scholarly journals Fracture Properties and Softening Curves of Steel Fiber-Reinforced Slag-Based Geopolymer Mortar and Concrete

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1445 ◽  
Author(s):  
Yao Ding ◽  
Yu-Lei Bai
Keyword(s):  
Fracture Toughness ◽  
Fracture Energy ◽  
Inverse Analysis ◽  
Steel Fiber ◽  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Opening Displacement ◽  
Fracture Properties

Adding short steel fibers into slag-based geopolymer mortar and concrete is an effective method to enhance their mechanical properties. The fracture properties of steel fiber-reinforced slag-based geopolymer concrete/mortar (SGC/SGM) and unreinforced control samples were compared through three-point bending (TPB) tests. The influences of steel fiber volume contents (1.0%, 1.5% and 2.0%) on the fracture properties of SGC and SGM were studied. Load-midspan deflection (P-δ) curves and load-crack mouth opening displacement (P-CMOD) curves of the tested beams were recorded. The compressive and splitting tensile strengths were also tested. The fracture energy, flexural strength parameters, and fracture toughness of steel fiber-reinforced SGC and SGM were calculated and analyzed. The softening curves of steel fiber-reinforced SGC and SGM were determined using inverse analysis. The experimental results show that the splitting tensile strength, fracture energy, and fracture toughness are significantly enhanced with fiber incorporation. A strong correlation between the equivalent and residual flexural strengths is also observed. In addition, the trilinear strain-softening curves obtained by inverse analysis predict well of the load-displacement curves recorded from TPB tests.

Research on Fracture-CMOD Toughness of Steel Fiber Reinforced Concrete

2010 ◽  
Vol 168-170 ◽  
pp. 1784-1787
Author(s):  
Xiao Wei Wang ◽  
Wen Ling Tian ◽  
Ling Ling Fan ◽  
Ming Jie Zhou ◽  
Xiao Yan Zhao
Keyword(s):  
Fracture Toughness ◽  
Reinforced Concrete ◽  
Steel Fiber ◽  
Estimation Error ◽  
Mouth Opening ◽  
Fiber Reinforced Concrete ◽  
Crack Mouth Opening Displacement ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Toughness Index

In order to study the fracture toughness of steel fiber reinforced concrete (SFRC) and the postcracking toughness evaluation method, the fracture toughness tests were done for the four types of steel fibers and three kinds of matrix strength. According to the experiment curves of the load and the crack mouth opening displacement (Load-CMOD), the fracture toughness of SFRC was studied; the formulas of the postcracking toughness coefficient and the Fracture-CMOD toughness index were established. The experiment results show that the Fracture-CMOD toughness index can reflect sensitively to the effect on concrete toughness of the type of the steel fiber, and then it is avoid that the estimation error of the initial cracking point led to the evaluation error of the toughness.Comparison with other fibers B fiber shows the best crack resistance and the toughening ability.

scholarly journals Steel fiber bond strength to estimate fRi parameters

2021 ◽  
Author(s):  
Aaron Kadima ◽  
Jeandry Bule Ntuku ◽  
Dênio Ramam Carvalho de Oliveira
Keyword(s):  
Bond Strength ◽  
Steel Fiber ◽  
Mouth Opening ◽  
Fiber Reinforced Concrete ◽  
Crack Mouth Opening Displacement ◽  
Steel Fiber Reinforced Concrete ◽  
Fiber Volume ◽  
Opening Displacement ◽  
Fiber Aspect Ratio ◽  
Model Code

This paper presents the results of the safety assessment of the β_1 coefficient that correlates the residual flexural tensile strength parameters fRi (i = 1, 2, 3, and 4) in steel fiber reinforced concrete (SFRC), collected through experimental notched beam flexural tests in three points, according to the fib Model Code 2010 (fib, 2013), with the bond strength (fu,f) of the hook-end type steel fiber in the concrete mix. The SFRC beams were chosen, which presents the load-opening ratio curve of the crack, F-CMOD (Crack Mouth Opening Displacement) in softening behavior, the compressive strength of the concrete, 25 MPa < fc < 80 MPa, the fiber volume content, 0.25 % < Vf < 0.80 % and the fiber aspect ratio, 60 < lf/df < 95. The results in 46 prisms notched of the database formed by 13 studies, showed a considerable influence of the fRi x fu,f ratio with lower variability of around 10%. Thus, through statistical resources, empirical proposals were established to estimate the residual flexural tensile strengths, as a viable and economical alternative to the design project.

Effect of Calcium Dissolution on the Fracture Properties of Concrete Exposed to Nitric Acid Environment

2011 ◽  
Vol 374-377 ◽  
pp. 1974-1978
Author(s):  
Hai Long Wang ◽  
Chun Ling Guo ◽  
Xiao Yan Sun
Keyword(s):  
Fracture Toughness ◽  
Nitric Acid ◽  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Unstable Fracture ◽  
Crack Mouth ◽  
Acid Attack ◽  
Opening Displacement ◽  
Fracture Properties ◽  
Initial Fracture

The effect of calcium leaching by nitric acid on fracture properties of concrete was experimentally studied. The double-K fracture parameters were investigated using three-point bending beams, and the deterioration regularity of fracture properties of concrete chronically attacked by nitric acid was gotten on basis of these results. The load-crack mouth opening displacement curves under different nitric attack periods were obtained by pasting some strain gauges onto the pre-crack tip. On basis of the double-K criterion, the unstable fracture toughness as well as the initial fracture toughness was calculated according to the critical crack mouth opening displacement, the unstable fracture load and initial cracking load which can be obtained from the test. The experimental results indicated that the ratio of the initial fracture toughness to the unstable fracture toughness varied between 0.47 and 0.61 approximately. Both of the unstable fracture toughness and the initial fracture toughness decrease with attack period especially during the early 60 days, then drop to a stable trend gradually. In addition, the initial fracture toughness is less sensitive to acid attack compared with the unstable fracture toughness.

scholarly journals An Investigation of Softening Laws and Fracture Toughness of Slag-Based Geopolymer Concrete and Mortar

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5200
Author(s):  
Yao Ding ◽  
Yu-Lei Bai ◽  
Jian-Guo Dai ◽  
Cai-Jun Shi
Keyword(s):  
Fracture Toughness ◽  
Inverse Analysis ◽  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Unstable Fracture ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Tension Softening ◽  
Initial Fracture ◽  
Crack Tip Opening

This paper aimed to determine the softening laws and fracture toughness of slag-based geopolymer (SG) concrete and mortar (SGC and SGM) as compared to those of Portland cement (PC) concrete and mortar (PCC and PCM). Using three-point bending (TPB) tests, the load vs. mid-span displacement, crack mouth opening displacement, and crack tip opening displacement curves (P-d, P-CMOD, and P-CTOD curves) were all recorded. Bilinear softening laws of the PC and SG series were determined by inverse analysis. Furthermore, the cohesive toughness was predicted using an analytical fracture model. The cohesive toughness obtained by experimental study was consistent with that predicted by analytical method, proving the correctness of the tension softening law obtained from inverse analysis. In addition, both initial and unstable fracture toughness values of SG mortar were lower than those of PC mortar given the same compressive strength. Moreover, the initial fracture toughness of SG concrete was generally lower than that of PC concrete, whereas the unstable fracture toughness exhibited an opposite trend.

Experimental Research on the Fracture Properties of Roller Compacted Steel Fiber Recycled Concrete

2011 ◽  
Vol 299-300 ◽  
pp. 135-138 ◽  
Author(s):  
Yan Dong Jia ◽  
Zheng Wei Zhou ◽  
Yan Dong Qu ◽  
Ao Shuang Tian
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
Fracture Energy ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Recycled Concrete ◽  
Fiber Volume ◽  
Replacement Ratio ◽  
Fracture Properties ◽  
Ordinary Steel

Comparative experiments on the ordinary steel fiber recycled concrete (SFRC) and roller compacted SFRC were carried out to research the fracture properties of roller compacted SFRC. The results show that compressive strength, fracture toughness and fracture energy of roller compacted SFRC increase with the increase of fiber volume fraction. Compressive strength increase with the increase of recycled aggregate replacement rate and fracture toughness decrease, however, Crack tip opening displacement has little changes and fracture energy features fluctuation with the replacement ratio of recycled coarse aggregates increasing. The rolled formed layers have significant influence on the fracture properties of SFRC. The fracture toughness of roller compacted SFRC is generally lower than ordinary SFRC and compressive strength is higher than ordinary steel fiber concrete for the same aggregate replacement ratio and fiber volume fraction. Fracture energy of roller compacted SFRC is higher than ordinary SFRC for the higher steel fiber volume ratio.

Experimental Study on Fracture Properties of Cementitious Materials

2007 ◽  
Vol 348-349 ◽  
pp. 157-160
Author(s):  
Yu Zhu ◽  
Shi Lang Xu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Cement Paste ◽  
Mouth Opening ◽  
Material Design ◽  
Cementitious Materials ◽  
Crack Mouth Opening Displacement ◽  
Unstable Fracture ◽  
Opening Displacement ◽  
Fracture Properties

For micro-fiber reinforced strain-hardening cementitious materials, in addition to the basic characteristics and mechanical properties of fiber and interfacial properties between fiber and matrix, mechanical properties of matrix such as strength and crack resistance are essential parameters for material design, too. Therefore, the fracture properties of cement paste and mortar which are two most basal cementitious materials were studied, using three-point bending beams of which strength and depth are varied. Complete load versus crack mouth opening displacement (P-CMOD) curve directly obtained, and double-K fracture parameters ini Ic K and un Ic K were subsequently determined. The initial cracking load Pini was determined using resistant strain gauges. The results show that an apparent stable crack propagation before unstable failure was observed both in cement paste and in mortar. For cement paste, due to the influence of shrinkage crack, the divergence of the unstable fracture toughness un Ic K is more evident than initial fracture toughness ini Ic K .

scholarly journals Experimental Study on the Fracture Parameters of Concrete

2020 ◽  
Author(s):  
Zhanqiao Wang ◽  
Jin Gou ◽  
Danying Gao
Keyword(s):  
Steel Fiber ◽  
Volume Fraction ◽  
Mouth Opening ◽  
Critical Stress Intensity Factor ◽  
Crack Mouth Opening Displacement ◽  
Crack Tip Opening Displacement ◽  
Fiber Volume ◽  
Opening Displacement ◽  
Critical Crack ◽  
Fracture Parameters

Abstract: This study was aimed to determine the influence of the volume fraction of steel fibers and on fracture parameters of concrete. Fifty notched steel fiber reinforced concrete (SFRC) beams and ordinary concrete beams with dimensions of 100mm&times;100mm&times;515mm were cast and tested via three-point bending test. Among them, the type of steel fiber is milling type (MF), and the volume fraction of steel fiber added is 0%, 0.5%, 0.5%, 1.5%, 1.5%, 2%, respectively. The effects of the steel fiber volume fraction (VF) on the critical stress intensity factor (KIC), fracture energy (GF), the deflection at failure(&delta;0), the critical crack mouth opening displacement (CMODC) and the critical crack tip opening displacement (CTODC)were studied. Through the analysis of test phenomena and test data such as load-deflection (P-&delta;) curve, load-crack mouth opening displacement (P-CMOD) curve and load-crack tip opening displacement (P-CTOD) curve following conclusions are drawn: With the increase of steel fiber volume fraction, some fracture parameters increase gradually and maintain a certain linear growth. The gain ratio of fracture parameters increases significantly, and the gain effect is obvious. Through this law of growth, the experimental statistical formulas of fracture energy and critical stress intensity factor are summarized.

scholarly journals Experimental Study on the Fracture Parameters of Concrete

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 129
Author(s):  
Zhanqiao Wang ◽  
Jin Gou ◽  
Danying Gao
Keyword(s):  
Steel Fiber ◽  
Volume Fraction ◽  
Mouth Opening ◽  
Critical Stress Intensity Factor ◽  
Crack Mouth Opening Displacement ◽  
Crack Tip Opening Displacement ◽  
Fiber Volume ◽  
Opening Displacement ◽  
Critical Crack ◽  
Fracture Parameters

This study aimed to determine the influence of the volume fraction of steel fibers on the fracture parameters of concrete. Fifty notched steel-fiber-reinforced concrete (SFRC) beams and ordinary concrete beams with 100 mm × 100 mm × 515 mm were cast and tested via a three-point bending test. Among them, the type of steel fiber was the milling type (MF), and the volume fraction of steel fiber added was 0%, 0.5%, 1%, 1.5% and 2%, respectively. The effects of the steel fiber volume fraction (VF) on the critical stress intensity factor (KIC), fracture energy (GF), the deflection at failure(δ0), the critical crack mouth opening displacement (CMODC) and the critical crack tip opening displacement (CTODC) were studied. Through the analysis of test phenomena and test data such as the load-deflection (P-δ) curve, load-crack mouth opening displacement (P-CMOD) curve and load-crack tip opening displacement (P-CTOD) curve, the following conclusions are drawn: with the increase of the steel fiber volume fraction, some fracture parameters increase gradually and maintain a certain linear growth. The gain ratio of the fracture parameters increases significantly, and the gain effect is obvious. Through this law of growth, the experimental statistical formulas of fracture energy and the critical stress intensity factor are summarized.

scholarly journals Steel fiber bond strength to estimate fRi parameters

2021 ◽  
Author(s):  
Aaron Kadima ◽  
Jeandry Bule Ntuku ◽  
Dênio Ramam Carvalho de Oliveira
Keyword(s):  
Bond Strength ◽  
Steel Fiber ◽  
Mouth Opening ◽  
Fiber Reinforced Concrete ◽  
Crack Mouth Opening Displacement ◽  
Steel Fiber Reinforced Concrete ◽  
Fiber Volume ◽  
Opening Displacement ◽  
Fiber Aspect Ratio ◽  
Model Code

This paper presents the results of the safety assessment of the β coefficient that correlates the residual flexural tensile strength parameters f (i = 1, 2, 3, and 4) in steel fiber reinforced concrete (SFRC), collected through experimental notched beam flexural tests in three points, according to the fib Model Code 2010 (fib, 2013), with the bond strength (f) of the hook-end type steel fiber in the concrete mix. The SFRC beams were chosen, which presents the load-opening ratio curve of the crack, F-CMOD (Crack Mouth Opening Displacement) in softening behavior, the compressive strength of the concrete, 25 MPa < f < 80 MPa, the fiber volume content, 0.25 % < V < 0.80 % and the fiber aspect ratio, 60 < l/d < 95. The results in 46 prisms notched of the database formed by 13 studies, showed a considerable influence of the f x f ratio with lower variability of around 10%. Thus, through statistical resources, empirical proposals were established to estimate the residual flexural tensile strengths, as a viable and economical alternative to the design project.

Studies on effect of steel fiber and coarse aggregate on fracture properties of self compacting concrete using wedge splitting test

2019 ◽  
Vol 11 (6) ◽  
pp. 751-767
Author(s):  
Raja Rajeshwari B. ◽  
Sivakumar M.V.N.
Keyword(s):  
Fracture Energy ◽  
Coarse Aggregate ◽  
Peak Load ◽  
Mouth Opening ◽  
Test Method ◽  
Crack Mouth Opening Displacement ◽  
Fine Aggregate ◽  
Content Type ◽  
Fracture Properties ◽  
Splitting Test

Purpose Fracture properties depend on the type of material, method of testing and type of specimen. The purpose of this paper is to evaluate fracture properties by adopting a stable test method, i.e., wedge split test. Design/methodology/approach Coarse aggregate of three different sizes (20 mm, 16 mm and 12.5 mm), three ratios of coarse aggregate, fine aggregate (CA:FA) (50:50, 45:55, 40:60), presence of steel fibers, and specimens without and with guide notch were chosen as parameters of the study. Findings Load-crack mouth opening displacement curves indicate that for both fibrous and non-fibrous mixes, higher volume of aggregate and higher size of coarse aggregate have high fracture energy. Originality/value For all volumes of coarse aggregate, it was noticed that specimens with 12.5 mm aggregate size achieved highest peak load and abrupt drop post-peak. The decrease in coarseness of internal structure of concrete (λ) resulted in the increase of fracture energy.

Sign in / Sign up

Export Citation Format

Share Document