Carbonation Depth of Sustainable Concrete Made with Agroindustrial and Industrial Waste Exposed to the Urban Environment of the City of Xalapa, Ver; Mexico

In the present investigation the effect of the urban environment of the city of Xalapa, Ver., México in the depth carbonation in Sustainable Concrete made with Agro-Industrial and Industrial Waste Materials like Sugar Cane Bagasse Ash (SCBA) and Silica Fume (SF), was evaluated. The Sustainable Concretes and the Conventional Concrete (Concrete of reference) were designed for a relation water/cement= 0.65 according to the indicated for the ACI 211.1. The Conventional Concrete was elaborated with 100% of Portland cement, and the Sustainable Concretes with partial substitution of Portland cement for the waste of SCBA and SF in percentages of 10, 20, 30, 40, and 50%. The results through the application of phenolphthalein, indicate that the Carbonation depth is proportional to the increase of the substitution of Portland Cement for agro-industrial and industrial waste. The sustainable concrete with 50% of substitution of SCBA-SF presents the worst performance, with a carbonation depth of 1.48 cm, which represents an increment of more of 350% than the conventional concrete at being exposed for one year to the present environment of stud

Corrosion Behaviour of 304 Austenitic, 15-5PH and 17-4PH Passive Stainless Steels in acid solutions

The objective of this work was to study is use electrochemical techniques to determinate the growth conditions, characteristics and resistance of passive layers of stainless steel (SS): 304 austenitic, 17-4PH (precipitation hardening) and 15-5PH. Passivation of the SS was performed in 15% citric acid at temperatures of 25 and 49 °C. The corrosion kinetics was obtained using the electrochemical technique as potentiodynamic polarization (PP), in a three-electrode system. The electrolytes used were sodium chloride (5 wt. % NaCl) and sulfuric acid (1 wt. % H2SO4). Passivation in citric acid allows obtain passive layers at temperatures of 49°C with immersion times of 30 minutes. In precipitation hardening steels, passive layers up to 360 mV in sodium chloride. Can be obtained. In sulfuric acid, there is a mechanism of passivation – transpassivation - secondary passivation, this due to the high electropositive values of potential

Electrochemical corrosion behavior of passivated precipitation hardening stainless steels for aerospace applications

Precipitation-hardening (PH) stainless steels (SS) are widely used in various aerospace applications. These steels exhibit good mechanical and corrosion resistance. The electrochemical behavior of 15-5PH, 17-4PH, Custom450 and AM 350 stainless steels passivated with citric and nitric acid baths for 60 and 90 min at 25 and 49 °C were evaluated in 5 wt.% sodium chloride (NaCl) and 1 wt.% sulfuric acid (H2SO4) solutions. The electrochemical behavior was studied with potentiodynamic polarization curves (PPC) according to the ASTM G5-13 standard. The results indicated that there are two characteristic mechanisms that are present in the potentiodynamic polarization curves. When the PHSS is immersed in an H2SO4 solution, there is a secondary passivation, and in the NaCl solution, there is a pseudo-passivation (not stable passivation film). The current densities in the NaCl solution were between 10−4 and 10−5 mA/cm2, while those of H2SO4 were recorded around 10−2 and 10−3 mA/cm2. Citric acid does work as a passivating solution, and in some cases, the corrosion resistance of the stainless steel was comparable to that of nitric acid

Electrochemical Characterization of Modified Concretes with Sugar Cane Bagasse Ash

Corrosion is one of the most serious causes that reduce service life of Reinforced Concrete Structures (RCS). This is why it is necessary to create concrete mixtures that add durability for steel and that reduce impact on the environment. The use of agro-industrial waste materials rich in SiO2, Al2O3 and Fe2O3, added to concrete, has been the subject of research in recent years, because these pozzolanic materials improves o mecharacteristics of concrete, as mechanical strength, sulfate resistance and lower permeability. Binary Concretes were made and evaluated in the impact of Sugar Cane Bagasse Ash (SCBA) as a partial substitute for Portland cement, with the aim of reducing gtherate of corrosion induced by chloride ions and sulfate. The behavior of corrosion was monitored for 14 months in two aqueous solutions of NaCl and Na2SO4 both at 3.5%, using electrochemical techniques of corrosion potential (Ecorr) and linear polarization resistance (Rp). Under the conditions of study, the binary mixture that showed a better corrosion protection was the one that contained 80% from sugar Cane bagasse ash and 20% Portland cement

Delamination and tensile effect of fine z-binder reinforced on fiberglass/polyester composite for aerospace applications

Delamination propagation in laminated composite materials is a common issue that always concerns us when we consider composites for structural purpose. Many possible solutions have been studied; the most famous is the three-dimensional (3D) woven composites materials, which have promising interlaminar fracture resistance but at the cost of increasing density, which for aerospace industry is very important. In this chapter, mode 1 double cantilever beam (DCB) interlaminar fracture toughness tests according to the American Society for Testing and Materials (ASTM) D5528 standard were performed on composite specimens made of E-Glass Saertex 830 g/m2 Biaxial (+/−45°) with Sypol 8086 CCP polyester resin with orthogonal z-axis oriented yarn woven of 0.22 mm diameter nylon monofilament. Four specimens were made with a longitudinal distance between the warp binders of 0.5, 1, 1.5, and 2 cm, respectively. A tensile test according to the ASTM D3039 standard was performed to study how z-binder may affect tensile resistance. The results show a considerable increase in interlaminar fracture toughness, several stress concentrators have been created because of the new yarn and premature failure in the matrix

Corrosion of Titanium Alloys Anodized Using Electrochemical Techniques

The anodization of titanium has been an excellent option for protecting titanium and its alloys from corrosive environments such as acids and chloride systems, by generating a homogenous oxide layer. The objective of the current investigation was to evaluate the electrochemical corrosion behavior of alloys Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V anodized in 1MH2SO4 andH3PO4 solutions at a current density of 2.5   10–3 A/cm2. The anodization’s electrochemical characterization was achieved in NaCl and H2SO4 at 3.5% wt. electrolytes. Scanning electron microscopy (SEM) was employed to determine the anodized thickness and morphology. Cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS), based on ASTM G61-86 and G106-15 Standards, were the electrochemical techniques mainly employed. The anodized samples presented a change in Ecorr values and a higher passivation zone. The EIS plot showed a higher resistance for samples anodized in H3PO4 and Ti-6Al-2Sn-4Zr-2Mo

Corrosion of Anodized Titanium Alloys

Ti and Ti alloys are employed in demanding industries such as aerospace, automotive, biomedical, aeronautic, structural, naval, and chemical, thanks to their resistance to corrosion due to the formation of the TiO2 film on the surface. Diverse research has established that different corrosive media could attack the oxide layer. One way to generate a stable, compact, and continuous oxide film is through anodizing treatment. The efficiency of anodization depends on diverse factors such as the microstructure, chemical composition of alloys, pH of electrolyte, time, and temperature of anodizing. This review aims to examine the corrosion resistance of the anodized layer on Ti and Ti alloys, with different parameters. The discussion is centered on the influence of the different parameters and alloy properties in the effectivity of anodizing when they are characterized by electrochemical techniques while studying the behavior of oxide

Characterization of Corrosion Behavior of Painted Galvanized Steel under Accelerated Conditions

In the present study three systems of carbon steel (1008) are evaluated, which were provide of two corrosion control methods, barrier and cathodic protection (painted and galvanized respectively) commonly used in the construction industry. They were evaluated under accelerated conditions exposed in fog chamber, according to ASTM B-117, which specifies continues exposition of sodium chloride at 5% and 35 °C. The main aim of the research was to characterize the corrosion resistance and to determine the degradation mechanism under test’s conditions. The results after 1080 and 3500 hours of exposure are presented, with adhesion measure (ASTM D-3359) and scratch resistance measure (D-1654) for each exposure time, as well as the characterization of corrosion attack through the mapping analysis of Scanning Electron Microscope / Energy Dispersive X-ray. According to the results it is proposed that the corrosion of the systems under study begins at galvanized – metal base interface. Later advances due to formation of porous layer of zinc hydroxi-chloride, which it’s characteristic of environments with chloride ions, forming zinc’s corrosion products like zinc oxide and zinc hydroxide on the porous layer until iron starts to dissolve, producing iron oxide and iron oxy-hydroxide on the zinc’s corrosion products and porous layer

Anticorrosive efficiency of the AISI 316 SS in sustainable ecological concrete manufactured with SCBA-SF exposed to magnesium sulphate

In this research, it was evaluated the anticorrosive efficiency of AISI 316 SS embedded in sustainable ecological concrete (SEC) manufactured with partial substitutions of portland cement by combinations of SCBA and SF in 10%, 20%, and 30%. For the electrochemical evaluation, the sustainable ecological concretes (SEC) were exposed to solution at 3.5% of MgSO4, these aggressive ions are found in soils, industrial or marine environments and that interact with the civil works that are built in these places. The dosage or proportioning of the sustainable ecological concrete (SEC) mixtures was carried out as indicated by ACI 211.1. The anticorrosive efficiency of the AISI 316 SS was evaluated through the tests of the potential of corrosion (Ecorr) and corrosion rate (Icorr) during a period of 180 days of exposition to the aggressive medium. The values of ecorr indicate in the AISI 316 SS a 10% of corrosion risk and uncertainty at the end of monitoring, according to the norm ASTM C-876-15, in all the mixtures, but the values of icorr in the specimens manufactured with SEC indicate resistance to sulfate corrosion more than 10 times compared to conventional concrete and AISI 1018 steel

Corrosion Behavior of Galvanized Steel Embedded in Concrete Exposed to Soil Type MH Contaminated With Chlorides

The behavior of corrosion in reinforced concrete, buried in a soil type silt of higher plastic (MH), the present study represents the conditions of exposure that can find the foundations of infrastructure such as bridges, buildings, pavements, when in contact with a soil that could contain aggressive agents like chlorides and sulfates. In such concrete specimens a carbon steel bar AISI 1018 and Galvanized Steel was embedded as reinforcement, the mixed concrete was of ratio water/cement (w/c) = 0.45 (compressive strength, f'c = 350 kg/cm2), according to ACI 211.1, using cements Portland Cement Composite [CPC 30R (Type I) and CPC 30R RS (Type V)]. The used electrochemical techniques such as Corrosion Potentials (ASTM C-876-15) and Linear Polarization Resistance. LPR (ASTM-G59). The specimens were buried in a soil type MH contaminated with 0, 1, 2, and 3 wt.% NaCl as aggressive agent by weight of soil, the exposure time was 260 days where, the results show that when the presence of NaCl in the soil was increased to 2 and 3% the levels of corrosion are from high to very high in all concretes, presenting a little better performance the concretes reinforced with galvanized steel and a small benefit could be identified or related to the properties of a denser and less impermeable matrix that presented the concrete mix made with cement CPC 30R RS