University Centre of Energy Efficient Buildings and Faculty of Civil Engineering CTU in Prague Tereza PAVLŮ, Magdaléna ŠEFFLOVÁ, Petr HÁJEK THE USE OF RECYCLED MATERIALS FOR CONCRETE IN THE CONTEXT OF BUILDING STRUCTURES APPLICATION

Structure of Presentation  Introduction  Motivation, Objectives and Questions  Recycled Aggregate Production  Experimental Part  Examination of Recycled Aggregate  Examination of Recycled Aggregate Concrete  Environmental analysis  LCA of Recycled Aggregate  LCA of Recycled Aggregate Concrete  Conclusion

Motivation, Questions and Objectives  The reduction of environmental impact of concrete production.  The optimization of concrete mixture depending on recycled aggregate properties and environmental impacts.  The application of recycled aggregate for concrete structures.

Recycled Aggregate Procedure  Simplified recycling process= less energy and costs, but worse quality of recycled aggregate  Recycling process begins during demolition

Recycled Aggregate Properties  Recycled aggregate originated from pure recycled waste concrete- waste concrete was from highway  The fragments of waste concrete were crushed on fraction 0/16 mm and sieved  Coarse recycled aggregate of fraction 4/8 mm and 8/16 mm  Fine recycled aggregate of fraction 0/4 mm  The oven-dry density was higher than 2000 kg/m 3  The water absorption of recycled aggregate was higher

Recycled Aggregate Concrete Properties  The concrete mixtures were as strength class 30/37  The skeleton was design according to Bolomey method  The different replacement ratios were design  Conventional concrete (REF)- 0% replacement rate  Recycled aggregate concrete (RAC100)- 100% replacement rate of coarse fraction  Recycled aggregate concrete (RAC100.F30)- 100% replacement rate of coarse fraction and 30% replacement of fine fraction

Environmental Assessment of Recycled Aggregate  As a system boundaries = gate of recycling plant (cradle to entry gate).  In this case, recycling process was considered as process included in new material production.  The recycling process is operated by crushing, separating and transport machines powered by diesel.  Emissions from diesel production  Emissions caused by combustion of diesel during recycling process  The inventory data = local recycling plants in the Czech Republic.

Environmental Assessment of Concrete  The case study included:  Natural aggregate production (gravel, at mine), natural sand production, recycled aggregate production, cement production, concrete production, construction phase, operation phase, demolition, landfill and transportation.

Conclusion- Discussion of the Results  The results show worse properties of recycled aggregate in comparison with natural aggregate especially water absorption.  The poor quality of recycled aggregate is probably caused by the simple recycling process.  On the contrary, the simple recycling process show the lower environmental impact of recycled aggregate.  The decrease of Global Warming Potential is around 50% for recycled aggregate in comparison with natural aggregate and sand.  The environmental impact of aggregate production is lower for recycled aggregate that for natural aggregate and sand. The possible reason is simple recycling process in Czech recycling plants.  The environmental impact of concrete production is influenced by high impact of cement production. The values for all impact categories are similar for all assessed mixtures.  The use of recycled aggregate from construction and demolition waste saves natural resources of mineral aggregate and reduces the pressure on landfilling sites. These are the clear benefits of recycling and reusing C&D waste.

Tereza Pavlů Thank you for your Attention