Using Sewage-Sludge Ash as Filler in Bituminous Mixes

In this study, the behavior of bituminous mixes made with sewage sludge ash (SSA) as mineral filler was investigated. The behavior of these mixes was evaluated with the Cantabro, indirect tensile strength, water sensitivity, permanent deformation, and resilient modulus tests. The results show that SSA waste may be used in bituminous mixes at approximately 2–3% weight percent, maintaining adequate levels of cohesion and adhesion in the mixtures, which is comparable to mixtures made with active fillers such as hydrated lime and cement. Moreover, its use does not increase permanent deformations. However, the resilient modulus test gave slightly lower results for mixes made with SSA than for mixtures made with other fillers. It may be concluded that SSA waste may be used as a filler for bituminous mixes with better results than for mixes made with limestone fillers and with similar results for mixes made with other fillers such as hydrated lime and cement.This work has been financed by the University of Alicante through projects VIGROB-256 and GRE10-28 and by the Valencian Provincial government through Project GV/2012/113

Chapter Experiences with beach nourishments on the coast of Alicante, Spain

The historical evolution of sandy beaches on the coast of Alicante (Spain) has been analysed from aerial images from 1956 to 2019. The beach nourishments carried out in the 1990s to avoid coastal damages and to improve the touristic offer were studied. Shoreline evolution and beach surface has been obtained using GIS. The change of the sediment composition, from gravel to sand, due to the fills has caused a relevant imbalance. Beach nourishments failed its main aim of avoiding the shoreline erosion, causing environmental damages to the nearby Posidonia oceanica meadows

Influence of The Segregation Phenomenon on Structural Efficiency of Lightweight Aggregate Concretes

Lightweight aggregate concretes (LWAC) are versatile and interesting materials for projects that require greater structural efficiency. Due to the difference that exists between the densities of the materials used in these types of concrete, during transport and mainly compaction, their aggregates tend to separate from the mortar matrix, floating towards the surface, a phenomenon called segregation. Segregation in LWAC can affect its durability properties, its density, and directly affect its structural efficiency. In this work, different concrete densities (1700 kg/m3 and 1900 kg/m3) manufactured with different dosages (two different lightweight aggregates) and compaction methods (one or two layers) were analyzed to verify the impact of segregation on its structural efficiency. For this purpose, the segregation index of the LWAC was obtained by means of the image analysis technique. In addition, to obtain their structural efficiency, the density and compressive strength were obtained at different heights of the tested specimens. The results show the vibration of the samples in two layers leads to a more efficient elimination of trapped air, a reduction in the risk of segregation, and better structural efficiency.This research was funded by the University of Alicante ((GRE13‐03) and (VIGROB‐256))

A Machine Learning Approach to Prediction of the Compressive Strength of Segregated Lightweight Aggregate Concretes Using Ultrasonic Pulse Velocity

Lightweight aggregate concrete (LWAC) is an increasingly important material for modern construction. However, although it has several advantages compared with conventional concrete, it is susceptible to segregation due to the low density of the incorporated aggregate. The phenomenon of segregation can adversely affect the mechanical properties of LWAC, reducing its compressive strength and its durability. In this work, several machine learning techniques are used to study the influence of the segregation of LWAC on its compressive strength, including the K-nearest neighbours (KNN) algorithm, regression tree-based algorithms such as random forest (RF) and gradient boosting regressors (GBRs), artificial neural networks (ANNs) and support vector regression (SVR). In addition, a weighted average ensemble (WAE) method is proposed that combines RF, SVR and extreme GBR (or XGBoost). A dataset that was recently used for predicting the compressive strength of LWAC is employed in this experimental study. Two different types of lightweight aggregate (LWA), including expanded clay as a coarse aggregate and natural fine limestone aggregate, were mixed to produce LWAC. To quantify the segregation in LWAC, the ultrasonic pulse velocity method was adopted. Numerical experiments were carried out to analyse the behaviour of the obtained models, and a performance improvement was shown compared with the machine learning models reported in previous works. The best performance was obtained with GBR, XGBoost and the proposed weighted ensemble method. In addition, a good choice of weights in the WAE method allowed our approach to outperform all of the other models.This research was funded by MCIN/AEI/10.13039/501100011033, grant PID2021-123627OB-C55 and by “ERDF A way of making Europe”

Classification of Sediment Quality according to Its Behavior in the Accelerated Particle Wear Test (APW)

One of the main problems faced in coastal management is the loss or destruction of beaches due to erosion. A considerable diversity of factors is involved in coastal erosion, which makes it a complex system to study. The quality of the material that constitutes the beach, as well as the choice of appropriate materials for its nourishment are two of the main ones. Therefore, to make future nourishment projects more sustainable and durable, this work proposes a sediment quality classification based on the physical properties and wear process obtained through laboratory tests. The study of these variables, using principal component analysis, discriminant analysis and ANOVA, has divided the quality of 70 samples into three main groups. A Sediment Quality Classification Index (SQCI) is proposed, which categorizes the quality of the material into poor, regular or good, providing the coastal engineer with a simple tool to ensure more sustainable beach nourishments.This research was funded by Generalitat Valenciana through the project GV/2019/017 (Estudio sobre el desgaste y composición de los sedimento y su influencia en la erosión de las playas de la Comunidad Valenciana)

Influence of Partial Coarse Fraction Substitution of Natural Aggregate by Recycled Concrete Aggregate in Hot Asphalt Mixtures

The main objective of this work is to evaluate the properties of hot asphalt mixtures that have been manufactured with different recycled concrete aggregate (RCA) percentages (0%, 20%, 40%, 60% and 80% of the fraction 5-13 mm) and asphalt (4%, 4.5% and 5%). Dense asphalt mixtures were made; partially replacing the natural aggregate (NA) fraction between 5 and 13 mm. Marshall specimens were manufactured to determine the main properties of the asphalt concrete (AC) in terms of density, voids, stability and deformation. Additionally, the optimal asphalt content (OAC) was determined, and measured the water sensibility, the stiffness modulus and the permanent deformation. The results corroborate the potential for using these sources of construction and demolition waste (CDW) as a RCA in asphalt concrete and show that the hot asphalt mixtures with up to 40% substitution of natural aggregate by recycled aggregate in the fraction 5-13 mm present good behavior.This research was funded by Pavasal Empresa Constructora S.A. and by the University of Alicante (Spain) under grant number [GRE13-03] and [VIGROB-256]

Chapter Relationship between shoreline evolution and sediment wear

The main objective to this work is to establish a relationship between shoreline evolution and sediment wear. The shoreline evolution trend is similar to of the results obtained by the accelerated particle wear test (APW). However, the relationship between the number of APW test cycles and the years of shoreline evolution is not clear. In Guardamar beach the ratio (years/cycles) is 9.7, in Marineta Casiana beach (it is 5.6, and in Arenal beach it is 3. Differences may be due to the different mineralogical composition and morphology of the sand particles

Wood Ash Versus Expanded Clay Aggregate as Internal Curing Water Reservoirs in High Performance Concrete

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] The performances of expanded clay aggregate and wood ash as internal curing water reservoirs were studied in the mortar phase of a hypothetical high performance concrete with a low water-to-binder ratio. The two materials substituted the 15 and 30% of the sand volume. Two different binders, Portland cement and high-volume fly ash blended cement, were used. The compressive strength and the volume stability of the mortars in sealed and air-drying conditions were studied. Furthermore, the desorption capacity of the internal curing water reservoirs and the internal humidity inside the mortars during the first days after casting were analysed. The results shown that the reduction in the self-desiccation shrinkage was higher when the expanded clay aggregate was used, even in air-drying curing conditions, due to its higher desorption capacity in low-relative-humidity environments in comparison to that of the wood ash. However, wood ash had a stronger beneficial effect on early age autogenous shrinkage without significantly increasing the drying shrinkage. The two alternative aggregates influenced the strength moderately. Considering the technical, economic, and environmental implications of using the two lightweight aggregates, wood ash is recommended.Funding for open access charge: Universidade da Coruña/CISUG. This work has been carried out within the framework of the HACCURACEM project (BIA2017-85657-R), funded by the Ministry of Economy, Industry and Competitiveness, State Program for Research, Development and Innovation aimed at the challenges of Society, within the framework of the State Plan for Scientific and Technical Research and Innovation 2013–2016, Call 2017. We also thank the Xunta de Galicia (Spain) for the financial support through its pre-doctoral contracts program. Finally, we highlight the collaboration of the companies Votorantim Cimentos and Grupo BASF, for the contribution of some of the materials used in this researc

Mineralogy and morphology of sand: Key parameters in the durability for its use in artificial beach nourishment

Sand is the third most consumed material in the world, although it is a very scarce material. An exhaustive knowledge of sand and its behaviour against the waves is important for selecting the most suitable material to avoid shoreline erosion. To this end, a pattern of behaviour against accelerated wear test has been sought for 26 sand samples with different characteristics and origins (natural, dredged and quarried), with a focus on their mineralogy as well as a comparison of beach evolution carried out by other authors. Several techniques have been applied for characterization: granulometry, calcimetry, XRD and SEM. The results show that the different degrees of sand grain wear are not only due to their size and mineralogy, but also to the morphology of the particles.This work was partially supported by the Universidad de Alicante through the project “Estudio sobre el desgaste y composición de los sedimentos y su influencia en la erosión de las playas españolas” (GRE16-09)

Factors Influencing the Retreat of the Coastline

One of the main problems of coastlines around the world is their erosion. There are many studies that have tried to link coastal erosion with different parameters such as: maritime climate, sediment transport, sea level rise etc. However, it is unclear to what extent these factors influence coastal erosion. For example, the Intergovernmental Panel on Climate Change (IPCC) has predicted an increase in sea level at a much faster rate than that experienced in the first part of this century, reaching 1 m of elevation in some areas. Another factor to consider is the lack of sediment supply, since currently the contribution of new sediments from rivers or ravines is interrupted by anthropic activities carried out in their basins (dams, channelling, etc.). The big storms, increasingly frequent due to climate change, also should be considered, since they produce an off-shore sediments transport, so that these cross the depth of clo- sure, causing nonreturn of the sediment to the beach. Also, the sediment undergoes a process of wear due to various reasons such as the dissolution of the carbonate fraction and/or breakage and separation of the components of the particles. All these elements, to a greater or lesser extent, lead to the retreat of the coastline. Therefore, the aim of this study is to analyse the different factors causing the retreat of the coastline, in order to determine the degree of involvement of each of them and, therefore, be able to pose different proposals to reduce the consequences of coastal erosion.This research has been partially funded by Universidad de Alicante through the project ‘Estudio sobre el perfil de equilibrio y la profundidad de cierre en playas de arena’ (YGRE15-02)