The possibility of adjusting concrete mixtures' fluidity by means of superplasticizer SNF

• Autorzy: Kapelko A.

Warianty tytułu

PL

Możliwość regulacji ciepłości mieszanek betonowych przez zastosowanie superplastyfikatora SNF

• Języki publikacji: EN

Abstrakty

EN

One of the disadvantages of superplasticizers' use is that the concrete mixture modified by this kind of admixtures loses its workability very quickly. This paper summarizes the current state-of-the-art in the field concerning the effects of superplasticizer's SNF addition to the material cement, in particular its mechanisms and methods of addition. The paper presents the author's experimental investigation on the variation of concrete mixtures' fluidity in the function of time and the change of concrete's technical properties as a result of superplasticizer's SNF addition. The experiments were carried out using two types of aggregates: mineral and granite, and two kinds of Portland cement: CEM I 32,5R and CEM I 42,5R. The tests shown that SNF has a significant influence on material cement's fluidity. The superplasticizer added three times in the total amount of 2,0% allows to regulate the fluidity of concrete mixtures and to keep the consistency at the fluid and half-fluid level. The faster fluidity loss of concrete mixtures, both control and modified by SNF, is taking place when more cement is added and is influenced by the following factors: fineness, cement's mineral composition and aggregate type. The author proposes to use a parameter Sm (average slump) as the estimation of the SNF's addition efficiency - retention of the high workability of concrete mixtures in the function of time. The modification of concrete mixtures by the superplasticizer's use, introduced to reduce the amount of water (water/cement ratio reduction), increases the compressive strength from 1 to 3 classes in comparison to compressive strength of control concrete. This modification increases reduces concrete's water absorption. Moreover, superplasticizer's addition increases the brittleness of concrete.

PL

Jedną z niedogodności stosowania superplastyfiaktorów jest szybka utrata urabialności mieszanek betonowych modyfikowanych tym rodzajem domieszek. Dokonano podsumowania stanu wiedzy w zakresie efektów związanych z mechanizmem i sposobem wprowadzenia superplastyfikatora SNF do tworzyw cementowych. W pracy przedstawiono badania własne autora obejmujące zachowanie się ciekłości mieszanek betonowych w funkcji czasu oraz zmianę właściwości technicznych betonu przy 3-krotnym dozowaniu superplastyfikatora typu SNF. Eksperymenty przeprowadzono w dwóch rodzajach kruszyw: mineralnym i granitowym oraz cementach portlandzkich CEM I 32,5 R i CEM I 42,5 R. Przeprowadzone badania wskazały na istotny wpływ SNF na uplastycznienie tworzyw cementowych. Dodanie superplastyfikatora w trzech porcjach o łącznej ilości 2,0 % pozwala na regulowanie ciekłości mieszanek betonowych i utrzymywanie na poziomie konsystencji ciekłej i półciekłej. Szybsza utrata ciekłości mieszanek betonowych kontrolnych i modyfikowanych SNF występuje przy większej zawartości cementu i jest związana z miałkością, składem mineralogicznym cementu oraz rodzajem kruszyw. Autor proponuje wykorzystać parametr Sm (średni opad stożka) do oceny efektywności dodawania superplastyfikatora SNF i zachowania wysokiej urabialności mieszanek betonowych w funkcji czasu. Modyfikacja mieszanek betonowych superplastyfikatorem w celu obniżenia ilości wody (zmniejszenie w/c) podwyższa wytrzymałość na ściskanie od 1 do 3 klas, w porównaniu z wytrzymałością betonów kontrolnych. Ta modyfikacja istotnie obniża nasiąkliwość betonów. Dodanie superplastyfikatora zwiększa kruchość betonów.

Słowa kluczowe

EN

concrete mixtures; superplasticizer SNF; fluidity; concrete properties

PL

superplastyfikatory; mieszanka betonowa

• Wydawca: Springer ; Wrocław University of Science and Technology
• Czasopismo: Archives of Civil and Mechanical Engineering
• Rocznik: 2006
• Tom: Vol. 6, no 3
• Strony: 37--53
• Opis fizyczny: Bibliogr. 36 poz., tab., wykr.

Twórcy

autor

Kapelko A.

• Wrocław University of Technology, Institute of Building Engineering, Pl. Grunwaldzki, 50-377 Wrocław

Bibliografia

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