Wyniki wyszukiwania - BazTech

1

Effect of curing regimes on the mechanical and fresh properties of steel fiber-reinforced concrete

Öztürk Oguzhan, Yenidünya Eren, Keskin Ülkü Sultan

Architecture Civil Engineering Environment

|

2021

|

Vol. 14, no. 1

69--82

EN

Properties of concrete are affected by its fabrication process such as preparation, mixing, placing, finishing and curing. Since curing process is the ultimate stage of the fresh state of concrete before it is put into service, it is of great significance that is needed to be strictly handled. In the present study, steel fiber reinforced concrete was investigated in terms of different curing regimes including precast technology and comparative analysis was performed. To this end, beams and cubes specimens were fabricated and cured under steam process to represent the applications of precast concrete industry. Findings were compared with the other types of curing regimes. Mechanical behaviors of specimens were evaluated along with their strength development and workability in the presence of steel fiber. Results indicated that adequate workability and mechanical properties were obtained for steam-cured specimens compared to other specimens produced with different curing regimes. However, production parameters such as mixture proportion and fiber dosage were more pronounced for low-strength concrete specimens compared to high strength steam cured concrete specimens.

2

Analysis of fees for connecting the infrastructure of generally accessible charging stations to networks with rated voltage not higher than 1 kV

Ślęzak Anna

Architecture Civil Engineering Environment

|

2021

|

Vol. 14, no. 1

107--114

EN

On 22 February 2018, the Act on electromobility and alternative fuels came into force (Journal of Laws of 2018, item 317). This legal Act sets out the rules for the development and operation of infrastructure for the use of alternative fuels, which is closely related to the development of electromobility. The Act (2011/C81E/17) regulates and defines, among others obligations in the scope of technical requirements for the construction of a charging station and their minimum number in municipalities. This Act was introduced in order to develop electromobility, which in turn is to contribute to the reduction of CO2 emissions [1]. The aim of the paper is to show the relationship between the geographical location of the connection of road charging infrastructure in our country, and the costs of its connection to the low voltage network, understood as the costs of the connection fee, which are paid to the Distribution System Operators. The costs of the connection fee in the case of power supply from low voltage lines cover the actual connection costs of generally available charging stations, i.e. the connection costs, i.e. the network section used to connect the devices or installations or the network of the entity with the connection capacity required by it, with the remaining part of the Distribution System Operators network. The Distribution System Operator also covers the costs of the measurement and settlement system. In addition, the paper indicates the preferential treatment of connecting charging stations, which are defined as reduced costs of connecting them in relation to other objects.

3

Wpływ warunków autoklawizacji na właściwości tworzyw krzemianowych

Gębarowski P., Łaskawiec K., Skorniewska M.

Prace Instytutu Ceramiki i Materiałów Budowlanych

|

2015

|

R. 8, nr 20

23--33

PL

W artykule omówiono produkty hydratacji powstające w betonie komórkowym przy różnym prowadzeniu procesu autoklawizacji. Przedstawiono również badania, realizowane przez autorów, zależności wytrzymałości na ściskanie od ciśnienia maksymalnego nasyconej pary wodnej podczas autoklawizacji, wytrzymałości na ściskanie od czasu trwania fazy III dla tych samych ciśnień, składu fazowego od ciśnienia maksymalnego nasyconej pary wodnej podczas autoklawizacji oraz wytrzymałości na ściskanie od składu fazowego.

EN

The article discusses the hydration products formed in autoclaved aerated concrete under different autoclaving process conduct. It also presents the research conducted by authors, on dependency of the compressive strength on the maximum pressure saturated steam during autoclaving, the compressive strength of the duration of the third autoclaving phase for the same pressure values, the phase composition of the maximum pressure of saturated steam during the autoclaving and the strength compression of the phase composition.

4

Sporządzanie mieszanki betonowej w wysokich temperaturach: urabialność, wytrzymałość i trwałość

Frigione M., Mairo N.

Cement Wapno Beton

|

2015

|

R. 20/82, nr 2

115--129

PL

Zmniejszenie wytrzymałości po dłuższym okresie, a nawet pogorszenie trwałości betonu może nastąpić w przypadku poddania go obróbce cieplnej. Jako prawdopodobny powód podaje się, między innymi, powstawanie gradientów temperatury w betonie, w trakcie obróbki cieplnej. W celu wyeliminowania naprężeń cieplnych zaproponowano następujący tok postępowania w tej pracy: składniki mieszanki betonowej ogrzewa się do 80°C, a próbki formuje się w gorących formach i natychmiast poddaje obróbce parą w 80°C w ciągu 4 godzin. Następnie, po ochłodzeniu przechowuje się je w powietrzu w temperaturze 20°C i W. W. > 95% aż do czasu pomiarów. Dla porównania, w przypadku drugiego betonu składniki mieszano w 20°C, a próbki po związaniu betonu poddawano obróbce parą w 80°C, stosując klasyczną technologię. Trzeci beton przygotowano mieszając składniki w 20°C oraz przechowując beton w powietrzu, w temperaturze 20°C i W.W. > 95%. Wszystkie betony uzyskano równolegle z cementu portlandzkiego i hutniczego. Stwierdzono, że zaproponowana technologia, polegająca na podgrzewaniu składników mieszanki i formowaniu próbek w 80°C oraz ich obróbce parą w tej temperaturze, jest korzystna dla betonu z cementu hutniczego, tak w odniesieniu do wczesnej wytrzymałości jak i po dłuższym twardnieniu oraz w odporności na korozję siarczanową.

EN

Loss of durability and strength after longer time of hardening can occur when concrete is heat treated. An explanation is the presence of fine cracks caused, among other, by the temperature gradient in concrete, during thermal treatment. In order to avoid thermal stresses, the following treatment was proposed in the present study: concrete mix ingredients were heated at 80°C and test specimens, were cast in the hot moulds and immediately steam treated at 80°C tor 4 hours. They were, then, cooled and cured at 20°C and R.H. > 95% up to testing age. For comparison second concrete components were mixed at 20°C. Test specimens, after concrete set, were steam treated at 80°C, in a classic manner. The third concrete was mixed at 20°C and cured in air at 20°C and R.H. > 95%. All concretes were made parallel of Portland cement and slag cement. It was found that the effect of the proposed treatment (heating the concrete mix ingredients) on the resistant to sulphate attack and on early strength as well as after longer hardening was very favourable for slag cement concrete.