The purpose of the present paper is to set forth a methodology proposal for assessing quality pathologies (aesthetic and superficial) in historic buildings located in the city center of Lima (Peru), in order to identify the pathologies having the strongest impact on the overall quality of the structure, as well as their main causes. As a study case, the methodology is applied to the “Basilica and Convent of San Francisco”, which allowed concluding that fissures are the pathologies that most affect the structure and earthquakes, and external vibrations are the main causes thereof
Undefinable nature of overseas markets substantially impacts the enterprises’ decision to pursue projects abroad. This study aims at identifying and prioritizing the determinant factors which considerably influence the decision to go/not go for projects in overseas from the Indonesian construction enterprises’ (ICEs) perspective. A comprehensive literature review purposed to identify the determinant factors of enterprises’ decision in selecting overseas projects was undertaken at the beginning of study. Of 131 successfully identified, 31 factors were specified after a series of following screening methods. Firstly, the factors having similar meaning were incorporated into a term. A tally technique to indicate frequency of the factor appearance then was applied for which four times emergence as cut-off point. A two-round Delphi survey involving 11 industrial experts was carried out to assess the importance and frequency level of risk occurrence of the 31-factors. Significant index (SI) were calculated to prioritize these factors to which 21 items were defined as the determinant factors to go/not go for projects in overseas. The top ten ranking factors are: (1) quality and clarity of contract condition, (2) project scale/size, (3) complexity of project, (4) financial capability and support, (5) types of contract, (6) type of contract, (7) project/contract duration, (8) client’s reputation, (9) political stability, and (10) economic health and stability. Besides defining the determinant factors, the findings of this research may assist other typical contracting companies to spotlight the central features of OCM in order to manifest their global vision.
To study the influence of the curing procedure polymer-modified cement mortars (PMCM) were realized in two stages. In stage 1, PMCM with different percentages of PVA (5, 10, and 15%) were produced considering two times of PVA addition in the mix (3 and 6 minutes) evaluating the fresh and the hardened state. Stage 2, focuses on analyses of different cure procedures: dry, wet, and two types of intermittent cure (dry/wet and wet/dry) by compressive, tensile strength, water absorption, and dynamic modulus of elasticity. In stage 1, the mixtures produced with 10 and 15% of PVA were selected for their results. Regarding the time of addition of the PVA to the mix, the results obtained do not show significant differences when the samples were produced with the two times. Then the addition time of 3 minutes is considered optimal, for manufacturing efficiency. In stage 2, the results show that the cure influences the performance of the PMCM, wherein the M1 cure showed the best results in the mechanical properties (justified by the correct hydration of the cement). In general, the incorporation of polymer reduced the absorption of water and the dynamic modulus of elasticity, thus contributing to producing more durable materials.
This study determine the mechanical performance of a 40 mm thick overlay using UHPFRC (Ultra High-Performance Concrete) as the outer surface for restoring a flexible pavement structure. A 30 m long test section was built, divided into two 15 m sections. Section 1 was restored with a 60 mm overlay of Hot Mix Asphalt -HMA- and Section 2 was restored with a 40 mm overlay of UHPFRC without intermediate transverse joins. The two sections were instrumented with pressure cells in order to evaluate the vertical load in the inner fiber of each restoration layer. The mechanical properties of the materials were evaluated, the structural modeling was carried out with the falling weight deflectometer (FWD) and the Bisar 3.0 software. The structural modeling showed an 82% increase in the lifecycle for the section restored with UHPFRC. The functional evaluation of the rehabilitated structures was carried out considering parameters as: friction, percentage of cracking, rutting, international roughness index -IRI- and smoothness.
Pervious concrete (PC) is considered a solution to reduce the effects of heat islands, runoff problems, as well as reduce the concentrations of pollutants present in the water; however, its potential as a filter bed is used in the treatment of sanitary sewage has never been evaluated. This work aimed to evaluate the influence of photocatalytic TiO2 addition in PC on the concentration of total phosphorus, total ammonia, nitrate, total solids, and turbidity for application in the treatment of sanitary sewage. Sunlight was used as a radiation source. A flat photocatalytic reactor was built, in which 100 liters of raw sewage were pumped, with a flow of 100 L/min over the PC slabs, covering a total area of 1 m². The TiO2 concentrations added to the PC were 3, 6, and 10%. The results indicate efficiency in the adsorption of total phosphorus, total ammonia, nitrate, total solids, and turbidity. Thus, the use of PC associated with 10% TiO2 can add efficiency to the sanitary sewage treatment process by maintaining good mechanical and hydraulic behavior.
The usage of aggregates has caused serious ecological problems leading to the requirement of an alternative material to meet the demand. The alternative construction material for the upcoming graduates thus chosen for replacing cement and aggregates should not only meet the design and strength requirements but also the ecological criteria. The present research work tries to improve the service life of sea sand concrete by using them in combination with epoxy resin. The scope of the work revolves around the extended to earlier assessment of the properties of concrete manufactured using sea sand as replacement for natural river sand upto 50% and 12% epoxy resin as partial substitute for cement.
The paper presents the statistical analysis on the compressive strength of concrete with strength ranging from 30 MPa to 130 MPa. To obtain these concrete strengths, concrete mixes with virgin aggregates were prepared with four different wate r to cementitious content (w/c) ratios i.e., 0.45, 0.36, 0.24, and 0.18. With w/c ratio of 0.45, a mix is also designed using recycled construction and demolition coarse aggregate to compare statistical characteristics with respect to concrete made using virgin aggregates. The presented statistical analysis includes measure of central tendency, dispersion of the data, distribution shape properties, and precision of the mean. A normal and a log-normal distribution has been established and validated for the experimental data set of all the mixes. A correlation has also been established for the compressive strength of 100mm cube and 150mm cube. Analysis shows an increase in dispersion of data with increase in the mean compressive strength of the mix. The mix with Construction and demolition waste aggregate shows a higher standard deviation than the mix with virgin aggregates at the same w/c ratio. The correlation curve for the compressive strength of 100 mm and 150 mm size cubes, shows a conversion factor of 1.04, suggesting an insignificant difference of the compressive strength values of 100 mm and 150 mm cubes for the mix studied.
Mortar is considered one of the construction materials in great demand in the world, obtaining materials for its preparation require the exploitation of a large part of renewable and nonrenewable resources. In order to dissipate the consumption of natural aggregates, the reuse of different materials that are normally discarded has been studied; glass is an important option for the preparation of mortar. Therefore, the objective of the present investigation was to design a mortar for masonry incorporating crushed glass. The mixing design was made for dosages of 1: 3.5, 1: 4, 1: 5 and 1: 6 with substitution of 5%, 10%, 15%, 20%, 25% and 30% of fine aggregate by crushed glass; tested at the age of 7, 14, 21 and 28 days. The fluidity of the mortar in fresh state and the mechanical properties such as the resistance to compression and bending of the mortar, resistance to adhesion by bending in masonry piles, resistance to axial compression of piles and resistance to diagonal compression in walls were evaluated. of bricklayer. The highest resistance was obtained for the dosage of 1: 3.5 with 30% as the optimum percentage of substitution, reaching a higher resistance compared to the standard mortar; for the dosage of 1: 4 the optimum percentage was 25%; for 1: 5 it was determined with 20%; and finally, 10% was obtained as the best percentage for the 1: 6 dosages. From these values it was determined that, once the optimal percentages were reached, the strength of the mortar decreases as the substitution increases. The results obtained allowed to conclude that the crushed glass significantly influences the mortar properties.
The objective is to evaluate 22 time and 12 cost forecasting methods based on Earned Value (EVM/ES) under three assumptions of future performance and in terms of the opportunity, accuracy, and stability of the forecasts. Little attention has been paid in the literature to future performance assumptions and evaluation under these parameters. Method: A total of 6,951 entry data points were used applying statistical measures of error and dispersion based on empirical evidence from 34 hospital construction projects in Mexico. Findings: Using contractor payment estimates as Actual Cost (AC), the more predictive time forecasting methods are those under the assumption that future performance will be as planned and, for cost, under the SPI(t) Schedule Performance Index. Relevance: The research shows the conditions under which the diverse methods offer timely and realistic predictions to be used as a reference in the monitoring and control of hospital construction projects. The limitation of the research consists of using durations and costs from completed projects without considering the possible changes formalized in contractual modifications throughout project’s execution. Future research using EVM/ES input data from the project owner's perspective is suggested.
Housing prices have been the subject of many studies, and some of them have tried to determine the influencing structural and location factors through hedonic econometric models. One of the main factors considered in the literature on real estate appraisals is the location of the dwellings. For this reason, this study combines the spatial methodologies of geostatistics and spatial econometrics. On the one hand, this work uses geostatistics to estimate missing data to account for the lack of information in the sampled real estate websites. On the other hand, the explanatory factors of prices are determined through spatial conometrics. The combination of both methods facilitates estimating housing prices in Santa Marta (Colombia), solving the problem of missing data. In the modeling, the problems of spatial heteroscedasticity and multicollinearity are corrected. This combination of methods could be of great interest to company ies and public agencies related to real estate activity, which is sustained by the information available on these real estate websites.
The use of recyclable materials in the elaboration of hydraulic concrete is currently booming in order to reduce environmental impacts and improve the mechanical properties of concrete, representing optimal adhesion between aggregates, cement and water. The objective of this work was to evaluate the mechanical behavior of hydraulic concrete with the addition of nylon fibers and microparticles of PET plastic bottles. The mortars or specimens had their physical properties evaluated in fresh state and hardened their resistance to compression and flexural tensile, for these 6 dosages were made: a control mixture and others with designed fibers. For the execution of the tests, an Amsler universal testing machine with a nominal capacity of 30,000 kilograms and a resolution of 10 kg, calibrated for analysis in accordance with ISO 376, was used. It was evidenced that the flexural strength improved by 80% (c), 75% (d), 80% (e) and 95% (f) at 28 days, for compression an 80% increase in strength was evidenced in all samples with respect to the control specimen. It was concluded that the performance of hydraulic concrete with the addition of PET fibers was better than conventional concrete, the properties of the studied specimens improve with respect to the control specimen.
Indian standard Code-IS:456-2000 and Eurocode EC:02-2004 for the design of the concrete structure is limited to the concrete with compressive strength of 55 MPa and 90 MPa respectively. For defining the stress block parameters and for the design of concrete structures using Very high strength concrete (100 MPa to 150MPa); a well-defined stressstrain behavior becomes necessary, particularly the experimental values for the strain at peak stress and ultimate strain capacity. The presents study attempts to cater to these needs by experimentally evaluating the unconfined stressstrain behavior of nine cylindrical specimens with a compressive strength between 100 MPa to 150 MPa, in a servocontrolled (Strain-controlled) compression testing machine. The strain values recorded at peak stress for 100 MPa and 150 MPa concrete are approximately 3000 microstrains and 3500 microstrains respectively. Compared to normal and high-strength concrete, the rising limb of the curves for VHSC (Very high strength concrete) is much steeper and approaches a straight path, also the strain at peak stress and ultimate strain coincide, depicting a negligible post-peak strain hardening region. LVDT and compressometer gave different strains for the same load and specimen. This signifies the role of the gauge length ratio used in these strain measuring devices.
One of the most common products in the construction industry is brick due to its advantages over other building materials such as blocks. In developing countries like Ecuador, brick is handcrafted and is the source of income for thousands of families. These bricks lack a systematized process that optimizes resources to make a brick that meets local regulations. This study evaluates the use of the different raw materials used in production through experimental designs to determine the amount of optimal components locally available (“White Clay,” “Black Clay,” “Water”) and achieve the maximum compressive strength in dry-pressed ceramic bricks. This research also identifies the behavior of the compressive strength based on the compaction pressure in the molding stage, concluding that the model that best fits the behavior is a quadratic model, and from the trace plot, it was observed that compared with “White Clay,” “Black Clay” contributes further to the brick strength. The optimal amount of components to meet the 6 MPa pressure standard required in the brick was 5% water, 85% “Black Clay” and 10% “White Clay.” The pressure value required in the compaction stage was 4.9Mpa (712psi,) and greater strength can be achieved by only adding “Black Clay” and water.
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