Effect of Sodium Hydroxide Concentration on the Mechanical Property of Non Sodium Silicate Fly Ash Based Geopolymer

Abstract

Cosmetic products are generally formulated as emulsions, ointments, solutions or powders containing active ingredients. According to EU legislation, a cosmetic product is "any substance or preparation intended to be placed in contact with the various external parts of the human body with a view exclusively or mainly to cleaning, perfuming them, changing their appearance, and/or correcting body odors and/or protecting them or keeping them in good conditions". However, science advancement in both active carriers and ingredients has streamlined the process through which many cosmetic products by their delivery systems can induce modifications on the skin physiology. This is the reason why Reed and Kligman redefined these products as "cosmeceuticals", which refers to the combination of cosmetics and pharmaceuticals. Until recently, the term of cosmeceuticals has not had legal significance. The so-called cosmeceuticals, in fact, may induce modifications on the skin physiology, modifying, for example, transepidermal water loss, keratinocytes cohesion and turnover, modulating the inflammatory cascade, and/or altering the surface microbiota by the activity of the preservatives content. For these reasons, they are claimed to have medical or drug-like benefits. Naturally, their effectiveness on minor skin disorders or mild skin abnormalities has to be shown by in vitro and in vivo studies. On the other hand, their formulations contain emulsifiers, preservatives, and other chemicals which, by their cumulative use, may provoke side effects, such as allergic and/or sensitization phenomena. Moreover, many ingredients and packaging for such products are not biodegradable. In this study, we would like to introduce an innovative category of cosmeceuticals made by biodegradable nonwoven tissues. These cosmeceutical tissues, produced through the use of natural fibers, may Alkali activator and materials rich in Si and Al are the requirements for the geopolymer synthesis. The common activator use is sodium hydroxide with silicate solution. There is limited literature on the mechanical property of geopolymer in the Alkali activator and materials rich in Si and Al are the requirements for the geopolymer synthesis. The common activator use is sodium hydroxide with silicate solution. There is limited literature on the mechanical property of geopolymer in the absence of silicate solution. In this study, fly ash was used as the raw material to provide Si and Al and sodium hydroxide (NaOH) as the only activator for the synthesis of geopolymer. This study describes the effect of varying the sodium hydroxide concentration with respect to curing time and temperature on mechanical properties of non-sodium silicate fly ash based geopolymer. The samples were prepared by mixing fly ash with 8, 10 and 12 M of NaOH concentration and cured in room temperature and 60°C for 1, 7 and 28 days. The highest alkali concentration of 12 M showed the fastest setting time and the highest compressive strength regardless of days of curing. The highest compressive strength obtained for curing at 60°C was 59.81 MPa and 45 min was recorded for the setting time. Meanwhile, at room temperature, the highest strength obtained was 17.71 MPa and 248 min for setting time.