IOP Con e ence Se ies: Ma e ials Science and Enginee ing
PAPER • OPEN ACCESS
Cha ac e is ics o Recycled Conc e e Agg ega es
om P ecas Slab Block Buildings
To ci e his a icle: Václa Venk bec e al 2017 IOP Con . Se .: Ma e . Sci. Eng. 245 032076
View he a icle online o upda es and enhancemen s.
Rela ed con en
Aspec s Conce ning he Use o Recycled
Conc e e Agg ega es
I Robu, C Mazilu and R Deju
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Nanoma e ials in cons uc ion and
demoli ion - how can we assess he isk i
we don' know whe e hey a e?
Wendy Jones, Alis ai Gibb, Ch is Goodie
e al.
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The in luence o kind o coa ing addi i e on
he comp essi e s eng h o RCA-based
conc e e p epa ed by iple-mixing me hod
K U ban and A Sicako a
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Cha ac e is ics o Recycled Conc e e Agg ega es om P ecas
Slab Block Buildings
Václa Venk bec a, I e a No áko á a, S a a a Henko á a
a Facul y o Ci il Enginee ing, B no Uni e si y o Technology, Ve e i 331/95, B no,
Czech Republic
[email p o ec ed]
Abs ac . P ecas slab block buildings (PSBB) ypically and equen ly occu in Cen al and
Eas e n Eu ope, as well as elsewhe e in he wo ld. Some o hese buildings a e cu en ly used
beyond hei se ice li e capaci y. The u iliza ion o ecycled ma e ials om hese buildings
wi h ega d o applying he p inciples o sus ainable cons uc ion and using ecycled ma e ials
will p obably be signi ican in he ollowing yea s. Documen a ion om he manu ac u ing
p ocesses o p e ab ica ed blocks o p ecas slab block buildings is no a ailable, and also i is
di icul o decla e echnological discipline du ing he cons uc ion o hese buildings.
The e o e, p ope ies o ecycled conc e e agg ega es (RCA) p oduced om cons uc ion and
demoli ion was e (C&DW) o p ecas slab block buildings build be ween 1950s o 1990s a e
no su icien ly known. The demoli ion o hese buildings is e y a e oday, bu i can be
assumed an inc ease in demoli ions o hese buildings in he u u e. The use o RCA in new
conc e e equi es e i ica ion/ es ing o he geome ical and physical p ope ies o RCA
acco ding o he EN 12 620+A1 s anda d. The aim o he con ibu ion is o p esen a case s udy
o he demoli ion o slab block building wi h emphasis on RCA usage. The pape p esen s
he esul s o he es s acco ding o Eu opean s anda ds o de e mining selec ed geome ical
and physical p ope ies o he RCA. The pape desc ibes and e alua es es s such
as de e mina ion o pa icle size dis ibu ion - Sie e Analysis, con en o ine pa icles,
de e mina ion o densi y and wa e abso p ion. The esul s o he p ope ies es ing o RCA a e
compa ed wi h he p ope ies o na u al agg ega e. The gene al bounda y condi ions o RCA
pa icula es s a e p esen ed.
1. In oduc ion
Reducing he olume o cons uc ion and demoli ion was e is one o he wo ld's and Eu opean's
p io i ies [1] [2]. The global olume o C&DW is cu en ly es ima ed abou 3 billion ons pe yea [3].
Since mos o he buildings con ain a signi ican amoun o conc e e, i is logical ha conc e e ubble
becomes a la ge p opo ion o he C&DW olume. Mo eo e , up o 70% o he conc e e olume is
cons i u ed by agg ega es [4]. I is una oidable o handle ecycled conc e e e icien ly and exploi i s
ull po en ial o he c ea ion o he sus ainable cons uc ion indus y p inciples. The cu en usage
o conc e e wi h ecycled conc e e agg ega es depends on he a ailable in o ma ion abou i s physical
and geome ical p ope ies. Especially, i we alk abou he u iliza ion o RCA in a highe s eng h
class conc e e, pa icula ly he u iliza ion o RCA in he mix design o s uc u al conc e e. This issue
is in Cen al and Eas e n Eu ope augmen ed by widesp ead p opo ion o p e ab ica ed buildings,
cons uc ed be ween 1950s and 1990s. All his is he eason o de e mining he app op ia e manne
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IOP Con . Se ies: Ma e ials Science and Enginee ing 245 (2017) 032076 doi:10.1088/1757-899X/245/3/032076
o eusing o RCA in he ollowing yea s. Excep o he ex ensi e econs uc ions and e i aliza ions
ha a e cu en ly unde way, hese buildings a e al eady occasionally demolished now.
The demoli ions o PSBB a e pe o med in he cen al Eu ope e y a ely. I can be supposed ha
he numbe o demoli ions o PSBB will g ow o e ime due o hei incon enien com o pa ame e s,
and hus a educed demand o his ype o housing. O he easons a e s uc u al de iciencies,
inadequa e he mal insula ing, i e sa e y equi emen s, e c. Many PSBB do no sa is y cu en
legisla i e s anda ds. The e a e also loca ions whe e a e blocks o la s unoccupied and uined
in he Czech Republic and i is he e o e a b own ields. The au ho s p esen ed a pape abou he e-use
o hese b own ields o ec ea ional pu poses in p e ious yea s [5], bu he cu en si ua ion and
especially he la ge amoun o hese ypes o buildings also calling o he es ablishmen
o a sus ainable solu ion o e-using ma e ials om exis ing buildings which a e nea o end o hei
se ice li e capaci y and going o be demolished. The u he applica ion as a illing ma e ial can be
conside ed as a was e o ma e ial wi h p o i able p ope ies. The pape p esen s a new indings
abou ecycled agg ega es, which comes om a PSBB nea he ci y o B no in he Czech Republic.
Resul s om es ing o p ope ies o RCA o igina ing om hese ypes o buildings ha e no been
p esen ed ye .
1.1. P ecas slab block buildings
To unde s and he scale o he p oblem o PSBB in Cen al and Eas e n Eu ope, i is app op ia e
o p esen some s a is ical in o ma ion. The e a e 214,760 esiden ial buildings in he Czech Republic
and 65,641 o hem a e p ecas slab block buildings, which is 35.56%. In hese buildings li es 26.79%
o he Czech popula ion, which is 2,760,142 people. In hese buildings a e he o al o 1,218,788 la s,
which is 29.69% o all la s in he coun y. The la s de e mined as educed quali y housing is 66,831
la s, which a ec s app oxima ely 5.5% o all la s [6]. The PSBBs a e om 25 o 60 yea s old,
depending on he yea o execu ion. I means ha in many cases PSBBs panels ha e achie ed almos
70-75% o he es ima ed se ice li e, i.e. hey ha e eached app oxima ely 25-70% o he expec ed
"accoun ing li e" (75-85 yea s). Mo e han hal o hese buildings will each 50-60% du abili y un il
yea 2025 [7]. This is he e o e a la ge and complex p oblem. In he Figu e 1 he ypical example
o p ecas slab block building is p esen ed.
Figu e 1. A ypical p ecas slab block building in i s o iginal condi ion in B no
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IOP Con . Se ies: Ma e ials Science and Enginee ing 245 (2017) 032076 doi:10.1088/1757-899X/245/3/032076
1.2. Recycled conc e e agg ega es
Ob aining app op ia e quali y o RCA om PSBB is he basic p econdi ion o u he e ec i e use.
Hi he o, he PSBB a e demolished only in he adi ional way, i.e. wi hou ma e ial ype sepa a ion.
Componen s (conc e e, glass, insula ing ma e ial, e c.) a e hus mixed and some o hem e en
in an i e e sible manne . Mixed C&DW does no ha e any meaning ul use and hus gi es ise
o inapplicable C&DW. The ecycled agg ega es wi h unde ined p ope ies could be used o places
wi h ze o o low p ope ies equi emen s. The new app oach consis s in de e mining o he necessa y
es s o e alua ion o he p ope ies o RCA, bu also in he iden i ica ion o app op ia e ecycling
p ocedu es o C&D was e o a subsequen use. Figu e 2 shows a mobile jaw c ushe o cons uc ion
ubble in he p ocess. The c ushe is loca ed on a ypical cou ya d owned by a cons uc ion company
engaged in ecycling o cons uc ion ubble in he ci y o B no. In p oposed case s udy was necessa y
o sepa a e es ed RCA immedia ely a e he c ushing di ec ly in o loade spoon and hen in o
he bags.
Figu e 2. Mobile jaw c ushe du ing ope a ing p ocess a he plan
2. Me hodology o RCA es ing p ocess
I is necessa y o ake p elimina y es specimens om he demolished building be o e he RCA es
pe o ming. Specimen collec ion can be pe o med be o e he o al demoli ion h ough pa ial
sampling o emo ing pa s o he cons uc ions using co e d ills; o samples can be collec ed
a e he o al demoli ion. In he case o co e d illing, he co es ha e usually insu icien olume
o an objec i e assessmen o he en i e building. In ou case, he es specimens (conc e e pieces)
we e collec ed a e he o al demoli ion o he PSBB Ho el Dukla in he own o Blansko.
The indi idual elemen s o he cons uc ion o his PSBB we e made in he p ecas ac o y in Blansko
and cons uc ion was inished in 1981. Due o sys em planning o he Communis Pa y, mix design
and ypes o used componen s o p e ab ica ed elemen s can be ead om he his o ical documen
"En e p ise Ma e ial Consump ion S anda ds" o he "Building S uc u es B no En e p ise"
om Janua y 1975. This documen p esc ibes he mix design o conc e e mix u es o he p ecas
pa en conc e e wi h he designa ion B170, B250 and B330. A cemen wi h he designa ion SPC250
which co esponds o oday's Mixed Po land Cemen CEM II 42.5 o PC400 was used which
co esponds o oday's Po land cemen CEM I 42.5. Sand 0-4mm and g a el 4-8mm and 8-16mm has
been anspo ed om he qua ies Os ožská No á Ves, B a čice and Božice. Plas icize was p obably
used in he mix u e in dosage 0.735l/l q o cemen because his admix u e was ecommended
o he p ecas p oduc ion.
I is necessa y o be able o clea ly iden i y which s uc u e (walls, ceilings and s ai s) each sample
comes om. Fo he expe imen wo ypes o conc e e we e selec ed, namely R4 om pe iphe al
conc e e wall and R5 om conc e e in e io walls. The samples o conc e e we e c ushed by mobile
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jaw c ushe o a ac ion o 0-32mm and hen so ed by coa se sie es in o he basic ac ions 0-4 mm,
4-8 mm, 8-16 mm and 16-32 mm.
Fo es ing i is equi ed o es ablish he minimum olumes o es samples o analysis, which a e
de ined by he s anda ds. The minimum amoun o agg ega e o indi idual es s is gi en o each es
in he ex below. Fo he app op ia e use o ecycled agg ega e i is necessa y o es ablish indi idual
es me hods by which we can indica e he p ope ies o RCA. Valid me hods o es ing o agg ega es
acco ding o EU s anda d EN 12 620+A1 [8] o conc e e agg ega es we e selec ed. These indi idual
es s we e ca ied ou acco ding o he ch onology o implemen a ion.
2.1. De e mina ion o pa icle size dis ibu ion - Sie e Analysis
A necessa y cha ac e is ic o es ablishing new o mula ions o new conc e e om RCA is o iden i y
pa icle size dis ibu ion cu e by Sie e Analysis. The es was pe o med acco ding o EU s anda d
EN 933-1:2012 [9]. I was selec ed sie ing o he washed and d ied agg ega e. D ying o agg ega es
was ca ied ou o 24 hou s a ambien 110 ± 5 ° C. Then agg ega e was na u ally cooled down and
was weighed he mass M1. Fo he es i was used he s anda d se o sie es acco ding o EN933-2
[10] wi h squa e holes ne wo k: 0.063; 0.125; 0.25; 0.5; 1; 2; 3.15; 4; 5.6; 8; 11.2 and 16 mm. Tes
sample weigh was acco ding o EU s anda d o each ac ion, i.e. 0-4 mm, 4-8 mm, 8-16 mm and
16-32 mm. The weigh o agg ega es apped on each sie es we e eco ded and he pe cen age
o agg ega es apped on each sie e calcula ed acco ding o he o mula (1) om he s anda d [9]:


∗ 100󰇟%󰇠 (1)
whe e M1 is he o al mass o he es sample weigh and Ri is he weigh o ma e ial apped on each
sie e i. The esul s a e p esen ed g aphically in he pa icle size dis ibu ion cu es in Resul s.
2.2. Agg ega e ines pa icles analysis
To de e mine he con en o ine pa icles in he agg ega e i was used he EU s anda d EN933-1:
2012. A e he all o agg ega es h ough all sie es including sie e 0.063 mm, his esidue was d ied
o 24 hou s a 110 ± 5 °C. The sample was hen na u ally cooled and he mass o M2 was weighed.
The pe cen age o ine pa icles was calcula ed acco ding o he o mula (2) om he s anda d [9]:
󰇛󰇜

 100 (2)
whe e M1 is he d y mass o agg ega es samples in kilog ams, M2 is he d y mass o he esidue
apped on he sie e 0.063 mm in kilog ams and P is he mass o sepa a ed ma e ial passing he sie e
0,063 mm in kilog ams. Acco ding o Table 1 he con en o ine pa icles was e alua ed and
ca ego ized. The esul s o he p opo ion o ine pa icles M2 a e desc ibed in Resul s.
Table 1. Table o he e alua ion o ine pa icles con en s o 0-4mm ac ion [9]
Agg ega es Unde size o sie e 0.063 mm
0-4 mm
ac ion
≤ 3% 3
≤ 10% 10
≤ 16% 16
≤ 22% 22
˃ 22% decla e

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2.3. De e mina ion o pa icle densi y and wa e abso p ion
De e mina ion o pa icle densi y and wa e abso p ion o RCA was pe o med in acco dance
wi h he EN 1097-6: 2013. Pa icle densi y was de e mined on he agg ega e d ied in a d ying o en
a 110 ± 5 °C and hen by using a pycnome e me hod [11]. Fi s ly he agg ega e was subme ged
in wa e in he pycnome e and weighed. Then he agg ega e was aken ou , pycnome e illed up
wi h wa e and weighed. The p inciple o his es consis s in he di e ence o weigh s
o he pycnome e wi h and wi hou he agg ega e as well as he le el o g ains sa u a ion. Appa en
speci ic g a i y ρa, o en-d ied pa icles densi y ρ d and sa u a ed su ace d ied pa icles (SSD)
ρssd we e calcula ed acco ding o he o mula (3) (4) (5) om he s anda d [11]:



󰇛󰇜 [Mg/m3] (3)
 


󰇛󰇜 [Mg/m3] (4)
 


󰇛󰇜 [Mg/m3] (5)
Wa e abso p ion a e 24 hou s imme sion WA24 was calcula ed acco ding o he o mula
(6) om he s anda d [11]:
 󰇛󰇜

[%] (6)
whe e ρw is he densi y o wa e in Mg/m3, M1 he mass o sa u a ed su ace d y agg ega es in g ams,
M2 is he mass o he pycnome e con aining sa u a ed agg ega es imme sed in wa e in g ams, M3 is
he mass o he pycnome e illed wi h wa e and M4 is he mass o agg ega es a e d ying in g ams.
3. Resul s and discussion
Selec ed p ope ies o wo di e en kinds o RCA p ocessed om C&DW o igina ed om demoli ion
o p ecas slab block buildings we e es ed and compa ed wi h he p ope ies o na u al agg ega es.
Fo he es s was used ma king R4 o RCA om pe iphe al conc e e wall om ligh weigh conc e e
wi h ligh weigh g anule slug agg ega es and R5 o RCA om in e io conc e e wall. A e i s isual
check i can be s a ed ha he quali y o R4 is highe , conc e e has mo e g ey colou and g ains
o agg ega es a e i mly ixed in o cemen pas e. G ains o RCA R4 ha e sha p edges and i is isible
ha s eng h o agg ega es is compa able wi h cemen pas because c acks a e o med no only
in cemen pas e bu also h ough agg ega e g ains i sel . Fu he p ope ies o RCA R4 a e expec ed
o be in luenced by o po osi y o c ushed ligh weigh g anule slug agg ega es. G ains o RCA R5 a e
mo e yellow shade and seems o be mo e ounded, wi hou sha p edges om c ushing p ocess. I is
isible ha he quali y o conc e e om inne walls is lowe han conc e e o RCA R4.
Pa icle size dis ibu ion o whole amoun o supplied RCA was aken. Bo h RCA we e supplied
in wo di e en ac u es; ine abou 0-8 mm and cou se 8-32 mm. These wo ac u es we e
in labo a o y condi ions sie ed in o ac ions 0-4 mm, 4-8 mm, 8-16 mm and 16-32 mm, which a e
commonly used o a conc e e p oduc ion in Czech Republic. All p ope ies o RCA R4 and R5 we e
measu ed on hese ac ions p oduced in labo a o y.
Pa icle size dis ibu ion o single ac ions we e ca ied ou acco ding o EU s anda d and he esul s
a e p esen ed in Figu e 4. Bo h RCA ac u es 0-4 mm con ain highe amoun o ine pa icles unde
0.125 mm consis mos ly o c ushed cemen pas e and sand. These ines ha e highe wa e abso p ion
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IOP Con . Se ies: Ma e ials Science and Enginee ing 245 (2017) 032076 doi:10.1088/1757-899X/245/3/032076
bu also can con ain esidual unhyd a ed cemen g ains and ha could con ibu e o s eng h ise
o new conc e e. F ac ion 4-8 mm and 8-16 mm a e e y simila o all es ed agg ega es.
Figu e 3. Pa icle size dis ibu ion cu es o he RCA R4 and R5
Figu e 4. Pa icle size dis ibu ion cu es o he NA, RCA R4 and R5
The con en o ine pa icles o RCA R4 is 16.8%. This is p obably due o he ac ha he R4 comes
om pe iphe al conc e e wall which includes ligh weigh g anule slug agg ega es. The sample o RCA
R4 also c umbled mo e du ing c ushing han he sample RCA R5. Fo he sample RCA R5 which
comes om in e nal conc e e wall, he con en o ine pa icles eaches 9.97%. In his case i could
be caused by lowe con en o lowe s eng h class o cemen in ma e nal conc e e (conc e e used
o p oduc ion o RCA). These a e s ill high alues in compa ison wi h he 3% o NA. High con en
o ine pa icles is di ec ly linked wi h wa e abso p ion o RCA mos ly he ac ion 0-4 mm.
E alua ion o ine pa icles con en is p esen ed in Table 2 and in g aphical o m in Figu e 5.
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Table 2. E alua ion o ine pa icles con en in ac ion 0/4 mm
Agg ega es Unde sizeo sie e
0.063mm
NA 3 3%
R4 22 16.08%
R5 10 9.97%
Figu e 5. G aphical pa o con en o ine pa icles in ac ion 0-4mm.
Wa e abso p ion was de ec ed highe in ac ions o 0-4 mm, as expec ed, whe e i mo ed om 9.2%
o 9.6%. Highe wa e abso p ion is caused by con en o c ushed cemen pas e and in case o R4
by con en o c ushed ligh weigh g anule slug agg ega es. Wa e abso p ion o RCA R4 is almos
in all cases highe han wa e abso p ion o RCA R5 which is again p obably caused by con en
o ligh weigh g anule slug agg ega es. These agg ega es as hey a e c ushed ha e high su ace and
open po es which can easie hold wa e in hei s uc u e. Wa e abso p ion o each ac ion and ype
o agg ega e is p esen ed in Figu e 6.
Densi y o o en d ied pa icles is di ec ional o RCA o a oid dis o ion o esul s by highe wa e
abso p ion. S anda d CSN EN 12 620+A1 [8] s a es minimum densi y alue o o en d ied pa icles
2,000 kg/m3 o p oduc ion o all conc e es in con o mi y wi h CSN EN 206-1 [14], in A1
o men ioned no m is also co e s ecycled agg ega es wi h densi ies be ween 1,500 and 2,000 kg/m3.
F om esul s o densi y e alua ion can be s a ed ha densi y o o en d ied pa icles o RCA R4 is
compa able o all ac u es and ange om 1,997 o 2,083 kg/m3 in case o ac ion 4-8 mm. Lowe
densi y was expec ed as es ing RCA o igina es om ligh weigh conc e e. In case o R5 alues
o densi y o o en d ied pa icles we e in wide ange om 2,076 kg/m3 o ac u e 0-4 mm
up o 2,272 kg/m3 o ac u e 4-8 mm. Agg ega es in ma e nal conc e e o p oduc ion R5 we e
dense han he one in R4 and he e o e densi y is highe o bigge ac u es which con ain mo e
agg ega es han ac u e 0-4 mm. By isual con ol i was isible ha he agg ega es in R5 s ayed
in ac and c ucks we e o med only h ough cemen pas . Resul s o measu emen s o densi y a e
p esen ed in Figu e 7.
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Figu e 6. G aphical ep esen a ion o wa e abso p ion o es ed agg ega es NA, RCA R4 and RCE
R5.
Figu e 7. Speci ic densi y o he NA, RCA R4 and R5
4.
Conclusions
The s udy p esen s he esul s om es ing o wo di e en kinds o ecycled conc e e agg ega es and
he es om one kind o na u al agg ega e o he compa ison o he esul s. The sou ces
o cons uc ion and demoli ion was e o ecycled conc e e agg ega es we e aken om he demoli ion
o a conc e e p ecas slab block building made by p ecas p oduc ion in 1981.
I should be no ed ha he cha ac e is ics o RCA depend also on he ma e nal conc e e. The
quali y o he ma e nal conc e e mix u e, i.e. he mix design, he quali y o aw ma e ials, he
maximum agg ega e g ain size, anspo a ion ype, p ocessing me hods, e c. can a ec p ope ies o
he ma e nal conc e e and subsequen ly he RCA. Un o una ely, i is o en di icul o ob ain his
in o ma ion om he pas .
Resul s om es ing o wo kinds o RCA showed pa icle size dis ibu ion o RCA is simila o
sie e cu e o NA wi h small di e ence o i e pa icle con en unde 0.125 mm. Tes ed R4 had much