Changes in the Fracture Toughness under Mode II Loading of Low Calcium Fly Ash (LCFA) Concrete Depending on Ages

Golewski, Grzegorz Ludwik

doi:10.3390/ma13225241

Cited by 55 publications

(16 citation statements)

References 107 publications

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“…The second reason is that the better planned cracking and failure path of discs would result in a combined mode I and mode II fracture, which may lead to the tensile failure of the discs before being failed in shear [ 47 ]. The research outcomes obtained from this study is to deliver a baseline information for continuing a deeper research work on the fracture toughness of concrete [ 48 , 49 , 50 , 51 , 52 , 53 ].…”

Section: Resultsmentioning

confidence: 99%

Evaluation of Mode II Fracture Toughness of Hybrid Fibrous Geopolymer Composites

et al. 2021

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This research aims to examine the fracture toughness of hybrid fibrous geopolymer composites under mode II. For this purpose, eight geopolymer mixtures were cast and tested to evaluate the influence of steel and synthetic fiber hybridization on mode II fracture response. The first mixture was plain and was kept as a reference, while steel, polypropylene and glass fibers were used in the rest seven mixtures. The first three of which were mono-reinforced with one of the three fibers, while the rest of the four were hybrids reinforced with combinations of steel and synthetic fibers. The Brazilian center notched disc and the double notched cube test configurations were used to evaluate the mode II fracture toughness of the eight mixtures. The results of the tests showed that steel fibers played the vital role in enhancing the fracture toughness, where the mixtures S1.6 and S1.3G0.3 showed the best performance. The results also showed that increasing the notch depth decreased the fracture toughness with an approximate linear decrement fashion. It was found that the use of double-notched cubes resulted in much higher fracture toughness than the Brazilian notched discs, where the ratio of normalized fracture toughness of the disc specimens to cube specimens was approximately 0.37 to 0.47. This is attributed to the concentration of stresses along one defined path in the disc specimens compared to the multi-path stresses in the cube specimens. In addition, the accompanied tensile stresses in the disc specimens may lead to a mode I fracture before the designed mode II fracture.

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Section: Resultsmentioning

confidence: 99%

Evaluation of Mode II Fracture Toughness of Hybrid Fibrous Geopolymer Composites

et al. 2021

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“…It has been proven in numerous papers to date that these materials significantly modify the microstructure of concrete with a changed cement binder composition, which translates into an improvement in their mechanical parameters. This phenomenon applies to ordinary concretes, e.g., [ 90 , 91 , 92 , 93 , 94 ], and high-performance concretes, e.g., [ 95 , 96 ].…”

Section: Resultsmentioning

confidence: 99%

“…The exemplary curve of F – CMOD is shown in Figure 5 . Thanks to these graphs and the equations given in [ 90 ], the fracture mechanics parameters of individual concretes were determined.…”

Section: Methodsmentioning

confidence: 99%

Studies of Fracture Toughness in Concretes Containing Fly Ash and Silica Fume in the First 28 Days of Curing

Golewski

Gil

2021

Materials

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This paper presents the results of the fracture toughness of concretes containing two mineral additives. During the tests, the method of loading the specimens according to Mode I fracture was used. The research included an evaluation of mechanical parameters of concrete containing noncondensed silica fume (SF) in an amount of 10% and siliceous fly ash (FA) in the following amounts: 0%, 10% and 20%. The experiments were carried out on mature specimens, i.e., after 28 days of curing and specimens at an early age, i.e., after 3 and 7 days of curing. In the course of experiments, the effect of adding SF to the value of the critical stress intensity factor—KIcS in FA concretes in different periods of curing were evaluated. In addition, the basic strength parameters of concrete composites, i.e., compressive strength—fcm and splitting tensile strength—fctm, were measured. A novelty in the presented research is the evaluation of the fracture toughness of concretes with two mineral additives, assessed at an early age. During the tests, the structures of all composites and the nature of macroscopic crack propagation were also assessed. A modern and useful digital image correlation (DIC) technique was used to assess macroscopic cracks. Based on the conducted research, it was found the application of SF to FA concretes contributes to a significant increase in the fracture toughness of these materials at an early age. Moreover, on the basis of the obtained test results, it was found that the values of the critical stress intensity factor of analyzed concretes were convergent qualitatively with their strength parameters. It also has been demonstrated that in the first 28 days of concrete curing, the preferred solution is to replace cement with SF in the amount of 10% or to use a cement binder substitution with a combination of additives in proportions 10% SF + 10% FA. On the other hand, the composition of mineral additives in proportions 10% SF + 20% FA has a negative effect on the fracture mechanics parameters of concretes at an early age. Based on the analysis of the results of microstructural tests and the evaluation of the propagation of macroscopic cracks, it was established that along with the substitution of the cement binder with the combination of mineral additives, the composition of the cement matrix in these composites changes, which implies a different, i.e., quasi-plastic, behavior in the process of damage and destruction of the material.

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“…It is because that HSFRC had high strength and cracking resistance, and the common studs were not enough to destroy it. In addition, due to the existence of steel fiber, the HSFRC slabs had better fracture toughness than NSC, and so HSFRC slabs could withstand large deformation without cracking [ 27 ]. This illustrated that the stud connectors with larger diameter and higher strength were more suitable for HSFRC-steel composite beam to give full play to the advantages of HSFRC.…”

Section: Test Results and Discussionmentioning

confidence: 99%

“…The price of HSFRC was lower than UHPC, and the construction and maintenance were more convenient [ 26 ]. Moreover, different fracture toughness of various concrete will result in different failure modes [ 27 ]. At present, HSFRC was mainly used in special protection structures and structure-strengthening engineering [ 28 , 29 ].…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on the Static Performance of Stud Connectors in Steel-HSFRC Composite Beams

Tang

Xue

et al. 2021

Materials

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In this research, high strength fiber reinforced concrete (HSFRC) was used to replace the normal strength concrete (NSC) in steel-concrete composite beams to improve their working performance, which might change the static performance of stud connectors. Firstly, push-out tests were conducted to investigation on the static performance of stud connectors in steel-HSFRC composite beams and compared with steel-NSC composite beams. Studs of 8 sizes, 13 mm, 16 mm, 19 mm and 22 mm in diameter and 80 mm and 120 mm in height were adopted to study the influence of stud dimension. The test phenomenon shown that the crack resistance of HSFRC was better than that of NSC, and there were some splitting cracks on NSC slabs whereas no visible cracks on HSFRC slabs when specimens failed. Next, the load-slip curves of studs were analyzed and a typical load-slip curve was proposed which was divided into four stages. In addition, the effects of test parameters were analyzed according to the characteristic points of load-slip curve. Compared with NSC slab, HSFRC slab could provide greater restraining force to the studs, which improved the shear capacity and stiffness of studs while suppressed the ductility of studs. The shear capacity, stiffness and ductility of studs would significantly increase with the increasement of stud diameter and the studs with large diameter were more suitable for steel-HSFRC composite beams. The stud height had no obvious influence on the static performance of studs. Finally, based on the test results, the empirical formulas for load-slip curve and shear capacity of stud connectors embedded in HSFRC were developed which considered the influence factors more comprehensively and had better accuracy and applicability than previous formulas.

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Changes in the Fracture Toughness under Mode II Loading of Low Calcium Fly Ash (LCFA) Concrete Depending on Ages

Cited by 55 publications

References 107 publications

Evaluation of Mode II Fracture Toughness of Hybrid Fibrous Geopolymer Composites

Evaluation of Mode II Fracture Toughness of Hybrid Fibrous Geopolymer Composites

Studies of Fracture Toughness in Concretes Containing Fly Ash and Silica Fume in the First 28 Days of Curing

Experimental Investigation on the Static Performance of Stud Connectors in Steel-HSFRC Composite Beams

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