The Influence of Casein Protein Admixture on Pore Size Distribution and Mechanical Properties of Lime-Metakaolin Paste

Abstract

Biopolymers based on proteins are applied in the building materials technology to modify and improve their selected properties. These polymers are designed as natural admixtures that improve the workability of materials. Casein is an example of a protein-based organic polymer. It is a protein obtained from cow’s milk. The paper aimed at investigating the prospects of enhancing the strength properties of a binder prepared on a basis of metakaolin and hydrated lime. The mix was modified with powdered technical casein at 0.5%, 1%, 3%, and 5% as a partial replacement for the binder mix by mass. The study involved investigating the effect of the applied natural admixture on the flexural and compressive strengths, as well as pore size distribution. The average pore diameter decreased in the recipes with casein in the amount of 0.5% and 1%, while it increased when the amount of casein equaled 3% and 5%. Only the 0.5% casein admixture caused a decrease in the total porosity. The results show a clear dependence of the strength parameters on porosity. The admixture of casein significantly increased the flexural strength of the pastes, and decreased the compressive strength. The highest increase in flexural strength (by 205.7%) was caused by the admixture of 0.5% casein, while the greatest decrease in compressive strength (by 28%) was caused by the 3% casein admixture. The flexural strength was enhanced, i.a., due to the improved adhesion and mutual bonding of lime particles, resulting from the application of a sticky admixture. No notable difference was indicated during carbonation by the phenolphthalein test. The lime binder is characterized by a slow setting process and low mechanical strength. The results of the research showed the possibility of improving the flexural strength using small amounts of natural admixture, which may broaden the scope of application of this binder.

Optimization and mechanical characterization of casein and seaweed resin with hemp reinforcement: A review

“…Green-stem varieties are less successful at scutching than yellow-stem varieties. P. Brzyski and others [7] The average pore width decreased by 0.5% and 1% in recipes containing casein but increased when the casein level reached 3% and 5%. Only 0.5% of the casein admixture decreased the total amount of porosity.…”

“…Brzyski and others. [7] We evaluated the ability to strengthen a binder based on hydrated and metakaolin lime by looking at the impact of adding natural admixtures of compressive and flexural strengths, as well as the distribution of pore sizes. et al S. C. [8] Examined how the physical characteristics and behaviors of the biofilm were affected by plasticizers (glycerol), different ratios of seaweed, starch, and cellulose, and biodegradable seaweed-based bioplastic.…”

Crack Binding and Filling Properties of Modified Proteins in Sustainable Cementitious Materials

“…Their study showed that chemically synthesized calcium carbonate without the presence of organic matter was not able to consolidate the loose sands. Brzyski et al 16 reported that the addition of casein protein improved the flexural strength of lime−metakaolin paste, which they attributed to increased interfacial strength between lime particles due to the presence of casein. Ventol et al 17 demonstrated that the addition of adhesive protein enhanced the compressive strength and decreased the porosity of lime mortars.…”