Juan Carlos Arteaga-Arcos

High-Energy Ball Mill Parameters Used to Obtain Ultra-Fine Portland Cement at Laboratory Level

This paper describes how one of the most significant characteristics of ultra-fine cement (UFC) is its high fineness (maximum particle size below 787 μin. [20 μm]). This kind of cement is obtained once ordinary portland cement (OPC) is ground in common grinding devices. The main disadvantages of this type of processing are the amount of time spent in milling processing and the high production costs. Some novel grinding devices, such as high-energy ball mills (HEBMs), have been used as an alternative to the fine and ultra-fine grinding process, especially in the advanced materials processing research field. The aim of this article was to study the different milling parameters (time, ballpowder ratio [b/p], and milling speed) used in OPC dry-milling processing in order to determine the most suitable combination of these parameters to obtain UFC at the laboratory level. This combination was determined after the characterization of the processed cement powder. The carried-out characterization techniques used were chemical composition, crystallographic phase quantification, change of temperature during the hydration process, and scanning electron microscopy (SEM) images for the morphology of the milled cement. The optimal combination of parameters produced an UFC with a maximum particle size below 590 μin. (15 μm) and a Blaine specific surface area (BSSA) of over 9000 cm2/g.

Predicting Concrete Compressive Strength and Modulus of Rupture Using Different NDT Techniques

Quality tests applied to hydraulic concrete such as compressive, tension, and bending strength are used to guarantee proper characteristics of materials. All these assessments are performed by destructive tests (DTs). The trend is to carry out quality analysis using nondestructive tests (NDTs) as has been widely used for decades. This paper proposes a framework for predicting concrete compressive strength and modulus of rupture by combining data from four NDTs: electrical resistivity, ultrasonic pulse velocity, resonant frequency, and hammer test rebound with DTs data. The model, determined from the multiple linear regression technique, produces accurate indicators predictions and categorizes the importance of each NDT estimate. However, the model is identified from all the possible linear combinations of the available NDT, and it was selected using a cross-validation technique. Furthermore, the generality of the model was assessed by comparing results from additional specimens fabricated afterwards.

Woody debris trapping phenomena evaluation in bridge piers: A Bayesian perspective

Abstract A flood occurs when water and other materials such as woody debris overflow dry areas. If there is infrastructure present, woody fragments could be transported downstream and eventually trapped, leading to increments in the hydrodynamic forces over, say, a bridge. Moreover, local scour can be developed in the structure piers. The purpose of this research is to investigate the bridge pier scour phenomena induced by woody debris from a probabilistic point of view. A Non Parametric Bayesian Belief Network comprising seven nodes has consequently been developed. They are: water level, Froude number, blockage amount, drag force, scour depth, damage and overturning. Through both Monte Carlo Simulation and data from a real structure, the nodes’ non parametric probability distributions have been established, an area that has, to date, received very little attention in the literature. By combining the variables under study, it was possible to determine their interaction and dependencies, showing that the depth of the approaching flow is correlated with two nodes: damage and overturning. The results are useful for bridge managers willing to rank investments in maintenance actions within the industry, and to develop optimal risk based strategies for efficiently employing the scarce resources used to that end.

Mechanical Properties of Rocks Used for the Construction of Vehicular Bridges Supported by Pier Masonry

In Mexico, since the early stages of the civilization, the stone masonry has assumed an important role in construction due to the wide availability of this kind of material. Masonry is a material composed by bricks, carved or even rubble stones jointed without (dry joint) or with mortar (mortar joints); which is principally formed with sand, water and cementitiuos materials. The research presented in this paper deals with the procedure of obtaining the mechanical properties of rocks placed on piers of four vehicular bridges located in the south of the state of Mexico, these mechanical properties are compressive strength, modulus of elasticity, Poisson ratio, Cohesion and Internal friction Angle of the rocks as independent units, also are reported the Density values. All of these properties are necessary to conduct further research regarding the mechanical behavior of the pier as a structure since this piece of research is part of an ongoing project concerning risk assessment of vehicular bridges developed in Mexico. The identified rocks in masonry were volcanic igneous materials such as dacites, basalts, rhyolites, andesites and rusted andesites. The materials with the highest and the lowest mechanical properties are the basalt and the dacite respectively. It is recommended to use the dacite’s properties in order to perform a conservative analysis of the mechanical behavior of any masonry structure, located near the selected sample studied herein.

Influence of the Organic and Mineral Additions in the Porosity of Lime Mortars

The main objective was to determine the effect of additions of cactus mucilage (colloquially called cactus slime which on drying produces weddellite and whewellite crystals, calcium oxalates) and/or volcanic ash in masonry mortars made with lime, on the properties as mechanical resistance to compression, tension and bending, and the physical properties such as porosity which,leachates and capillary absorption. The Fagerlünd method was used, on lime mortar specimens according to ASTM standards. Four mortar mixtures were debeloped: with additions and without them, like sample witness. The lime is slaked handcrafted and comes from Piedras de Lumbre Quarry Stone, Zitacuaro, Michoacan, Mexico; the volcanic ash is a mud from Acambaro, Guanajuato, Mexico and the fine aggregate, sand, proceeds from Joyitas Quarry stone in Morelia, Michoacan, Mexico. A correlation of the mechanical properties of the four mortar mixes versus its degree of porosity was made. Porosity and absorption were affected by the mucilage and/or ashes addition increasing the mechanical strength; however this was not the aim of the research, since it is not intended that the mortars were rigid, it was intended that they were capable of absorbing deformations of the natural stone masonry. The addition of mucilage and/or ash, did reduce the percentage of total porosity, the cactus mucilage when dried formed crystals of whewellite and wheddellite which filled in the pores of the mortar matrix, and the ash, mud, as it is an igneous extrusive stone, in crypto crystallite form, it presented puzolan activity forming new minerals filling the matrix pores.

Damaged and Healthy Ignimbrites from the Surroundings of Morelia, Mexico; Uses for Restoration of the Colonial Inheritance

The historic centre of Morelia, Mexico has over a thousand architectonic monuments catalogued. This allowed the city to become part of the list of world heritage site by UNESCO in the 90s of 20th century. The location of Michoacan, the State in which Morelia is the capital, allowed it to have an abundance of acidic extrusive igneous rocks such as the ignimbrite quarry stones. The ignimbrites were carved into blocks to build vertical elements such as the walls and the foundations. Cases of carved and sculpted blocks were not designed to be coated with mortars, non sculpted ignimbrites were used in the case of buildings that were designed to carry coatings mortars and/or paintings; constructions in which the time to build was small, the money was scarce or the destination was not particularly important. These monuments are colonial ones, the European brought building techniques in vogue in Europe; books written by Vitruvius, Palladio and Alberti were adapted to local conditions as ethnic and regional materials and costumes. Ignimbrites, after exposed to the environment have begun to damage on the blocks posted as facades. In cases of severe exfoliation or acute devitrifying of the matrix in the ignimbrites, it is necessary to replace the damaged blocks by healthy rocks earned from the quarry stones of the surrounding places but it has not been able to find full match between rocks; sometimes do not match the resistance, porosity, durability, color or geographical location in the historical archives. Results to date show matches and the discrepancies between the different quarry stones and uses that are targeting in heritage buildings.

Advances of a FEM for the Failure Probability Evaluation of Masonry Vehicular Bridge Support Piers

One of the responsibilities of a Civil Engineer is to make decisions regarding preservation of infrastructure; therefore, there have been established concepts such as risk and risk analysis. Risk analysis, is a methodology applied to determine and evaluate the risk magnitude. From the structural engineering point of view, it is required that any structure become secure, this means that the capacity to withstand external actions (strength) will be higher than these actions (loads). In order to determine the structural safety, it is required to define the failure of the structure that it is not strongly related with the collapse of the structure; the failure criteria needs to be fixed depending on the use of the building and the consequences associated with the interruption of services provided by the facility. The failure then, is calculated by means of a limit state function in where it is established the failure criteria; failure is reached when a specific condition (strength) is surpassed by the actions over the structure. The present work aims to propose a preliminary Finite Element Model (FEM) that represents a pier used as support for vehicular bridges. This FEM is required for the assessment of mechanical behavior of the structure that will be used for the determination of the limit state function needed for risk assessment. Most of the simulations with FEM presented in literature are very used for modeling of masonry walls, but it is not usual to model structures such as bridge piers.