Susana Paola Arredondo-Rea

Influence of Size on the Microstructure and Mechanical Properties of an AISI 304L Stainless Steel—A Comparison between Bulk and Fibers

In this work, the mechanical properties and microstructural features of an AISI 304L stainless steel in two presentations, bulk and fibers, were systematically studied in order to establish the relationship among microstructure, mechanical properties, manufacturing process and effect on sample size. The microstructure was analyzed by XRD, SEM and TEM techniques. The strength, Young’s modulus and elongation of the samples were determined by tensile tests, while the hardness was measured by Vickers microhardness and nanoindentation tests. The materials have been observed to possess different mechanical and microstructural properties, which are compared and discussed.

An Experimental Study of Mortars with Recycled Ceramic Aggregates. Deduction and Prediction of the Stress-Strain

The difficult current environmental situation, caused by construction industry residues containing ceramic materials, could be improved by using these materials as recycled aggregates in mortars, with their processing causing a reduction in their use in landfill, contributing to recycling and also minimizing the consumption of virgin materials. Although some research is currently being carried out into recycled mortars, little is known about their stress-strain (σ-ε); therefore, this work will provide the experimental results obtained from recycled mortars with recycled ceramic aggregates (with contents of 0%, 10%, 20%, 30%, 50% and 100%), such as the density and compression strength, as well as the σ-ε curves representative of their behavior. The values obtained from the analytical process of the results in order to finally obtain, through numerical analysis, the equations to predict their behavior (related to their recycled content) are those of: σ (elastic ranges and failure maximum), ε (elastic ranges and failure maximum), and Resilience and Toughness. At the end of the investigation, it is established that mortars with recycled ceramic aggregate contents of up to 20% could be assimilated just like mortars with the usual aggregates, and the obtained prediction equations could be used in cases of similar applications.

Mechanical properties of mortars containing recycled ceramic as a fine aggregate replacement

We study the behavior of mortars where 0%, 10%, 20%, 30%, 50% and 100% of their original natural sand was replaced by ceramic sand in a search of potential new building materials that will help to conserve natural resources and that are environmentally friendly. In this paper, the physical properties of the sands and their derived mortars, including their compressive strength, flexural strength, and shrinkage due to base and total drying, are characterized. Our results show that the compressive and flexural strengths of the recycled mortars decrease proportionally to the amount of natural sand replacement used. A similar behavior is observed for the shrinkage due to drying in mortars with low ceramic substitutions (10%, 20% and 30%). Based on these findings, we believe that the use of mortars made with recycled sand (with substitution contents lower than 30%) could be feasible in applications where the mechanical requirements are low.

Comparative by simulating the eventual waste generation of building indoor pavements construction

The construction sector affects the environment through CO2 emissions generated by use of massive quantities of materials, energy, and waste during the construction and demolition process. Moreover, current technology offers a wide variety of materials, products and construction systems that could be used for a similar solution; however, the decision to select one or other element lies with the price and then by regulatory requirements and availability (ignoring the issue of sustainability). In an apartment building, the pavements are one of the elements with major representativeness and more possibilities of alternative variables in its materials; so, this research expose three different types of pavements with similar prices, comparable functions, and normative compliance, but providing a new sustainable perspective: The construction and demolition waste (C&DW) analysis. The results (simulation of waste) evidence the differences between the wastes generated from each type of pavement, pointing that the application of sustainable management criteria can be significant for sustainable buildings construction. This research shows a new criterion applicable to the construction sector that could improve the selection (with equal requirements) of one type of pavement into a more environmentally friendly pavement, allowing the achievement of profits for the builders.

Influence of the shape of the natural aggregates, recycled and silica fume on the mechanical properties of pervious concrete

Currently the problems of water quality are increasing; much of the material is rinsed and is dragged into streams, rivers, and groundwater from the contaminated superficial draining, which contains materials that are applied to the soil surface. Therefore is that the provide the greatest amount of uncontaminated water to the subsurface is of great importance, since it can still potentially solve some important collateral problems, such as the settlement in the soil, which is related largely to levels low capacity of the aquifer. Therefore, use Pervious Concrete (PCo) can help prevent physical barrier between rainwater and underground (especially in urban areas). For the investigation of the feasibility of PCo three types of aggregate were used: Round Natural Aggregate (RNA), Natural Crushed Aggregate (NCA) and Recycled Aggregate from Concrete crushed (RAC),since the shape of the aggregates generally determines the mechanical properties; and yet very little is known about their correlation with permeability. Moreover, concrete recycling is an effective way for the elimination of debris from demolition as well as replace part of the cement by waste material as the Silica Fume (SF); in both cases, these actions production decreases and CO2 emissions associated with their production.

Dielectric and electrochemical properties of sustainable concrete

It is planned to improve the durability of reinforced concrete structures and the total or partial replacement of their components by the use of recyclable materials; as strategies to contribute to the concrete industry sustainability. The electrical resistivity and its relationship with the microstructure and electrochemical corrosion resistance in reinforced concrete manufactured with sustainable characteristics, that is, with recycled aggregates and supplementary cementitious materials; was evaluated in this study. The electrical resistivity in reinforced concretes is closely related to the microstructure of the cementitious matrix, and with the pore structure and distribution. As a consequence of the their components nature, it is assumed that the proposed sustainable concretes present different microstructure and porosity than the conventional concretes; because of this, the electrical and electrochemical response of those systems was analyzed with the help of the electrochemical impedance spectroscopy technique.