This research was carried out by the Research Group of Materials Modification at PUCP. The authors would like to acknowledge the Pontificia Universidad Católica del Perú PUCP and its funding office DGI-PUCP (project 2013-0061) for providing funds to the project within which this work was developed. The forth author would also like to thank the fellowship funding for postgraduate studies by CONCYTEC, PERU (Contract N° 012-2013-FONDECYT). Finally, the authors thank the Soils Laboratory of the Civil Engineering Department at PUCP for the availability of their installations and equipment, and Manuel Otero, for providing the carrageenan extract for this study.

A synthesis of a geopolymer binder using spent fluid catalytic cracking (FCC) catalyst is evaluated in this research. Spent FCC catalyst is a solid waste product from the oil refining industry worldwide. It is composed mainly by aluminium and silicon oxides. The silica modulus (Ms), NaOH molar concentration, and liquid/solid (AS/FCC) weight ratio were studied as key factors of the mixture composition for the evaluation of the compressive strength and bulk density of geopolymers. Additional total ratios of SiO2/Al2O3, Na2O/SiO2, and H2O/total solids, which consider chemical composition of the final mixture, were studied. Results indicate that there is an optimum value for each Ms, NaOH molar concentration and AS/FCC that produces the maximum compressive strength. These values also match with the optimized total ratios of SiO2/Al2O3, N2O/SiO2 and H2O/total solids in the mixture, which can ...

This research evaluates the effect of the curing conditions on the mechanical properties of geopolymers containing spent fluid catalytic cracking catalyst (SFCCC) generated as a waste by the Peruvian oil-refinery industry. For this purpose, two curing conditions were evaluated: i) sample sealing during oven curing to avoid water loss, and ii) the time before curing (pre-curing time or delay time, before heating). The curing temperature was varied from 25°C up to 100°C. The performance of samples was assessed measuring the compressive strengths and the bulk densities. The results reveal that there are optimal curing conditions associated with the higher compressive strength of the SFCCC-based geopolymers. This optimal condition occurred when water loss was reduced by sealing, and samples were allowed to rest before curing (pre-curing). These two conditions assured not only a higher comp...

Polysaccharides from various species of algae have many applications in the food and biomedical industry. The aim of this study was to characterize nanocomposites developed from carrageenan extracted from the red algae Chondracanthus chamissoi and reinforced with montmorillonite and chitin nanowhiskers. The nanocomposites showed improved mechanical properties compared to the biopolymeric matrix. Montmorillonite-reinforced nanocomposites displayed the most favorable properties at 5% of clay concentration; meanwhile, the chitin-nanocomposites showed an improvement in the mechanical properties correlating to the increase in chitin concentration. These results will aid in the development of more environmentally friendly materials.

Geopolymer technology has allowed the development of eco-friendly construction materials with high mechanical properties using industrial wastes and residues. However, geopolymers show fragility and low ductility behavior similar to Portland cement-based materials. This article focuses on the evaluation of jute and sisal fibers as reinforcement of a geopolymer matrix produced from residues of Fired Clay Brick Powder (FCBP). Control samples with no fibers and reinforced matrices with different contents of jute (ranging from 0.5 to 2.0 wt%) and sisal fibers (ranging from 0.5 to 3.0 wt%) were produced to study the effect of the fiber type and content on the mechanical properties of the resulting geopolymer composites. Mechanical characterization consisted of compression, splitting tensile, and three-point bending tests. The results of compression and splitting tensile tests showed the exist...

The application of additive manufacturing technologies to the construction industry has a wide range of advantages from the economic, social and design flexibility point of view. However, most of up to date research studies have been performed using ordinary Portland cement (OPC)-based mortars and concretes. Therefore, the objective of this article is to explore the development of an eco-friendly earth composite reinforced with natural sisal fibers and chemically stabilized with a hydraulic binder. Analysis of the workability by shear vane tests was performed on fresh earth samples to find the optimum water content in sisal fiber-reinforced earth stabilized with OPC. Afterward, the effect of the addition of OPC on the hardening process was evaluated through shear vane and Vicat needle tests from 0 to 180 min after mixing. The results indicate that water content, fiber addition and OPC re...

Chitosan is a biodegradable, antibacterial, and nontoxic biopolymer used in a wide range of applications including biotechnology, pharmacy, and medicine. The physicochemical and biological properties of chitosan have been associated with parameters such as the degree of polymerization (DP) and the fraction of acetylation (FA). New methods are being developed to yield chitosans of specific acetylation patterns, and, recently, a correlation between biological activity and the distribution of the acetylated units (PA: pattern of acetylation) has been demonstrated. Although there are numerous well-established methods for the determination of DP and FA values, this is not the case for PA. The methods available are either not straightforward or not sensitive enough, limiting their use for routine analysis. In this study, we demonstrate that by applying HOmodecoupled Band-Selective (HOBS) decou...

In this research, the nanostructured alginate (AL) membranes were prepared with natural bioactive compound, Cat's claw (Uncaria tomentosa) extract (UT). UT is broadly used as an anti-inflammatory agent and the effect on the treatment of Rheumatism was proved by many scientists. For this reason, we added this bioactive compound in the process of AL membrane formulation to improve the biological activities. 2-dimentional (2-D) and 3-dimentional (3-D) AL membranes were prepared with and without addition of UT extracts. 3-D AL membranes were prepared using ultrasound with high intensity. The wettability of AL membranes depending on the concentration of AL was studied by measuring contact angle and surface energy. Stabilization agent, poloxamer 407, was used to improve the stability of AL nanoemulsion. The effects of UT in 3-D AL membranes were studied by measuring swelling behavior and conta...

The development of alkaline activated materials has enabled the production of eco-friendly alternatives for the construction industry. In the present article, the mechanical characterization of a new structural masonry system composed of fiber-reinforced lightweight pozzolana-based blocks and cement-lime mortar was performed. The mechanical characterization involved uniaxial compression tests in prisms and diagonal compression in wallets. The results indicate that the compressive and shear strength of the masonry system is up to 3.24 MPa and 0.38, respectively. The results obtained indicate that the evaluated system is structurally efficient and that can be used as both non-load and load-bearing walls. © 2020 Trans Tech Publications Ltd, Switzerland.

The development of new building materials requires intensive analyses of their durability under aggressive conditions. Therefore, the current study evaluated the capacity of a fiber-reinforced lightweight pozzolana-based geopolymer mortar to resist the action of fire, high temperatures and water erosion. The fire resistance and heat absorption capacity were evaluated through the exposure of disc samples to a direct flame at 1000 °C and the measurement of reverse-side temperature, respectively. To evaluate the high-temperature resistance, uniaxial compression tests were performed on cubic samples after their exposure to oven-temperatures of 300°C, 500°C, 800°C, and 1000°C. Finally, water jet erosion and permeability tests were performed to analyze the interaction of the material with water. The results of the fire tests indicate that fiber-reinforced lightweight pozzolana-based geopo...

Lightweight geopolymers are alternative low-carbon footprint building materials with high potential to produce value added products for the construction industry such as low-density masonry units. This work focuses on presenting the development of a new lightweight masonry block using natural pozzolana-based geopolymer mortar, hydrogen peroxide as a foaming agent and jute fibers as reinforcement additive. The experimental plan allowed the optimization of the production process and the definition of the optimum quantities of hydrogen peroxide content, pozzolana: fine aggregate ratios and the appropriate amount of fibers to be incorporated. The experimental results demonstrate the feasibility of the production of new masonry units, which can achieve up to 8.1 MPa of compressive strength after 28 days of fabrication with reduced bulk densities of 1269 kg/m3.

Sacha inchi oil is rich in essential and non-essential fatty acids and other types of bioactive agents like tocopherols and polyphenolic compounds, which are very well-known antioxidants. In this study, the encapsulation of sacha inchi oil in alginate (AL) and chitosan (CS) nanoparticles was achieved with the assistance of high-intensity ultrasound. Nanoemulsion is the most effective delivery and high stability system for lipophilic bioactive agents. Chitosan and surfactant concentrations were varied to study their effect on particle formulations. Size, zeta-potential, polydispersity, and stability of particles were determined in time to optimize the preparation conditions. Sacha inchi oil encapsulated in AL-CS nanoparticles showed a higher loading efficiency and stability for short and long periods compared with other vegetable oils such as olive and soybean. Also, because of the types ...

The improvement of the mechanical properties of geopolymer matrices relies on the characteristics of the source materials as well as in proper optimization of the alkaline activating solution and curing conditions during geopolimerization. This study presents the optimization analyses carried out to determine the proper production conditions of Fired Clay Brick (FCB) and Natural Pozzolana (NP)-based geopolymers. The results indicate that high compressive strengths of up to 37 MPa and 26 MPa can be obtained for FCB and NP-based geopolymers, respectively when the proper production conditions are employed. The optimum alkaline solution for FCB consisted of Ms = 0.60, Na2O content of 8%, water/binder ratio = 0.27 with oven curing conditions between 65 and 80 °C for 7 days. On the other hand, NP-based geopolymers with the highest mechanical properties were obtained with an alkaline solution ...

The study investigates the feasibility of using chitosan biopolymer as an admixture, or as an external coating, for earthen constructions to improve their resistance in two components: water induced degradation and key mechanical properties. The resistance to water induced degradation was evaluated in terms of contact angle and drip erosion tests, while the influence on mechanical properties was measured through compressive, tensile and three-point bending tests. The results indicate that the use of low concentrations of chitosan can improve significantly the performance in the two components and therefore was found to be a promising treatment for new or existing construction.