C-S-H i właściwości betonu

• Autorzy: Nonat A.

Warianty tytułu

EN

C-S-H and concrete properties

• Języki publikacji: PL

Abstrakty

PL

C-S-H jest najważniejsza fazą w betonie, która decyduje o jego właściwościach. C-S-H w zaczynie cementowym tworzy więźbę nanocząstek, a oddziaływania przyciągające pomiędzy nimi są wynikiem sił Van der Waalsa oraz wiązań jonowych, spowodowanych przez podwójne warstwy elektryczne. Zaczyn cementowy wykazuje mały zakres lepkosprężysty, w którym zachowuje się jak ciało stałe. Jest on ograniczony odkształceniem krytycznym yc, po przekroczeniu którego materiał ulega zniszczeniu. Powstawanie C-S-H rozpoczyna się od powolnej trakcji alitu z wodą, co odpowiada okresowi zarodkowania. W tym okresie należy zakończyć prace betonowania. Następnie zachodzi szybka hydratacja, która obejmuje 15% alitu i zbiega się z wiązaniem betonu i w końcu szybkość hydratacji maleje w sposób ciągły wiążąc się z twardnieniem betonu. Obok oddziaływań między cząstkami ważną właściwością żelu C-S-H jest jego porowatość. Żel C-S-H stanowi upakowanie nanocząstek i stąd związane z nim pory mają także takie wymiary. W przypadku niskiego w/c C-S-H praktycznie krystalizuje jedynie na powierzchni ziarm alitu w formach o najgęstszym upakowaniu i porowatość żelu maleje. Wpływa to na właściwości betonu zwiększając jego wytrzymałość.

EN

C-S-H is the most important phase of concrete which is governing the majority of its properties. C-S-H in hydrated cement paste forms a network of nanoparticles and the interaction between them is caused by the Van der Waals as well as by ionic forces, linked with ionic double layer. Cement paste has a short linear viscoelastic domain in which it behaves as a solid. In terms of deformation this linear viscoelastic domain is limited by the critical strain yc beyond which the structure is destroyed. The C-S-H formation starts with low evolution of alite which corresponds to the nucleation period. In this period concrete should be put in place. Then a strong acceleration of hydration is leading to hydration of 15% of alite and it is the setting of concrete and finally the rate of hydration continuously decreases upon the long period of time, during which concrete hardens. Besides the particles interactions the other important property of C-S-H is its porosity. C-S-H gel is a packing of nano particles and then the size of the pores is at the same scale. In the case of low w/c ratio C-S-H practically only precipitates onto the alite surfaces in the densest packing and the nano-porosity of the gel is also reduced. It also influences the properties of concrete increasing its strength.

Słowa kluczowe

PL

C-S-H; beton; żel C-S-H; nanocząsteczka C-S-H; reologia żelu; kinetyka hydratacji; właściwości zaczynu; powstawanie

EN

concrete; C-S-H gel; C-S-H nanoparticle; gel rheology; hydration kinetics; paste properties; C-S-H formation

• Wydawca: Fundacja Cement, Wapno, Beton
• Czasopismo: Cement Wapno Beton
• Rocznik: 2010
• Tom: R. 15/77, nr 6
• Strony: 315--326
• Opis fizyczny: Bibliogr. 40 poz., il.

Twórcy

autor

Nonat A.

• Universite de Bourgogne, Laboratoire de Recherches sur la Reactivite des Solides UMR CNRS Dijon, France

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