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In the present world economic situation, the resources directed to the maintenance of buildings are very limited. Therefore, an increasing concern arises for the planning and prioritization of necessary maintenance works during buildings’ life cycle. The planning of maintenance action is achieved by predicting the moment when construction elements reach degradation levels that exceed acceptable standards. To be able to make such forecasts, crucial developments must be made regarding the methods to predict the serviceability of building materials and components. In this study, 444 facades located in the cities of Lisbon and Almada and the Algarve region (Portugal) are analysed based on in situ visual inspections. The approach proposed can be employed in various scopes of service life prediction and maintenance of constructions. This paper develops a priority hierarchy of maintenance actions for the claddings under analysis. The expertise acquired in buildings’ serviceability is very useful to support decision-making in the development of proactive maintenance strategies. The results reveal accurate outcomes in the correlation with the functionality and degradation parameters of facade claddings. The serviceability of the most common types of facades claddings (render, ceramic and paints) applied in Portugal is analysed. © 2017 Informa UK Limited, trading as Taylor & Francis Group.

Due to their outstanding mechanical, thermal, and durability properties, polymer matrix nanocomposites (PMCs) are currently a prominent area of research. The opportunity of applying PMCs in structural reinforcement and rehabilitation of damaged infrastructures, as well as working as a new structural material, justifies the increasing number of recent studies. In this review article, the effect of adding different reinforcements at nano-scale, such as carbon nanotubes, nanoclay, graphene, or nanosilica to polymer matrices, is discussed and the improvement in mechanical properties of PMCs is evaluated. Some concluding remarks and new perspectives on the use of PMCs in structures are given.

Recently, both nationally and internationally, cement-treated granular materials (CTGMs) have been widely used as road base layer. However, all the researches on CTGM with recycled aggregates (RA) are limited to the coarse fraction, with a size range of 0–40 mm. In Spain, one of the recycled materials most commonly produced in construction and demolition waste (CDW) treatment plants is a mixture with around 75% of fine recycled aggregates (hereby called FRA), with 5–8 mm nominal maximum size. This material is commonly used in pipe bedding, an application that provides little or no added-value. The intent of this paper is to study the feasibility of using CTGM made with FRA as road base layer. For this purpose, six mixtures have been produced, comprising 0–8 mm FRA and 0–40 mm coarse aggregates, made of mixed recycled aggregates and recycled concrete aggregate. The main mechanical (unconfined compressive strength and modulus of elasticity) and durability (dimensional changes) properties were studied and th...

The study of the application of nanotechnology in the construction industry and building structures is one of the most prominent priorities of the research community. The outstanding chemical and physical properties of nanomaterials enable several applications ranging from structural reinforcement to environmental pollution remediation and production of self-cleaning materials. It is known that concrete is the leading material in structural applications, where stiffness, strength and cost play a key role in the high attributes of concrete. This paper reviews the literature on the application of nanotechnology in the construction industry, more particularly in concrete production. The paper first presents general information and definitions of nanotechnology. Then, it focuses on the most effective nanoadditives that readily improve concrete properties, such as (i) nanosilica and silica fume, (ii) nanotitanium dioxide, (iii) iron oxide, (iv) chromium oxide, (v) nanoclay, (vi) CaCO3, (vii) Al2O3, (viii) carb...

The service life of cement-rendered facades is closely related to the environmental conditions that they are exposed to. The probability distribution is determined for the degradation condition of render facades considering different environmental exposures. A sample of 100 render facades was subjected to meticulous fieldwork to determine their condition. The analysis focuses on the environmental factors that most influence the overall degradation of the facades, evaluated through the condition level. Probabilistic models based on Markov chains are developed to predict the evolution of facade deterioration according to exposure to outdoor environmental conditions. The proposed model provides data on the synergy between the degradation agents and the degradation condition of render facades, the average time of permanence in each degradation level and indications of the effect of degradation on the durability of render that may be applied in the implementation and fine tuning of maintenance procedures. Better understanding the durability of render facades allows a more rational management of their maintenance, contributing to a reduction of their life cycle costs. The proposed stochastic model provides information that can be applied in the context of insurance policies, allowing an evaluation of the risk of failure of coatings.

This paper provides a systematic review of 119 publications, selected from 235, published over a period of 36 years from 1978 to 2014, relating to the effect on concrete compressive strength of the various aspects related to the use of recycled aggregates (RA) such as replacement level, size, origin, moisture content, exposure of the resulting concrete to different environmental conditions, use of chemical admixtures and additions, and strength development over time. The data were collectively subjected to a statistical analysis, the results of which allowed producing a model for predicting concrete strength, based on the quality and content of the RA.

This paper presents a review of the literature published so far on the use of fine aggregates from construction demolition waste used as a partial or total replacement of fine natural aggregates in concrete production. The review presents the initial works on this subject and an overview of the existing regulations. It goes on to describe the production, treatment and properties of the fine recycled aggregates (FRA). The most suitable mixing techniques for concrete with this type of aggregates are then discussed. The properties of these concrete mixes are analysed in detail, after which a few examples of structures with this type of concrete are described and compared. The acquisition of fine natural aggregates and the dumping of the fine fraction of construction and demolition waste are two serious environmental problems that can be solved simultaneously by using FRA in concrete production, a subject that is lagging behind the use of the corresponding coarse fraction.

Service life prediction is assuming a primary role as it allows a more rational use of scarce resources; its methods are useful for defining preventive maintenance plans, thereby increasing performance and reducing costs. A new mathematical model is presented that uses artificial neural networks to evaluate the service life of painted surfaces. The data on facade degradation were collected from field observations on 160 buildings (220 painted surfaces) in Lisbon, Portugal, examining several degradation agents. In service conditions, the mean estimated service life of exterior painted surfaces is found to be 9.49 years, with a standard deviation of 0.633 years. Detailed factors are identified and incorporated into the model, which account for variations in degradation. Some statistical parameters are used to evaluate the validity and efficiency of the model. The values obtained are consistent with the existing perception relative to the durability of painted coatings. These values can be used to evaluate t...

The use of service life prediction tools can allow a more rational management of the maintenance of a building and its components by supporting reduced life cycle costs of constructed assets. A study was conducted to evaluate the degradation of facades of buildings located in Lisbon, Portugal, and in which visual in-situ inspections of 140 stone cladding facades were completed. Based on this information, different models were proposed to describe the degradation of masonry stone-clad buildings and a novel approach to predicting service life was developed. A description is provided for the use of artificial neural networks to predict the service life of stone cladding of the type that is directly adhered to a building substrate. With the use of artificial neural networks an analytical expression was established to estimate the degradation of this type of cladding system. The viability of this method was then compared with other methods used for service life prediction including multiple linear regression a...

In this paper, repair decision criteria are presented as part of a management system which involves the definition of a periodic inspection strategy and the selection of the repair works. These tasks are performed with the support of a knowledge-based interactive system. The repair decision is based on a cost/value analysis, which estimates both the costs and the economic benefits during the expected remaining service life of the structure for each repair alternative. (A)

A standardized methodology to estimate the technical demand for fertilizers, lime, and phosphate rock is proposed. The model is concerned with three principal criteria: (1) by groups of crops, the fertilized surfaces (ha); (2) soil test summaries in terms of percentage distribution of P: K soil relationships and pH‐calcium by textural types; and (3) soil test general recommendations. This information is presented in matrix figures. For 1990 and 12 groups of crops considered, nitrogen (N) requirements totaled 331,685 metric tons, phosphorus (P2O5) requirements totaled 174,087 metric tons, and potassium (K2O) requirements totaled 185,517 metric tons for Venezuela. It seems likely that this strategy could be applied in other geographical areas to estimate fertilizers, lime, and phosphate rock.