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The analysis of adhesion mechanisms between mortar lining and porous substrates has been the target of innumerous researchers due to its importance in ensuring system performance. Based on the theoretical reference of the topic, this work of experimental nature aimed to analyze the influence of the superficial topography of ceramic blocks in bonding slurry mortars and their relationship with the set of characteristics of fine aggregates that make up slurry mortars. Initially, the substrates and component materials of the mortars were characterized according to the Brazilian Association of Technical Standards; afterwards, characterization tests of fresh and hardened mortars were carried out. In the testing phase, the blocks received the slurry mortars. The experimental variables studied were: three types of ceramic blocks (ceramic sealing block with smooth surfaces, ceramic sealing block with horizontal grooved surfaces, and ceramic sealing block with vertical grooved surfaces); and two types of slurry mortars (one was prepared with coarse sand and the other with medium sand). Thus, six interfaces were evaluated through aspects of bonding strength and permeability and absorption by the pipe method. In order to observe the extent of adhesion and involvement of the grains of sand through the paste of the slurry mortars, interface analyses were conducted through observation by magnifying glass and petrographic microscope. The characteristics of the sands that influence the performance of fresh and hardened slurry mortars were analyzed, with emphasis on the textural parameters of the sands, which were evaluated with the aid of petrographic analysis. Results showed that there is direct correlation between the extent of adhesion provided by the grooves of the blocks, and bond tensile strength, made possible by the fluid nature of the slurry mortar. Therefore, this indicates the strong influence of the type of ceramic block on results of bond strength. On the other hand, the study of the characteristics of the sands, represented mainly by the granulometric composition, density, unitary mass, void content, degrees of roundness and sphericity, and mineralogy, proved to be useful in order to understand the role of the fine aggregates in the performance of the slurry mortar. Additionally, we observed that the tensile bonding strength was higher for the slurry mortars with coarse sand than with medium sand, when comparing the same type of block, although the tests have pointed to non-significant differences. This fact can be explained by the small difference between some of the characteristics of the sand used; however, the coarse sand studied seems to provide greater integration of the grains involved by the mortar paste, which was indicated by the degree of roundness. Moreover, it was also possible to observe direct relations in achieving results when comparing the permeability and absorption by the pipe method with the initial rate of absorption test (IRA) and extended IRA test. The final observation is that the basic treatment using slurry mortar can provide several benefits: increased roughness of the base, increased tensile bonding strength, adjustment of the suction capacity. This way, it was possible to homogenize the absorption of water by the substrate, thus avoiding different screeding times and performance for the lining layer. Thus, the treatment of the base with the use of slurry mortar can increase the performance and durability of the mortar lining. / A análise dos mecanismos de aderência entre argamassas de revestimento e substratos porosos tem sido alvo de muitos pesquisadores, devido à importância que tem para garantir o desempenho do sistema. Com base no referencial teórico sobre o tema, este trabalho de natureza experimental teve como objetivo principal analisar a influência da topografia superficial de blocos cerâmicos na aderência de argamassas de chapisco e a sua relação, ainda, com o conjunto de características dos agregados miúdos que compõem as argamassas de chapisco. Inicialmente, os substratos e os materiais componentes das argamassas foram caracterizados através do grupo de normas da Associação Brasileira de Normas Técnicas; na sequência, foram realizados ensaios de caracterização das argamassas nos estados fresco e endurecido. Na fase de testes, os blocos receberam as argamassas de chapisco. As variáveis experimentais estudadas foram: três tipos de blocos cerâmicos (bloco cerâmico de vedação com faces lisas, bloco cerâmico de vedação com faces ranhuradas horizontais, e bloco cerâmico de vedação com faces ranhuradas verticais); e dois tipos de argamassas de chapisco (uma elaborada com areia grossa e outra com areia média). Dessa forma, surgiram seis interfaces que foram avaliadas através de aspectos relacionados à resistência de aderência à tração e à permeabilidade e absorção pelo método do cachimbo. Na intenção de observar a extensão de aderência e o envolvimento dos grãos de areia pela pasta das argamassas de chapisco, foram feitas análises da interface através da observação por lupa estereoscópica e microscópio petrográfico. Foram pesquisadas as características das areias que influem no desempenho das argamassas de chapisco em seu estado fresco e endurecido, com ênfase nos parâmetros texturais das areias, avaliados com auxílio da análise petrográfica. Os resultados mostraram que há correlação direta entre a extensão de aderência, proporcionada pelas ranhuras dos blocos cerâmicos e a resistência de aderência à tração, possibilitada pela natureza fluida da argamassa de chapisco, indicando, assim, a forte influência do tipo de bloco cerâmico nos resultados de aderência à tração. De outro lado, o estudo das características das areias, representadas, principalmente, pela composição granulométrica, massa específica, massa unitária, índice de vazios, graus de arredondamento e esfericidade e mineralogia revelou-se útil no sentido de compreender o papel dos agregados miúdos perante o desempenho das argamassas de chapisco. Notou-se que a resistência de aderência à tração foi maior para as argamassas de chapisco com areia grossa do que com areia média, quando se compara um mesmo tipo de bloco, embora os testes tenham apontado diferenças não significativas. Esse fato pode ser explicado pela pouca diferença entre algumas das características das areias utilizadas; porém, a areia grossa estudada parece proporcionar um maior entrosamento dos grãos envolvidos pela pasta da argamassa, indicado pelo grau de arredondamento. Foram observadas, ainda, relações diretas na obtenção de resultados quando se compara a permeabilidade e absorção pelo método do cachimbo com o ensaio do índice de absorção inicial de água (AAI) e AAI estendido. A constatação final é de que o tratamento de base através do emprego de chapisco pode proporcionar vários benefícios: aumento da rugosidade da base, aumento da resistência de aderência à tração e regulagem da capacidade de sucção. Possibilitando, com isso, homogeneizar a absorção de água por parte do substrato, evitando diferentes tempos de sarrafeamento e desempeno para a camada de revestimento. Assim, o tratamento da base com uso do chapisco pode aumentar o desempenho e a durabilidade dos revestimentos de argamassa.

M. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology. / For centuries the contamination of surface water has been problematic, especially in third world countries whereby socio-economic issues are prevalent. With the development of various technologies for surface water rehabilitation, adsorption has been found to be the most viable due to its lower cost implications. As such the development of innovative adsorbents which are synergistic to the low cost method have been sought. Herein, the use of fossil coral limestone from Mauritius as adsorbents for the removal of Pb(II), Cr(VI) and methylene blue is presented. The pristine material (PCLS) was thermally treated by calcination to temperatures 800°C (CLS-800) and 900°C (CLS-900) and chemically treated by using an acid HCl (ACL) and base NaOH (BCL). The optimum conditions found for chemical and thermal treatment of the pristine material were used for the one pot synthesis of magnetite and maghemite calcium carbonate based nanocomposites. The pristine fossil coral limestones were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDS), X-ray fluorescence XRF), X-ray diffractometer (XRD), Brunauer, Emmett and Teller (BET) and Fourier transformed infrared (FTIR) spectroscopy, UV visible spectrophotometer (UV/vis) and Photolumiscent spectroscopy (PL). Surface morphology of the material was found to contain an interconnected framework of pores, with a surface area of 20.45 m2/g and pore with of 4.04 nm. Thermal treatment of the material was found to increase the surface area of the materials to 64.10 and 63.28 m2/g for CLS-800 and CLS-900. The surface morphology of the calcined materials compared to the pristine were fibrous like and irregularly shaped for CLS-800 and CLS-900 respectively. The FTIR revealed the dominant surface groups to be (-C-O) and (-C=O) asymmetric stretch of the in and out of plane bend of carbonate (-CO32-), with the composition of the material being 91.76 % (-CaO) and 3.32% SrO. The thermally treated materials also exhibited vibrations of asymmetric stretch, which are characteristics of the carbonates as with the pristine material. However, EDS of the pristine compared to that of the calcined materials show a decline in the carbon and oxygen content, due to calcination. The XRD analysis confirmed the orthorhombic structure of aragonite, while CLS-800 was rhombohedral calcite with newly developed (-CaO) peaks. CLS-900 showed complete removal of CaCO3 polymorphs with more (-CaO) peaks. The surface morphology of the chemically modified samples show irregularly shaped surface. The XRD analysis confirmed that chemical treatment did convert the materials to a different polymorph. The FTIR of the chemically modified materials compared to the pristine, were found to reveal a removal of the vibrations of the asymmetric stretch associated with carbonates. However, vibrations associated with (-CaO) were observed. The SEM of the nanocomposites was observed to deviate from sphericity with variable size distribution. The materials were both red and blue shifted due to their variable sizes. Their UV/vis revealed absorption bands in the visible region. The adsorption analysis was done by varying parameters such as time, pH, concentration and temperature. The data was such that the highest capacity for the pristine material was found to be 37.24, 39.26 and 69.42 mg/g for MB, Pb(II) and Cr(VI) respectively. The removal of MB and Pb(II) pollutants were due to physical adsorption, as observed from the good fitting to pseudo first order model (PFOM). The removal of Cr(VI) was due chemisorption and the good fit on pseudo second order model (PSOM). The adsorption process was supported on a heterogeneous surface whereby multilayer adsorption could occur. Adsorption was spontaneous and feasible, exothermic for MB and Pb(II) and endothermic for Cr(VI) at all the studied temperatures as observed from thermodynamics. The adsorption of methylene blue was found to be more favourable on adsorption compared to photo-degradation Chemical modification was observed to increase adsorption and the maximum removal capacities for PCLS, ACL and BCL for Cr(VI) ions were 69.42, 65.04, 64.88 mg/g, Pb(II) ions 39.36, 74.11, 78.34 mg/g and methylene blue 37.24, 46.28, 46.39 mg/g, respectively. Uptake of Cr(VI) and methylene blue on ACL and BCL was feasible on a heterogeneous surface whereby multilayer adsorption took place. Monolayer adsorption on a homogenous surface of ACL and BCL was observed for Pb(II) uptake. The uptake of Pb(II) was exothermic on PCLS and ACL while methylene blue only on PCLS. The adsorption of Cr(VI) ions onto PCLS, ACL and BCL and methylene blue dye onto ACL and BCL were endothermic in nature. The adsorption process was spontaneous and feasible at all the studied temperatures. Thermal modification further increased the adsorption uptake of the pollutants. The recorded uptake for Cr(VI) and Pb(II) were 99.12 and 98.42 mg/g onto CLS-800 and CLS-900, respectively. The adsorption process was found to be physisorption, due to the good fit on PFOM. In addition, the adsorption occurred on a heterogeneous surface whereby multilayer adsorption was possible. The removal of Cr(VI) was found to be exothermic for both the materials and Pb(II) was found to be endothermic. The materials were tested for their reusability to up to four cycles, whereby the removal on the fourth cycle were 16.87, 63.60, 73.13 mg/g for Cr(VI), 9.87, 64.19 and 70.95 mg/g for Pb(II) on PCLS, CLS-800 and CLS-900. While the leaching test for PCLS, CLS-800 and CLS-900 for the release of Ca2+ into solution was found to be within the permissible limits of world health organisation (WHO). The as synthesized nanocomposites increase adsorption of the pollutants. Maximum capacities were found to be 345.34, 388.31, 377.92 and 375.35 mg/g for Pb(II) onto magnetite-PCLS, magnetite-CLS, maghemite-PCLS and maghemite-CLS, respectively and 308.01, 335.3, 335.29 and 335.27 mg/g for Cr(VI) onto magnetite-PCLS, magnetite-CLS, maghemite-PCLS and maghemite-CLS, respectively. From the data it was observed that the maghemite samples were much more favourable for the removal of the pollutants. The removal was due to chemical adsorption, as observed from the good fit onto PSOM and intraparticle diffusion (IPD), whereby surface adsorption was the rate limiting step. The adsorption process was heterogeneous and multilayer, while thermodynamic data reveal that adsorption was spontaneous and favourable at the studied temperature.