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 ...

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...

Los geopolímeros tienen un gran potencial para el desarrollo de materiales de construcción sostenibles debido a la utilización de subproductos industriales y materiales de desecho para su producción. La introducción de fibras naturales en matrices de geopolímeros ha mostrado resultados interesantes para producir materiales de construcción alternativos con propiedades mecánicas mejoradas. Esta investigación explora el uso de fibras de lino (lino) como refuerzo de geopolímeros a base de polvo de ladrillo de arcilla y geopolímeros a base de cenizas volantes. Las fibras de lino se obtuvieron del Instituto de Fibras Naturales y Plantas Medicinales, mientras que el polvo de ladrillo de arcilla se obtuvo de los residuos de construcción en Lima (Perú) y las cenizas volantes se extrajeron de Skawina (Polonia). La influencia de la adición de fibras de lino en las propiedades mecánic...

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...

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...

Tomo 2. Páginas 255-265

The objective of the study was to evaluate the effect of the supplementation of organic acids (AO) on the productive parameters of guinea pigs (Cavia porcellus). Eighty male guinea pigs were randomly distributed in 20 experimental units, and these randomly assigned to five treatments: T1: Control (basal diet), T2: Growth Promoter Antibiotic (APC) (basal diet plus 200 ppm Zinc-Bacitracine), T3, T4, and T5: Organic acids (AO) (basal diet plus 100, 200 or 300 ppm respectively, of a mixture of acetic, lactic, and propionic acid in equal proportions). The basal diet was composed of wheat bran and fodder (rye grass plus clover). The animals were exposed to the treatments over 10 weeks. Body weight gain, dry matter intake, and feed conversion ratio (ICA) were evaluated. Significant quadratic response patterns to the AO were observed in body weight gain and ICA (p<0.035 and p<0.005 respect...

The objective of the present study was to determine the frequency of left displacement of the abomasum in dairy cows in 10 farms of the Lima region between years 2000 to 2004. The frequency occurrence was 6‰ (121 cases within 20 131 parturitions), where the largest number of cases occurring during the 2nd and 4th week after calving. Also, 74% of affected cows were sent to the slaughterhouse.

The objective of the study was to evaluate the effect of the supplementation of organic acids (AO) on the productive parameters of guinea pigs (Cavia porcellus). Eighty male guinea pigs were randomly distributed in 20 experimental units, and these randomly assigned to five treatments: T1: Control (basal diet), T2: Growth Promoter Antibiotic (APC) (basal diet plus 200 ppm Zinc-Bacitracine), T3, T4, and T5: Organic acids (AO) (basal diet plus 100, 200 or 300 ppm respectively, of a mixture of acetic, lactic, and propionic acid in equal proportions). The basal diet was composed of wheat bran and fodder (rye grass plus clover). The animals were exposed to the treatments over 10 weeks. Body weight gain, dry matter intake, and feed conversion ratio (ICA) were evaluated. Significant quadratic response patterns to the AO were observed in body weight gain and ICA (p<0.035 and p<0.005 respect...

El objetivo del presente trabajo fue determinar la frecuencia de casos de desplazamiento de abomaso a la izquierda (DAI) en 10 establos de la cuenca lechera de Lima en el periodo comprendido entre los años 2000 y 2004. Se encontró una frecuencia de ocurrencia de 6‰ (121 casos entre 20 131 partos), donde el mayor número se presentó entre la 2ª y 4ª semana postparto. El 74% de vacas afectadas fue enviado al camal.

The objective of the present study was to determine the prevalence of linguatulosis in bovine viscera in a slaughter house in Curicó, VII Region, Chile. The macroscopic examination of the liver, lungs, heart and the mediastinal, mesenteric and hepatic lymph nodes of 269 cattle was performed. In cases of lesions compatible with linguatulosis, the viscera were considered positive and these were observed under a stereoscope to reach the etiological diagnosis, considering as positive the lesions that presented one or more nymphs. The results showed that 11.89% of the cattle presented lesions compatible with linguatulosis in the viscera analysed and only one (0.37%) presented the positive etiological diagnosis of Linguatula serrata nymphs. The largest number of compatible lesions was found in the liver (81.8%), followed by mesenteric lymph nodes (9.1%), hepatic lymph nodes (6.1%) and lungs (...

The aim of this study was to determine the prevalence of findings compatible with hydatidosis and fertility of hydatid cysts in bovines of a slaughterhouse in Curicó, Chile. Lungs, livers, hearts, spleens and kidneys of 218 animals slaughtered in April 2017 were analyzed. The prevalence of findings compatible with hydatidosis was 12.4%, where 74.1% of affected animals presented lung cysts, 11.1% liver cysts and 14.8% of both types. Older animals concentrated the greatest number of findings. In samples of hydatid fluid from unilocular cysts a fertility of 6.25% was obtained. The prevalence of findings found was lower than the data described in national studies.  

The objective of the present study was to determine the prevalence of linguatulosis in bovine viscera in a slaughter house in Curicó, VII Region, Chile. The macroscopic examination of the liver, lungs, heart and the mediastinal, mesenteric and hepatic lymph nodes of 269 cattle was performed. In cases of lesions compatible with linguatulosis, the viscera were considered positive and these were observed under a stereoscope to reach the etiological diagnosis, considering as positive the lesions that presented one or more nymphs. The results showed that 11.89% of the cattle presented lesions compatible with linguatulosis in the viscera analysed and only one (0.37%) presented the positive etiological diagnosis of Linguatula serrata nymphs. The largest number of compatible lesions was found in the liver (81.8%), followed by mesenteric lymph nodes (9.1%), hepatic lymph nodes (6.1%) and lungs (...

The aim of this study was to determine the prevalence of findings compatible with hydatidosis and fertility of hydatid cysts in bovines of a slaughterhouse in Curicó, Chile. Lungs, livers, hearts, spleens and kidneys of 218 animals slaughtered in April 2017 were analyzed. The prevalence of findings compatible with hydatidosis was 12.4%, where 74.1% of affected animals presented lung cysts, 11.1% liver cysts and 14.8% of both types. Older animals concentrated the greatest number of findings. In samples of hydatid fluid from unilocular cysts a fertility of 6.25% was obtained. The prevalence of findings found was lower than the data described in national studies.  

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.

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.

A new arbuscular mycorrhizal fungus was found in an agricultural plantation of Plukenetia volubilis, the inka nut (also called “sacha inchi” or “inka peanut”) in the Amazonia region of San Martín State in Peru. In this site, the inka nut was grown in mixed cultures together with Zea mays and Phaseolus vulgaris. The fungus was propagated in bait and single-species cultures on Sorghum vulgare, Brachiaria brizantha, Medicago sativa, and Plukenetia volubilis as host plants. The fungus differentiates hyaline spores terminally or intercalary on cylindrical to slightly funnel-shaped hyphae, singly or in spore clusters with up to ca. 90 spores per cluster. The spores are bi-layered, (20–)25–36(–45) ?m in diameter and show regularly a visible septum at the spore base, despite the small spore and tiny hyphae sizes. Phylogenetically, the new fungus represents a new genus in a separat...