Primjena nerazornih ispitivanja u građevinarstvu

Testing properties of materials and structures using non-destructive testing today it is an everyday necessity in modern the construction industry. Mostcommonly used methods of non-destructive testing of reinforced concrete structures are presented in the paper. Some of these methods are: visual inspection, Schmidt hammer, ultrasound, rebar detection system, galvanostatic pulse measurements technique and air permeability. For each method are given the main features and the possibility to use a certain method to determine the specific properties of materials and structures

COMPARISON OF THE MEASUREMENT RESULTS OF LARGE SCALE FAÇADE FIRE TESTS USING IR THERMOGRAPHY AND THERMOCOUPLES

In this paper the effectiveness of using a high temperature range, microbolometer infrared (IR) camera for the study of large scale façade fire tests will be investigated. The long-wave microbolometer camera has the ability to measure temperatures but the smoke and the flames itself influence the measurement results. This is due to the absorption of the infrared radiation by both smoke and flames while at the same time they emit radiation due to their high temperatures. The purpose of this study is to demonstrate the usefulness of an IR camera when studying large scale façade fire tests. The problems are difficulties in verification how representative measurements are and consequently it is not clear and sure if conditions for reliable measurements are really fulfilled. The measurement results acquired by the IR camera will be compared to the measurement results acquired by the thermocouples 1 mm, 3 mm in diameter and plate thermometers

Detecting Defects in Reinforced Concrete Using the Method of Infrared Thermography

This paper presents a method for detecting defects in reinforced concrete structures by using the method of active infrared (IR) thermography. Non-destructive testing using infrared (IR) thermography consists of thermal stimulation of the object of interest and monitoring of the surface temperature variation during the transient cooling or heating process. The paper includes short descriptions of the post-processing methods used for detection of defects, together with the results of the research conducted on reinforced concrete samples. It was concluded that the method of IR thermography can be used for the detection and quantification of defects in reinforced concrete structures

Preliminary monitoring results of ventilated heavyweight building envelope from recycled aggregate

Potential of recycled aggregate concrete (RAC) has already been acknowledged by many researchers, but the focus was primarily on its mechanical and durability properties at material level. If the focus is shifted to element and whole building level, then the question can be raised; how building envelopes made from RAC behave when exposed to real environment? The present paper describes an experimental set up to monitor hygrothermal behaviour of one three-storey family house built with prefabricated ventilated sandwich wall panels made from recycled concrete and recycled brick aggregate. This type of building envelope can be classified as a heavyweight envelope. In ground-floor flat a wall in the living room facing south is analysed in terms of internal temperature evolution and humidity distribution. Conditions of indoor and outdoor environment were monitored as well. Time lag and decrement of temperature extremes were observed and these benefits can be attributed to the presence of thermal mass. Ventilation of air in cavity ensured acceptable humidity level in all characteristic layers of wall panel. Summer overheating occurred due to insufficiently shaded large transparent openings. Further step is validation of numerical model and assessing the suitability of presented envelope type to different climates. This paper indicates the great potential of RAC application in energy efficient and moisture safe building envelope design

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%

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

FROM ENERGY STRATEGIES THROUGH ENERGY RETROFITTING TO FIRE SAFETY OF BUILDINGS

European policy is reflected in a 10-year strategy called 2020 proposed to revive European economy and it is deeply interconnected with Energy Performance of Building Directive and its Recast. Republic of Croatia, as an EU member state, is aligning its national energy policy with European policy. By boosting energy retrofitting of existing and constructing energy efficient new buildings, thermally enhanced building envelope represents significantly increased fire load on building, thus fire safety becomes inevitable segment of energy efficiency of buildings. Croatia has no national test method for determining fire performance of building façade, while harmonized EN test method is currently being developed. In this paper an overview and comparison of BS 8414-1:2002 and DIN Entwurf 4102-20 standards will be presented, since they are proposed as a basis for future harmonized EN test method. For similar configuration of test specimens, BS 8414-1:2002 defines significantly more severe heat exposure compared to DIN Entwurf 4102-20

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

Properties of self-compacting concrete with high fly-ash content

Opisuje se samozbijajući beton kao nova vrsta betona koja ne zahtijeva zbijanje pri ugradnji. U radu su prikazana eksperimentalna ispitivanja svojstava samozbijajućeg betona s dodatkom letećeg pepela (30- 50 % mase cementa). Utvrđeno je da povećanje količine letećeg pepela utječe na poboljšanje svojstava trajnosti i na smanjenje tlačne čvrstoće. Analizom rezultata pokazano je da, u slučaju istog vodovezivnog omjera, samozbijajući beton ima bolja svojstva trajnosti od običnog betona.The new self-compacting concrete, which requires no compaction during placement, is described. The experimental study of properties of the self-compacting concrete to which the fly ash is added (30-50 percent of the cement mass) is presented. It was determined that the increase in the fly-ash content improves durability and reduces compressive strength. The analysis of results revealed that, in case of similar water/cement ratios, the self-compacting concrete has better durability properties when compared to ordinary concrete

Properties of self-compacting concrete with high fly-ash content

Opisuje se samozbijajući beton kao nova vrsta betona koja ne zahtijeva zbijanje pri ugradnji. U radu su prikazana eksperimentalna ispitivanja svojstava samozbijajućeg betona s dodatkom letećeg pepela (30- 50 % mase cementa). Utvrđeno je da povećanje količine letećeg pepela utječe na poboljšanje svojstava trajnosti i na smanjenje tlačne čvrstoće. Analizom rezultata pokazano je da, u slučaju istog vodovezivnog omjera, samozbijajući beton ima bolja svojstva trajnosti od običnog betona.The new self-compacting concrete, which requires no compaction during placement, is described. The experimental study of properties of the self-compacting concrete to which the fly ash is added (30-50 percent of the cement mass) is presented. It was determined that the increase in the fly-ash content improves durability and reduces compressive strength. The analysis of results revealed that, in case of similar water/cement ratios, the self-compacting concrete has better durability properties when compared to ordinary concrete