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Management of the Special Processes – An Experimental Study of Bent Reinforced Concrete Beams

Michałowska-Maziejuk Dorota, Klimecka-Tatar Dorota, Ingaldi Manuela, Kaczmarska Bożena, Czajkowska Agnieszka

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 2

248--265

EN

The article presents an analysis of the results obtained from the testing of simply supported reinforced concrete beams subjected to four-point bending. The beams, with two levels of steel reinforcement (ρs1=1.26%, ρs2=0.71%), and dimensions of 0.12x0.30x3.30m, were subjected to loading involving a sudden increase in force with multiple unloading cycles to zero. The study included comparative analysis of deflection results obtained from experimental tests (calculated based on the curvature of the element and readings from measurement devices) with deflection values obtained through calculations based on two selected standards. Real values of ultimate bending moments were also compared with theoretical values. Additionally, compressive strength tests were conducted on eight cubic concrete specimens with a side length of b=150mm, obtained for each concrete batch. They constitute accompanying studies. Using standard procedures, strength and statistical parameters were estimated and evaluated, taking into account the assessment of the quality of the concrete production used to make the reinforced concrete beams. Ensuring compliance with the process of producing full-sized reinforced concrete beams with existing standard procedures, as well as attention to the quality of concrete production, contributed to achieving satisfactory results in the experimental tests. Knowledge about the impact of loading on mechanical properties enables effective management of factors shaping quality to obtain a construction material with optimal parameters.

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Economical aspects concerning quality control of concrete

Skrzypczak Izabela, Słowik Marta

Budownictwo i Architektura

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2019

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Vol. 18, nr 1

49--56

EN

The paper deals with economical aspects concerning the quality control of concrete. About 70% of total concrete production is connected with the structural concrete, the subject of quality control and/or conformity. When checking the conformity criteria for a compressive strength of concrete for a small number of samples, qualification errors do not affect the formation of costs associated with losses on external deficiencies. In order to avoid costs related to qualification errors and losses on external deficiencies, the number of samples should be set larger than the minimum (included in contract’s clauses). Furthermore, the designer recommendations should be indicated in the specification. In the paper the costs concerning quality control for concrete have been analyzed.

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Properties of coarse mineral aggregates against properties of concrete

Piasta W., Budzyński W., Góra J.

Architecture Civil Engineering Environment

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2018

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Vol. 11, no. 3

97--105

EN

The paper concerns the effect of coarse aggregate type on the strength and strain properties of concrete under instantaneous loading. The studies deal with properties of the crushed aggregates and their effect on the basic mechanical properties and instant deformability of concretes in comparison to gravel concrete. The paper presents test results of mineral composition, crushing strength, absorption by weight, content of irregular grains and mineral dust as well as bulk and specific density of the 5 coarse aggregates: basalt, granite, dolomite, quartzite and natural aggregate (gravel) derived from the Polish rock beds. Strength and strain properties of concretes under compressive instantaneous loading were analyzed. The analysis showed that strength properties and modules of elasticity of tested concretes are proportional to crushing strength of aggregates. Based on the test results of strains it was concluded that the effect of coarse aggregate type on the modulus of elasticity and the limit strain is more significant than that of concrete strength.

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Zasadność przyjmowania normowych wartości fci oraz fcm przy szacowaniu klasy betonu dla małej próby

Jasiczak J., Kanoniczak M.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

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2017

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z. 64, nr 3/I

203--212

PL

Przedmiotem analizy są normowe wartości fci oraz fcm przy szacowaniu klasy betonu dla małej próby. W minionych latach zmieniło się podejście do szacowania tych wartości i istnieje uzasadniona obawa o zakwalifikowanie betonu do niższej klasy mimo, że ciąg wartości z tzw. małej próby o tym nie świadczy. Ponieważ ostatecznie klasę betonu określa się ex post po wykonaniu konstrukcji konsekwencje dla wykonawcy, który nie dotrzymał projektowanej klasy betonu, są daleko idące. W artykule przeanalizowano dwa ciągi wyników badań wytrzymałości betonu na ściskanie uzyskane podczas budowy obwodnicy autostradowej miasta Poznania. W wyniku obliczeń zaproponowano konieczne wartości dwóch wymienionych parametrów by spełnić warunek bezpieczeństwa konstrukcji.

EN

The subject of the analysis are normative values fci and fcm in the estimation of concrete class for a small sample. In the past years, the approach to estimating these values has changed and there is a well-grounded concern that concrete will be classified as lower class concrete, despite the fact that the value chain from the so called small sample does not justify it. Because ultimately concrete class is defined ex post after the erection of a structure, there will be far reaching consequences for the contractor who has not met the designed class of concrete. The paper analyses two series of test results for the compressive strength of concrete obtained during the construction of motorway ring road of the city of Poznan. After making calculations, necessary values of the two above mentioned parameters were proposed to meet the safety requirements of the structure.

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Stochastic identity of test result series of the compressive strength of concrete in industrial production conditions

Jasiczak J., Kanoniczak M., Smaga Ł.

Archives of Civil and Mechanical Engineering

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2015

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Vol. 15, no. 2

584--592

EN

The article provides the scientific basis of interval identity of the compressive strength of concrete, as well as includes calculation examples concerning the application of concrete apron paving with the use of concrete pavers. It was found that in order to control the compressive strength of concrete formed in a continuous, cyclically repetitive mode, standard statistical assessment of concrete strength is not sufficient since, in the case of deviations in the studied characteristics of concrete from the project assumptions, it is not possible either to implement corrections in the concrete manufacturing process or to change the location of the concrete structure with decreased strength parameters. Due to this, the analysis of the qualitative and quantitative production of concrete mix and its application at the construction site required the use of appropriate calculation procedures, allowing to extract subsets of the results of the compressive strength of concrete projecting technological disturbances and assign to them time intervals, in which the disturbances occurred. This is a completely different approach to the issue of determining the compressive strength properties of tested concrete volume than presented in the construction standards. For this reason, to present the real picture of the compressive strength variability, the division of tests results was made by grouping the data belonging to one population with probabilistically stabilized strength parameters forming a family of concrete. In order to do this it was necessary to use appropriate calculation procedures based on verification of statistical hypotheses. The authors proposed three independent methods based on statistical tests: Pearson χ2 test, t-Student's test and Mann–Whitney's U test. The results series were divided into families of concretes and were given different sensitivity of each method. However, the breakdown of the whole series achieved by the three methods is comparable and occurred in the areas of high variability of strength.

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Normowe pojęcie rodzina betonów na przykładzie ciągłej produkcji płyt Spiroll

Jasiczak J., Kanoniczak M., Smaga Ł

Budownictwo i Architektura

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2014

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Vol. 13, nr 2

99--108

PL

W artykule przedstawiono podział na rodziny betonów ciągu wyników badan wytrzymałości betonu na ściskanie przy ciągłej produkcji mieszanki betonowej na potrzeby wytwarzania prefabrykowanych płyt stropowych w technologii Spiroll. W oparciu o procedurę obliczeniową, polegającą na weryfikacji założonych hipotez statystycznych, dokonano rozdziału zbioru wyników reprezentującego wytrzymałość po 1 oraz po 28 dniach dojrzewania. Uzyskano rodziny betonów reprezentujące statystyczną niezmienność parametrów wytrzymałościowych betonu wyprodukowanego w określonym przedziale czasu.

EN

The article presents the division of test results series for the compressive strength of concrete into concrete families for the continuous production of concrete mix used for the manufacture of precast concrete slabs in Spiroll technology. On the basis of a calculation procedure involving the verification of assumed statistical hypotheses, the division of a set of concrete strength results achieved after 1 and 28 days of curing was made. Concrete families were obtained representing the statistical invariability of strength parameters for the concrete manufactured in a defined period of time.