In recent years, the use of natural zeolites to synthesize geopolymer composites (pastes, mortars and concretes) has gained increasing interest among researchers seeking to replace partially or totally the use of ordinary Portland cement. The main objective of this paper is to broaden the information available on the development of alternative materials, for which the present research prepared samples of natural zeolite-based geopolymer mortar as a possible building material application, in which their mechanical properties were evaluated in terms of compressive strength. Additionally, the mix design was optimized by using two alkali activators (NaOH 14M and Na2SiO3) in different proportions, river sand as fine aggregate, and curing time and temperature. All samples were characterized by quantitative X-ray diffraction, SEM-EDS, simultaneous TGA-DSC analysis and compressive strength. The results showed that the best mix corresponds to NaOH: 14M, Na2SiO3/NaOH: 3, activator/zeolite: 0.5, sand/zeolite: 1.5, cured at 60°C, which showed a compressive strength increase (17.3 MPa) at an early age as well as in the long term.
Prefabrication in a high-rise building can reduce construction waste. In this research, high-rise construction companies in Iran were studied, and the advantages and disadvantages of prefabrication were identified; then the development strategies of this industry were reviewed. For this purpose, the questionnaires were used to select the proper sub-systems for prefabrication. Delphi Snowball method was applied according to experts 'opinion, and these questionnaires were identified and adopted. Then the effect of prefabrication on non-structural components was examined on the extent of waste reduction. Consequently, the investigation results of waste production on a high-rise building revealed that prefabrication can reduce the cost of waste to 97.54%, and the total cost of the project would be reduced by 5.06%.
Photocatalytic mortar with TiO2 leads to a reduction in air pollution due to vehicle emissions. For this purpose, the experimental method was used, which consisted of the preparation of mortars with the same proportion of 1: 4, a strength of 145 kg / cm2 and with different percentages of titanium dioxide (0% and 10%), which were evaluated under the same conditions through the following tests: Quantity of polluting gases, compressive strength and photocatalytic capacity. The results obtained—reduction of carbon dioxide by 97.9%, hydrogen sulfide by 72.9%, sulfur dioxide by 67.2%, nitrogen monoxide by 63.4%, carbon monoxide by 40.5% and oxygen recovery by 7.7%—confirmed the performance of the photocatalytic process through titanium dioxide (TiO2) in terms of an improvement in air quality, and the reduction of colorants, rhodamine by 89.10% and methylene blue 53.06% confirmed its self-cleaning capacity, thus improving the reduction of air pollution.
Cold-formed Steel profiles are structural profiles widely used in civil construction. They are often manufactured with perforations. The designing can be performed using the direct resistance method. Formulations were adapted by Moen and Schafer (2008) to consider the presence of perforations in these profiles. The objective of this study is to investigate the structural safety of columns with web perforations. The calculation of the resistance capacity was performed using the formulations proposed by the authors. The reliability indexes were determined using the First Order Reliability Method (FORM), First Order Second Moment (FOSM) and Monte Carlo Method (MCM), which are reliability methods for the Load and Resistance Factor Design (LRFD) and Limit States Design (LSD) philosophies. Following the same criteria performed by AISI S100, the resistance factors were obtained from the FOSM method. Based on the results, it was found that the desired security level for the LSD philosophy was not achieved. The calculated resistance factors are predominantly lower than the target. However, for the LRFD philosophy, the safety level was achieved, and the resistance factors were higher than the target.
The aim of this research is to test the characteristics of concrete by substitute fine aggregate with iron ore tailings and partial glass powder as in the place of cement. Concrete with waste products such as glass powder and iron ore tailings offers technical, economic and environmental advantages. In this experimental investigation, glass powder is replaced with cement by 10%, 20% and 30% and iron ore tailings with fine aggregates by 30% which is the optimum percentage. To study the role of glass powder and iron ore tailings combination in concrete, The properties such compressive strength, flexural strength, tensile strength and also durability parameters likely water absorption investigation for M40 concrete is carried out with different percentages of glass powder by keeping the iron ore tailings percentage constant. At 30% glass powder substitution as cement and sand with IOT increases concrete effectiveness. The concrete with 10% glass powder & 30% iron ore tailings showed a higher strength compared to the conventional mix for 28 days. Concrete mix containing 10% GP and 30% IOT showed higher flexural strength of 5.05 MPa for 28 days. Splitting tensile strength value is also increasing i. e for 10% glass powder and 30% IOT, obtained splitting tensile strength was 4.48 MPa and modulus of elasticity value was has also increased. Water absorption experiment consequences results that water absorption decreases with an increase in GP percentage. The concrete workability tends to decrease when with glass powder content increase. Concrete containing 10% glass powder and 30% IOT showed maximum strength and it is considered as the optimum dosage.
This paper analyzed the behavior of mixed mortars incorporated with rubber from the tire retreading process, based on partial sand substitution. The content of rubber incorporation in the mortars was 5%, 10%, 15%, and 20% by volume. The different granulometries of rubber were denominated as thick (passed through a sieve # 1.19 mm) and fine (passed through a sieve # 0.60 mm). Tests were performed to evaluate water retention, capillary absorption, drying, immersion absorption, water vapor permeability, and permeability to water under pressure. The results showed that the fine rubber was distinguished by its higher retention of water at the contents of 15% and 20%, lower absorption via both capillary and immersion, higher drying capacity, higher permeability to water vapor, and lower permeability to water under pressure.
Due to high consumption of concrete constituents namely, natural aggregates and cement, their de-pletion is observed globally. Over the years, many researchers have come up with alternatives to these basic constituents of concrete. Ceramic waste (CW) generated from ceramic industries (indus-tries producing tiles, sanitaryware, ceramic refractories, ceramic insulators, ceramic crockery) have not found any reuse and is deposited as landfills, which further increases land pollution and also give rise to health issues. The CW can be easily grinded as per required size, which have interested many researchers to use it in the production of concrete. Till date CW has been used as partial re-placement to cement, fine aggregates and coarse aggregates. This review paper discusses the poten-tial of CW as replacement to concrete constituents in the production of concrete and its effect on mechanical and durability properties. The literature review is carried in three parts – review on use of CW to replace cement, fine aggregates and coarse aggregate. The study shows different research-es using different sources of CW having varied properties being used as partial replacement. The effect of replacement on concrete strength and durability is reported.
The present research aimed to provide a broad overview regarding the management of construction materials. As a starting point, the conception of the set of actions that make up the materials management is described and its importance within the construction sector is pointed out; It also addresses the various obstacles that this sector currently faces when managing its materials, in a global scope, and which hinder the optimal development of the sector. Likewise, new management support technologies such as Radio Frequency Identification (RFID) web-based systems for materials management and data storage applications are described, offering a vision of the advantages and disadvantages involved in implementing these information technologies. In the same way, the most common support techniques for inventory control are outlined. It is concluded that the construction industry knows the concept of materials management, however, it still faces problems for the application of a correct execution of said concept; In addition, it is at an early stage in the adoption of new techniques and technologies to support the management of construction materials.
In the search for adopting methods that provide more comfort in the housing system, they require better structural performances in current buildings. Construction practices in the region have been discredited over time, conceiving vulnerable buildings whose inhabitants are subject to risk.
The objective of this research is to comprehensively analyze the technical, construction, and design characteristics of reinforced concrete slabs regarding their implementation as a reinforcing structure for green roofs in the city of Tuxtla Gutiérrez, Chiapas, Mexico. To carry out the structural analysis, the intrinsic properties of the supporting members (slabs) were considered, as well as their current condition, and design based on durability standards. The research results revealed that the slab depth and the amount of steel were lower for average spans, as stipulated by the corresponding technical standards. Corrosion damages in steel bars are expected and they were found under an inadequate design standard, combined with deficiencies throughout the construction process. The constructions analyzed and developed with formal construction or self-build processes show similar pathologies.
The city of Tuxtla Gutiérrez lacks training centers for homeowners and workers to be able to adopt self-build methods. Moreover, the authority is not rigorous regarding the compliance with building codes. These members have become a key knowledge gap. Finally, the implementation of green roofs in these structures is unlikely without prior significant changes in the entire construction.
This article describes the main stages involved in the construction of the vertical shafts (large-diameter vertical wells), which are necessary for the subsequent construction of the tunnel´s sections. The different risk situations existing during the construction of the Eastern Drainage Tunnel in the valley of Mexico City (in Spanish, "Tunel Emisor Oriente") are analyzed. In order for this 52 km-long and 7.5 m-wide tunnel to carry part of the city’s sewage, 25 shafts must first be built, ranging from 55 to 150 meters deep. The magnitude of such a project implies working in different geographical areas and varied geological strata involving the presence of groundwater, which increases the risks due to possible landslides or flooding during excavation. As digging will occur in different types of soil, varying procedures must be used depending on soil type. Likewise, due to the magnitude of this kind of project, detailed scheduling and planning are required as simultaneous works on different fronts are necessary to meet deadlines. The study mentions that, while projects like these involve high risks for workers, analysis of activities and situations are conducted precisely to demonstrate that such risks can be considerably reduced.
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