Paulava I., Belamesava K.
https://doi.org/10.35579/2076-6033-2020-12-11
ABSTRACT
The use of expansive additives based on sulpho-alumina compositions to modify cement systems not only compensates for shrinkage, but in some cases allows for expansion and self-stressing. Today the market is replete with expansive additives based on sulfoaluminate compositions, which are both artificially synthesized materials and mechanical mixtures based on metakaolin, high alumina cement and gypsum (type “M” cement). The choice of a particular type of additive, as well as its dosage, is determined depending on the design requirements for concrete: shrinkage compensation, achieving the required values of linear expansion and self-stress, etc. Each individual case of this type of concrete admixture requires additional research in concrete under the existing norms, which take 14 to 28 days. In some cases, such a test period is too long and requires accelerated methods to determine efficiency.
This article presents research into the possibility of using the pozzolana activity of expansive additive as one of the performance criteria. It has been substantiated that pozzolanic activity can be determined using the accelerated Chapelle test, which will allow a short period of time (1-2 days) to determine the choice of a particular expansive additive.
Expansive complexes based on mechanical mixtures of alumina cement and gypsum, metakaolin and gypsum, also with the addition of lime, have been considered as additions under study.
The range of pozzolanic activity values required to produce cements with compensated shrinkage or self-stress of 1 MPa is proposed.
Keywords: sulfo-aluminate type expansive additive, mechanical mix, Pozzolanic activity, Chapelle test, ettringite, self-stressing.
For citation: Paulava I., Belamesava K. Ekspress-otsenka putsolanovoy aktivnosti pri opredelenii effektivnosti rasshiryayushchikhsya dobavok sulfoalyuminatnogo tipa [Rapid assessment of pozzolanic activity in determining the effectiveness of expansive sulfo-aluminate type additives]. In: Contemporary Issues of Concrete and Reinforced Concrete: Collected Research Papers. Minsk. Institute BelNIIS. Vol. 12. 2020. pp. 173-184. https://doi.org/10.35579/2076-6033-2020-12-11 (in Russian).
References:
- Michailov V. V., Litver S. L. Rasshiryayushchiysya i napriagayuschiy tsementy i samonapriazgennye zhelezobetonnye konstruktsii [Expansive and self-stressed cements and ferroconcrete structures]. Moscow: Stroyizdat, 1974. 312 p. (rus)
- Damidot D., Glasser F. P. (1993). Thermodynamic Investigation of the CaO-Al2O3-CaSO4-K2O-H2O System at 25 °C. Cement and Concrete Research 1993. No.23 (5). pp. 1195-1204.
- D’Ans J., Eick H. (1953). Das System CaO-Al2O3-H2O bei 20°C und das Erhärten der Tonerdezemente. Zement – Kalk – Gips. 1953. 6 s. (de)
- Bollmann K. Ettringitbildung in nicht wärmebehandelten Betonen. DISS. zur Erlangung des akademischen Grades Dokt.-Ing. 31. Mai 2000. (de)
- Pavlova I. P., Kalenyuk T. V., Belomesova K. Yu. Vestnik of Brest State Technical University. Civil Engineering and Architecture. 2016. No.1. pp. 123-127. (rus)
- NF P 18-513. Metakaolin. Pozzolanic addition for concrete. Definitions, specifications and conformity criteria. Association Française de Normalisation, La Plaine Saint-Denis, 2010.
- Tsement napryagayushchiy. Tekhnicheskie usloviya [Self-stressing cement. Technical conditions] : STB 1335-2002. Introduced: 01.01.03. Minsk: Minstroyarkhitektury, 2002. 11 p. (rus)
ISSN 2664-567X (Online)
ISSN 2076-6033 (Print)
ISSN 2076-6033 (Print)