Abstract
The construction industry keeps on demanding huge quantities of natural resources, mainly minerals for mortars and concrete production. The depletion of many quarries and environmental concerns about reducing the dumping of construction and demolition waste in quarries have led to an increase in the procuring and use of recycled aggregates from this type of waste. If they are to be incorporated in concrete and mortars it is essential to know their properties to guarantee the adequate performance of the end products, in both mechanical and durability-related terms. Existing regulated tests were developed for natural aggregates, however, and several problems arise when they are applied to recycled aggregates, especially fine recycled aggregates (FRA). This paper describes the main problems encountered with these tests and proposes an alternative method to determine the density and water absorption of FRA that removes them. The use of sodium hexametaphosphate solutions in the water absorption test has proven to improve its efficiency, minimizing cohesion between particles and helping to release entrained air.
Highlights
By the year 2010, construction was responsible for consuming annually about 37.4 billion tons of natural aggregates and it is expected that by the year 2015 those figures can reach about 48 billion tons[1]
In concrete production it is common practice today as a partial replacement of natural aggregates since various studies have demonstrated that its performance is satisfactory[4,5,6,7,8,9]
This paper presents a new method to measure the density and water absorption of fine recycled aggregates (FRA) with the goals of overcoming the problems of the lab measurements yielded by the existing standard and determining their water absorption during the test
Summary
By the year 2010, construction was responsible for consuming annually about 37.4 billion tons of natural aggregates and it is expected that by the year 2015 those figures can reach about 48 billion tons[1]. Reusing coarse recycled aggregates (CRA) from construction and demolition waste (C&DW) has been successfully implemented in road pavements[2,3]. In concrete production it is common practice today as a partial replacement of natural aggregates since various studies have demonstrated that its performance is satisfactory[4,5,6,7,8,9]. The use of recycled aggregates on mortars has been studied with very interesting results reported[10,11,12]. Several countries already enforce regulations that encourage its use and define the percentage of natural aggregates to be replaced by recycled aggregates[13]
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