Abstract
This study analysed the fine particle (<5 mm) waste generated during siliceous or calcareous (depending on the composition of the original aggregate) concrete waste crushing. In the absence of industrial applications, such waste is amassed in open-air stockpiles on construction and demolition wastes (CDW) management plant grounds. The aim pursued was to find an outlet for that material in the cement industry. The starting waste, sourced from six Spanish management facilities, was characterised for its chemical and mineralogical composition, physical properties and pozzolanicity. The mineralogical phases in the CDW/lime system and their variations during the pozzolanic reaction were likewise identified. The findings showed that the fine waste consisted primarily in quartz, calcite, micas and feldspars, with smaller fractions of kaolinite and cement anhydrous phases. No portland cement hydration phases were identified. All six types analysed exhibited medium to low pozzolanicity, with the highest values recorded for the siliceous waste. Ettringite, C–S–H gels and calcium aluminate hydrates (C4AH13, C4AcH12) were identified during the pozzolanic reaction in CDW/lime system. Therefore, this type of waste can be reused as supplementary cementitious material with low-medium pozzolanic activity.
Highlights
IntroductionThe construction industry is one of the mainstays of countries socio-economic development, it is directly associated with adverse environmental impacts such as high energy consumption and global warming, among others [1]
The construction industry is one of the mainstays of countries socio-economic development, it is directly associated with adverse environmental impacts such as high energy consumption and global warming, among others [1].In addition, the large volumes of non-biodegradable construction and demolition wastes (CDW) generated at the end of a structure’s service life are normally stockpiled in landfills, prompting economic, technical, environmental and social problems [2,3].The 820 Mt/year of CDW generated in Europe account for 50% of the continental total [4].An estimated 43% of such CDW is landfilled [5]
Some agglomerations of the finest particles during storage are observed in the figure, which are dispersed when introduced into the saturated lime solution
Summary
The construction industry is one of the mainstays of countries socio-economic development, it is directly associated with adverse environmental impacts such as high energy consumption and global warming, among others [1]. At the European level, countries such as Spain [28] Belgium [29], Germany [30], Italy [31], the United Kingdom [32], allow a percentage of replacement of concrete crushing aggregate between 15%–60% of the coarse fraction for the manufacture of structural concrete. Not all this waste is recycled, for the crushing entailed to produce aggregate of suitable particle size generates fine,
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