Utilizing recycled plastic beads (RPB) as lightweight waste aggregates in the concrete and geopolymer application is quite attractive. This study presented the mechanical behavior, density, porosity, water absorption, abrasion resistance, thermal conductivity, and ultrasonic pulse velocity (UPV) of geopolymer lightweight concrete containing RPB. River sand in each mixture was replaced by various proportions of RPB ranging between 0-100% by weight. Sodium hydroxide concentration of 15 M, activator solution to fly ash ratio (L/A) of 0.40, sodium silicate and sodium hydroxide ratio of 1.0, and aggregate to fly ash ratio of 1.0 were used throughout the experiment. The results indicated that the replacement of sand by 25% and 50% of RPB had a positive impact on the weight, density, water absorption, and thermal insulating property. The strength and density of the concretes met the minimum requirements of structural lightweight concrete according to ASTM C330.

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Glutinous rice bran (GRB) is a byproduct of milling rice. Because of its high protein content, GRB can be used to produce protein hydrolysate with antioxidative properties. The antioxidant activity of protein hydrolysate depends on hydrolysis conditions. In this study, protein from GRB cv. RD6 was prepared and then subjected to proteolytic hydrolysis by alcalase. The hydrolysis conditions were optimized using response surface methodology (RSM). We investigated two independent variables: the enzyme to substrate (E/S) ratio (0.59-3.41%, w/w) and the time taken for hydrolysis to occur (45-555 minutes). The E/S ratio and hydrolysis time significantly affected the yield, DPPH radical scavenging activity, metal chelating activity, degree of hydrolysis (DH), and average molecular weight (MW) of the protein hydrolysates. The optimum conditions for hydrolysis were an E/S ratio of 2.84% and 480 minutes for hydrolysis, which obtained a yield of 40.73 ± 0.44%, an IC 50 value of 0.87 ± 0.02 mg/ml in the DPPH assay, a metal chelating activity of 72.80 ± 1.79%, a DH of 22.18 ± 0.42% and a MW of 3.07 ± 0.14 kDa. GRB protein hydrolysate, produced using alcalase, could have potential applications as an ingredient in functional food products due to its high antioxidative properties.

The compressive strength of cement paste specimens containing Bacillus pseudofirmus ATCC 700159 was investigated in order to study the self-healing ability in cement specimens. A partial replacement of bacteria suspension by 10%, 20%, 30% and 40% by weight was mixed into the cement paste before casting. At age 28 days of curing in lime water, cement paste specimens were pre-cracked by 40% of maximum compressive strength in order to make the crack allowing moisture and air to pass through. After that, these specimens were left curing in the air until 60 days prior to the compressive test. Results showed that the specimens containing bacteria had a potential to form a new compound which was created by bacteria. XRD and FTIR analysis proved that bacteria could produce carbonate ion and therefore, combined with calcium ion in cement paste becoming calcium carbonate compound. This leads to the increase in compressive strength of pre-cracked specimens where the one with 40% bacteria giving satisfactory results of self-healing cement.