Coal combustion residuals (CCR) are waste products generated during the operation of coal-fired electric power stations, but the effect of CCR inclusions on the deterioration of road infrastructure at or near power plants remain uncertain. This study measured the resilient modulus (Mr) of low-plasticity clay (FS) mixtures with different proportions of CCR obtained from a coal-fired power station, without any additional cementitious substances or stabilizers. Resilient moduli were determined for both the raw materials (FS and CCR) and for mixtures ranging between 10% and 40% CCR by weight. All materials were characterized physically, chemically, and mineralogically. Resulting physical and mechanical-behavior parameters were compared across the CCR content range, specifically the change in index properties, USCS classification, maximum dry density, and resilient-modulus degradation. Results highlight the strong dependence of the soil’s resilient moduli on water content due to the inherent partially-saturated character of the material.
The main problems in the industry of architecture, engineering, and construction (AEC) are the low indices of productivity and the high fragmentation and complexity, which directly affect the quality of the projects. To provide tools to mitigate and/or solve the current situation in the sector, a compilation of the problems in the area of quality management and technical inspection of work, which were validated through interviews according to the experience of professionals, is presented from the literature. Subsequently, an analysis of the relative importance index was applied, obtaining an ordered list of the problems according to their importance in the Chilean context. In this way, the project directors can consider them from the beginning of the projects, considering that quality is planned, managed, and controlled. This makes it possible to prioritize and make better decisions in the allocation of resources, which are generally scarce, in the various processes of the item, both in the office and in the field.
In the last great fire of 2014 that affected Valparaíso, numerous building and structural deficiencies about slope construction were found. This issue was a significant factor in the number of homes destroyed. Then, the motivation arises to develop inexpensive retaining wall technologies, structurally validated, that can be implemented by people without greater technical knowledge. In parallel, Chile has a fleet close to 5,000,000 vehicles (INE 2017). This means a potential replacement of 20,000,000 tires in 4 or 5 years, transforming them into an abundant and environmentally persistent volumetric residue, which accumulates especially in the gorges of Valparaíso. In this context, and as the first objective of this research, we identify the opportunity to contain landfills with recycled tire structures. In the present work, a vision about the state of international, national and local art about retaining wall with tires is shown and examples are presented. Then, exploratory proposals are developed, which finally settle in a definitive proposal of a retaining wall with mechanically stabilized tires. This proposal was submitted to structural calculation according to current engineering criteria, to lastly recommend it as a valid option for containing a horizontal plane with satisfactory building standards.
The development of asphalt mixture fatigue models used in pavement design is part of the advanced characterization procedures for this material. However, several different analysis approaches and fatigue failure criteria may be used. These approaches and criteria can deliver different fatigue models and, consequently, asphalt layers with different thicknesses in the pavement structure. The present study reports the results concerning the influence of two analysis approaches (phenomenological and cumulative dissipated energy) and two fatigue failure criteria (conventional and Pronk & Hopman) on the development of asphalt mixture fatigue models and their effect on predicting the life cycle of the wearing course in the pavement structure. The results show that the phenomenological approach is more conservative than the cumulative dissipated energy approach, as well as the Pronk & Hopman criterion in relation to the conventional criterion, that is, the type of approach and the adopted failure criterion will have a direct impact on the final thickness of the designed layer.
Infrared Thermography (IRT) is a technique used in the inspection of constructive elements in buildings. It has a great potential for the investigation of pathological manifestations because it is a strictly non-destructive procedure that could be rapidly applied in fieldwork. This research analyzes the possibility of using active IRT to detect internal defects caused by xylophagous insects in bamboo culms, in order to apply it in the fieldwork for the inspection of pathological manifestations in buildings. In laboratory, samples of bamboo culms of Bambusa tuldoides and Phyllostachys bambusoides species were submitted to a thermographic experiment using a thermographic camera and FLIR B400 software. Subsequently, the potential for using this technique in the fieldwork was evaluated. The results point the limitations of both, technique and method used, to identify perforations of diameter less than or equal to 3 mm located in the inner wall of the bamboo culms.
Standard Work (SW) focuses on reducing variability and waste based on three conceptual elements: takt-time, work sequence, and work-in-process. Considering the importance of SW implementation in the Construction Industry, there is a need for adapting the conceptual elements due to differences between the production systems. This paper discusses the singularities of SW concepts adaptation in construction processes and proposes four implementation rules. A participatory case study was conducted aimed at the implementing SW in the construction of the reinforced concrete structure of a 26-floor residential building developed by a Brazilian construction company. This process is characterized by long cycle time, a great number of interrelated operations performed by workers with specialized skills who traditionally have autonomy in organizing their work. The singularities refer to the adaptation of the conceptual elements to the context investigated and resulted in four rules to implement SW in the construction industry: (a) define daily work packages as a control parameter due to the long takt- time; (b) focus the specifications of standard work sequences on the team, allowing space for autonomous decisions; (c) establish batches’ size prioritising the sharing of resources between work packages; and (d) define specifications for transporting and storing resources since there are constant modifications of the workstations.
Generally, a deteriorated concrete pavement is restored by a layer of asphalt reinforcement. Currently, an appropriate intervention consists of interposing a geosynthetic material to delay the growth of existing fissures in the old pavement towards the new upper layer. The dilemma raised is the adherence that is achieved between the layers of the old and new pavement by interposing a geosynthetic, because the effective operation of a pavement occurs when the layers that make it work together. Previous work experiences showed problems in the adhesion with the interposition of geosynthetics. Therefore, the study of the adhesion between a layer of Portland Cement Concrete and a layer of Conventional Asphalt Mixture is proposed, interposing a geogrid with different mesh opening, using as an adhesion agent an asphalt emulsion modified with polymer. It is found that the mesh opening geogrid that offers the best adhesion performance is that which has a mesh size of 40x40 mm. It is also observed that whatever the mesh size of the material, it generates a benefit compared to the system that does not consider the material, that is, to the intimate contact between concrete-asphalt by emulsion.
The concept of ‘nearly zero energy buildings’ (nZEB) could represent a more sustainable aspiration within construction policies, although it has been a little analyzed approach in the Latin-American context. Currently there are different approaches in the world to determine the appropriate requirements and methodologies to define buildings as nZEB. The present work is based on an analysis of the main common variables defined in the international literature to establish this classification such as the buildings passive design, the energy balance methodology and the indicators of renewable energy. It is defined and it is discussed the five main challenges for Cuba, analyzed country as a study case, if a similar energy efficiency directive is implemented in buildings, based on a comparison between the European experience in energy efficiency and the national situation. The presented discussion about the challenge of establishing a suitable national directive according the regional features is useful for analyzing the Latin-American region.
Experimental tests carried out in the laboratory of structures of the National Polytechnic School (Ecuador) in beams with hybrid nodes, increasingly used in the construction of buildings with steel deck slabs, demonstrated that the hybrid nodes does not decrease the strength of concrete beams, reaching approximate values to the theoretical ones for the beam without nodes.
With the results of the experimentation and models in finite elements, the trajectory of efforts to perform a Strut and Tie Model (STM) was sought, obtaining areas of steel 15% superior to the design with the flexion formulas of the ACI 318-14. General formulas of the STM are presented for beams of any light with a single hybrid nodes, but it is possible to extend them to several nodes. The experimental evidence and STM shows that the point load is transferred better with the steel beam penetrating the concrete beam, which does not decrease the strength.
Multiple attributes make construction projects to be likely to face disputes during its execution, such as the nature of adversarial relationships between stakeholders, tight budgets, and the lack of incentives in contracts encouraging collaboration. Furthermore, the impact of claims will vary but is likely to have a negative impact on projects. Consequently, stakeholders have to manage the process of claim resolution. A challenge of this process is the understanding and clarity of the information used to resolve construction claims. A technology that has faced a steady growth in the construction industry is Building Information Modeling (BIM). The benefits of implementing BIM in construction projects are widely recognized such as automation of the quantity take-off estimation process, quick reaction to design changes, better visualization of the construction schedule, and design coordination. Nonetheless, limited studies have addressed how the existing benefits from implementing BIM can be used as a platform to facilitate the resolution of construction claims. This study explores and discusses the existing literature to identify the main benefits of implementing BIM in the resolution of construction claims. The aim is to assess what exists in the legal branch of implementing BIM in construction to suggest its use in this regard.
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