Methylcellulose was produced from the fibers of Mangifera indica L. Ubá mango seeds. MCD and MCI methylcellulose samples were made by heterogeneous methylation, using dimethyl sulfate and iodomethane as alkylating agents, respectively. The materials produced were characterized for their thermal properties (DSC and TGA), crystallinity (XRD) and Degree of Substitution (DS) in the chemical route. The cellulose derivatives were employed as mortar additive in order to improve mortar workability and adhesion to the substrate. These properties were evaluated by means of the consistency index (CI) and bond tensile strength (TS) tests. The methylcellulose (MCD and MCI) samples had CI increased by 27.75 and 71.54% and TS increased by 23.33 and 29.78%, respectively, in comparison to the reference sample. Therefore, the polymers can be used to produce adhesive mortars.

Neste trabalho foi investigado o uso do Poliestireno sulfonado (PSSNa), produzido a partir de copos plásticos descartáveis de Poliestireno (PS), como aditivo em argamassas e concretos de cimento Portland CPV32. A avaliação do PSSNa como aditivo foi baseada em ensaios de fluidez e resistência mecânica à compressão de corpos de prova. Foi observado, em argamassas com relação água/cimento (a/c) de 0,48, um aumento na fluidez com o aumento das porcentagens de PSSNa (0,25 a 1,00%). A adsorção do PSSNa sobre as partículas de cimento melhora a dispersão dos componentes da argamassa, aumentando a resistência mecânica à compressão dos corpos de prova após a cura. A aplicação do PSSNa em concreto apresentou o mesmo efeito. O abatimento do concreto sem PSSNa foi de 50 mm, atingindo cerca de 200 mm com o uso do polieletrólito. Devido à elevada plasticização observada é possível empregar o PSSNa como aditivo redutor de água. Foi produzido um concreto com o mesmo abatimento da referência sem aditivo reduzindo-se a quantidade de água em 20,8%. O ganho de resistência mecânica à compressão obtido foi de 21,5 e 26,3 %, respectivamente aos 7 e 28 dias de cura. Estes resultados mostraram que soluções de PSSNa podem atuar eficientemente como aditivo superplastificante ou redutor de água em argamassas e concretos.

In this work an investigation was made of the effects from adding PSSNa, obtained from disposable polystyrene (PS) cups, as admixture agent in mortars and concrete with varying ratios from 0.25 to 1.00%. The evaluation of PSSNa as additive was based on results of fluidity and mechanical strength to compression. In mortars with water/cement ratio of 0.48, an increase in flow was observed when the dosage of PSSNa varied from 0.25 to 1.00%. The dispersion of mortar components was improved due to the adsorption of PSSNa on cement particles, which increased the mechanical strength of mortars. Similar results were obtained with the application of PSSNa to concrete. The slump of the concrete taken as reference was 50 mm, while for the concrete with PSSNa it reached about 200 mm. Because of its plasticization of concrete, PSSNa can be used as additive to reduce the amount of water required. For instance, a concrete with the same slump of the reference concrete was produced using PSSNa and a reduction of 20.8% in the volume of water. The increase in mechanical strength was 21.5 and 26.3%, respectively, at 7 and 28 days of curing. These results showed that PSSNa solutions can act as superplasticizer or as admixture to reduce the amount water in mortars and concretes.