scholarly journals Modification of Alkali Activated Blast Furnace Slag for Pothole Repairs

2019 ◽  
Vol 274 ◽  
pp. 04003
Author(s):  
Minna Sarkkinen ◽  
Kauko Kujala ◽  
Seppo Gehör
Keyword(s):  
Blast Furnace ◽  
Portland Cement ◽  
Blast Furnace Slag ◽  
Negative Impact ◽  
Positive Impact ◽  
Optimization Method ◽  
Strength Development ◽  
The Impact ◽  
Furnace Slag ◽  
Alkali Activated

Potholes denote small, typically sharp edged holes in the pavement. The aim of this research was to study the usability of alkali activated (AA) blast furnace slag based material in the repair of paved roads, especially during the cold winter and spring seasons when such repairs are needed most and the use of hot asphalt is not possible. The objective was to a find material which is both more cost-efficient and durable than plain cold asphalt. Properties like rapid strength development, good bonding with old paving material, weather resistance, abrasion resistance, and low shrinkage were required. The influence of the chosen factors on the performance of the material was studied applying the multi-attribute optimization method. The impact of different additives, such as Portland cement, fibers and crushed tire rubber were studied. The results indicated that the AA slag based materials studied can be improved by suitable additives to make them reach desired performance. According to the tests, adding Portland cement increased compressive strength threefold after 3 hours and reduced shrinkage by 34% but should be a negative impact on higher levels related to freeze-thaw resistance. In addition, crushed rubber was indicated to have a positive impact related to all the studied performance properties.

scholarly journals Geopolymer Based on Mechanically Activated Air-cooled Blast Furnace Slag

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1134 ◽  
Author(s):  
Ilda Tole ◽  
Magdalena Rajczakowska ◽  
Abeer Humad ◽  
Ankit Kothari ◽  
Andrzej Cwirzen
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Portland Cement ◽  
Sodium Silicate ◽  
Blast Furnace Slag ◽  
Ball Mill ◽  
Efficient Solution ◽  
Building Materials ◽  
Furnace Slag ◽  
Alkali Activated

An efficient solution to increase the sustainability of building materials is to replace Portland cement with alkali-activated materials (AAM). Precursors for those systems are often based on water-cooled ground granulated blast furnace slags (GGBFS). Quenching of blast furnace slag can be done also by air but in that case, the final product is crystalline and with a very low reactivity. The present study aimed to evaluate the cementitious properties of a mechanically activated (MCA) air-cooled blast furnace slag (ACBFS) used as a precursor in sodium silicate alkali-activated systems. The unreactive ACBFS was processed in a planetary ball mill and its cementing performances were compared with an alkali-activated water-cooled GGBFS. Mixes based on mechanically activated ACBFS reached the 7-days compressive strength of 35 MPa and the 28-days compressive strength 45 MPa. The GGBFS-based samples showed generally higher compressive strength values.

scholarly journals Cement Kiln By-Pass Dust: An Effective Alkaline Activator for Pozzolanic Materials

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1770 ◽  
Author(s):  
Lukáš Kalina ◽  
Vlastimil Bílek ◽  
Tomáš Kiripolský ◽  
Radoslav Novotný ◽  
Jiří Másilko
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Autogenous Shrinkage ◽  
Cement Industry ◽  
Strength Development ◽  
Cement Kiln ◽  
Binder Phase ◽  
Fine Grained ◽  
Furnace Slag ◽  
Alkali Activated

Cement kiln by-pass dust (CKD) is a fine-grained by-product of Portland clinker manufacturing. Its chemical composition is not suitable for returning back into feedstock and, therefore, it has to be discharged. Such an increasing waste production contributes to the high environmental impact of the cement industry. A possible solution for the ecological processing of CKD is its incorporation into alkali-activated blast furnace slag binders. Thanks to high alkaline content, CKD serves as an effective accelerator for latent hydraulic substances which positively affect their mechanical properties. It was found out that CKD in combination with sodium carbonate creates sodium hydroxide in situ which together with sodium water glass content increases the dissolution of blast furnace slag particles and subsequently binder phase formation resulting in better flexural and compressive strength development compared to the sample without it. At the same time, the addition of CKD compensates the autogenous shrinkage of alkali-activated materials reducing the risk of material cracking. On the other hand, this type of inorganic admixture accelerates the hydration process causing rapid loss of workability.

Characterization of Carbonatation Rate of Alkali-Activated Blast Furnace Slag in Various Environments

2021 ◽  
Vol 325 ◽  
pp. 40-46
Author(s):  
Richard Dvořák ◽  
Petr Hrubý ◽  
Libor Topolář
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Destructive Testing ◽  
Time Intervals ◽  
Impact Echo ◽  
The Impact ◽  
Non Destructive ◽  
Furnace Slag ◽  
Alkali Activated

Carbonatation represents one of the potential degradation processes whose can negatively affect the service life of constructions based on the inorganic binders. The carbonatation depth of the constructions when exposed to various environments is significantly dependent on the existing conditions. The most crucial parameters are the partial pressure of carbon dioxide and humidity. There were selected four environments for the deposition of samples made of the alkali-activated blast furnace slag mortars (exterior, interior, water and CO2 chamber) in this study. These types of environments guarantee the variation of desired parameters influencing the carbonatation rate. The progress of carbonatation was evaluated with a selected technique in time intervals of 28; 56 and 84 days of the sample's exposition to the selected environments. The characterization was done using the destructive techniques (compressive and flexural strength, phenolphthalein method) as well as the non-destructive one like the Impact-Echo or the Ultrasound time passage measurement. The combination of these techniques allows to determine and evaluate the progress of carbonation without the destructive testing of the samples which is necessary for the real applications of these materials.

scholarly journals Calorimetric Studies of Alkali-Activated Blast-Furnace Slag Cements at Early Hydration Processes in the Temperature Range of 20–80 °С

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5872
Author(s):  
Aleksandr Usherov-Marshak ◽  
Danutė Vaičiukynienė ◽  
Pavel Krivenko ◽  
Girts Bumanis
Keyword(s):  
Blast Furnace ◽  
Portland Cement ◽  
Heat Release ◽  
Structure Formation ◽  
Blast Furnace Slag ◽  
Cement Clinker ◽  
Formation Stage ◽  
Portland Cement Clinker ◽  
Furnace Slag ◽  
Alkali Activated

In the hydration process of inorganic cements, the analysis of calorimetric measurements is one of the possible ways to better understand hydration processes and to keep these processes under control. This study contains data from the study of thermokinetic processes in alkali-activated blast-furnace slag cements compared to ordinary Portland cement (OPC). The obtained results show that, in contrast to ОРС, the heat release values cannot be considered as a characteristic of the activity of alkali-activated blast-furnace slag cements. In addition, it is concluded that in the case of OPC cements, cumulative heat release is a criterion for the selection of effective curing parameters, while in the case of alkali-activated blast-furnace slag cements, a higher heat rate (which increases sharply with increasing temperature from 20 to 40 °С) is a criterion. From the point of views of thermokinetics, the rate of heat release at temperatures up to 40 °С can be a qualitative criterion that allows to choose the parameters of heat curing of alkali-activated cement concretes. By introducing a crystallo-chemical hardening accelerator, such as Portland cement clinker, into the composition of alkali-activated blast-furnace slag cements, it is possible to accelerate the processes not only in the condensation-crystallization structure formation stage, but also in the dispersion-coagulation structure formation stage. Portland cement clinker increased the efficiency of thermal curing at relatively non-high temperatures.

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