scholarly journals Air Content in Fresh Air-Entraining Cement Mortars

2021 ◽  
Vol 1203 (3) ◽  
pp. 032016
Author(s):  
Patrycja Miera
Keyword(s):  
Blast Furnace ◽  
Frost Resistance ◽  
Blast Furnace Slag ◽  
Air Entrainment ◽  
Cement Composite ◽  
American Concrete Institute ◽  
Frost Damage ◽  
Air Content ◽  
Cement Mortars ◽  
Furnace Slag

Abstract The durability of a cement composite is the most important criterion for assessing this material. However, due to the durability of the cement composite, its frost resistance is an important property. In order to ensure concrete frost resistance, the European standard PN-EN 206-1: 2013 requires its aeration at the level of 4 - 7%. The Committee 201 of the American Concrete Institute (ACI) also requires the use of an air-entraining admixture in concretes exposed to frost damage. The amount of air-entraining admixture is significantly influenced by the composition of the cement used. In order to minimize the problems with obtaining frostresistant concrete, an attempt was made to create air-entraining cements. This article presents the effect of the amount and type of dosing of air-entraining admixtures (natural and synthetic) on the air content in fresh air-entraining cement mortars. The test cements used also differed in the production method: joint mixing of components and joint grinding of components. Based on the research, a lot of valuable information was obtained related to the influence of the preparation of air-entraining cements on the air content in the mortar, e.g. mortars with mixed cement with natural air-entraining admixture have a higher air content. The air content is higher in the cement co-ground with natural air-entraining admixture. A synthetic air entraining admixture added separately to mixed cements with silica fly ash and ground granulated blast furnace slag increases air entrainment in mortars. The synthetic air-entraining admixture added separately to co-milled cements causes an increase in air entrainment in the mortars, except for those containing cement with ground granular blast furnace slag.

scholarly journals MECHANICAL PROPERTIES OF CEMENT COMPOSITE CONTAINING RECYCLED CONCRETE AND ALKALI ACTIVATED BLAST FURNACE SLAG

2020 ◽  
Vol 26 ◽  
pp. 30-33
Author(s):  
Jan Horych ◽  
Pavel Tesárek ◽  
Zdeněk Prošek
Keyword(s):  
Mechanical Properties ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Cement Composite ◽  
Strength Loss ◽  
Recycled Concrete ◽  
Cement Composites ◽  
Positive Effect ◽  
Furnace Slag ◽  
Alkali Activated

Recycling of materials is very popular and very important in these days. Finding the new ways to process and use these materials is a key to get rid of a lot of construction waste. The amount of landfilling needs to be reduced. This study observes mechanical properties of the cement composites containing recycled concrete powder and alkali-activated blast furnace slag processed on a high- peed mill as a potential binder replacement up to the 60 wt. %. These materials have a positive effect on hydration process, increase flexural strength. It can reduce compressive strength loss when an amount of cement in the mixture is reduced.

scholarly journals Frost Resistance Number to Assess Freeze and Thaw Resistance of Non-Autoclaved Aerated Concretes Containing Ground Granulated Blast-Furnace Slag and Micro-Silica

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4151
Author(s):  
Eldar Sharafutdinov ◽  
Chang-Seon Shon ◽  
Dichuan Zhang ◽  
Chul-Woo Chung ◽  
Jong Kim ◽  
...  
Keyword(s):  
Blast Furnace ◽  
Frost Resistance ◽  
Blast Furnace Slag ◽  
Autoclaved Aerated Concrete ◽  
Granulated Blast Furnace Slag ◽  
Freeze And Thaw ◽  
Aerated Concrete ◽  
Micro Silica ◽  
Furnace Slag ◽  
Scaling Resistance

Aerated concrete (AC), such as cellular concrete, autoclaved aerated concrete (AAC), and non-autoclaved aerated concrete (NAAC), having excellent insulation properties, is commonly used in buildings located in cold regions, such as Nur-Sultan in Kazakhstan, the second coldest capital city in the world, because it can contribute to a large energy saving. However, when the AC is directly exposed to the repeated freeze and thaw (F-T) cycles, its F-T resistance can be critical because of lower density and scaling resistance of the AC. Moreover, the evaluation of the F-T resistance of the AC based on the durability factor (DF) calculated by using the relative dynamic modulus of elasticity may overestimate the frost resistance of the AC due to the millions of evenly distributed air voids in spite of its weak scaling resistance. In the present study, the F-T resistance of NAAC mixtures with various binary or ternary combinations of ground granulated blast-furnace slag (GGBFS) and micro-silica was assessed mainly using the ASTM C 1262/C1262M-16 Standard Test Method for Evaluating the Freeze-Thaw Durability of Dry-Cast Segmental Retaining Wall Units and Related Concrete Units. Critical parameters to affect the F-T resistance performance of the NAAC mixture such as compressive strength, density, water absorption, air–void ratio (VR), moisture uptake, durability factor (DF), weight loss (Wloss), the degree of saturation (Sd), and residual strength (Sres) were determined. Based on the determined parameter values, frost resistance number (FRN) has been developed to evaluate the F-T resistance of the NAAC mixture. Test results showed that all NAAC mixtures had good F-T resistance when they were evaluated with DF. Binary NAAC mixtures generally showed higher Sd and Wloss and lower DF and Sres than those of ternary NAAC mixtures. It was determined that the Sd was a key factor for the F-T resistance of NAAC mixtures. Finally, the developed FRN could be an appropriate tool to evaluate the F-T resistance of the NAAC mixture.

Alkali Activation of Blast Furnace Slag by Various Types of Activators

2015 ◽  
Vol 244 ◽  
pp. 94-101 ◽  
Author(s):  
Pavel Mec ◽  
Jana Boháčová ◽  
Josef Koňařík ◽  
Petr Závrský
Keyword(s):  
Blast Furnace ◽  
Frost Resistance ◽  
Blast Furnace Slag ◽  
Setting Time ◽  
Inorganic Materials ◽  
Alkali Activation ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Furnace Slag ◽  
Alkali Activated

Alkali-activated systems, formed by the alkaline activation are inorganic materials characterized by the potential of ecological use. The objective of experiment was to investigate the influence of different activators on selected properties of alkali-activated systems based on granulated blast furnace slag. At the beginning of the experiment, 21 different samples prepared of 12 types of activators were tested to the basic properties. Then, selected samples with the best potencial to use were tested to compressive and flexural strength, frost resistance and surface resistance to chemical de-icing substances. The initial setting time achieved 25 - 95 minutes and final setting time achieved 30 - 105 minutes, compressive strengths were in the range 40 - 100MPa, frost resistance and resistance of surface to water and defrosting chemicals were confirmed.

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