The Role of Alkalis in Hydraulic Mixtures

2019 ◽  
Vol 955 ◽  
pp. 62-67
Author(s):  
Lukáš Procházka ◽  
Jana Boháčová
Keyword(s):  
Mechanical Properties ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Alkali Silica Reaction ◽  
Type Ii ◽  
Hydration Products ◽  
Experimental Part ◽  
Ph Values ◽  
Furnace Slag

Alkali substances are present in cements used as a binder in concrete only in a minimum content. The most known process that alkali causes is the alkali-silica reaction. In this reaction, the alkali contained in the cement or supplied from the outside with an inappropriately selected aggregate containing amorphous SiO2. This reaction results in the development of hydration products, resulting in an increase in the volume of the original components, which can cause a breakage of the concrete structure and subsequent disintegration. The range of alkali-silica reaction can be reduced by the use of a suitable aggregate or the use of Type II admixtures which are characterized by pozzolanic or latently hydraulic activity. These admixtures react with alkali and then no longer react with the amorphous SiO2 contained in the aggregate. Alkalis also affect other properties of concrete such as basic physical-mechanical properties, frost resistance and pH.In the experimental part the pH values were compared between mixtures of Portland cement and alkaline activated blast furnace slag using slag aggregate from the heap Koněv.

Mechanical Properties and Microstructure Analysis of Copper Tailings Solidifying with Different Cementitious Materials

2014 ◽  
Vol 878 ◽  
pp. 171-176 ◽  
Author(s):  
Xu Quan Huang ◽  
Hao Bo Hou ◽  
Min Zhou ◽  
Wei Xin Wang
Keyword(s):  
Mechanical Properties ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Calcium Silicate Hydrate ◽  
Steel Slag ◽  
Cementitious Materials ◽  
Cementitious Material ◽  
Hydration Products ◽  
New Type ◽  
Furnace Slag

With new type steel slag-blast furnace slag-fluorgypsum-based cemented material, P O42.5 cement, commonly used cementation agent in China, mechanical properties and microstructure of tailings solidification bodies are studied. The hydration products and morphology tailings concretion body in 60 days are analyzed by SEM and XRD test, which reveals the tailings cementation mechanism solidifying with different cementitious material. Furthermore, a large number of slender bar-like ettringite crystals and filamentous network-like calcium-silicate-hydrate gels bond firmly each other, which is the most important reason why steel slag-blast furnace slag-fluorgypsum base cemented material has the best tailings cementation mechanical properties.

scholarly journals Application areas of phosphogypsum in production of mineral binders and composites based on them: a review of research results

2018 ◽  
Vol 149 ◽  
pp. 01012 ◽  
Author(s):  
Leonid Dvorkin ◽  
Nataliya Lushnikova ◽  
Mohammed Sonebi
Keyword(s):  
Mechanical Properties ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Setting Time ◽  
Industrial Wastes ◽  
Cement Clinker ◽  
Complete Replacement ◽  
Slaked Lime ◽  
The Impact ◽  
Furnace Slag

The increase of the consumption of gypsum products in construction industry with a limited amount of natural gypsum deposits requires alternative sources of gypsum-containing raw materials. In some countries which have fertilizers industry plants, the problem can be solved using industrial wastes, e.g. phosphorgypsum – a byproduct of fertilizers’ production. Kept in dumps over decades, phosphorgypsum is subjected to the chemical changes due to washing out impurities with rain and other natural factors. However, there are observed deviations of harmful impurities in dumped PG depending on its age., Phosphorgypsum of any age requires chemical treatment to neutralize remains of phosphorus and sulfuric acids, fluorine compounds. According to our researches one of the most simple and effective method of neutralization the impurities is using lime-containing admixtures. The paper presents results of laboratory tests of phosphorgypsum as a component of clinker and non-clinker binders. There were investigated the impact of phosphorgypsum as admixture for clinker binders to substitute natural gypsum. Neutralized phosphorgypsum can be applied as mineralizing admixture in calcination of Portland cement clinker. Adding 2 to 2.5% of phosphorgypsum as setting time regulator resulted in a similar physical and mechanical properties compared to mix made with natural gypsum. Another important area of phosphorgypsum application is sulphate activatoion of low-clinker blast-furnace slag cement (clinker content is less than 19%). According to results, the incorporation of phosphorgypsum as sulphate activator in cement has the better effect as natural gypsum. Other development has been carried out to modify the phosphorgypsum binder properties. Complex additive consisted of polycarboxylate-based superplasticizer and slaked lime permitted an increase mechanical properties of hardened phosphorgypsum binder due to significant a reduction of water consumption. Such modified binder can be used as partial or complete replacement of gypsum binder for filling cements and finishing plasters. It can substitute gypsum in non-clinker binders like supersulphated cements. There were also developed compositions of supersulphated cements based on low-alumina blast furnace slag and phosphorgypsum. Supersulphated cements were tested in normal-weight and light-weight concrete.

scholarly journals RESEARCH OF PHYSICAL AND MECHANICAL PROPERTIES OF BLENDED BRICKS WİTH FLY ASH BASED, BLAST FURNACE SLAG ADDITION

2019 ◽  
Vol 7 (1) ◽  
pp. 126-136
Author(s):  
Hakan Çağlar ◽  
Arzu Çağlar
Keyword(s):  
Mechanical Properties ◽  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Physical And Mechanical Properties ◽  
Industrial Wastes ◽  
Second Stage ◽  
Volume Weight ◽  
History Of ◽  
Furnace Slag

In this study, it is aimed to make improvements on blended brick (1) which is the first building material has a history of at least 10,000 years. To the blended brick which is a traditional material was kept constant at 5% the addition of fly ash which is industrial waste. It was aim of determine of the effect on the physical and mechanical properties of the blended brick using different ratios (5%, 10%, 15% and 20%) blast furnace slag. In the first stage, the production of fly ash-based blast furnace slag doped sample of blended brick was performed. In the second stage, a variety of experiments were applied to determine the physical and mechanical properties of the blended brick sample. As a result; It has been determined that unit volume weight and compressive strength decreases with the use of industrial wastes in blended brick production. They have occured an increase in porosity and capillary water absorption values. The use of industrial wastes in the production of blended bricks will contribute both improve the properties of the bricks and   the reduction of wastes left to the environment.

Mechanical properties of alkali activated blast furnace slag pastes reinforced with carbon fibers

2016 ◽  
Vol 116 ◽  
pp. 63-71 ◽  
Author(s):  
J.L. Vilaplana ◽  
F.J. Baeza ◽  
O. Galao ◽  
E.G. Alcocel ◽  
E. Zornoza ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Blast Furnace ◽  
Carbon Fibers ◽  
Blast Furnace Slag ◽  
Furnace Slag ◽  
Alkali Activated

scholarly journals Advances in the Analysis of Properties Behaviour of Cement-Based Grouts with High Substitution of Cement with Blast Furnace Slags

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 561
Author(s):  
Francisca Perez-Garcia ◽  
Maria Dolores Rubio-Cintas ◽  
Maria Eugenia Parron-Rubio ◽  
Jose Manuel Garcia-Manrique
Keyword(s):  
Mechanical Properties ◽  
Blast Furnace ◽  
Steel Industry ◽  
Blast Furnace Slag ◽  
Mechanical Response ◽  
Cement Replacement ◽  
Fresh State ◽  
Different Types ◽  
Furnace Slag ◽  
Slag Waste

This article presents a study of the main properties (consistency, workability, leaching, unsoundness, and mechanical properties) of cement grouts prepared with cement replacement by blast furnace slag (GGBS). Mixtures have been analyzed in the absence of additives and reached high replacement percentages. As shown in the different tests presented, the observed evolution of the resistance and workability of the mixtures makes them very interesting for its application. Different types of cement (CEM-I 42.5 and CEM-I 52.5 R) and different water/binder values (1 and 0.67) are used. The results present opportunities for the steel industry by the intensive valorization of slag waste. The reduction of the use of cement in construction is also one of the key aims of this line of research. Results show improvements in the mechanical response with good fresh state properties for substitution percentages up to 70%. It is verified with leaching analysis that these products have less impact on the environment.

scholarly journals THE INFLUENCE OF PROCESS CONDITIONS ON GROUND COAL SLAG AND BLAST FURNACE SLAG BASED GEOPOLYMER PROPERTIES

2020 ◽  
Vol 35 (4) ◽  
pp. 15-20
Author(s):  
Quyen V. Trinh ◽  
Gábor Mucsi ◽  
Thai V. Dang ◽  
Ly P. Le ◽  
Van H. Bui ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Particle Density ◽  
Curing Temperature ◽  
Process Conditions ◽  
Ph Values ◽  
Specimen Density ◽  
Coal Slag ◽  
Furnace Slag

In this study, the material characterization of Vietnamese ground coal slag and ground granulated blast furnace slag (GGBFS), such as particle size distribution, chemical composition, bulk density and particle density are shown. The geopolymer specimens were prepared by mixing an 80 m/m% mass of solid materials (ground coal slag and GGBFS in a different ratio) with 20 m/m % of a 10M NaOH alkaline activator. A systematic experimental series was carried out in order to optimize the preparation process. In that series, the heat curing temperature was 60°C for 6 hours, and then selected specimens were heat treated at a high temperature (1000 °C) for 1 hour. After 7 days of ageing, the physical properties of the geopolymer (compressive strength, specimen density) were measured. Also, after 180 days of ageing, the pH values of water in the geopolymer leaching preparation were determined. The results show that the geopolymer can be used for refractory applications due to its good heat resistance properties. However, geopolymers that were heated at 1000 °C had lower compressive strength, specimen density and pH values of water containing the geopolymer than those that were cured at 60 °C.

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