Recycled aggregate

Classification of the constituents of coarse recycled aggregates Particle density and water absorption CEN EN 933-1 1 (2009) Yes... 

CEN EN 933-11. 2009. Tests for geometrical properties of aggregates - Part 11 Classification test for the constituents of coarse recycled aggregate. Brussels CEN. 

The materials used for the construction of the capping layer or the formation of subgrade may be (a) collective granular soil material (b) unbound mixtures of natural, artificial and recycled aggregates and (c) soil material treated (stabilised) with hydraulically bound binders. 

May include recycled aggregates with not more than 50% by mass of recycled bituminous planings and granulated asphalt, but excluding materials that contain tar. 

The aggregate material for the CSMs may be select granular material, crushed or uncrushed gravel or stone, recycled aggregate, recycled crushed and graded Portland cement concrete, crushed and graded iron blast furnace slag or a combination thereof, as well as approved select soil. 

Resulting recycled aggregates generally more porous If used as sand, workability of the concrete mix is reduced... 

The existence of reinforcement increases slightly the recycled aggregate production cost... 

Figure 12. Sieve analysis of natural and recycled aggregates used in the project...

A Type 1 recycled aggregate supplied by J.C. Balls and Sons (wvm.jcballs.co.uk /recycling.htm) was used to make concrete mixes. This recycled aggregate (Figure 11) contained crushed rocks, crushed concrete and masonry blocks, asphalt and fine materials such as silt and clay. The maximum size of recycled aggregates used was 75 mm and the average density was measured at about 2.5 g/cm. ... 

Figure 13. BS limits compared with coarse and fine fractions of recycled aggregates used.

As shown in Figure 13, the calculated coarse and fine fractions of the recycled aggregate complied with the requirements of BS-EN 12620-2002. 

PG BPD BOS ROSA Water Water reducer Sand Coarse 10 mm Recycled aggregate ... 

PPG = processed plasterboard gypsum PSP = poljmier superplasticiser RA = recycled aggregate SP = superplasticiser... 

Blended novel binder Water Recycled aggregate ... 

Natural a regate may be replaced with recycled aggregate from old crushed concrete in various proportions, or even only recycled aggregate may be used. 

Durability of concrete elements made with recycled aggregate may be lower when exposed to various aggressive media and should be carefully checked. In such a case, application of natural fine aggregate (natural sand) is preferable (Brozovsky et al. 2006). The use of recycled aggregate is very important for ecological reasons, but should be preceded by careful testing because with old concrete various deleterious influences may be introduced to new structures. The bulk application of recycled aggregate is Umited to secondary structures, e.g. as a sub-base for roads and pavements. 

Brozovsky, J., Zach, J., Brozovsky, J. Jr. (2006) Durability of concrete made from recycled aggregates, in Froc. Int. RILEM-JCI Sem. Concrete Life 06, Israel Ein-Bokek pp. 436-43. 

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