Experimental analysis of enhanced cement-sand-based geothermal grouting materials

Nowadays, Ground Source Heat Pumps (GSHP) are achieving significant efficiencies, mostly because of the development of their electromechanical components. However, concepts such as the technical performance of the grouting materials deserve more profound analysis, as becoming essential in areas where good potential thermal performance of the GSHP and serious risks of groundwater contamination exist. In this paper, several fluid mortars with enhanced characteristics have been evaluated. Results show improved mechanical and thermal properties compared to conventional grouting materials. Likewise, mortars exhibited good performance after being subjected to durability treatment. For now, the cost of some mortars may constitute a barrier.This work is based on the project with reference BIA2013-40917-R. This project was financed by the Ministry of Economy and Competitiveness through the State General Budget and the European Regional Development Fund (FEDER)

Durability of geothermal grouting materials considering extreme loads

The concern about the massive use of the non-renewable and very limited fossil fuels together with the well-known effects of the global warming makes it more necessary the efficient use of the current forms of renewable energy generation. Because of the crucial role played by the grouting materials in the Ground Source Heat Pumps (GSHP), a proper selection of these elements should be made based on a deep knowledge of their performance. In this paper, thermal conductivity, mechanical strength and grout-pipe permeability of four different highly workable grouts have been tested before and after they were subjected to wet-dry and freeze-thaw durability treatments. Results obtained demonstrated the harmful effects of using a large amount of mixing water in grouts subjected to those extreme loads. However, the use of these type of grouts with very good workability is still possible in GSHP installations with balanced thermal designs provided that regular operational and environment conditions are considered.The authors wish to express their gratitude to the Ministry of Economy and Competitiveness which funded this study within the Spanish National Plan for Scientific and Technical Research and Innovation (INNPACTO program) through the research project IPT-2011-0877-920000. The authors are also grateful to all the organizations and companies participating in this project: Sacyr Industrial, Universidad Politécnica de Madrid and Cype

Influence of early colour degradation of asphalt pavements on their thermal behaviour

Environmental goals such as the reduction of fossil fuel consumption or greenhouse gas (GHG) emissions through the development of new renewable energy sources have led to the emergence of the so called asphalt solar collectors. Moreover, in recent years, engineers are devoting increased interest to the effect of the thermal loads on the mechanical behaviour of pavements. Several approaches to these topics can be found in the literature. However, a study of the influence of the colour degradation suffered by pavements on their thermal behaviour is still necessary since both the efficient application of the asphalt collectors and the proper study of the effect of the solar radiation on the asphalt pavement behaviour are directly affected by the loss of colour occurring as time goes by. Therefore, the thermal behaviour of two different asphalt mixes was studied before and after being subjected to a colour degradation process. The degradation of five different asphalt mixes was studied and the results were compared to those obtained in the access roads to seven low volume car parks. The final results show that there are large differences between the two asphalt mixes with different gradations and densities. The importance attributed by other authors to conductivity was also confirmed. Furthermore, the results showed that it was possible to simulate the early colour degradation suffered by a low volume road. Finally, a slight reduction in temperature and energy collection capacity was measured after the colour degradation process

Development of an estimative model for the optimal tack coat dosage based on aggregate gradation of hot mix asphalt pavements

In this work the performance of tack coats on asphalt pavement layers is analysed. Adjustment models based on experimental measurements were implemented, relating surface layer macro-texture and aggregate content larger than 8 mm. The best fits were obtained with a Gompertz model, which follows the expected physical macro-texture changes outside the test range. Shear strength was analysed, through prediction curves of each evaluated tack coat dosage, with an optimum tack coat performance for aggregate contents larger than 8 mm between 45% and 50%, and no relevant influence of the tack coat dosage used.The authors would like to acknowledge the support provided by the Technologic Research Construction Group (GITECO) and the Group of Roads of Santander at Cantabria University for the development of tests and samples. We would also like to thank the company Emilio Bolado S.L. and the Society for the Development of Cantabria Region (SODERCAN) for the material provided, and the DID Research Department from the Austral University of Chile for the support

Test methods and influential factors for analysis of bonding between bituminous pavement layers

The durability and maintenance of pavements depend on several factors. One of the most influential is the bond between layers. This bond is responsible for ensuring all layers behave as a single entity, reducing cracks and deformation of the pavement. Several methods, developed by different authors over the past 30 years, to measure bonding between layers are analyzed in this paper. Different research lines are discussed, concluding that the most influential variables are: tack coat type, dosage, mixture type, surface characteristics, temperature, and emulsion breaking time. In order to reach the highest bond strength values, the following factors should be considered: high values of surface macro-texture, low temperatures, the use of heat-adhesive emulsion, a dosage from 300 to 450 g/m2 of residual bitumen and the compaction after emulsion break. Moreover, a non-destructive test method to assess tack coat dosage on site is proposed

Fast falling weight accelerated pavement testing and laboratory analysis of asphalt pavements reinforced with geocomposites

Many reinforcement systems have been designed to improve fatigue life and to prevent or mitigate reflective cracking and rutting in asphalt pavements. The goal of this research was to assess the effectiveness of asphalt pavement rehabilitation with geocomposites to limit fatigue cracking, reflective cracking and rutting by using Accelerated Pavement Testing (APT) and laboratory testing. APT was used to evaluate the pavement performance, simulating the effects of long-term vehicular traffic on the pavement structure in a relatively short period of time. Accelerated pavement tests were performed using the Fast Falling Weight Deflectometer (FastFWD) equipment in a trial section characterized by different types of interfaces (reinforced with geocomposites and unreinforced). In addition, two types of specimen were taken from the trial section to carry out laboratory testing: cores for Ancona Shear Test Research and Analysis (ASTRA) tests and beams for three point bending (3PB) tests. The APT and 3PB tests results demonstrated that the geocomposites investigated are an effective method to enhance asphalt pavement performance. Moreover, ASTRA tests showed that the application of geocomposite at the interface causes a de-bonding effect between asphalt layers that could be beneficial to promote stress-relieving in case of reflective cracking and thermal cracking

Sleep, Glial Function, and the Endocannabinoid System: Implications for Neuroinflammation and Sleep Disorders

The relationship between sleep, glial cells, and the endocannabinoid system represents a multifaceted regulatory network with profound implications for neuroinflammation and cognitive function. The molecular underpinnings of sleep modulation by the endocannabinoid system and its influence on glial cell activity are discussed, shedding light on the reciprocal relationships that govern these processes. Emphasis is placed on understanding the role of glial cells in mediating neuroinflammatory responses and their modulation by sleep patterns. Additionally, this review examines how the endocannabinoid system interfaces with glia-immune signaling to regulate inflammatory cascades within the central nervous system. Notably, the cognitive consequences of disrupted sleep, neuroinflammation, and glial dysfunction are addressed, encompassing implications for neurodegenerative disorders, mood disturbances, and cognitive decline. Insights into the bidirectional modulation of cognitive function by the endocannabinoid system in the context of sleep and glial activity are explored, providing a comprehensive perspective on the potential mechanisms underlying cognitive impairments associated with sleep disturbances. Furthermore, this review examines potential therapeutic avenues targeting the endocannabinoid system to mitigate neuroinflammation, restore glial homeostasis, and normalize sleep patterns. The identification of novel therapeutic targets within this intricate regulatory network holds promise for addressing conditions characterized by disrupted sleep, neuroinflammation, and cognitive dysfunction. This work aims to examine the complexities of neural regulation and identify potential avenues for therapeutic intervention