Visnyk LNAU: Architecture and Farm Building 2018 №19: 90-93
RESEARCH OF RAPID HARDENING CONCRETES, MODIFIED BY COMPLEX NANOADMIXTURE
Marushchak U., Candidate of Engineering Science
Sydor N., graduate student
National University "Lviv Polytechnic
Mazurak O., Candidate of Engineering Science
Mazurak R., graduate student
Lviv National Agrarian University
AnnotationIt is shown that one of the innovative ways of Rapid-hardening concrete obtaining is the use of nanotechnological techniques for the modifying of their structure. It is established that the introduction of a complex nanomodifier on the basis of polycarboxylate superplasticizer and an innovative hardening accelerator based calcium silicate hydrate colloidal particles ensures the high flowability and stability of fresh concretes. Flowability of nanomodified fresh concrete measured by slump test is 210 mm with the providing of a water-reducing effect W/C = 42,6-49,1%. The stability indicators (water and mortar liberation) of concrete mixtures, modified by complex nanoadmixture, are improved compared to control concrete mixture. The concretes nanomodified by calcium silicate hydrate colloidal particles and polycarboxylate superplasticizer characterize by significant acceleration of the early strength kinetics. It is established that nanomodified concrete is characterized by high early strength (specific strength (fcm2/fcm28 = 0,63-0,72) and high strength after 28 days (85-92 MPa). The enhanced performance of Rapid hardening concretes is provided by fill up the empty space inside cementitious matrix, seeding effect whereby the C-S-H additive provides new nucleation sites within the pore space between the cement particles, high water reducing effect combined with an efficient dispersion effect of polycarboxylates. Designed nanomodified concretes are Rapid hardening high strength ones. The use of a complex nanomodifier increases the efficiency of using Portland cement in concrete (specific consumption of Portland cement is 4,1-4,8 kg/MPa).
rapid hardening concrete, complex nanomodifier, polycarboxylate superplasticizer, hardening accelerator, flowability, early strength
- Czarnecki L., Kurdowski W. Trends determining the future of concrete. Days of Concrete. Materials of International conference, 2006. Wisła. S. 3 18.
- Plank J. Concrete Admixtures – Where Are We Now and What Can We Expect in the Future? 19 Internationale Baustofftagung, 2015. Weimar. Band 2. Р. 11–17.
- Ashani H. R., Parikh S. P., Markna J. H. Role of Nanotechnology in Concrete a Cement Based Material: A Critical Review on Mechanical Properties and Environmental Impact. International Journal of Nanoscience and Nanoengineering. 2015. № 2(5). Р. 32-35.
- Falikman V. Nanomaterials and nanotechnologies in modern concretes. Industrial and civil construction. 2013. No. 1. P. 31-34.
- Sheinich L. A., Pushkareva E. K. Processes of structure self-organization of building composites: monograph / Kyiv: Gamma-print, 2009. 153 p.
- Hajok D. When it is important quality and speed of hardening. Poland cement. Construction, technologies, architecture. 2011. No. 3 (55). P. 42–43.
- Effectiveness of polycarboxylate superplasticizers in ultra-high strength con-crete / Plank J. [et al.] Journal of Advanced Concrete Technology, 2009. № 1. Р. 5-12.
- Research of nanomodified Portland cement compositions with high early age strength / U. Маrushchak, M. Sanytsky, T. Mazurak, Yu. Olevych // Eastern-European Journal of Enterprise Technologies, 2016. № 6/6. P. 50-57.
- Nanomodified Portland cement compositions with alkaline activation / U. Marushchak, M. Sanytsky, T. Mazurak, Yu. Olevych // Budownictwo o zopty-malizovanym potenciale energetycznym, 2016. № 2(18). Р. 61–66.