Alkali-activated cement using slags and fly ash

Application of the response surface method to optimize alkali activated cements based on low-reactivity ladle furnace slag

“…All the tested mixtures showed compression strength values above 10 MPa, after 7 days curing, which is deemed satisfactory for the envisaged application. The authors tested very similar mixtures in previous research [4,33], with the same raw materials and compositions, obtaining significantly lower strength values, which was a consequence of the fact that both the fly ash and the slag were not milled, indicating that this has a determinant influence on the precursor reactivity. The central point results (mixtures 5 and 7) were quite similar between them, giving a positive feedback about the methodology and increasing the confidence on the reproducibility of the results.…”

“…An additional parameter was included, which was the relation between FA and SG. The liquid content, in terms of the ratio between the quantity of activator solution and the quantity of slag and fly ash, was set constant to L/S = 0.4, based on previous work from the authors [4,33], using similar materials and conditions. It is important to notice that this method requires the input variables to be continuous so, the variables considered in the statistical study were the following:…”

“…Alkaline activation (AA), can be described as a reaction between aluminosilicate materials (precursors) and alkali or alkali-based earth substances namely, ROH, Ca(OH) 2 , R 2 CO 3 , R 2 S, Na 2 SO 4 , CaSO 4 Á2H 2 O, R2(n)SiO 2 , in which R represents an alkaline ion, such as sodium (Na) or potassium (K), or an alkaline-earth ion, such as calcium (Ca). This technique is particularly adequate to create binders based on residues, such as fly ash or slag, which constitute very effective options due to their amorphous or vitreous aluminosilicate microstructure [4][5]. The reactions begin with destruction of the covalent bonds Si-O-Si, Al-O-Al, and Al-O-Si present in the glassy phase of the precursor.…”

“…The design of the experimental work was based on the response surface method (RSM), to obtain an appropriate mathematical model, capable of minimizing the required experiments while, at the same time, producing a highly effective tool for data analysis and interpretation, allowing efficiency and economy in the experimental process and scientific objectivity in the conclusions. Rios et al, [4] explains that these methods are especially advantageous for mixtures with several constituents, as is the case of AAC, where the best performing blend is the target. This is usually achieved by changing the amount of each constituent at a time, following the traditional method of changing a factor at a time.…”

Simultaneous Oil Sono-Extraction And Sono-Transesterification (In Situ) Of Soybean And Sunflower Seeds For The Production Of Biodiesel

“…Finally, there are other alternatives that can be used in the production of FAME that do not necessarily have to be vegetables. Within this group are animal fats among which stand out; beef tallow, lard, chicken's skin waste and sh oil [9][10][11][12]. It is also possible to obtain FAME from used cooking oils which makes it possible to revalue a residue [13,14].…”