Advanced Materials Research Vol. 831

Abstract: Improving concrete performance and minimizing corrosion-induced deterioration of reinforced concrete structures are mandated Building Codes Practices and Specifications in arid regions such as the Arabian Gulf. Concrete structures resist corrosion due to the passivating properties of the hydrated cement around the steel reinforcement created by the high alkaline environment within the composite structure (pH > 12). However, the presence of chloride ions in the pore structure of the concrete destroys this passivating layer, which makes the steel reinforcement vulnerable to chloride-induced corrosion attack that accelerates degradation and deterioration of concrete structures. Corrosion activities-related tests such as Time-to-Corrosion Initiation (Modified ASTM G-109)⁶, and Corrosion Rate Test (Lollipop Test), can be effectively used to monitor the behavior of corrosion development, while chloride ingress characteristics tests such as Electrical Indication of Concretes Ability to Resist Chloride Ion Penetration ASTM C-1202-91)⁷, and the Resistance of Concrete to Chloride Ion Penetration (AASHTO T 259-80)⁸, are applied to evaluate the rate at which chloride ions can diffuse through concrete to onset the time-to-corrosion initiation, which will impact the structure service life and compromise its sustainability. Efforts have been made by scientists to develop mathematical simulation models that predict the service life of the structure based on Ficks Second Law for semi-finite diffusion of chloride ions, concentrated at different concrete depths. The study concluded that mineral admixtures have contributed to the enhancement of concrete performance and its resistance to chloride diffusivity, as well when in combination with corrosion-inhibiting admixture such as calcium nitrite.

Abstract: This study analyses the durability of rammed-earth wall construction techniques. The analysis focuses on three medieval masonry types from the Castle of Villavieja (Castellón, Spain) using two variations of lime-reinforced rammed earth in its walls: lime-crusted rammed earth and brick-reinforced rammed earth. Materials analysis reveals the good properties of the materials used in the outer wall facing despite its age. It also clearly shows how deterioration depends more on the construction technique (construction of the wall with a base, cornice, facings, core; on-site installation, bonds, etc.) than on the material itself. These two types of lime-reinforced rammed earth (lime-crusted rammed earth and brick-reinforced rammed earth) are the most common kinds of fortified architecture in the Iberian Peninsula as well as in northern Africa and the Middle East. The case presented herein is therefore highly relevant as it advances our knowledge of the behaviour of the materials comprising these walls and lays the foundations for suitable future conservation works of a vast array of architectural heritage.

Abstract: A basic study is performed on the application of highly ductile SHCC(Strain Hardening Cementitious Composites) to precast method. A special focus was placed on applying class C fly ash with a high CaO content to secure early-age strength of the steam cured SHCC. The flexural strength of the SHCC panels dependent on fly ash type and varied curing methods were evaluated. The results showed that class C fly ash could enhance the flexural strength of 1 day-old steam cured SHCC panels. Additionally, 1 day-old steam cured specimens produced with class C fly ash exhibited up to 58% of the flexural strength of 28 day-old wet cured specimens produced with class F fly ash.

Abstract: Self-compacting concrete (SCC) is a highly workable concrete that can flow through densely reinforced complex structural elements under its own weight and adequately fill all voids without vibration or mechanical consolidation. Effective use of industrial waste products in concrete gains many economic, environmental, and social benefits rather than disposing of it as waste. The objective of this study is to investigate the effect of blast furnace slag as a partial replacement for coarse aggregate in M20, M30 and M40 grades of fly ash blended self-compacting concrete. The coarse aggregate was replaced at a range of 30% by blast furnace slag aggregate and the various fresh and hardened concrete properties were determined and compared. From the results, it is recommended that 30% of slag aggregate can be effectively utilized for various self-compacting concrete applications.

Abstract: In this study, the chloride resistant properties of concrete with MBC (marine blended cement) were evaluated by an accelerated corrosion test of reinforced concrete. The half-cell potential measurements indicated that the chloride resistance of MBC concrete is approximately 32% larger than that of TBC (ternary blended cement) concrete. As for the reinforcement corrosion area, while the TBC specimens exhibited 5.32-6.11% corrosion at the final 40^th cycle, the MBC specimens did not show any sign of steel corrosion. The chloride penetration depth of the MBC specimens was approximately 41-79% smaller than that of the MBC specimens.

Abstract: Kwanar-Are reservoir is located along Katsina Kano Federal road (Northern Nigeria). It has been used for over two decades as a source of water for irrigation and infrastructural development in Kasina city and environs.This study is intended to determine the quality of water in the reservoir to establish its suitability or otherwise for use in mixing concrete. The investigation is very necessary having in mind that the irrigarion activities take place on substantial portion within the reservoir for which the long term application of fertilizer and pesticides might have negetive impact on it. Samples of water were collected and examined. Parameters such as pH value, chlorides, sulphates, alkalies, and solids as well as organic impurities were determined which essentially affect the setting time of cement, strength, durability and other properties of the concrete. Result obtained shows the tested parameters in negligible quantities. Metals are in trace quantities also. The determined compressive strength of concrete cubes of the diamension 150x150x150 made from water in the reservoir for 7 and 28 days after curing are within normal range. Frequent monitoring of the reservoir is necessary by all stake holders especially the Regulatory Bodies of water resources in Katsina state.

Abstract: Because of the high-rise of apartment houses, diversity of planar forms, and need for environmental improvement, the development of eco-friendly dry materials becomes necessary. Dry wall panels should be easy enough to use that they can be installed and dismantled, and have fundamental performance items for dry wall (sound insulation, fire resistance, strength, specific gravity etc.). In this study, we intend to develop dry wall panels using eco-friendly and recyclable byproducts of a thermal power plant such as fly ash and bottom ash. With the performance items and level set to develop dry wall, we developed dry wall panels by adjusting mixing ratio.

Abstract: The article gives the results of scanning electron microscopy (SEM) studies of the structure of ceramic matrix composite materials produced from iron ore waste. It is established that inside the matrix and the granules during the firing the processes of solid-phase and liquid-phase sintering with formation of new mineral phases take place. It is shown that in the matrix a liquid phase is formed, which fills intergranular cells and binds the particles of minerals together.

Abstract: Thermal insulation materials are among the simplest ways of decreasing heat loss in the buildings. When insulation materials are installed in the walls, floors and roof of a building to prevent heat loss from the building, materials must be used with the appropriate structural and thermal properties. In this paper, a laboratory test of the thermal conductivity and cell structure of building insulation materials was conducted. From the experiment results, the correlation expression between thermal conductivity and density was derived. In the case of the insulation materials that were made of expanded polypropylene (EPP), as the density increased, the thermal conductivity tended to decrease; and in the case of ethylene-vinyl acetate co-polymer (EVA) and polyethylene (PE), as the density of the insulation materials increased, the thermal conductivity tended to also increase.