Elucidating the Crack Resistance of Alkali-Activated Slag Mortars Using Coupled Fracture Tests and Image Correlation

2015 ◽  
Vol 99 (1) ◽  
pp. 273-280 ◽  
Author(s):  
Akash Dakhane ◽  
Sumanta Das ◽  
Siva Kailas ◽  
Narayanan Neithalath
Keyword(s):  
Crack Resistance ◽  
Image Correlation ◽  
Alkali Activated Slag ◽  
Fracture Tests ◽  
Activated Slag ◽  
Alkali Activated

scholarly journals Enhancement of alkali-activated slag cement concretes crack resistance for mitigation of steel reinforcement corrosion

2020 ◽  
Vol 166 ◽  
pp. 06001
Author(s):  
Pavlo Krivenko ◽  
Oleh Petropavlovskyi ◽  
Oleksandr Kovalchuk ◽  
Igor Rudenko ◽  
Oleksandr Konstantynovskyi
Keyword(s):  
Crack Resistance ◽  
Structure Formation ◽  
Water Glass ◽  
Sodium Metasilicate ◽  
Steel Reinforcement ◽  
Reinforcement Corrosion ◽  
Slag Cement ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Alkali Activated

The paper is devoted to mitigation of steel reinforcement corrosion in alkali-activated slag cement (further, AASC) concretes, based on soluble sodium silicates (further, SSS’s), obtained from high consistensy concrete mixes. Enhancement of AASC fine concretes crack resistance due to modification by complex shrinkage-reducing additives (further, SRA’s) based on surfactants and trisodium phosphate Na3PO .12H2O (further, TSP) was proposed for mitigation of steel reinforcement corrosion. SSS’s were presented by sodium metasilicate (silica modulus 1.0, dry state) and water glass (silica modulus 2.9, density 1400 kg/m3). In case of sodium metasilicate the application of SRA composition “ordinary portland cement clinker – TSP – sodium lignosulphonate – sodium gluconate” provides enhancement of crack resistance starting from early age structure formation with restriction of drying shrinkage from 0,984 to 0,713 mm/m after 80 d. The effect is caused by reduction of water and by higher volume of crystalline hydrates. In turn, SRA presented by compositions “TSP – glycerol” and “TSP – glycerol – polyacrylamide” provide enhancement of AASC fine concretes fracture toughness during late structure formation with increasing ratio of tensile strength in bending to compressive strength up to 37 – 49 % if compare with the reference AASC when water glass is used.

scholarly journals Components of the Fracture Response of Alkali-Activated Slag Composites with Steel Microfibers

2019 ◽  
Vol 9 (9) ◽  
pp. 1754 ◽  
Author(s):  
Hana Šimonová ◽  
Petr Frantík ◽  
Zbyněk Keršner ◽  
Pavel Schmid ◽  
Pavel Rovnaník
Keyword(s):  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Model Parameters ◽  
Crack Model ◽  
Mechanical Fracture ◽  
Alkali Activated Slag ◽  
Fracture Parameters ◽  
Fracture Tests ◽  
Activated Slag ◽  
Alkali Activated

Knowledge of the mechanical and primarily fracture parameters of composites with a brittle matrix is essential for the quantification of their resistance to crack initiation and growth, and also for the specification of material model parameters employed for the simulation of the quasi-brittle behavior of structures made from this type of composite. Therefore, the main target of this paper is to quantify the mechanical fracture parameters of alkali-activated slag composites with steel microfibers and the contribution of the matrix to their fracture response. The first alkali-activated slag composite was a reference version without fibers; the others incorporated steel microfibers amounting to 5, 10, 15 and 20% by weight of the slag. Prism specimens with an initial central edge notch were used to perform the three-point bending fracture tests. Load vs. displacement (deflection at midspan) and load vs. crack mouth opening displacement diagrams were recorded during the fracture tests. The obtained diagrams were employed as inputs for parameter identification, the aim of which was to transfer the fracture test response data to the desired material parameters. Values were also determined for fracture parameters using the effective crack model, work-of-fracture method and double-K fracture model. All investigated mechanical fracture parameters were improved by the addition of steel microfibers to the alkali-activated matrix. Based on the obtained results, the addition of 10 to 15% of microfibers by weight is optimal from the point of view of the enhancement of the fracture parameters of alkali-activated slag composite.

scholarly journals Experimental and numerical analysis of the fracture response of alkali-activated slag-based materials

2020 ◽  
Vol 323 ◽  
pp. 01006
Author(s):  
Martin Lipowczan ◽  
David Lehký ◽  
Hana Šimonová ◽  
Barbara Kucharczyková
Keyword(s):  
Crack Model ◽  
Fracture Test ◽  
Mechanical Fracture ◽  
Alkali Activated Slag ◽  
Fine Grained ◽  
Shrinkage Reducing Admixture ◽  
Edge Notch ◽  
Fracture Tests ◽  
Activated Slag ◽  
Alkali Activated

The paper deals with the experimental and numerical determination of mechanical fracture parameters of fine-grained composites based on the alkali-activated slag (AAS) at different ages of hardening. Two AAS composites, which differed only in the presence of shrinkage reducing admixture, were studied. The prismatic specimens with the nominal dimensions of 40 × 40 × 160 mm and initial central edge notch were subjected to fracture tests in a three-point bending configuration. The results of the fracture tests in the form load F versus deflection d diagrams were used as input data for the identification of parameters via the inverse analysis based on the artificial neural network whose aim is to transfer the fracture test response data to the desired material parameters. The modulus of elasticity, tensile strength, and fracture energy values were identified and subsequently compared with values obtained based on the direct fracture test evaluation using the effective crack model and work-of-fracture method.

Crack Initiation of Alkali-Activated Slag Based Composites with Graphite Filler

2018 ◽  
Vol 761 ◽  
pp. 57-60
Author(s):  
Hana Šimonová ◽  
Libor Topolář ◽  
Pavel Rovnaník ◽  
Pavel Schmid ◽  
Zbyněk Keršner
Keyword(s):  
Crack Initiation ◽  
Crack Propagation ◽  
Building Materials ◽  
Crack Opening ◽  
Graphite Powder ◽  
Unstable Crack ◽  
Alkali Activated Slag ◽  
Fracture Tests ◽  
Activated Slag ◽  
Alkali Activated

The alkali-activated slag is an alternative building material to ordinary Portland cement based materials. This type of material is effective in reducing CO2 emissions and energy consumption. Addition of graphite powder increases its electric conductivity, hence, introducing new functionality to building materials such as self-sensing and self-heating properties. In this study, the effect of graphite filler on the crack initiation of alkali-activated slag composite is investigated. The graphite powder was added in the amount of 5, 10 and 15% with respect to the slag mass. Beam specimens with an initial stress concentrator were tested in three-point bending at the age of 28 days. The load versus crack mouth crack opening displacement (F–CMOD) diagrams were recorded during the fracture tests and subsequently evaluated using the Double-K fracture model. This model allows the quantification of two different levels of crack propagation: initiation, which corresponds to the beginning of stable crack growth, and the level of unstable crack propagation. The course of fracture tests was also monitored by acoustic emission (AE) method.

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