Compressive Strength Of Ultra-high Performance Concrete Research Articles

Mechanical Properties and Anti-Spalling Behavior of Ultra-High Performance Concrete with Recycled and Industrial Steel Fibers.

Experimental investigations on the mechanical properties of ultra-high performance concrete (UHPC) incorporating two types of recycled steel fiber processed from waste tires and three types of industrial steel fiber were carried out for comparison. Mechanical properties of UHPC include compressive strength, splitting tensile strength, fracture energy, and elastic modulus. Their explosive spalling behaviors under high temperatures were also investigated. The results show that all types of steel fiber exhibit a beneficial effect on the mechanical properties and the anti-spalling behavior of UHPC, except that recycled steel fiber with rubber attached (RSFR) has a slightly negative effect on the compressive strength of UHPC. Compared to industrial steel fibers, recycled steel fibers have a more significant influence on improving the splitting tensile strength and fracture energy of UHPC, and the improvement of RSFR was much higher than that of recycled steel fiber without rubber (RSF). UHPC that incorporates industrial hooked-end steel fiber (35 mm in length and 0.55 mm in diameter) exhibits the best resistance to explosive spalling, and the second is the RSF reinforced UHPC. The positive relationship between the fracture energy and the anti-spalling behavior of steel fiber reinforced UHPC can be presented. These results suggest that recycled steel fiber can be a toughening material and substitute for industrial steel fibers to be used in ultra-high performance concrete, especially RSFR.

The Influence of Granite Cutting Waste on The Properties of Ultra-High Performance Concrete

This study analyzes the effect of using waste by-products generated in the process of granite cutting as part of the granular structure of Ultra High Performance Concrete (UHPC). The manufactured concrete has a compressive strength greater than 115 MPa. This study substitutes 35%, 70% and 100% of the volume of micronized quartz powder (<40 μm) with granite cutting waste. This is an innovative study where the feasibility of using waste from granite quarries as a replacement for micronized quartz in UHPC has been analyzed. The results show an improvement in the workability and compressive strength of UHPC, for all substitution ratios. The flexural strength and tensile strength increase when the substitution ratio is 35%, and even the values obtained for 100% substitution are acceptable. In view of the results obtained in this study, granite cutting waste, instead of the micronized quartz powder usually used, is a viable alternative for the manufacture of expectedly more sustainable UHPC.

Quasi-static and dynamic mechanical properties of eco-friendly ultra-high-performance concrete containing aeolian sand

Currently, researchers have been studying ways to reduce the raw materials costs and energy consumption of ultra-high-performance concrete (UHPC) production. Therefore, the feasibility of using aeolian sand to partially or totally replace natural river sand in UHPC is studied. The workability and quasi-static and dynamic mechanical properties were comprehensively studied to investigate the effect of aeolian sand on UHPCs. It was found that: 1) The workability of UHPCs was significantly improved when river sand was partially or totally replaced by aeolian sand; 2) The compressive strength of UHPCs could be enhanced when river sand was partially or totally replaced by aeolian sand, and the differences in flexural strength among all the mixtures were not distinct; 3) Incorporation of aeolian sand as a fine aggregate slightly increased the toughness of UHPCs under uniaxial compression test; 4) The differences in the dynamic impact parameters among UHPCs containing aeolian or river sand, as well as those in the parameter evolution rules regarding impact times, were not obvious. The findings of this research promote the preparation of eco-friendly UHPC and provide a new way to use waste resources.

Ultra high-performance concrete utilizing fly ash as cement replacement under autoclaving technique

This study investigated the mechanical and permeability properties of Ultra-high performance concrete (UHPC) under autoclaving and water curing conditions. The influence of autoclave time and incorporation of five different dosages of fly ash were also examined. Test results revealed a considerable increase in compressive strength of UHPC after water curing. Also, the mechanical performance of UHPC was significantly influenced by the autoclave time and temperature and could be affected negatively beyond the stated value. In addition, the effects of fly ash dosage on the permeability of UHPC were studied. Increase in the workability of the concrete mixes as the dosage of fly ash increased from 0% to 40% was reported.

Development of sustainable ultra-high performance concrete

To design Ultra-high performance concrete (UHPC) in a sustainable way, this paper investigates the properties of UHPC containing supplementary cementitious materials (SCMs), such as fly ash (FA) and silica fume (SF). The flexural strength, compressive strength, and microstructure of the UHPC are examined. Results indicate that it is possible to design UHPC with very low cement amount. On the basis of 30% FA replacement, the incorporation of 10% and 20% SF shows equivalent or higher mechanical properties compared to the reference samples. The microstructure and pore volume of developed UHPC indicated a high correlation with its compressive strength. Efficiency factor (k-value) is calculated as an indicator to predict the flexural and compressive strength of UHPC with SCMs in terms of their synergistic effects.

Comparative study on flexural properties of ultra-high performance concrete with supplementary cementitious materials under different curing regimes

This study investigated the effects of curing regimes (standard, hot water, and steam curing) on mechanical properties of ultra-high performance concrete (UHPC) with different supplementary cementitious materials (SCMs). The flowability, compressive strength, flexural load-deflection relationship, ultimate flexural strength, and toughness of UHPC mixtures with 0, 20%, 40%, and 60% of either ground granulated blast-furnace slag (GGBS) or fly ash, by the mass of cement, were evaluated. Test results indicated that the increase in GGBS or fly ash content had limited or negative influence on the compressive strength of UHPC in terms of curing regime type . For the flexural strength, there existed an optimal SCM content, which was 40% for GGBS and 20% for fly ash. Excessed this dosage could result in a drop in flexural strength and toughness. The hot water and steam curing significantly improved the flexural properties. However, prolonging the standard curing over 28d led to comparable flexural properties as those under hot water and steam curing showed. The production of UHPC with appropriate GGBS or fly ash content with adequate standard curing, therefore, offers an effective way to obtain satisfactory flexural properties.

Effect of Density on Compressive Strength of Ultra High Performance Fiber Reinforced Concrete (UHPFRC) Using Design of Experiment

This paper aims to model the effect of density in 7, 14, 28 days on compressive strength of Ultra High Performance Concrete (UHPC) in same compaction and curing conditions by Design of Experiments (DOE) methodology using vary range of 5 variables: Silica fume (SF), Steel Fiber, Cement 42.5, Superplasticizer (SP), and water cemetiotious ratio (w/c).The results shows the significance effect of density on compressive strength of UHPC in different days, The models are valid for the mixes made with 1.0 sand, 0.15-0.30 silica fume amount, 0.70-1.30 cement amount, 0.10- 0.20 steel fiber, 0.04- 0.08 superplasticizer (all values are by sand by weight mass) and 0.18- 0.32 water cementitious ratio.

Relationship between 28-days Compressive Strength and Compression Toughness Factor of Ultra High Performance Concrete Using Design of Experiments

Usually, a material of higher strength does not necessarily indicate in a higher structural performance. While a higher energy absorbing material usually expresses higher structural performance when failure happens. This study aims at finding the relation between 28-days compressive strength and Compression toughness factor of Ultra High Performance Concrete (UHPC) using varying range of five variables which include; Steel Fiber, Silica fume (SF), Cement 42.5, Superplasticizer (SP), and water to cemetiotious ratio (w/c) by Design of Experiments (DOE) methodology. The results shows the significant relationship between the Compression toughness factor and 28 days compressive strength of UHPC. The model is valid for the mixes made with 1.0 sand, 0.15-0.30 silica fume amount, 0.70-1.30 cement amount, 0.10- 0.20 steel fiber, 0.04- 0.08 superplasticizer (all values are by aggregate weight mass) and 0.18- 0.32 water to cementitious ratio.

Compression Testing of Ultra-High-Performance Concrete

Abstract The compressive mechanical response of ultra-high-performance concrete (UHPC) surpasses that exhibited by the types of concrete for which the ASTM C39 compressive strength test and ASTM C469 compression modulus of elasticity test were developed. When attempting to complete these tests on UHPC, one will likely face challenges related to both the required load rate of 35 psi/s (0.25 MPa/s) and the cylinder end preparation requirements. Compression strength test durations for concretes with compressive strengths up to and exceeding 29 ksi (200 MPa) can be excessively long. Common cylinder end preparation techniques are not acceptable because of the high strength of the concrete, resulting in the requirement that the cylinder ends be ground to a plane, parallel finish. Researchers at the U.S. Federal Highway Administration are developing solutions to these challenges. Research on the compressive strength of UHPC has demonstrated that the strength determined through the use of an ASTM C109 type of test on concrete cubes is very similar to the strength reported with ASTM C39 tests on cylinders. Thus cubes, which do not require end preparation, can be used as a surrogate for cylinders. A separate study investigating the effect of increasing the load rate during cylinder compressive tests to 150 psi/s (1 MPa/s) was also completed. In this testing program, 400 cylinders with strengths between 18 and 30 ksi (124 and 200 MPa) were tested at a range of load rates. The strength and modulus of elasticity increases resulting from the load rate increase were observed to be minimal.

The Application and Development of Ultra-High-Performance Concrete in Bridge Engineering

Ultra-High Performance Concrete (UHPC) is a relatively new kind of matierials with excellent mechanical and durability performance compared with the conventional concrete. By making a comparison with the conventional concrete ,the compressive strength of UHPC may reach about 200MPa,which is its significant advantage and potential in applications of bridges. The performance of high tensile strength (especially with some steel fibers) enables the UHPC members to absorb energy and resist impulsive loading. In addition, because of the low porosity, the durability of the material is excellent. Based on collecting and analyzing international research results. the materials and production, and mechanical properties of UHPC were summarized. Together with a general introduction of existing international projects ,the summarization provides a comprehensive reference to further application and development of UHPC products.

Research on Ultra-High Performance Concrete with Rice Husk Ash

Tests were carried out on the properties of Ultra-High Performance Concrete (UHPC) by partially or completely replacing Silica Fume (SF) by Low-temperature Rice Husk Ash (L-RHA) .The results show that the activity and adsorptive capacity of L-RHA is greater than SF; The compressive strength of UHPC is increased by both the filling effect and the secondary hydration effect for L-RHA, but only by the filling effect for SF. However, more than 10% dosage of L-RHA or SF reduces the early compressive strength of UHPC. The compressive strength of UHPC with two blends of L-RHA and SF with less than 10% dosage of each ingredient is higher than the one with only a blend of ingredient, L-RHA or SF.