The tensile bond strength is one of the main properties of rendering mortars. It represents the adhesiveness ability between the mortar itself and the substrate. This property depends on several factors, such as the proportion and characteristics of the mortar materials and the substrate, along with the mode of application and climate conditions. The purpose of this paper was to analyze the tensile bond strength between three rendering mortar proportions in volume – 1: 1: 6, 1: 2: 9, and 1: 6 (with plasticizer additive) – each one applied on two substrates, ceramic structural blocks with roughcast and concrete structural blocks. The rendering mortars had their physical properties evaluated in fresh and hardened stages, as well as their compressive and tensile strengths in flexure. The tensile bond strength was determined by a pullout test on ceramic and concrete masonry walls exposed to external weather. The results showed that the 1: 1: 6 mixed mortar exhibited higher tensile bond strength in both substrates of ceramic blocks with roughcast and concrete blocks without preparation. Besides, among 1: 2: 9 and 1: 6 mortars there is no significant difference in tensile bond strength considering both substrates. Another conclusion was that the substrate type did not affect the final bond strength between the mortars.
Seismic events for decades have caused great prejudice to countries causing human and economic losses due to the collapse of houses, therefore the relevance of this research lies in offering a management model with processes to identify the seismic vulnerabilities of houses and validate the correlation between whether there is dependence between the Knowledge of the Management Model with Processes and its application (hypothesis). A mixed method (quantitative and qualitative) is presented, generating reliable and concise results, issuing Chi-Square values to prove that they are greater than 0.05, implying a very weak or low dependence relationship. Consequently, it is concluded with a confidence level of 95%, indicating the way in which the knowledge of the model is developed and its application, has very little dependence in the local governments of the Moquegua Region, since they do not know the proposed model.
The construction companies have achieved different levels of BIM use and in some developed countries, it is very advanced. Traditionally, the use of BIM has been evaluated by maturity models; however, it does not provide an integral evaluation of BIM use. BIM Use Assessment (BUA) was proposed as a tool to satisfy this need, it is based on the evaluation of several states that compose necessary characteristics to perform each BIM use successfully. BUA was applied to measure projects that have BIM advanced use in Colombia, Chile, and Spain. However, there is none an integral evaluation in the early stages of BIM use. Therefore, the objective of this research was to evaluate the incipient BIM use. Accordingly, 23 private Ecuadorian projects, were evaluated using BUA. As expected, the analyzed projects have lower levels than the other projects evaluated by BUA. The high percentage of projects were at the levels that require the appropriate use of 3D models, and the collaboration issues were common deficiencies. This research results could be used in the development of strategies to reduce mistakes; thus, leading to an agile BIM implementation.
Due to increased competition enterprises have sought alternatives to improve their processes and increase the quality of their products and services. The enterprises of construction sector are related to the buildings construction. They have adopted Quality Management System (QMS) to improve their processes and to fill the demands of the market. Among the existing QMS, the Brazilian Program of Habitat Quality and Productivity (PBQP-H/Siac) has distinguished itself by offering benefits that are favorable to the enterprises in this segment. However, unlike medium and large enterprises, the Micro and Small enterprises (MSEs) have limited financial resources, lack on quality management, and others obstacles. MSEs have fitted their quality implementation to match with the larger construction enterprises, to better competition and to get opportunities in the market. Because of this, the present paper proposes an approach to self-evaluation requirements of PBQP-H/Siac, using fuzzy logic as a measurement tool. The fuzzy logic will formalized the assessed requirement, providing better definition on decision making. The approach exposed as a simulation based on real case to demonstrate their applicability. As a result the approach determines the degree of formalization of the desired level.
Concrete is one of the most studied industrial products with the aim of improving its durability, strength, and workability, as well as developing innovative alternatives in its production to reduce the environmental footprint (Rivera, 2013). This research validates the use of industrial waste generated in the department of Boyacá - Colombia, within the production of concrete for the construction of rigid pavements. The research followed several stages, beginning with the physical, chemical, and mechanical characterization of the materials and the design of the standard mixture following the ACI 211 methodology. Subsequently, the 25%, 50%, 75%, and 100% of the gravel was replaced by electric arc furnace slag (EAFS), and 20, 30 and 40% of the sand by the recycled ground glass (RGG). Finally, the compressive strength of the concrete mixtures was analyzed.
This research was conducted to determine the effect of the scallop shell lime (SSL) on the compressive strength of concrete made with Portland cement type Ico and natural aggregates from a quarry, where SSL was added at 3%, 4% and 5%. The physical and mechanical characteristics of the aggregates were determined based on the N.T.P. 400.037/ASTM C22 standard, and the mix design was carried out through the ACI method. The SSL was used due to the high calcium content present in the valve. Standard concrete controls were prepared and cured by adding 3%, 4% and 5% SSL (339.0183/ASTM C192M), which were analyzed at 7, 14 and 28 days of curing. The results showed that the compressive strength at 28 days was 242.63 kg/cm2 when 3% SSL was added, increasing with respect to the standard control by 16%. With the addition of 4% SSL, the maximum strength reached was 245.25 kg/cm2, and with 5%, the compressive strength reached was 261.17 kg/cm2, increasing by 24%. In conclusion, the SSL positively affects the increase of concrete strength, and the percentage with the highest incidence is 5%.
Multiple studies have found that productivity in Chilean construction has been stagnated during recent decades; thus, creating the need to understand better what factors have led to these results in the construction sector. In the international literature, studies have found that changes are the leading cause of productivity losses in construction projects; however, limited studies have been done in Chile in this regard. This context is understood as an opportunity to learn from the existing literature about the impact of changes in construction productivity, more importantly, such learning can contribute to the discussion of productivity improvement in the Chilean construction sector. This study recommends that more studies are necessary to be done in Chile regarding the impact of changes in construction projects. Namely, future studies should be based on an extensive database of projects so that generalization can be drawn for the construction industry. Additionally, the data collection process of changes in construction should be improved, paying specific attention to the size of changes, the timing of changes, and the scale of assessment—namely activity, project, and industry levels. Ultimately, this study aims to contribute to the discussion about productivity improvement in Chilean construction as this remains one of the main challenges in the industry
The Pedernales earthquake in 2016 affected several structures, an example is the UVC in the city of Manta, in which a post-earthquake reinforcement with inverted V-shaped diagonals was performed. This paper presents an analysis of the structure without reinforcement and with longitudinal reinforcement, using functions of the CEINCI-LAB Computational System to determine displacements, drifts, and floor shear, in a seismic analysis with the spectral and static equivalent modal method using the spectrum of Manta 2016. In addition, the demand is determined according to the NEC-15 load combinations, using the live, dead and earthquake load states; for the verification of the axial capacity of columns, the effect of the earthquake is used, considering the over-resistance. After that, a design by capacity is carried out in the structure without reinforcement, based on the capacity of the beams, and in the case of reinforcement, an analysis is carried out based on the capacity of the diagonals. It is observed that both the original structure and the reinforcement do not comply with the earthquake resistant philosophy, and it is likely that an earthquake will be affected in a future.
Fernanda M. Cavalcante de Melo, José Nilton Soares Santos, Herbet Alves Oliveira, Cochiran Pereira dos Santos, Zélia Soares Macedo, Vanessa Gentil de Oliveira Almeida
Lightweight concrete has as main characteristic its low density due to the incorporation of light materials such as expanded clay, or even the incorporation of air whose function is to reduce the density, characteristic of cellular concrete. In Aracaju city, there are companies that promote tire reconditioning, generating large amounts of waste dust. The aim of this work is to study the reuse of tire rubber waste in light concrete from expanded clay. An experimental program was developed for the analysis of these concretes, varying the percentage of 1%, 2.5% and 5% of the tire rubber waste to replace the natural fine aggregate and 100% replacing the natural coarse aggregate by expanded clay (50% of expanded clay C1506 and 50% of C2215). The materials (cement, sand, expanded clays and tire rubber waste) were characterized through tests of particle size analysis and unit mass. The hardened concrete was evaluated through mechanical tests of axial compression strength, modulus of elasticity and tensile strength by diametrical compression, physical tests of water absorption and specific mass, in addition to image analysis by scanning electron microscopy. The use of expanded clay with incorporation of 1% of tire rubber waste guaranteed better results in mechanical resistance, lower water absorption and greater specific mass than the mixtures with 2.5 and 5%, reaching values close to the reference concrete. Thus, the residue can be an alternative for reuse, avoiding disposal.
Executing projects according to its estimated cost and schedule is fundamental to guarantee the economic and financial viability of the businesses associated with them. In this context, the estimated duration of an activity is very important for the development of the project schedule and budget. Therefore, determining the main factors that contribute to labor productivity becomes imperative. This research identified the main factors affecting labor productivity in construction projects around the world. Then, it was verified the pertinence of these factors to the Brazilean industry . The 56 factors identified were prioritized, according to the importance index, and categorized into four main groups: management, labor, external and technological. Factors such as: poor material management, lack of construction manager’s leadership, site supervision inefficiency, strikes and lack of tools are at the top of the list. It was also observed the balance between the management, technological and external groups. Finally, when compared to researches carried out in other countries, there is a reasonable correlation between the results identified by this research and those found by previous researches.
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