio and optimizing mix ratio. The test results show that the compressive strength of ultra-high performance aeolian sand concrete loses obviously after 300 freeze-thaw cycles. However, the splitting tensile strength is not affected by the number of freeze-thaw cycles; the strength of ultra-high performance aeolian sand concrete is not affected by sulfate immersion; with the increase of the number of drywet cycle-sulfate erosion coupling cycles, the compressive strength and splitting tensile strength of ultra-high performance aeolian sand concrete decrease rapidly at first, then increase gradually, and then decrease rapidly.

Tensile behaviour and durability aspects of sustainable ultra-high performance concrete incorporated with GGBS as cementitious material

The supplementary cementitious materials (SCMs) are used as a substitute for the cement to reduce the environmental issues backed by concrete industry for the past three decades. Additionally, the use of industrial waste as SCMs can mitigate the wastes dumped in lagoons and landfills sites. Ground granulated blast furnace slag (GGBS) is one of the potential candidates as it possesses strength, durability, economic, and environmental benefits. In this study, GGBS is used in Ultra high performance concrete (UHPC) up to 80% replacement level of cement. Various properties such as flowability, compressive strength, tensile strength, fracture, and durability of UHPC with a high volume GGBS are experimentally evaluated under two curing conditions (Standard water and elevated temperature curing). Uniaxial tensile (UAT) strength test is conducted to determine the tensile strength for UHPC. The test results inferred that the hardened properties of GGBS based UHPC are significant upto 40% cement replacement level under standard water curing. Elevated temperature curing, improves its performance upto 60% replacement level. Finally, microstructure properties are studied using scanning electron microscopy which confirms the dense microstructure of UHPC with a high volume GGBS.

Durability of ultra-high performance concrete in tension under cold weather conditions

Freezing and thawing resistance is a key characteristic for concrete materials in cold weather conditions. In this study, the tensile properties and elastic modulus of ultra-high performance concrete (UHPC) under accelerated freeze-thaw cycles are characterized. Six series of UHPC specimens are experimentally tested with a well-designed direct tension test (DTT) method to capture complete tensile stress-strain responses. Both the dynamic and wave moduli of elasticity of UHPC are measured at specific cycles using the standard impact test and self-designed “smart aggregate” technology, respectively. Long term freezing and thawing cyclic conditioning of UHPC samples results in reductions of elastic modulus, tensile strength, strain capacity, and energy absorption capacity. The tensile stress-strain curves of UHPC demonstrate distinct descending with increasing freeze-thaw cycles, particularly in the strain softening region. The energy-based approach is found to be more sensitive and effective than the elastic modulus-based approach when evaluating material deterioration over time and capturing accumulative material degradation subjected to rapidly-repeated freezing and thawing actions. As from the test results, UHPC is characterized as a very durable cementitious material, but it is not inherently unconquerable. Extended freezing and thawing actions can still lead to deterioration of the material, with respect to its elastic modulus, tensile strength, energy absorption capacity, etc. As demonstrated, the DTT method can be used to effectively characterize the long-term performance of UHPC in tension under cold weather conditions.

Evaluation and optimization of Ultra-High Performance Concrete (UHPC) subjected to harsh ocean environment: Towards an application of Layered Double Hydroxides (LDHs)

In this study, the feasibility of improving the durability of Ultra-High Performance Concrete (UHPC) by incorporating calcined Layered Double Hydroxides (C-LDHs) was investigated. The spread flow, air content, permeable porosity, compressive strength, and durability of the designed UHPC were evaluated. Furthermore, the influence of C-LDHs on cement hydration and microstructure of the designed UHPC were studied. Experimental results indicated the incorporation of 1% C-LDHs improved durability of UHPC in chloride and sulfate environment, with compressive strength enhanced simultaneously. The chloride binding capacity of C-LDHs is far better than that of cement, fly ash and silica fume, reaching a chloride absorbance of 3.28 mg/g. Therefore, C-LDHs is a functional anions absorbent materials in UHPC system, which is promising in the currently critical components of offshore buildings and structures.

Mix design and characteristics evaluation of an eco-friendly Ultra-High Performance Concrete incorporating recycled coral based materials

This paper addresses the mix design and properties evaluation of an eco-friendly Ultra-High Performance Concrete with recycled coral based materials. The modified Andreasen & Andersen particle packing model is utilized to achieve a densely compacted cementitious matrix. Micro-coral sand and coral sand are used to replace cement and sand, respectively. By adopting the Response Surface Method, the effect of blending micro-coral sand and coral sand on the mechanical properties of the designed UHPC is analyzed, aiming at a maximum use of recycled coral based materials. After that, the individual and interactive effects on the durability, autogenous shrinkage and ecological properties of the designed Ultra-High Performance Concrete are evaluated. The results show that the addition of individual recycled coral based materials can improve the workability and reduce the autogenous shrinkage of Ultra-High Performance Concrete without decreasing the durability of Ultra-High Performance Concrete. Compared to the mixture with micro-coral sand, the one with coral sand has less autogenous shrinkage and better durability. Moreover, the designed Ultra-High Performance Concrete with 15% micro-coral sand and 30% coral sand together show the best properties in this study. Additionally, the ecological evaluation demonstrates that the designed Ultra-High Performance Concrete with recycled coral based materials has relatively low environmental impact, which is promising to generate a cleaner product in the near future.