A failure analysis of concrete composites incorporating fly ash during torsional loading

2017

Materials

The paper presents the results of tests on the effect of the low calcium fly ash (LCFA) addition, in the amounts of: 0% (LCFA-00), 20% (LCFA-20) and 30% (LCFA-30) by weight of cement, on fracture processes in structural concretes. In the course of the experiments, compressive strength of concrete and fracture toughness for: I (tensile), II (in-plane shear) and III (anti-plane shear) models of cracking were measured. The tests determined the effect of age of concretes modified with LCFA on the analyzed parameters. The experiments were carried out after: 3, 7, 28, 90, 180 and 365 days of curing. Fracture toughness of concretes was determined in terms of the critical stress intensity factors: KIcS, KIIc, KIIIc and then a generalized fracture toughness Kc was specified. The obtained results are significant for the analysis of concrete structures subjected to complex loading. The properties of composites with the additive of LCFA depend on the age of the concrete tested. Mature concretes exhibit high fracture toughness at 20% additive of LCFA, while the additive of LCFA in the amount of 30% weight of cement has a beneficial effect on the parameters of concrete only after half a year of curing.

Section: Discussion Of Scientific Objectivesmentioning

confidence: 99%

“…Fracture toughness under mode I—

and mode II—

for plain concretes containing LCFA additives are the topics of several articles [ 46 , 47 , 48 , 49 , 50 ], while only three papers presents the fracture toughness for the mode III—

[ 51 , 52 , 53 ] and work of fracture—

[ 38 ]. The comprehensive study [ 38 ], devoted to cracking processes of concrete specimens containing LCFA under torsional loading, examined the effect of the LCFA additive on the

. Furthermore, the paper [ 38 ], assessed the values of critical torsion moment

and dissipated energy

at the fracture initiation point.…”

Section: Discussion Of Scientific Objectivesmentioning

confidence: 99%

“…The comprehensive study [ 38 ], devoted to cracking processes of concrete specimens containing LCFA under torsional loading, examined the effect of the LCFA additive on the

. Furthermore, the paper [ 38 ], assessed the values of critical torsion moment

and dissipated energy

at the fracture initiation point.…”

Section: Discussion Of Scientific Objectivesmentioning

confidence: 99%

See 1 more Smart Citation

Generalized Fracture Toughness and Compressive Strength of Sustainable Concrete Including Low Calcium Fly Ash

2017

Materials

“…Structural cracks in the material caused by dynamic loads are similar to damages, occurring in concrete structures working in conditions of complex stress . It should be noted, however, that with properly conducted structure analysis and correct selection of construction materials, the adverse effect of vibrations may be reduced almost entirely.…”

Section: Introductionmentioning

confidence: 99%

Physical characteristics of concrete, essential in design of fracture‐resistant, dynamically loaded reinforced concrete structures

Mat Design & Process Comms

2019

Dynamic loads are all forces acting on the structure, which are characterised by variability in a short period of time in relation to the essential dynamic characteristics (a period of natural vibrations) of the loaded structure. The use of materials with appropriate parameters is required for the construction of dynamically loaded structures, as it allows to reduce crack formation in the material structure. Reinforced concrete (RC) is an essential and widely used construction material for dynamic load‐bearing structures. Therefore, the most important physical parameters of materials used for the construction of RC structures, subjected to dynamic loads, are described in this paper. The significant physical parameters of concrete, affecting the work of dynamically loaded reinforced concrete structures, include dynamic coefficient of concrete elasticity, vibration energy absorption, dumping coefficient, and fatigue strength.

“…[4,5] and siliceous fly ash FA e.g. [6][7][8][9][10][11] for concrete, as well as an assessment of the properties of composites, to which a combination of both materials was used e.g. [12,13].…”

Section: Introductionmentioning

confidence: 99%

Potential of siliceous fly ash and silica fume as a substitute for binder in cementitious concretes

Gil

2018

E3S Web Conf.

Nowadays, concrete constructions are often erected from a material that has been modified with mineral additives or chemical admixtures. Thanks to such modifications, modern and innovative visions of architects and constructors are realizable. Modification of concrete microstructure with mineral additives results in a partial change of its properties as well as physical and mechanical parameters. Ecological and economic reasons are an additional cause of increased interest in the potential use of such additives as fly ash (FA), silica fume (SF), lime powder or granulated blast-furnace slag. The basic physical mechanism of interaction of FA and SF with concrete is primarily to seal the composite microstructure. In the paper a concrete modified with a constant amount of densified silica fume, and a variable percentage amount of siliceous fly ash was analyzed. Concrete samples have been subjected to mechanical and physical tests. Their results allowed to determine the optimal composition of a concrete mix containing the mineral supplements in the context of planned experiments. The use of a combined SF and FA additive as a substitute for a cement binder in a concrete mix allows for an optimal increase in the strength parameters of the concrete, thus not degrading its physical properties. The article presents the characteristics of materials used to make concretes and then analyzes the results of the composites' tests. An in-depth analysis of the results showed the usefulness of silica fumes and siliceous fly ashes as useful raw materials for a concrete production.