RAC: Structural behaviour and innovation of recycled aggregate concrete

General Information

Chair: Prof. Dr. Jianzhuang XIAO

Deputy Chair: Yamei ZHANG

Activity starting in: 2015

Cluster C

Subject matter

The areas of RILEM TC’s technical work and interest will include but not be limited to:

Structural behaviour and innovation of recycled aggregate concrete (RAC)

Stress-strain relationship of RAC

Hybrid RAC with natural aggregate concrete (NAC) components

Performance under restraints by steel and FRP tubes or bars

Component structural behavior (moment, shear, punching)

Case-studies in structural applications of RAC

Time-varying reliability models of RAC components

Fire-resistant performance and fire design of RAC structures

Fiber-reinforced concrete and composite structures

Monitoring and numerical simulation models for practical designs

Note: This TC will be collaborated with fib considering the material properties of RAC

Long term properties

New technologies for improving the properties of recycled aggregate (RA) / RAC

Properties of fresh and early-age RAC and their predictions

Influence of different sources of RA on RAC

RAC mix design

Terms of reference

Several case studies regarding environmental design of concrete and concrete structures will be collected. Some background research will be carried out in related research institutes. The details of these case studies will be investigated before preparing the next draft of the TC’s report. 

The proposed members are from academics, universities, national labs, engineers, research students.

Collaboration with other TC groups and fib Task Groups

238-SCM (2011) De Belie, Lothenbach, Hydration and microstructure of concrete with supplementary cementitious materials.

CCF (2014) Serna, Cavalaro, Creep behavior in cracked sections of fiber reinforced concrete.

246-TDC (2011) Yao, Wang, Test methods to determine durability of concrete under combined environmental actions and mechanical load. 

242-MDC (2010) Bažant, Jirásek, Multi-decade creep and shrinkage of concrete: material model and structural analysis.

244-NUM (2011) van Breugel, Brameshuber, Numerical modeling of cement - based materials.

FRS (2013) Noguchi, Imamoto, Fire resistance of concrete structures repaired with polymer cement mortar.

230-PSC (2008) Beushausen, Fernandez Luco, Performance - based specifications and control of concrete durability.

EEC (2012) Katz, Habert, Environmental evaluation of concrete structures toward sustainable construction.

250-CSM (2012) De Felice, Oliveira, Composites for sustainable strengthening of masonry. 

fib Task Group 3.9, Application of environmental design to concrete structures.

fib Task Group 3.10, Concrete made with recycled materials - life cycle perspective.

fib Task Group 3.11, Environmental  product  declarations  and  equivalent  performance  for  concrete products.

fib Task Group 3.12, Sustainable civil structures.

Detailed working programme

The main heading of the TC is “Structural behaviour and innovation of recycled aggregate concrete”.

The items of this work include:

Summary of previous related research background and scope; 

Statistic of engineering applications of RAC;

Areas of the TC’s technical work and interest; 

Woking plan of workflow and timeline;

Collaboration with other TC groups and fib Task Groups; 

Expected outcomes and delivery dates. 

At this period of time, the potential members hope to communicate with each other for evaluating RAC research status in different countries / regions in order to guide the next step of our work. A report on RAC material properties will be published in 2017. And, a report on RAC structural performance will be published in 2018. We believe that it will have a deep understanding of RAC through our work and provide contribution to promote the applications of RAC in real engineering. 

Technical environment

RAC is a type of green material, its special characterizes (such as fresh and early-age properties and influence of different resources of RA on RAC) should be thoroughly assessed. There are many TCs and fib Task Groups which focus on material properties in RILEM and fib, such as 238-SCM (Hydration and microstructure of concrete with supplementary cementitious materials), 242-MDC (Multi-decade creep and shrinkage of concrete: material model and structural analysis) and fib Task Group 3.10 (Concrete made with recycled materials - life cycle perspective).The TC will communicate with those TCs and fib Task Groups to promote the investigation of RAC material properties.

Popularizing the applications of RAC in civil engineering structures is a key step to promote sustainable development. Based on the research achievements of RAC material properties, the TC would pay additional attention to RAC structural performance. For RAC structures, its further studies are necessary, such as monitoring of full-scale structures, and case-studies of using RAC in building structures and infrastructures) are still required. The TC will communicate with those TCs and fib Task Groups, such as fib Task Group 3.12(Sustainable civil structures), FRS (Fire resistance of concrete structures repaired with polymer cement mortar), EEC (Environmental evaluation of concrete structures toward sustainable construction), etc., to promote the investigation of RAC structural performance.

The heading of cluster C is “Structural Performance and Design” and cluster C focuses on similar research contents to that of the TC. So, we think cluster C would be the most appropriate for the proposed TC to be assigned to.

Expected achievements

A report on RAC material properties will be published in 2017. And, a report on RAC structural performance will be published in 2018.

Group of users

Academia, research institutes, engineering consultants, authorities/governmental institutions, producers/suppliers (concrete, concrete additives/extenders, cement, aggregate), contractors

Specific use of the results

A large amount of concrete waste from demolished structures is generated annually and the amount is expected to increase in the future. Using recycled coarse aggregate (RCA) to replace part or all natural coarse aggregate (NCA) in concrete mixing is one of the effective methods for reclaiming wasted concrete. As a type of green material, in recent years, many researchers have engaged in exploring ways to improve RAC performance. There are many groups in RILEM and fib focus on the material properties of RAC. Based on their achievements, the TC can conduct fundamental investigations such as stress-strain relationship, fresh and early-age properties and influence of different resources of recycled aggregates on RAC by collaborating with these groups in RILEM and fib. We do believe the collaboration of fundamental research will contribute to the next step of investigation – structural behavior and construction innovation.

To promote sustainable development, it is necessary to popularize the use of RAC in civil engineering structural applications. The structural performance of RAC has been investigated, including shear capacity and flexural performance of RAC beams, seismic behavior of beam-column joints and seismic performance of components made of RAC under cyclic loading, seismic performance of RAC filled steel square hollow section beam-columns, bearing capacity and deformability of beams and columns made of RAC and structural reliability. But further studies (such monitoring of full-scale structures, case-studies of using RAC in building structures and time-varying reliability models of RAC components/structures) are necessary. 

Through this TC research, we will have a better understanding of RAC, which will help us to evaluate the applications of RAC in real engineering projects. Finally, we hope to see additional structures will be made of RAC and promote sustainable development around the world.