Form Pressure of Precast Prestressed Self-Consolidating Concrete

2010 ◽  
Vol 168-170 ◽  
pp. 1991-1998
Author(s):  
Wu Jian Long ◽  
Guillaume Lemieux ◽  
Kamal Henri Khayat ◽  
Feng Xing
Keyword(s):  
High Performance ◽  
Lateral Pressure ◽  
High Performance Concrete ◽  
Setting Time ◽  
Volume Ratio ◽  
Initial Pressure ◽  
Binder Content ◽  
Experimental Program ◽  
Self Consolidating Concrete ◽  
Form Pressure

Some precast, prestressed beams can reach heights of 2.4 m or more necessitating special considerations for lateral pressure to ensure formwork tightness. In order to investigate the initial form pressure of the precast, prestressed self-consolidating concrete (SCC), an experimental program was undertaken. Sixteen non air-entrained and four air-entrained SCC mixtures with a slump flow of 680 ± 20 mm were evaluated. These mixtures were made with 440 to 500 kg/m3 of binder, Type MS cement or HE cement and 20% Class F fly ash, 0.34 to 0.40 water-cementitious material ratio (w/cm), viscosity modifying admixture (VMA) content of 0 to 100 mL/100 kg of binder, and 0.46 to 0.54 sand-to-total aggregate (S/A) volume ratio. Two high-performance concrete (HPC) mixtures with 0.34 and 0.38 w/cm and slump of 150 mm were also investigated. Moreover, decay in lateral pressure with time was also determined in order to evaluate the rate of pressure drop and the time required for pressure cancellation. Test results indicated that SCC proportioned with higher binder content developed higher relative initial pressure for the 2.0-m deep section. For a given binder content, the more viscous mixtures made with 0.34 w/cm exhibited lower relative initial pressure and longer duration before pressure cancellation. It is worthy to note that air-entrained SCC exhibited higher initial pressure. Finally, a good correlation was established between the final setting time and pressure cancellation time.

Prediction on Autogenous Shrinkage of Self-Consolidating Concrete

2010 ◽  
Vol 150-151 ◽  
pp. 288-292 ◽  
Author(s):  
Wu Jian Long ◽  
Kamal Henri Khayat ◽  
Feng Xing
Keyword(s):  
High Performance ◽  
Prediction Models ◽  
Autogenous Shrinkage ◽  
Volume Ratio ◽  
Experimental Program ◽  
High Quality ◽  
Self Consolidating Concrete ◽  
Slump Flow ◽  
Binder Type ◽  
Class F Fly Ash

Proper estimate of autogenous shrinkage of self-consolidating concrete (SCC) can provide engineers with the information necessary for producing high quality products manufactured with SCC. An experimental program was undertaken to evaluate autogenous shrinkage of precast, prestressed SCC. Sixteen SCC with slump flow of 680 ± 20 mm were evaluated. These mixtures were made with 440 to 500 kg/m3 of binder, Type MS cement or HE cement and 20% Class F fly ash, 0.34 to 0.40 w/cm, viscosity-modifying admixture content of 0 to 100 mL/100 kg of binder, and 0.46 to 0.54 sand-to-total aggregate volume ratio. Two high-performance concretes (HPC) with 0.34 and 0.38 w/cm and slump of 150 mm were also investigated. HPC developed similar autogenous shrinkage at 56 days compared to SCC made of a given binder type. Shrinkage was compared to prediction models proposed by Tawaza and Miyazawa 1997, Jonasson and Hedlund 2000, and CEB-FIP 1999. The Tazawa and Miyazawa model was modified to provide adequate prediction of autogenous shrinkage for precast, prestressed SCC.

scholarly journals Tests of Residual Shear Transfer Strength of Concrete Exposed to Fire

2018 ◽  
Vol 64 (2) ◽  
pp. 187-199
Author(s):  
Muhaned A. Shallal ◽  
Aqil Mousa K. Al Musawi
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Concrete Strength ◽  
Real Life ◽  
Shear Plane ◽  
Concrete Cover ◽  
Experimental Program ◽  
Fire Exposure ◽  
Structural Components ◽  
Shear Transfer

AbstractReinforced concrete is one of the most widely used structural components about which much scientific research has been conducted; however, some of its characteristics still require further research. The main focus of this study is the effect of direct fire on the shear transfer strength of concrete. It was investigated under several parameters including concrete strength, number of stirrup legs (the steel area across the shear plane), and fire duration. The experimental program involved the testing of two sets (groups) of specimens (12 specimens each) with different concrete strengths. Each set contained specimens of two or four stirrup legs exposed to direct fire from one side (the fire was in an open area to simulate a real-life event) for a duration of one, two, and three hours. The results of the comparison showed the importance of using high-performance concrete (instead of increasing the number of stirrup legs) to resist shear stress for the purpose of safety. A significant reduction in shear strength occurred due to the deterioration of the concrete cover after three hours of direct fire exposure.

Macroscopic and Microscopic Properties of High Performance Concrete with Partial Replacement of Cement by Fly Ash

2019 ◽  
Vol 292 ◽  
pp. 108-113 ◽  
Author(s):  
Josef Fládr ◽  
Petr Bílý ◽  
Roman Chylík ◽  
Zdeněk Prošek
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Fly Ash ◽  
High Performance ◽  
High Performance Concrete ◽  
Partial Replacement ◽  
Experimental Program ◽  
Second Phase ◽  
Depth Of Penetration ◽  
Cement Replacement

The paper describes an experimental program focused on the research of high performance concrete with partial replacement of cement by fly ash. Four mixtures were investigated: reference mixture and mixtures with 10 %, 20 % and 30 % cement weight replaced by fly ash. In the first stage, the effect of cement replacement was observed. The second phase aimed at the influence of homogenization process for the selected 30% replacement on concrete properties. The analysis of macroscopic properties followed compressive strength, elastic modulus and depth of penetration of water under pressure. Microscopic analysis concentrated on the study of elastic modulus, porosity and mineralogical composition of cement matrix using scanning electron microscopy, spectral analysis and nanoindentation. The macroscopic results showed that the replacement of cement by fly ash notably improved compressive strength of concrete and significantly decreased the depth of penetration of water under pressure, while the improvement rate increased with increasing cement replacement (strength improved by 18 %, depth of penetration by 95 % at 30% replacement). Static elastic modulus was practically unaffected. Microscopic investigation showed impact of fly ash on both structure and phase mechanical performance of the material.

Flexural Behavior of Prestressed UHPC Beams

2011 ◽  
Vol 243-249 ◽  
pp. 1145-1155
Author(s):  
Jian Yang ◽  
Zhi Fang ◽  
Gong Lian Dai
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Strain Curve ◽  
Flexural Behavior ◽  
Experimental Program ◽  
Ultra High Performance Concrete ◽  
Stress Strain ◽  
Flexural Response ◽  
Strain Relationship ◽  
Relationship Of

Ultra High Performance Concrete (UHPC), which has very special properties that are remarkably different to the properties of normal and high performance concrete, is being increasingly used for the construction of structure. In this paper, an experimental program was formulated to investigate the characteristics of complete stress-strain curve of UHPC in uniaxial compression and flexural behaviors of prestressed UHPC beams. The particular focus was the influence of the partial prestress ratio and jacking stress on the flexural response of UHPC beams. The results show that UHPC is of good deformability, and a general form of the serpentine curve is proposed to represent the complete stress-strain relationship of UHPC in compression. The tests of beams demonstrated that the UHPC beams have an excellent behavior in load carrying capacity, crack distribution and deformability, their ultimate deflection can reach 1/34～1/70 of the span. Based on this investigation, theoretical correlations for the prediction structure response of UHPC beam are proposed.

Evaluation of Setting Time in Ultra High Performance Concrete

2012 ◽  
Vol 525-526 ◽  
pp. 621-624
Author(s):  
Sung Wook Kim ◽  
Jung Jun Park ◽  
Doo Youl Yoo ◽  
Young Soo Yoon
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Setting Time ◽  
Autogenous Shrinkage ◽  
High Strength ◽  
Initial Crack ◽  
Test Method ◽  
Plastic State ◽  
Ultra High Performance Concrete ◽  
Confining Stress

Ultra high performance concrete (UHPC), characterized by a high strength and high ductility, is also subjected to large shrinkage due to its low water-to-binder ratio and its large content in high fineness materials. The large amount of autogenous shrinkage of UHPC can induce crack on structural member when it was restrained with reinforcement and form. However, shrinkage of UHPC in plastic state is not generating confining stress, which is the main cause of initial crack. Normally, the setting time in concrete is an index to distinguish shrinkage which occur confining stress or not. An estimation of setting time is conducted in compliance with ASTM C 403 till now however, that test standard reveals error of results due to discordance of test condition as following with concrete type. This study therefore evaluated setting time of UHPC through the modified test method which was proposed by KICT. Test results and analyses proved a discrepancy of setting time between ASTM and proposed method. The proposed method put faith in evaluation of setting time in accordance with UHPC.

Factorial Design Approach of Ultra-High Performance Concrete

2013 ◽  
Vol 405-408 ◽  
pp. 2847-2850
Author(s):  
Wu Jian Long ◽  
Wei Lun Wang ◽  
Qi Ling Luo ◽  
Bi Qin Dong
Keyword(s):  
Mechanical Properties ◽  
Factorial Design ◽  
Statistical Models ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Design Approach ◽  
Ultra High Performance Concrete ◽  
Self Consolidating Concrete ◽  
Slump Flow

In order to understand the influence of mixture parameters on ultra-high strength self-consolidating concrete (UHS-SCC) behaviour, an experimental design was carried out in this investigation. In total, 19 SCC mixtures were prepared to determine several key responses that affect the slump flow and compressive strength of UHS-SCC. The statistical models derived from the factorial design approach can be used to quantify the effect of mixture parameters and their coupled effects on fresh and mechanical properties of SCC.

Shear resistance of self-consolidating concrete beams — experimental investigations

2005 ◽  
Vol 32 (6) ◽  
pp. 1103-1113 ◽  
Author(s):  
M Lachemi ◽  
K M.A Hossain ◽  
V Lambros
Keyword(s):  
High Performance ◽  
Failure Modes ◽  
Coarse Aggregate ◽  
High Performance Concrete ◽  
Maximum Size ◽  
Shear Resistance ◽  
Resistance Mechanisms ◽  
Experimental Investigations ◽  
Self Consolidating Concrete ◽  
Aggregate Interlock

Self-consolidating concrete (SCC) is a new generation of high performance concrete known for its excellent deformability and high resistance to segregation and bleeding. Lack of information regarding in situ properties and structural performance of SCC is one of the main barriers to its acceptance in the construction industry. There is some concern among researchers and designers that SCC may not be strong enough in shear because of some uncertainties in mechanisms resisting shear — notably the aggregate interlock mechanism. Because of the presence of comparatively smaller amount of coarse aggregates in SCC, the fracture planes are relatively smooth as compared with normal concrete (NC) that may reduce the shear resistance of concrete by reducing the aggregate interlock between the fracture surfaces. The paper compares the shear resistance of SCC and NC based on the results of an experimental investigation on 18 flexurally reinforced beams without shear reinforcements. The test parameters include concrete type, maximum size of coarse aggregate, coarse aggregate content, and beam shear span-to-depth ratio. Shear strength, shear ductility, crack patterns, and failure modes of all experimental beams are compared to analyze the shear resistance mechanisms of SCC and NC beams in both pre- and post-cracking stages. The recommendations of this paper can be of special interest to designers considering the use of SCC in structural applications.Key words: self-consolidating concrete, shear resistance, shear resistance factor, aggregate interlock, dowel action.

scholarly journals Performance of SIFCON with Steel Slag

10.29007/jxp9 ◽  
2018 ◽  
Author(s):  
Shashi Kant Sharma ◽  
Aniruddha Chopadekar ◽  
Samarth Bhatia
Keyword(s):  
Industrial Waste ◽  
High Performance ◽  
High Performance Concrete ◽  
Steel Slag ◽  
High Strength ◽  
Partial Replacement ◽  
Experimental Program ◽  
Fine Aggregate ◽  
Unique Type ◽  
The Matrix

Slurry infiltrated fibrous concrete (SIFCON) is a new and unique type of high performance concrete invented by Lankard in 1979, containing high percentage of fiber about 6% to 20% by volume. SIFCON possesses high strength as well as large ductility and has excellent potential for structural application. The matrix in SIFCON has no coarse aggregate but high cementitious content. The aim of study is to evaluate the performance of SIFCON mortar with lower fiber percentage and to minimize the fine aggregate usage by replacing it with industrial waste i.e. steel slag. Thereby, it also helps in effective disposal of industrial waste and helps in mitigating environmental pollution. The main objective of this study is to determine the effect of partial replacement of sand with steel slag on the mechanical properties of SIFCON mortar. The experimental program was carried out with 2%, 3% and 4% of fiber content by volume combined with replacement of sand by steel slag in proportion of 10% and 20% by weight. For this purpose, compressive strength, flexural strength, split tension and impact strength of SIFCON specimens were tested after 7 and 28 days of curing, yielding positive results.

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