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This paper deals primarily with research and testing of ultra-high performance concrete (UHPC) made with or without the addition of steel fibers. Two stages of research are presented and discussed in detail: first - UHPC based mostly on local component materials and produced in the form of a premix with a commercial name ForteCrete150®, and second – modified UHPC, made with a partial cement substitution by limestone filler, as a more eco-friendly and sustainable solution. The obtained results indicate that there is a great potential for application of ultra-high performance concrete, especially in the form of premix that can be prepared on-site. The addition of limestone filler (and potentially other types of mineral additives) as SCM, could generally contribute to improvement of a negative agenda surrounding the cementitious composites.

U ovom radu ispitani su različiti tipovi kompozitnih materijala, koji su po sastavu većim delom od cementa, a jednim delom od recikliranog otpadnog praškastog materijala, neutrala. Ispitivanja su obuhvatila uticaj kompozitnih materijala na kvalitet vode u šaržnom sistemu. Ispitani su ključni parametri na osnovu kojih se može oceniti uticaj na promenu kvaliteta vode. Deo materijala čini i reciklirani otpadni materijal koji ima komercijalni naziv „neutral“. Neutral nastaje od sirovine koju predstavljaju različiti tipovi (često opasnog) otpada, koji se u reaktoru sa kalcijum-oksidom prevodi u prah koji se može koristiti kao beozopasan. Ovo istraživanje predstavlja preliminarna ispitivanja koaj će ukazati na mogućnost korišćenja neutrala kao materijal koji bi, u kontaktu sa vodom, otpuštao zagađujuće materije u ekološki prihvatljivom obimu i/ili ne.

In this research, tests of mortar and porous concrete made with solidified waste water treatment sludge (SWWTS) used in two forms as a partial replacement of cement were carried out. SWWTS mainly consisted out of CaCO3 and Ca(OH)2, having no pozzolanic properties. For this reason, it was used both, as produced, and modified by adding Al2O3 and Mg3Si4O10(OH)2 in certain percentages. One mortar type and two types of porous concrete were tested. For each of the three products two mixtures were prepared: the reference mixture and the mixture made with 30% replacement of cement, while the other components remained the same. Based on the given comparative analysis, conclusions were drawn regarding the structure of porous concrete slabs, which refer to individual analyzed properties, but also to the possibility of applying energy-efficient materials. The obtained results point to the conclusion that the use of SWWTS reduces the values of almost all tested properties of porous concrete (flexural and compressive strength, pull-off strength, abrasion resistance), but also that the modification of SWWTS led to a smaller difference in the results of the samples made with 30% of cement replacement and the reference samples. Although, the use of SWWTS led to the reduction of mechancal properties of concretes, the most important benefit is development of possible way for reuse of this waste material and avoid its disposal in the landfills.

Pervious concrete and different types of permeable products for paving are in the spotlight of the researchers from different areas: material engineering, urbanization, water management, sustainable development, renewable energy resources, etc. The paper presents the most important parameters related to production and application of pervious concrete, and the ways of using these products in various conditions. Additionally, mechanical properties of pervious concrete slabs produced with 30% of cement replaced with modified solidified waste water treated sludge are presented, as a possible way of sustainable usage of these products.

Koncept korišćenja otpadnih materijala uz nastanak novih, korisnih materijala predstavlja primenu koncepta nula otpada. Ideja je da se materijali koriste za bolje upravljanje poplavama u gradovima. U pitanju je interdisciplinarni pristup rešavanju odvođenja vode i poboljšanju upravljanja poplavama u gradovima u Srbiji i na globalnom nivou. Glavni naučni i inženjerski cilj je razvoj multifunkcionalnog prototipa poroznog materijala za zaštitu of gradskih poplava i istovremeno uklanjanje zagađujućih materija iz atmosferskih voda.

U radu je prikazana ocena stanja armiranobetonske (AB) konstrikcije primenom nedestruktivnih i destruktivnih in-situ metoda ispitivanja. Analziriana je zavisnost rezultata dobijenih primenom pomenutih metoda u skladu sa važećom tehničkom regulativom. Za AB grede i stubove kod kojih nije ostvarena projektovana marka betona dati su primeri sprovedenih sanacionih mera. U prikazanim primerima detaljno su opisani svi relevantni aspekti praktične pirmene sprovedenih sanacionih mera karbonskim trakama i betoniranjem.

U radu je dat prikaz metodologije ispitivanja i ocene stanja betonskih konstrukcija koja se koristi u savremenoj građevinskoj praksi. Poseban akcenat stavljen je na postupke ispitivanja kvaliteta ugrađenog betona, u skladu sa važećom Evropskom tehničkom regulativom. Dat je prikaz destruktivnih i nedestruktivnih postupaka ispitivanja koji se najčešće koriste u praksi, kao i principi dobijanja zavisnosti između rezultata indirektnih ispitivanja i čvrstoće betona pri pritisku.

The results of comparative testing of porous lightweight aggregate concrete made with various percentages of neutral as a partial replacement of cement are presented in this paper. Neutral represents non-hazardous, inert and solidified material obtained after the treatment of industrial waste materials that have further use value. Four types of prefabricated cavernous concrete flags with different percentages of cement replacement with neutral (0, 10, 20 and 30%) were tested regarding the following properties: density, compressive strength, tensile strength, frost resistance, hydraulic conductivity and thermal conductivity coefficient.

Building industry presents one of the biggest pollutant producers, with simultaneous use of large quantities of natural materials. For this reason, in scientific cycles, in the last years analysis and testing of the possibilities of applying sustainable development principles during the production of building materials, have been performed. Special attention has been paid to the application of recycled concrete aggregate, having in mind that its consumption reduces the quantities laid on the waste fields. Within this paper possibilities of replacing 30% and 45% of natural stone aggregate with recycled concrete aggregate of the same fineness, in the production of asphalt mixtures for the base course has been analyzed. First, results of the standard test of asphalt mixtures were shown, and than the assessment of the energy savings during the mixture production has been presented.

Dobra adhezija čelika i betona u elementima AB konstrukcija ostvaruje se, između ostalog, i odgovarajućim orebravanjem šipki armature. Standard SRPS EN 10080 prepoznaje tri različita tipa geometrije rebara, kod građevinskih proizvoda namenjenih za armiranje betona: šipki, koturova, armaturnih mreža i reštekastih nosača. Kvalitet geometrije rebara se proverava putem određivanja sledećih parametara: maksimalna visina poprečnih i podužnih rebara, rastojanje između poprečnih rebara, nagibi urebrenja i boka poprečnog rebra i relativna površina rebra. Metodologija njihovog ispitivanja definisana je u standardu SRPS EN ISO 15630-1, a kriterijumi usaglašenosti su dati u standardu SRPS EN 10080. U radu su prikazani primeri određivanja ovih parametara za različite tipove čelične armature, sa posebnim osvrtom na utvrđivanje relativne površine rebara.

Copper slag, a by-product of the pyrometallurgical process used for obtaining copper from copper ore in Bor, Serbia, contains mainly silicon, iron, calcium, and aluminium oxides. Due to such properties, it is disposed of in landfills. Despite the favourable technical properties copper slag aggregates possess, such as low-water absorption (WA24 0.6%), low resistance to fragmentation (LA 10%), and low resistance to wear (MDE 4%), its use in the construction industry is still limited. The results of testing the technical properties of copper slag aggregates (CSAs) as a potential replacement for natural river aggregate (RA) are presented in this paper. The experiments included tests on three concrete mixtures with partial replacement of coarse natural aggregate with copper slag. The replacement of RA particle sizes of 8/16 mm and 16/31.5 mm with CSA in the amount of 20% + 50% and 50% + 50% resulted in an increase in the compressive strength of 12.4% and 10.5%, respectively. The increase of CSA content led to a decrease in water penetration resistance and salt-frost resistance of concrete, whereas the resistance to chloride ion penetration did not change significantly.

This research was conducted in order to evaluate the influence of different curing conditions on rheological and mechanical properties of high volume fly ash concrete (HVFAC) in comparison with the ordinary Portland cement concrete (OPC). Four types of concrete were made: two HVFAC and two OPC designed to have the same consistency and 28-day compressive strength for samples cured in water. Also, three different curing regimes were chosen: standard water curing (W), standard laboratory air curing (L) and curing in standard laboratory conditions using curing compound based on the polyolefin emulsion (C). The main objectives were to evaluate the influence of these curing regimes on the compressive strength, flexural tensile strength, modulus of elasticity development over time, water permeability of concrete and concrete shrinkage. The use of curing compound improved previously mentioned properties in some extent compared with the samples cured in standard air conditions.

This study investigates the feasibility of using recycled concrete aggregate (RCA) as a partial substitution of natural aggregate in pavement engineering. Despite RCA’s good properties, such as polishing value and freeze-thaw resistance, its use is limited by low resistance to fragmentation and high-water absorption. This paper parent the experimental results of mineralogical-petrographic and physical-mechanical properties of RCA, natural stone (dolerite) and their combination (RCA content—15%, 30%, 45%, and 60%). The tested granular mixtures showed good resistance to fragmentation and wear (LA 22–27%, MDE 14–15%), as well as satisfactory Polished Stone Value of 55–57, which means they can be used in different layers of pavement structures. According to the obtained testing results, the application of RCA is possible in different flexible and rigid pavement layers and for various traffic loads.

The need for road (re)construction materials is constantly growing. At the same time, there is a limited quantity of new, high-quality materials available and a buildup of secondary/recycled construction materials. One possible solution may be the use of recycled concrete aggregate (RCA) in asphalt mixtures instead of natural aggregate (NA), which also promotes economic and environmental sustainability. The potential use of fine and coarse RCA in road asphalt mixtures is analyzed in this work. Nine asphalt mixtures were tested for base course layers, where RCA was used as a NA substitute. The impact of the quantity of RCA (up to 45% by mass) on the resulting physical and mechanical properties of asphalt mixtures was investigated, and consequently compared with the properties of a reference control mixture produced with NA only. Results reveal that the addition of RCA requires higher bitumen in comparison to the control mixture (up to 1%). Consequently, mixtures with RCA had 15-20% lower stiffness and up to 26% higher critical fatigue strain value (E6). Although RCA mixtures contained more bitumen, their low-temperature resistance was slightly inferior compared with the control mixture (failure temperatures were up to 4.3 C higher). In conclusion, asphalt mixtures with up to 45% RCA can be used without substantially reducing performance.

Recycled concrete aggregate (RCA), obtained by crushing of original (old) concrete, consists of natural aggregate grains and a cement mortar matrix. The presence of old adhered cement mortar, which has higher porosity than natural aggregate, causes unfavourable properties of RCA. The research conducted in order to improve the quality of RCA and to enable its greater application in the construction industry is presented in this paper. Therefore, RCA was subjected to quality improvement treatments with hydrochloric acid and carbon dioxide (accelerated carbonation). The first procedure was aimed at partially removing the adhered cement mortar and the second at reinforcing the cement matrix. The physical, mechanical and chemical properties of all three types of RCA were tested. After the pre-soaking acid treatment (0.1 mol/dm(3) HCl), RCA showed reduced water absorption (up to 3%); the process of accelerated carbonation also led to reduced water absorption (13-20%) as well as to improved mechanical properties (similar to 10%). A scanning electron microscopy investigation revealed that the carbonation process, as expected, significantly reduces porosity of RCA. The overall results show that if RCA is obtained by crushing of compact, high-quality concrete, the procedures of aggregate quality improvement are not necessary.

U cilju implementacije i promocije održivog razvoja u oblasti graditeljstva,sprovedena su obimna eksperimentalna ispitivanja kako karakteristika recikliranogagregata (RCA), tako i karakteristika asfaltnih mešavina sa delimičnom zamenomprirodnog agregata recikliranim. Reciklirani agregat koji je korišćen u istraživanjudobijen je drobljenjem originalnog cementnog betona klase čvrstoće C35/45.U cilju poboljšanja kvaliteta recikliranog agregata, krupan RCA (d>4 mm) jeizložen tretmanima hlorovodoničnom kiselinom (potapanjem u 0.1 mol/dm3 HCl) iubrzanoj karbonatizaciji (koncentraciji CO2 od 4%). Pomenutim tretmanima su umanjoj meri poboljšane karakteristike RCA, pa su dalja ispitivanja uticaja RCA nakarakteristike asfalt betona sprovedena samo za netretirani RCA.Eksperimentalnim ispitivanjima je obuhvaćeno 10 asfaltnih mešavina. Osimkontrolne mešavine, formirane su tri grupe mešavina sa delimičnom zamenom sitnog(0/4 mm), krupnog (4/22.5 mm) i sitnog i krupnog (0/22.5 mm) prirodnog agregatarecikliranim. Svaku grupu su činile mešavine sa tri različita sadržaja RCA: 15%, 30% i45%. Projektovane su asfaltne mešavine za noseći sloj kolovozne konstrukcije AC 22BASE sa ciljanim sadržajem šupljina ispunjenih vazduhom od 5.2%.Glavni deo eksperimentalnog rada je obuhvatio ispitivanje modula krutosti iotpornosti asfalntih mešavina na dejstvo vode, trajnu deformaciju, zamor i nisketemperature. Dobijeni rezultati su pokazali da je moguća primena kompletnog RCA (isitan i krupan agregat); da mešavine sa RCA imaju istu ili bolju otpornost na zamor uodnosu na kontrolnu mešavinu; i da je maksimalna količina RCA u manjoj meriograničena otpornošću na niske temperature.Na osnovu analize dobijenih rezultata razvijena je metodologija za upotrebuRCA kao delimične zamene prirodnog agregata i date su preporuke za dalja istraživanja., As a part of the implementation and promotion of sustainable constructiondevelopment, large experimental research was conducted. This research included testingof the recycled concrete aggregate (RCA) and properties of asphalt mixtures in whichthis aggregate was applied as a partial replacement of the natural aggregate. Recycledconcrete aggregate used in the conducted experiments was obtained by crushing of theoriginal cement concrete (strength class C35/45).In order to improve it's quality, coarse RCA was exposed to the treatments withhydrochloric acid (by pre-soaking into 0.1 mol/dm3 HCl) and carbon dioxide(accelerated carbonation with 4% concentration of CO2). Mentioned treatments inducedimprovements in the properties of RCA, to a lesser extent. Therefore, only untreatedRCA was used as a partial replacement of the natural aggregate in production of asphaltmixtures.Experimental research was conducted on the 10 different asphalt mixtures. Threegroups of mixtures with RCA were tested in addition to the control mixture. In the firstgroup, only fine aggregate (0/4 mm) was replaced by RCA; in the second group, thereplacement was applied only to coarse aggregate (4/22.4 mm), while the third groupincluded mixtures in which both fine and coarse aggregate were replaced by RCA. Eachgroup included three different contents of RCA: 15%, 30%, and 45%. All asphaltmixtures were designed for the base course AC 22 BASE, targeting 5.2% of airentrained voids.Main part of the experiment consisted of different asphalt mixture’s testing, suchas measurements of: the stiffness modulus, resistance to water, permanent deformation,fatigue and low temperatures. Obtained results show that application of the total (bothfine and coarse) RCA is possible as mixtures with RCA expressed equal or improvedfatigue resistance when compared to the referent mixture. Still, the amount of the RCAused should be limited according to its low temperatures resistance.Methodology for the RCA application, when it i

Recycled concrete aggregate (RCA), obtained by crushing of original (old) concrete, consists of natural aggregate grains and a cement mortar matrix. The presence of old adhered cement mortar, which has higher porosity than natural aggregate, causes unfavourable properties of RCA. The research conducted in order to improve the quality of RCA and to enable its greater application in the construction industry is presented in this paper. Therefore, RCA was subjected to quality improvement treatments with hydrochloric acid and carbon dioxide (accelerated carbonation). The first procedure was aimed at partially removing the adhered cement mortar and the second at reinforcing the cement matrix. The physical, mechanical and chemical properties of all three types of RCA were tested. After the pre-soaking acid treatment (0.1 mol/dm3 HCl), RCA showed reduced water absorption (up to 3%); the process of accelerated carbonation also led to reduced water absorption (13–20%) as well as to improved mechanical properties (∼10%). A scanning electron microscopy investigation revealed that the carbonation process, as expected, significantly reduces porosity of RCA. The overall results show that if RCA is obtained by crushing of compact, high- -quality concrete, the procedures of aggregate quality improvement are not necessary