Influence of Construction Materials on the Environment

Obilježje ekološki održive gradnje jest smanjenje utjecaja na okoliš tijekom građenja, ali i cijelog uporabnog vijeka građevine. Za procjenu utjecaja građevine na okoliš potrebno je razmotriti sve faze gradnje uključujući korištenje prirodnih sirovina za proizvodnju građevnih proizvoda, način građenja, uporabu same građevine te naposljetku rušenje i recikliranje. Smatra se da je građevinarstvo jedna od djelatnosti koja troši najveću količinu prirodnih resursa kao što su agregat, voda, drvo te različite prirodne sirovine za proizvodnju legura. Cement kao glavni sastojak betona neizostavan je materijal u građevinarstvu, ali pri njegovoj proizvodnji dolazi do velike potrošnje energije i emisije stakleničkog plina CO2. Istraživanja su pokazala da je upravo cementna industrija odgovorna za 7% ukupne svjetske emisije CO2. Pri proizvodnji jedne tone klinkera portlandskog cementa u okoliš se emitira približno 850 kg CO2. Građevinarstvo utječe i na veliku potrošnju energije kako pri proizvodnji građevnih proizvoda i gradnji, tako i u samoj fazi korištenja građevine za potrebe grijanja, hlađenja i rasvjete. Recikliranjem građevnog otpada i njegovom ponovnom uporabom za različite namjene smanjuje se potreba za eksploatacijom prirodnih resursa te se rješava problem odlaganja i zauzimanja novog prostora. Unatoč tim informacijama, trenutni stupanj reciklaže građevnog otpada u Republici Hrvatskoj ne prelazi 7%, a iz građevnog otpada izdvoji se tek oko 11% sekundarnih sirovina. U radu su prikazani različiti aspekti održive gradnje s posebnim osvrtom na odabir materijala za građenje, ali i razvijanje svijesti o njihovu utjecaju na okoliš za vrijeme cijelog uporabnog vijeka.The environmentally sustainable construction characteristic is to reduce the environmental impact during construction, and the entire lifetime of the building. To estimate the impact of buildings on the environment, it is necessary to consider all construction phases including the use of natural raw materials for production of building products, construction method, the use of the building and eventually demolition and recycling. Construction is considered as an activity that consumes the largest amount of natural resources, such as aggregate, water, wood and various natural raw materials for production of alloys. Cement as the main constituent of concrete is very important material in construction, but its production requires high energy consumption and it leads to greenhouse gas emissions of CO2. Studies have shown that the cement industry is responsible for 7 % of total CO2 emissions. In the production of one ton of Portland cement clinker, into the environment is emitted approximately 850 kg of CO2. Construction also causes high energy consumption in the production of building products and in construction phase as well as in the use of the building for heating, cooling and lighting. The construction waste recycling and its reuse for various purposes reduces the need for the natural resources exploitation and solves the disposal problems and new space occupation. Despite these findings, the current level of construction waste recycling in the Republic of Croatia does not exceed 7 %, and from construction waste, only 11 % secondary raw materials is separated. The paper presents different aspects of sustainable construction, with special emphasis on the building materials selection, and developing awareness of their impact on the environment during the entire lifetime of the building

EXPERIMENTAL RESEARCH OF PRECAST CONCRETE FLOOR BLOCKS WITH IMPROVED RESISTANCE TO HIGH TEMPERATURE

The paper presents possibility of usage of crushed clay bricks and roof tiles as an aggregate for concrete in precast concrete floor blocks. According to literature review, concrete with crushed brick and roof tiles as an aggregate has better thermal properties than regular concrete with natural aggregate. Applicability of concrete mixture for precast concrete blocks was tested regarding the requirements set in HRN EN 15037-2 Precast Concrete products – Beam and block floor systems – Part 2: Concrete blocks. Precast concrete blocks with crushed bricks and roof tiles were made and their mechanical properties after exposure to high temperature were tested. Based on experimental results, conclusions are made about usage of crushed bricks and roof tiles as partial replacement of natural aggregate in concrete for precast concrete blocks with improved resistance to high temperatures

Utilization of Wood Biomass Ash in Concrete Industry

The use of energy from wood biomass plants results in the production of large quantities of wood biomass ash (WBA). Most of the WBA is disposed of and some are used as a soil supplement in agriculture. In the concrete industry, there is a high potential for substitution of certain components with suitable alternative materials. Depending on its physical and chemical properties, WBA can be used in concrete production as a partial replacement for cement or as a substitute for fine aggregates. The suitability of locally available WBA should be evaluated in terms of microtexture, chemical, and mineralogical composition. This paper presents the types of WBA produced by different combustion technology, the influence of WBA as a cement replacement on the properties of cement composites in the fresh and hardened state, an overview of the environmental impact of WBA cement composites, and the market opportunities and readiness for reuse of WBA as a new potential supplementary cementitious material

Razvoj Centra za istraživanje i razvoj sigurnog i održivog izgrađenog okoliša Građevinskog fakulteta u Zagrebu

Građevinski fakultet pokrenuo je osnivanje centra izvrsnosti pod nazivom ‘’Centar za istraživanje i razvoj sigurnog i održivog izgrađenog okoliša’’ u Sveučilišnom kampusu Borongaj u Zagrebu. U Centru će se stvoriti uvjeti za znanstvena istraživanja u svim granama građevinarstva te će se omogućiti značajno poboljšanje znanstvenog i istraživačkog rada Građevinskog fakulteta. Isto tako, važnu kariku u razvoju građevinske struke i novih tehnologija te njihove primjene predstavlja suradnja fakulteta s gospodarstvom. Sudjelovanje u rješavanju najzahtjevnijih inženjerskih zadaća u građevinarstvu stvara uvjete za stjecanje novih stručnih znanja i iskustava koja se dalje prenose na studente te pružaju snažnu osnovu za prijenos inovativnih rješenja u građevinsku praksu

Life cycle analysis of reinforced concrete floor slab through three different waste management scenarios

U radu je prikazana analiza životnog ciklusa armiranobetonske podne ploče s posebnim naglaskom na kraj životnog vijeka. Prikazana su tri scenarija kraja životnog vijeka odnosno gospodarenja otpadom: scenarij I (trenutna situacija gospodarenja građevnim otpadom u Republici Hrvatskoj), scenarij II (100 % odlaganje na odlagalište) i scenarij III (potpuna oporaba građevnog otpada). Cilj je prikazati ekološke prednosti recikliranja u smjeru održive gradnje, ali i odrediti faze u životnom vijeku armiranobetonske podne ploče koje imaju najnegativniji utjecaj na okoliš. Na osnovi provedene analize, najveći negativni doprinos utjecaju na okoliš ima faza proizvodnje koja obuhvaća nabavu sirovina, njihovu obradu i prijevoz do mjesta proizvodnje samog građevnog proizvoda. Analiza kraja životnog ciklusa proizvoda pokazala je da način gospodarenja građevnim otpadom ima značajan utjecaj na vrijednosti kategorije utjecaja toksičnosti na ljude (HTP), pitku vodu (FAETP i MAETP), tlo (TETP) i eutrofikaciju (EP). Ocjenjivanje životnog ciklusa (LCA) s fokusom na kraj životnog vijeka je ključno jer može pružiti vrijedan uvid o utjecaju faze odlaganja na okoliš te pomoći u razvoju strategija za održivo gospodarenje otpadom.This paper presents a life cycle analysis (LCA) of a reinforced concrete floor slab with special emphasis on the end of life (EoL). Three EoL waste management scenarios were presented: Scenario I (current situation of construction and demolition waste management in the Republic of Croatia), Scenario II (100% landfilling of construction and demolition waste), and Scenario III (complete recycling of construction and demolition waste). The aim of this study is to demonstrate the environmental benefits of recycling in terms of sustainable construction and to determine the phases in the life of reinforced concrete floor slabs that have the greatest negative impact on the environment. From the analysis, the largest negative contribution to the environmental impacts is in the production phase, which includes the supply of raw materials, their processing, and the transportation of products to the concrete and reinforcement plants. EoL analysis showed that the manner in which construction and demolition waste is managed has a significant impact on the values of the impact categories of human toxicity (HTP), freshwater and marine aquatic ecotoxicity (FAETP and MAETP), terrestrial ecotoxicity (TETP), and eutrophication (EP). Conducting an LCA focusing on the EoL is critical, as it can provide valuable insights into the environmental impacts of the disposal phase and help develop strategies for sustainable waste management

Mix design for self-compacting concrete

U radu su pregledno prikazani postupci ispitivanja, mogućnosti primjene i reološke osnove ponašanja svježeg samozbijajućeg betona. Prikazane su preporučene metode ispitivanja i zahtjevi za samozbijajući beton u svježem stanju. Uz navedeno također su prikazani rezultati provedenih vlastitih laboratorijskih ispitivanja svojstava samozbijajućeg betona. Dane su preporuke za projektiranje sastava kako bi se postigla zahtijevana svojstva samozbijajućeg betona za određenu namjenu.Testing procedures, application possibilities, and rheological behaviour of the fresh self-compacting concrete, are presented in the paper. Recommended test methods are presented, and requirements for the fresh self-compacting concrete are given. In addition, the results the authors obtained by testing properties of self-compacting concrete in laboratory conditions are presented. Mix design recommendations, enabling definition of use-specific properties of self-compacting concrete, are also given

Use of Sewage Sludge Ash in the Production of Innovative Bricks—An Example of a Circular Economy

In this paper the properties of clay bricks with 5 wt%, 10 wt%, and 20 wt% sewage sludge ash (SSA) were studied and compared with the properties of control bricks made of 100% clay. Sewage sludge (SS) was collected at two wastewater treatment plants (WWTPs) in Croatia— WWTP Zagreb and WWTP Karlovac—and incinerated at a temperature of 900 °C The bricks were produced on a laboratory scale. A total of seven types of bricks were produced—control bricks and six types of bricks as combinations of different wt% of SSA generated from SS that was collected at two different WWTPs. The physical and mechanical properties of produced bricks were tested. Compressive strengths of bricks with 5 wt% SSA (54.0–54.5 N/mm2) and 10 wt% SSA (50.2–51.0 N/mm2) were higher compared to the control bricks (50.4 N/mm2), while bricks with 20 wt% SSA (37.0–43.9) N/mm2) had noticeably lower compressive strenght. The coefficient of saturation was lower for bricks with SSA compared to control bricks. The initial absorption values were more pronounced for SSA fractions of 20 wt%

The methodology for defect quantification in concrete using IR thermography

This paper presents a procedure for detecting and quantifying defects in reinforced concrete structures by us-ing the method of active infrared thermography (IRT). For quantitative analysis, a methodology of thermal stimulation of concrete specimens and post-processing of the gathered data was developed. Presented methodology uses principles of step heating (SH) thermography, pulsed phase (PPT) thermography, principal component thermography (PCT) and correlation operators technique. A short descriptions of the post-processing methods used in the research is also provided in the paper. All three post-processing methods i.e. PPT, PCT and correlation operators technique have shown the pos-sibility to enhance the defect detection in concrete structures in comparison to raw thermograms. According to the data accessible to the authors, in presented research, correlation operators and PCT post-processing techniques are being suc-cessfully used for the first time for defect detection within concrete structures. The results of the research clearly show the possibility of using active IRT for the detection and assessment of defect depth (quantification) in reinforced concrete structures with the measurement error within 10%

Testing polymer modified concrete by non-destructive methods

Polimerom modificirani betoni često se rabe za sanaciju postojećih ab konstrukcija. U radu su prikazani rezultati laboratorijskog ispitivanja provedenog na 20 različitih sastava betonskih mješavina. Varirani su vodocementni omjeri, veličina zrna agregata i udio polimera u betonu. Utvrđena je ovisnost između mehaničkih svojstava betona ispitanih razornim ispitivanjem i nerazornim metodama i to određivanjem indeksa sklerometra i mjerenjem brzine prolaska ultrazvučnog impulsa.The polymer modified concrete is often used for the remedy of existing reinforced-concrete structures. Results of laboratory testing conducted on 20 different concrete mix compositions are presented in the paper. The water-cement ratio, aggregate grain size, and polymer content in concrete, were all varied in the course of the testing. The dependence between mechanical properties of concrete tested by destructive testing and that tested by non-destructive methods was determined, and this by defining the sclerometer index and by measuring velocity of ultrasound impulse