Crack Control of Fibre Reinforced Concrete

Transcription

1 Crack Control o Fibre Reinorced Concrete Presenter Biography Dr. Izni Syahrizal bin Ibrahim Working in UTM since 1998 Has been actively involved in the research o ibre reinorced concrete since 2008 Published more than 30 technical papers in International journals and conerence proceedings 1

2 What is Fibre Reinorced Concrete? Fibre Reinorced Concrete is concrete containing ibrous material which increases its structural integrity. Contains short discrete ibres that are uniormly distributed and randomly oriented. The concept o using randomly distributed ibres to reinorced concrete was pioneered in the USA. Types o ibre: carbon ibre, steel ibre, glass ibre, synthetic ibre and natural ibre. What is Fibre Reinorced Concrete? Carbon Fibre Synthetic Fibre Types o Fibre Steel Fibre Glass Fibre Natural Fibre 2

3 Types o Steel Fibre FLAT END WAVY HOOKED END TYPES OF STEEL FIBRE STRAIGHT CRIMPED The suitability o steel ibres depends on the required application Application 1 Precast slab ready to be assemble 2 Precast slab installation 3 BRC ixing 4 Concrete topping covered BRC The main idea in this research is the use o steel ibre to replace BRC in the in-situ concrete loor slab 3

4 Application Pavement Car Park Plastering Utilization o steel ibres have somehow been accepted in the construction industry, but it is limited or light duty applications Shotcrete Precast element Why Steel Fibre? With various types o steel ibres generated that dier in terms o size, shape and texture, this widens the scope o steel ibres itsel, as ibres with dierent capabilities were ound. In most o the research, it is agreed that, an addition o randomly distributed steel ibres improve concrete characteristics in: 3. Enhancing concrete ductility ater ormation o micro-cracks 1. Delaying concrete micro-cracks propagation 2. Restraining macro-cracks development 4

5 Why Steel Fibre? Unreinorced Fibre reinorced SFRC becomes common alternative in industrial looring to prevent opening o micro cracks. In concrete structures, crack growth due to loading and shrinkage ocrs at resh state. Short steel ibre will unction as a bridge by transerring tensile orces across the crack, hence, lower the stress concentration at the crack-end. Why Steel Fibre? Lapping in BRC Replace BRC with SF Advantages in Replacing BRC with Steel Fibre Reduce crack propagation as soon as microcracks appears Reduce higher dependency on oreign workers Increase the bearing capacity o the slab No problem with concrete cover Reduce slab thickness 5

6 Aspect Ratio, L/D 10/1/2013 Why Steel Fibre? Factors inluencing the mechanical properties o SFRC Shape Surace texture Aspect ratio Tensile Capacity Grade o mechanical anchorage Concrete strength Watercement ratio Author(s) A. R. Khaloo et. al. B. W. Xu et. al. I. S. Ibrahim et. al. Related Works Type o Steel Fibre Volume Fraction, v Specimen Size (mm) Splitting Tensile Test Hooked-End cyl. Straight Crimped Hooked-End Hooked-End 80 J. Gao et. al. Rectangular J. Thomas et. al. M. Ramli et. al. P.S. Song et. al. S. Yazici et. al cyl cyl be Hooked-End cyl. Hooked-End cyl. Hooked-End cyl. Hooked-End be Flexural Test General Regression Models or prediction o ct and t A A 2 1 AV BV A( ) A( ) B B 1 V BV L D plain / B RI CRI A BV CV AV BV 2 2 A B( L / D) CV 6

7 Standard Reerence SFRC ACI 544.1R-96 ACI 544.3R-08 ACI 544.4R-08 ASTM C1116/C1116M JCI-SF RILEM TC 162-TDF Mechanical properties BS EN : 2009 Slump BS EN : 2009 Curing BS EN : 2009 BS EN : 2009 t BS EN : 2009 ct Scope o Work 1. Hooked-end type steel ibre was used. The types o steel ibres were HE0.75/60 (SF60), HE0.75/50 (SF50), and HE0.55/33 (SF33). 2. The concrete strength ixed at C The size o specimens or the material properties investigations were: Cube o 150 mm 150 mm 150 mm Cylinder o 150 mm diameter 300 mm height Prism o 150 mm 150 mm 750 mm length 4. Floor slab: 350 mm width 500 mm length 75 mm height 7

8 Scope o Work Research Methodology Data sources were collected by carrying out experimental work at the Structure & Material Laboratory, Faty o Civil Engineering, Universiti Teknologi Malaysia, Skudai, Johor Steel Fibre SF60 SF50 SF33 Supplier Oriental Housetop Sdn. Bhd. Manuacturer X Sdn. Bhd. Manuacturer X Sdn. Bhd. 8

9 Slump (mm) 10/1/2013 Research Methodology Properties SF60 SF50 SF33 Appearance Length, L (mm) Diameter, D (mm) Aspect ratio, L/D Density (kg/m 3 ) Tensile strength (MPa) Research Findings 60 Max slump Min slump 30 SF60 20 SF50 10 SF Volume Fraction, v (%) Workability test: Slump at resh state 9

10 Cube Compressive Strength, (N/mm 2 ) 10/1/2013 Research Findings Design strength SF60 SF50 SF Volume Fraction, v (%) Compression test: Design strength o 40 N/mm 2 Research Findings Compression test: Design strength o 40 N/mm 2 10

11 Splitting Tensile Strength, ct (N/mm 2 ) 10/1/2013 Research Findings SF60 SF50 SF Volume Fraction, v (%) Splitting tensile test Research Findings Splitting tensile test 11

12 Load,kN Flexural Strength, t (N/mm 2 ) Load,kN Load,kN Load,kN Load,kN 10/1/2013 Research Findings SF SF50 SF Volume Fraction, v (%) Flexural test Research Findings 80 Control mix 80 HE0.75/60_0.50% 80 HE0.75/60_1.50% Delection,mm Delection,mm Delection,mm 80 HE0/75/60_1.00% 80 HE0.75/60_2.00% Delection,mm Delection,mm Flexural test 12

13 Research Findings Flexural test SFRC Perormance Perormance o SFRC can be estimated using the law o mixtures Contributed by three components: (i) Concrete matrix, c V c (ii) Steel ibres, V (iii) Interaction between concrete-steel ibres, c SFRC = c V c + V + c where: c is the concrete stress, is the ibre stress, V c is the concrete volume raction and V is the ibre volume raction 13

14 SFRC Perormance ct t V V V V ( L / D) ( L / D) In general term: SFRC A B V 2 C V ( L / D) Bending and Shear Test First crack At ailure 14

15 Applied Load (kn) 10/1/2013 Bending and Shear Test P cal = 174 kn Mid-span Delection (mm) 0-S S S S2 1.0-S1 Bending and Shear Test Failure Mode 1 Failure Mode 2 15

16 Thank You 16