R.V. Silva

The influence of the use of recycled aggregates on the compressive strength of concrete: a review

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.

Use of recycled aggregates from construction and demolition waste in geotechnical applications: A literature review

The use of recycled aggregates (RA) in construction constitutes a significant step towards a more sustainable society and also creates a new market opportunity to be exploited. In recent years, several case-studies have emerged in which RA were used in Geotechnical applications, such as filling materials and in unbound pavement layers. This paper presents a review of the most important physical properties of different types of RA and their comparison with natural aggregates (NA), and how these properties affect their hydraulic and mechanical behaviour when compacted. Specifically, the effects of compaction on grading size distribution curves and density are analysed, as well as the consequences of particle crushing on the resilient modulus, CBR and permeability. The paper also contains an analysis of the influence of incorporating different RA types on the performance of unbound road pavement layers as compared with those built with NA by means of the International Roughness Index and deflection values. The results collected from the literature indicate that the performance of most RA is comparable to that of NA and can be used in unbound pavement layers or in other applications requiring compaction.

Prediction of Chloride Ion Penetration of Recycled Aggregate Concrete

This paper provides a literature review and analysis of the various influencing aspects related to the use of recycled aggregates, sourced from construction and demolition waste, on the chloride ion penetration of concrete. A statistical analysis on the effect of incorporating increasing amounts of recycled aggregates of different type, size, and class on the chloride ion migration and total charge passed of concrete is also presented. The paper also presents the relationship between these properties and the corresponding compressive strength. The results show strong correlations between these parameters, which are independent of other aspects related to recycled aggregate use and made it possible obtaining a relationship between the values acquired via NT Build 492 and ASTM C1202.

Use of municipal solid waste incineration bottom ashes in alkali-activated materials, ceramics and granular applications: A review

This paper presents a literature review on the incorporation of municipal solid waste incinerated bottom ash as raw material in several markets, other than those where it is conventionally used, such as geotechnical applications and road pavement construction. The main findings of an ample selection of experimental investigations on the use of the bottom ash as precursor of alkali-activated materials, as an adsorbent material for the removal of hazardous elements from wastewater and landfill gases, as soil replacement in agricultural activities, as partial or complete substitute of raw materials for the manufacture of ceramic-based products, as landfill cover and as biogas production enhancer, were gathered, collated and analysed.

6 – Geotechnics and Road Pavements

Synopsis This chapter deals with the use of municipal incinerated bottom ash (MIBA) in unbound, hydraulically bound and bituminous-bound forms, in geotechnical and road pavement applications. As an unbound material, the geotechnical properties of MIBA are evaluated with respect to specified criteria for use as capping and subbase material, including its grading, organic content, compactability, shear strength, deformation behaviour, bearing capacity, permeability and durability. Similar analysis is undertaken on the performance of hydraulically bound mixes incorporating MIBA as an aggregate component. The use of hydraulic binder additives as a treatment to upgrade the mechanical properties of MIBA is also assessed. In bituminous-bound applications, the effect of MIBA on Marshall mix design parameters and the resultant optimal bitumen content are examined, along with testing of the deformation properties and durability of the pavement layers. Environmental impacts associated with the use of MIBA in unbound, hydraulically bound and bituminous-bound forms are covered, along with the relevant case studies that have been undertaken in this area.

3 – Municipal Solid Waste Composition, Incineration, Processing and Management of Bottom Ashes

Synopsis This chapter begins with a description of the legislation and policies affecting the practices of municipal solid waste (MSW) management, including an overview of economic and environmental aspects of waste management strategies. The composition of MSW is subsequently examined, including recent trends and the variability of its constituents across regions. A breakdown of existing types of MSW incineration systems and the main stages of these processes, including the air pollution control systems, is also provided. This chapter then describes the treatment techniques used to upgrade the performance of municipal incinerated bottom ash (MIBA), so that it can become a valuable resource for use in several markets. Finally, the chapter ends with an overview of MIBA management, covering the policies, standards and practices adopted in various countries worldwide.

9 – Case Studies and Standards

Synopsis In this chapter, information on numerous case studies is presented, providing an indication on how municipal incinerated bottom ash (MIBA) has performed in various applications in the construction industry, including aggregate manufacturing, raw feed for cement clinker production, aggregate replacement in concrete- and mortar-related materials, geotechnical applications and the construction of unbound, hydraulically bound and bitumen-bound road pavement layers. Some cases related to the management of municipal solid waste incineration plants, how some of the resulting MIBA has been processed or handled in terms of storage and some of the uses given to MIBA in ceramic-based applications and in landfills are also discussed. This chapter finishes with a section concerning the main existing standards and specifications related to the requirements for the aforementioned construction applications.