Mechanical and radiation attenuation properties of conventional and heavy concrete with diverse aggregate and water/cement ratios

Ovim istraživanjem predstavljaju se rezultati sveobuhvatnog laboratorijskog rada kojemu je cilj ispitati mehanička svojstva i svojstva smanjenja zračenja teških betona u kojima se kao agregat koristio pirit, krom i magnetit te betona normalne težine koji su se proizveli s tri različita vodocementna omjera (v/c = 0,4/0,5/0,6). U laboratoriju su provedena ispitivanja tlačne čvrstoće, brzine prolaska ultrazvuka, eksperimentalni modul elastičnosti te koeficijenta prigušenja mase tih betona. Na temelju provedenih ispitivanja utvrđeno je da betoni normalne težine i teški betoni imaju slično ponašanje u smislu tlačne čvrstoće i modula elastičnosti. U slučaju teških betona (njihovi v/c omjeri povećani su uslijed konstantne količine vode te smanjene količine cementa), gustoća se povećava zbog povećanja količine agregata veće gustoće u odnosu na cement u sastavu betona. To je razlog zašto teški betoni koji su proizvedeni s većim v/c omjerom te koji su manje čvrstoće mogu apsorbirati više rendgenskih zraka. Koeficijenti prigušenja mase konvergiraju pri visokim energetskim razinama kod teških i normalnih betona različitih gustoća.This paper presents the results of comprehensive laboratory work conducted for investigating the mechanical and radiation attenuation characteristics of heavyweight concrete produced with pyrite, chromium, and magnetite aggregates and normal weight concretes produced with three different water/ cement (w/c) ratios. Various experiments were conducted to determine the compressive strengths, ultrasound transmission velocities, experimental elasticity modules, and mass attenuation coefficients of these concretes. Heavy and normal weight concretes exhibited similar behaviour in terms of compressive strength and elasticity modules. In heavyweight concretes, with increased w/c ratios (by keeping the amount of water constant and decreasing the amount of cement), the corresponding density increased due to the increase in the amount of high-density aggregates rather than cement in the composition of concrete. Thus, heavyweight concretes produced with a high w/c ratio and low strength can absorb more X-rays. Mass attenuation coefficients converge in heavy and normal weight concretes with different densities at high energy levels

Unlocking energy efficiency: Experimental investigation of bamboo fibre reinforced briquettes as sustainable solution with enhanced thermal resistance

Energy consumption data reveals that buildings account for 40 % of overall energy usage. Without urgent intervention, this figure is poised to escalate alongside population growth, exacerbating the dependence on fossil fuels for energy production. Addressing this pressing issue demands effective measures to curtail energy consumption in buildings, a realm where research on bamboo's thermal performance still needs to be improved. This study fills a critical gap by investigating the integration of bamboo fibre in the briquettes, known for their high heat transfer coefficient (U-value). Leveraging the innovative coheating test method, the research pioneers an unexplored avenue to evaluate thermal performance. This novel approach distinguishes the study as a unique and original endeavour in the field. The findings demonstrate significant thermal enhancements by substituting bamboo fibre: 2 %, 4 %, and 6 % bamboo additions yield U-values of 4.698 W/m2K, 3.94 W/m2K, and 2.77 W/m2K, respectively. Notably, the 6 % bamboo-reinforced briquette showcases a remarkable 49.9 % improvement in thermal resistance compared to conventional counterparts. This study marks a pioneering effort towards achieving energy efficiency through sustainable materials in designing low/zero carbon buildings. By showcasing the potential of bamboo as a thermal insulator, the research illuminates a promising path for future construction practices. Embracing such innovations is paramount in mitigating the environmental impact and securing a sustainable future

Transition coefficients between compressive strengths of samples with different shape and size in mass concrete and use of weight maturity method in dam construction

WOS: 000530736700001Mass concrete (MC) is widely used in dam concretes due to their large aggregate grain diameters, low cement dosage, and low hydration temperatures. Monitoring of the hydration temperature and compressive strength is an important consideration during the casting of MC in the field. the purpose of this study is to determine the relationship between the compressive strengths of cylindrical specimens with different maximum aggregate grain diameters (D-max) and different dimensions in MCs used in dam construction and to investigate the usability of the weighted maturity method in determining the compressive strength of dam MC. in this study, the compressive strength transition coefficient (fck o15 x 30/fck o25 x 50) of the cylindrical samples with different dimensions in MC was found to be 1.135. It was found that the weight maturity method can be used to estimate concrete strength in dam MC with low hydration temperature

Comparing the pozzolanic activity properties of obsidian to those of fly ash and blast furnace slag

WOS: 000427218500027The use of pozzolan in cement provides economic advantages and improves the physico-mechanical properties of cement. Fly ash and blast furnace slag are widely used in cement as pozzolanic materials. in this study, obsidian known as volcanic glass which crops out in the lkizdere (Rize) region of NE Turkey was investigated as a pozzolana in cement. Mainly the pozzolanic activity, chemical and physico-mechanical properties of the obsidian cement were compared to the properties of the fly ash and blast furnace slag cement. According to laboratory test results, obsidian was seen to provide more positive effects compared to the properties of fly ash cement. It was concluded that obsidian was equivalent to blast furnace slag as a pozzolan. As a result, the obsidian located in the lkizdere region could be used as a pozzolana in cement. (C) 2017 Elsevier Ltd. All rights reserved.Scientific and Technological Research Council of Turkey (TUBITAK) - TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [214M023]Authors would like to express their sincerest gratitude to the editor and reviewers. Thanks are due to the Academic Writing and Translation Office of RTE University for improving the language of the manuscript. the authors gratefully acknowledge the Scientific and Technological Research Council of Turkey (TUBITAK) - Turkey for funding this work through research project no: 214M023

Determination of the Pozzolanic Activities of Trachyte and Rhyolite and Comparison of the Test Methods Implemented

WOS: 000530823000001Natural pozzolanas should be evaluated in terms of sustainability as well as their contribution to concrete durability. Therefore, the use of such materials in the production of cement as well as concrete industry has been gaining importance recently. in this study, the pozzolanic activities of ground trachyte and rhyolite, known as volcanic tuffs, were investigated in accordance with TS 25 standard. Pozzolanic properties of such materials, along with their pozzolanic activity indices, are investigated comparatively by the Frattini method, strength activity index, X-ray diffraction and thermogravimetric analysis. the morphologies of ground trachyte and rhyolite were also studied using SEM analysis. Based on the results obtained, the mortar samples containing blast furnace slag (BFS), fly ash (FA), trachyte and rhyolite were met the acceptable pozzolanic activity index at the end of 28 days with values of 90, 87, 89, 87, respectively. on the other hand at the end of 90 days, while the mortar samples containing BFS, FA and trachyte were met the acceptable pozzolanic activity index, that of containing rhyolite did not meet the acceptable pozzolanic activity index, with values of 93, 85, 87, 80, respectively. the pozzolanic activity index of the rhyolite was found to be quite close to that of the FA; however, the trachyte had a pozzolanic activity index close to the BFS. Comparisons of the methods implemented in the analyses were also conducted. According to the statistical evaluation of the test methods, it has been found that the relationships obtained using the direct methods as well as the indirect methods independently are highly correlated. Overall, it can be concluded that the ground trachyte may be utilized as a pozzolanas in the cement industry; however, the ground rhyolite does not meet some limits prescribed by the related standard

Fire retardation, compressive strength and durability analysis of concrete reinforced with novel plasters: An experimental, computational and statistical research

Concrete is an essential component of the construction industry, valued for its high compressive strength (CS) and durability. However, when exposed to extreme conditions like fire without protective structural elements, its physical integrity deteriorates rapidly, leading to significant alterations in its mechanical properties. This research aims to provide a potential solution to this issue by assessing the fire resistance of various concrete samples, including unplastered (UNP), roughly plastered (RP), and those with contemporary insulation plaster (CIP) substitutions, at different thicknesses. These samples are subjected to varying temperatures and exposure times within an oven, followed by CS testing. These temperature levels and time intervals correspond to 300 °C, 450 °C, and 600 °C, with the time range is restricted to 60, 90, and 120-min, respectively. The results indicate that an increase in sample thickness correlates with a reduction in concrete degradation at high temperatures. Moreover, the findings reveal that after 120-min of exposure at 600 °C, UNP, RP, and CIP-reinforced samples achieve CSs of 27.435 MPa, 27.74 MPa, and 30.28 MPa, respectively. Notably, the 3 cm CIP-reinforced sample exhibits a CS exceeding 30 MPa under the most extreme conditions. The research incorporates regression and computational fluid dynamics (CFD) analyses to complement the experimental investigation. The regression analysis suggests that CIP-reinforced samples can withstand temperatures up to 600 °C for approximately 173-min, while the study implies that they could endure temperatures as high as 861 °C during a 120-min exposure