Recikliranje betonskog otpada je jedno od održivih rešenja za rastuće probleme
sa deponijama građevinskog otpada i nekontrolisano iskorišćavanje prirodnih resursa.
Rezultat procesa je agregat od recikliranog betona koji se trenutno dominantno koristi
za podloge puteva i nekonstruktivne betonske elemente. Sa stanovišta zaštite resursa,
smanjenja energije i razvoja ekološke svesti, važno je istražiti da li se beton na bazi
recikliranog agregata može koristiti za elemente armiranobetonskih konstrukcija.
Predmet istraživanja u ovoj disertaciji su elementi konstrukcije, tačnije gredni nosači
napravljeni od betona na bazi recikliranog agregata (RAC) i njihovo ponašanje pod
dejstvom kratkotrajnog opterećenja do loma savijanjem ili smicanjem. Formirana je
baza podataka i obavljena statistička analiza o mehaničkim svojstvima RAC betona u
odnosu na uporedne betone sa prirodnim agregatom (NAC). Eksperimentalni rad
obuhvatio je ispitivanje recikliranog agregata, betona na bazi recikliranog agregat...a i
grednih nosača napravljenih od takvog betona. Rezultati ispitivanja svojstava agregata i
probna ispitivanja fizičko-mehaničkih svojstava serija RAC i NAC betona poslužili su
kao ulazni parametar za projektovanje sastava 3 betonske mešavine sa 0%, 50% i 100%
recikliranog agregata krupne frakcije, iste projektovane čvrstoće pri pritisku. Ukupno je
do loma ispitano 18 greda, statičkog sistema prosta greda, raspona 3.0 m. Od toga,
napravljene su 3 serije od po 3 grede sa različitom količinom podužne armature (0.28%,
1.46% i 2.54%). Koncept ispitivanja postavljen je tako da se faznim povećanjem
opterećenja dođe do loma nosača usled savijanja u sredini raspona. Takođe, napravljene
su 3 serije od po 3 grede od betona sa 0%, 50% i 100% krupnog RAC i sa različitom
količinom poprečne armature (0%, 0.14% i 0.19%), predviđenih za ispitivanje smičuće
nosivosti. Izvršeno je poređenje zavisnosti sila-pomeranje, slika prslina, ugiba, dilatacija
u betonu i armaturi, oblika loma i graničnih nosivosti greda od klasičnog i RAC betona,
bazirano na sopstvenim i drugim rezultatima ispitivanja. Testirana je mogućnost
primene savremenih propisa koji se odnose na NAC betone na gredne RAC elemente,
kroz poređenje analitičkih predikcija i eksperimentalnih vrednosti momenta savijanja
pri pojavi prve prsline, ugiba, graničnih momenata savijanja i granične smičuće sile.
Takođe, izvršeno je poređenje sopstvenih i drugih rezultata eksperimentalnih ispitivanja osnovnih parametara nosivosti greda koje su dominantno izložene savijanju ili
smicanju...
Recycling of waste concrete is one of the sustainable solutions for the growing
waste disposal crisis and depletion of natural aggregate sources. As a result, recycled
concrete aggregate (RCA) is produced, and so far it has mostly been used in low-value
applications such as for the pavement base. But, from the standpoint of promoting
resource and energy savings and environmental preservation, it is essential to study
whether a concrete made of recycled aggregates - recycled aggregate concrete (RAC)
can be effectively used as a structural material. Structural reinforced concrete elements
were in the focus of this investigation, i.e. beam girders made of RAC and their
behaviour up to flexural and shear failure under short-time loading. A very wide data
base was formed and statistic analysis of relations between mechanical properties of
RAC and corresponding natural aggregate concrete (NAC) was performed. The
experimental research consisted of investigations of recycled concrete aggregate...,
recycled aggregate concrete and structural behaviour of beams made of RAC. Test
results of RCA investigation and trial investigations of physical and mechanical
properties of RAC were used as basic parameters for the design of 3 concrete mixtures
with 0%, 50% i 100% of coarse RCA with the same compressive strength. Full-scale
tests were performed on 18 simply supported beams with span of 3.0 m until the failure
load due to flexure or shear was reached. Firstly, three series of beams made of three
types of concrete and different ratio of flexural reinforcement (0.28%, 1.46% and
2.54%) were formed. Experiment on beams was performed by increasing the load level
until flexural failure in the middle of span occurred. Furthermore, three series of beams
with different ratio of shear reinforcement (0%, 0.14% i 0.19%) and concrete with 0%,
50% and 100% of coarse RCA were prepared to examine shear behavior. Comparison
of load-deflection behavior, crack patterns, service deflections, strains in concrete and
reinforcement, failure modes and ultimate flexural and shear capacity of NAC and RAC
beams was made. The possibility of using equations from NAC codes to RAC beams
was tested by comparison of an analytical expressions and experimental results related
to cracking moments, deflections, ultimate bending moments and ultimate shear
capacity. The analysis of own and other authors’ test results was performed both on
flexural and shear behavior of RAC reinforced concrete beams...
