Lightweight concrete is characterized by its low density due to the incorporation of lightweight materials such as aggregate clay or lightweight materials in general. In the city of Aracaju there are companies that promote tire reconditioning generating large amount of waste powder. This study aims to study the reuse of tire rubber waste in lightweight aggregate clay concrete. An experimental program for the analysis of these concretes was developed, varying the percentage of 1, 2.5 and 5% of the tire rubber residue in replacement of the natural fine aggregate and replacing 100% of the natural coarse aggregate with expanded clay aggregate(50% C1506 expanded clay aggregateand 50% expanded clay aggregateC2215). The materials (cement, sand, expanded clays and tire rubber residue) were characterized by granulometric analysis tests and unit mass. The hardened concrete was evaluated by mechanical tests of axial compressive strength, modulus of elasticity and tensile strength by diametral compression, physical tests of water absorption and specific mass, as well as scanning electron microscopy image analysis. The use of expanded clay aggregateand 1% of tire rubber residue ensured better mechanical strength, lower water absorption and higher specific mass than mixtures with 2.5 and 5%, reaching values close to the reference concrete, and the residue be an alternative for reuse avoiding disposal.
Concrete is a material of massive use due to its strength and durability. However, it presents post-concreting anomalies that cause damage to structures, partially or totally, interrupting their service and reducing their designed useful life. The corrective maintenance is an anthropogenic intervention, which demands the use of epoxy additives, resins, tools, equipment and techniques that represent unforeseen costs, labor risks and environmental impact. In response is an anthropogenic, CaCO3 precipitating bacteria into concrete by biomineralization. This article seeks to determine the influence of Lysinibacillus sphaericus on the Compressive strength and self-repair of concrete f'c=350kg/cm2, previously carrying out tests for aggregates and culture media. The preparation of ABC concrete (Bacterial additive for concrete) in doses of 0, 15, 20 and 25ml/m3 of mix, the design of standard concrete with an A/C ratio of 0.43. At 28 days of setting, it reached a Compressive strength of 105% for the standard concrete, and the best strength obtained was by incorporating 25ml/m3, improving by 16% compared to the standard concrete. After 14 days of curing, SEM images showed 69% self-repair of the cracks.
The concrete construction materials are now being judged not only from their economical characteristics but also from their serviceability. Advancements in the concrete production now also focus on improving the fire resistant behaviour of concrete. The replacement of fine aggregates is much more desirable when they possess adequate fire resistant characteristics. The present research work understands the urgent need to pay attention to the fire resistant behaviour of concrete simultaneously minimizing the use of Natural River aggregate. In addition to the fine aggregate replacement nano alumina is used as cement additive to beneficially support the concrete durability through their nano characteristics. Zircon sand is used upto 50% of the natural river sand aggregate and nano alumina is used at 2% by weight of the cement binder. This research work focuses on the utilization of zircon sand as fine aggregate to produce concrete.
The methods of nonlinear analysis allow a better structural design and more accurate answers in the verification of a structure, through which it is based on the linear analysis of the educational institution Héctor Rene Lanegra Romero; this has a current systemic structural configuration 780, which has been designed under the parameters of the E.030 standard. To know, verify and analyze the structural performance in which the educational institution is located, nonlinear static analysis was used; which consists of a Pushover analysis. The Pushover analysis allows us to calculate the seismic actions in structures where the elastic behavior of each element is observed, it also allows us to see the operational seismic performance in which the educational institution is located, through which capacity curves are obtained, generation of plastic ball joints and the verification of the point of performance of the building; which allows identifying if the said structure is active for a seismic signal.
This study aims at identifying the main factors affecting design quality, identifying the main factors affecting material waste and addressing the relationship between design quality and waste on construction sites in residential building projects in Palestine. To identify the main factors of deign quality and material waste, a questionnaire survey is conducted. Fifteen (15) factors of design quality and 15 factors of material waste are identified from literature review and feedback from local experts. A questionnaire is designed to include these factors. Targeted population included contractors and consultants who have experience in residential projects. Forty five contractors and 35 consultants rank the identified factors according to their importance. The study reveals that the top factors of design quality are: lack of staff experience, inadequate time given for design, payments delay for design services, owners award bids for lowest price designer and copying and modifying from previous designs. It also indicates the significant factors of material waste, they include: design mistakes, late design changes, rework, lack of labor experience and purchasing materials not complying with specifications. Based on data collected from 33 building projects, a predictive model is established. The model indicates a good relation between material waste and design quality.
A methodology for quantifying the variation of the static friction coefficient µ due to different site surface conditions, and for metallic materials with hardness ratios ρ = 0.5 – 2, is proposed. ρ is defined as the ratio between the material hardness and the A36 steel hardness. For each material, 7 coupons were considered in the site conditions “clean”, “bought”, “polished” and “corroded”. Results show if surfaces are kept as “bought”, µ may increase or decrease up to 20%, if surfaces are polished, µ may increases up to 37%, and if surfaces are corroded µ may increases up to 410% when considering corrosion rates of 90 – 670 µm/year. These increments or reductions were calculated respect to the site condition “clean”. Results also show for “clean” surfaces and for ρ ≤ 1.7, µ is dependent on ρ, for ρ > 1.7, µ is approximately constant. A model for quantifying variations of µ for the considered site surface conditions was proposed.
Man-made and natural disasters destroy the buildings and render their habitable and operational functionalities unsafe and inappropriate. Thus, stakeholders shall respond to these catastrophes, assess their damages and assign suitable measures to overcome them. Despite several constraints in their implementations, multi-criteria decision-making is of paramount necessity to bridge the gaps between the adopted measures and the requested assistances. Therefore, this thesis will focus on the selection of criteria to conduct the objective and professional assessment. Chapter 1 will underline the topic importance and the primordiality to create a unified guideline for DMs to test the properties and help their residents. Therefore, chapter 2 reviews the numerous approaches and articles to specify their failures in satisfying the stakeholders and contribute in a JIT support. The condition assessments classes and types differ among fields and properties; thus, DMs shall apply the appropriate and accurate tool in examining and scoring their distresses. In the light of multiple techniques, extensions and combinations, this document introduced the first combined method, ITARA-R- modified TOPSIS, for weights eliciting, consistent buildings assessing and categorizing. The R-TOPSIS grants the accuracy and independence from rank reversal problems. Chapter 3 prepared the MCDM process by evaluating the current tools and techniques and result in the creation of a new MCDM modular approach. Thereafter, the modification of this classical TOPSIS approach by adding threshold alternatives discriminates among housing assistance classifications. On the other hand, the thresholds are also determined in weights allocations as well via the indifference threshold-based attribute ratio analysis. The proposed method is based on indifference thresholds and threshold alternatives scores on the selected. The assessment and evaluation of the previous publications and papers resulted in detecting the gaps in their approach and to orient the DMs toward a reliable yet flexible MCDM extension. Thereafter, its application prior Beirut blasts damaged buildings validate its contribution in the decision-making field and investigates its methods’ performance. The results validate its goals satisfactions and accomplishments; hence, modification of the combined tools enables its application for multiple catastrophes, situations, assets and stakeholders. Chapter 4 and 5 validate the work efficacity and flexibility and introduce a new methodology in housing support.
waste from the exploitation and processing of nickel laterites in Cuba and Brazil, the work takes as a hypothesis that, if it demonstrates the real possibility of using such waste as a partial substitute for aggregates in the production of asphalt concrete, the negative environmental impact caused by them in the places where they are deposited could be reduced. The objective of the work is, to demonstrate the suitability of mining waste from nickel and cobalt processing dams in the municipalities of Moa and Nicaro, in the province Holguín, Cuba. Such wastes come from Ammonium Carbonate Leaching and Pressurized Acid Leaching processes. The research methodology it has based on taking representative samples from the waste dams, their subsequent physical, chemical and mineralogical characterization, and the characterization of the aggregates and asphalt cement used in the mixtures under study. The design of the asphalt concrete mixtures was carried out using the Marshall method. Subsequently, a comparative analysis was made on the behavior of the asphalt concretes made with limestone and mining waste fillers investigated. It´s demonstrated, from the results of the laboratory tests, that it is possible to manufacture asphalt concretes with the use of mining residues from the processing of nickel laterites from Moa and Nicaro, satisfactorily fulfilling the required technical parameters.
The rapid deterioration and unsatisfactory performance of highway pavements are also related to the variation and excessive accumulation of moisture in the subgrade and in constituent layers. Hence, moisture control is essential to ensure, in part, the durability and good performance of these types of structures. Ground Penetration Radar (GPR) has proven to be a useful potential alternative for this purpose, given its non-invasive characteristics, preserving the integrity of the site under observation, in addition to the ability to quickly and continuously collecting data. This study aims at evaluating the sensitivity of the GPR to moisture changes and to investigate the influence that calibration models have on predicting moisture content in a compacted tropical soil. Deformed lateritic soil samples were used and subjected to physical properties' characterization and compaction tests. A 1600 MHz antenna GPR was used for data acquisition in a controlled laboratory environment. On the whole, the results showed that GPR is a promising alternative, with both satisfactory accuracy in moisture assessment and sensitivity when monitoring changes in moisture content in compacted soils.
Concrete is one of the most used materials in the building sector. Inevitably, concrete gains strength and develops shrinkage cracks during the curing process. Shrinkage cracks provide an entry point for reactive fluids to get into the concrete core. Under favorable conditions, the fluids reduce the pH of the core and consequentially corrode the reinforcing bars. This research shows the use of Bacillus megaterium MTCC 3353, which produces calcium carbonate and closes the minute fissures. Part substitution of cement with metakaolin was also done in the study. It was seen that the bio-based concrete specimens enhanced the mechanical strength and durability parameters. The calcite precipitation was validated using a microstructure study. FESEM and XRD tests show the presence of calcite (calcium carbonate) inside the concrete structure. The bacteria were tested for their growth when superplasticizers were added to them. The bacteria showed normal growth compared to the conventional testing.
The study presents an experimental investigation of the fracture behavior of hardened slag and fly ash-based alkali-activated normal and high-strength geopolymer concrete compared with conventional Ordinary Portland Cement (O.P.C.) based concrete with steel and hybrid fibers. The fracture parameters considered in the experimental investigation include fracture energy, stress intensity factor, energy release rate, and characteristic length. The study concludes that the observed differences in conventional and geopolymer concrete's fracture and mechanical performance agree with the microstructural differences between these concrete systems reported in past literature. The slag-based geopolymer concrete is marginally inferior to the O.P.C.-based concrete, with similar compressive strength in fracture performance. Also, hybrid fiber reinforcement improves the fracture performance of geopolymer concrete more than steel fiber alone. Contrary to geopolymer concrete, steel fiber reinforced conventional concrete is superior to hybrid fiber reinforced conventional concrete in terms of fracture behavior.
Keywords: The present analysis was developed by creating a detailed analysis of each article selected for the corroboration of the information and the subsequent comparison between them in order to encourage research of alternative methods of concrete production that will allow the reduction of pollution and will improve the quality and efficiency of concrete. The materials used were nanosilica, pozzolana, and recycled crushed brick that were subjected to laboratory studies with the goal of knowing their properties and of developing mix designs with different content percentages to have a broad study population and achieve representative results. These mix designs were used to create specimens that were tested in different periods to analyze their behavior in various situations. After testing, it was possible to determined that the addition of these materials are effective, in creating concrete of greater strength in the case with the addition of nanosilica, in the case of pozzolana, greater strength can be obtained at a reduced cost due to it being a natural material with various deposits where the material can be obtained in this country and throughout the world, and in the case of the addition of crushed brick, concrete with a similar strength to a conventional type can be obtained at a reduced cost of fabrication due to being a recycled
The phenomenon of clogging in pervious concrete (PC) has been one of the main causes of the hydraulic useful life reduction. This phenomenon begins with the partial or total clogging of the pore network and consequently the reduction of the permeability coefficient. Considering that the porous network of the PC is directly related to the aggregate used, the present work aims to evaluate the influence of granulometry on the clogging of the PC. The results showed that the largest aggregate size (D_max=19 mm) favors the hydraulic properties of the material. However, the variation of the granulometry grading distribution (poorly graded and single-sized) does not generate a significant difference in such results. In terms of clogging, there was a marked effect on the type of the granulometry grading distribution, the use of poorly graded aggregates led to a lower permeability reduction due to clogging when compared to PCs with single-sized aggregates.
This article presents a methodology to assess the seismic vulnerability of essential buildings through analytical fragility curves, applied to the administrative building of the Universidad Nacional del Centro del Perú, for various damage states and different levels of seismic demand according to ATC-40 and SEAOC -VISION 2000. It is shown that the fragility curves through the probability of damage matrices allow us to reasonably estimate the probable state of the building after a seismic event, which in the case of the building under analysis shows that it is more vulnerable in the North-South direction (Y axis).
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