EFFECT OF HARDENING TIME ON DEFORMATION-STRENGTH INDICATORS OF CONCRETE FOR INJECTION WITH A TWO-STAGE EXPANSION DURING HARDENING IN WATER

Abstract. Objectives Concretes for injection with a two-stage expansion are a kind of selfstressing concrete obtained with the use of self-stressing cement.The aim of the work is to study the influence of the duration of aging on the porosity, strength and self-stress of concrete hardening in water, depending on the expansion value at the first stage. At the first stage, the compacted concrete mixture is expanded to ensure complete filling of the formwork space. At the second stage, the hardening concrete expands due to the formation of an increased amount of ettringite. This process is prolonged in time, with the amount of self-stress and strength dependant on the conditions of hardening. Methods  Experimental evaluation of self-stress, strength and porosity of concretes that are permanently hardened in water, under air-moist and air-dry conditions after different expansion at the first stage. The self-stress of cement stone is the result of superposition of two processes: the hardening of the structure due to hydration of silicates and its expansion as a result of hydration of calcium aluminates with the subsequent formation of ettringite. The magnitude of self-stress is determined by the ratio of these two processes. The self-stress of the cement stone changes in a manner similar to the change in its expansion. The stabilisation of expansion is accompanied by stabilisation of self-stress of cement stone. Results  The relationship of self-stress, strength and porosity of concrete for injection with a two-stage expansion on the duration and humidity conditions of hardening, taking into account the conditions of deformation limitation at the first stage, is revealed. Conclusion During prolonged hardening in an aqueous medium, self-stresses are reduced up to 25% with the exception of expansion at the first stage and up to 20% with an increase in volume up to 5% at the first stage. The increase in compressive strength is up to 28% relative to the 28-day period.

self-stressing concrete, injectable concrete, two-stage expansion, water aging, deformation-strength characteristics, hardening time, self-stressing cement, expansion deformations, self-stress, strength, porosity

1. Krasil'nikov K.G., Nikitina L.V., Skoblinskaya N.N. Fiziko-khimiya sobstvennykh deformatsii tsementnogo kamnya. M.: Stroiizdatzh 1980. 255 s. [Krasil'nikov K.G., Nikitina L.V., Skoblinskaya N.N. Physical chemistry of own deformations of cement stone. M.: Stroiizdatzh 1980. 255 p. (In Russ.)]

2. Budnikov P.P., Kravchenko I.V. Rasshiryayushchiesya tsementy. Trudy 5-go Mezhdunarodnogo simpoziuma po khimii tsementa. Tokio: Tsementnaya Assotsiatsiya Yaponii. 1968;4:319-335. [Budnikov P.P., Kravchenko I.V. Expanding cements. Proceedings of the 5th International Symposium on Chemistry of Cement. Tokyo: Cement Association of Japan. 1968;4:319-335. (In Russ.)]

3. Zvezdov A.I. Betony s kompensirovannoi usadkoi na napryagayushchem tsemente. Materialy XXII Mezhdunarodnoi konferentsii molodykh uchenykh i spetsialistov v oblasti betona i zhelezobetona. Irkutsk. 1990. S. 53-55. [Zvezdov A.I. Concretes with compensated shrinkage based on tensile cement. Materials of the XXII International Conference of Young Scientists and Specialists in the Field of Concrete and Reinforced Concrete. Irkutsk. 1990. P. 53-55. (In Russ.)]

4. Zvezdov A.I., Martirosov G.M. Betony s kompensirovannoi usadkoi. Beton i zhelezobeton. 1995;3:2-4. [Zvezdov A.I., Martirosov G.M. Concretes with compensated shrinkage. Beton i zhelezobeton. 1995;3:2-4. (In Russ.)]

5. Kravchenko I.V. Rasshiryayushchiesya tsementy. M.: Izd. literatury po stroitel'stvu, arkhitekture i stroitel'nym materialam; 1962. 164 s. [Kravchenko I.V. Expanding cements. M.: Izd. literatury po stroitel'stvu, arkhitekture i stroitel'nym materialam; 1962. 164 p. (In Russ.)]

6. Kuznetsova T.V. Struktura i svoistva rasshiryayushchikhsya i napryagayushchikh tsementov. Sbornik dokladov Vsesoyuznoi konferentsii v g. Groznom: Resursosberegayushchie tekhnologii zhelezobetonnykh konstruktsii na osnove napryagayushchikh tsementov. M.: Stroiizdat. 1989. S. 8-9. [Kuznetsova T.V. Structure and properties of expanding and tensile cements. Collection of reports of the All-Union Conference in Grozny: Resource-saving technologies of reinforced concrete structures based on tensile cements. M.: Stroiizdat. 1989. P. 8-9. (In Russ.)]

7. Materialy seminara «Opyt i perspektivy primeneniya betonov na napryagayushchem tsemente v stroitel'stve». O-vo «Znanie» RSFSR. M. 1992. 117 s. [Materials of the seminar «Experience and perspectives of using concretes on tensile cement in construction». RSFSR «Knowledge» society. Moscow, 1992. 117 p. (In Russ.)]

8. Mikhailov V.V., Litver S.L. Rasshiryayushchiisya i napryagayushchii tsementy i samonapryazhennye zhelezobetonnye konstruktsii. M.: Stroiizdat; 1974. 312 s. [Mikhailov V.V., Litver S.L. Expanding and straining cements and self-stressed reinforced concrete structures. M.: Stroiizdat; 1974. 312 p. (In Russ.)]

9. Polak A.F. Tverdenie monomineral'nykh vyazhushchikh veshchestv. M. 1966. 208 s. [Polak A.F. Hardening of monomineral astringents. M. 1966. 208 p. (In Russ.)]

10. Kuznetsova T.V. Alyuminatnye i sul'foalyuminatnye tsementy. M.: Stroiizdat; 1989. 209 s. [Kuznetsova T.V. Aluminate and sulphoaluminous cements. M.: Stroiizdat; 1989. 209 p. (In Russ.)]

11. Nesvetaev G.V., Khomich L.A. Nekotorye svoistva napryagayushchikh betonov s dobavkoi «Embelit». Nauchnoe obozrenie. 2014; 10:642 – 645. [Nesvetaev G.V., Khomich L.A. Some properties of tensile concrete with the addition of «Embelit». Scientific review. 2014;10:642 – 645. (In Russ.)]

12. Nesvetaev G.V. Betony: uchebnoe posobie. Rostov-na-Donu: Feniks; 2011. 381 s. [Nesvetaev G.V. Concrete: a study guide. Rostov-on-Don: Phoenix; 2011. 381 p. (In Russ.)]

13. Nesvetaev G.V., Udodov S.A., Bychkova O.A. O vliyanii sostava modifitsirovannogo gipsoglinozemistogo rasshiryayushchegosya tsementa na prochnost' i temp tverdeniya. Naukovedenie. 2015;7(6):122. Rezhim dostupa: http:// naukovedenie.ru/PDF/01TVN615.pdf. [Nesvetaev G.V., Udodov S.A., Bychkova O.A. About the influence of the composition of the modified gypsum-aluminous expanding cement on the strength and rate of hardening. Naukovedenie. 2015;7(6):122. Available at: http:// naukovedenie.ru/PDF/01TVN615.pdf. (In Russ.)]

14. Zhil'nikova T.N., Koryanova Yu.I., Nesvetaev G.V. Vliyanie retsepturno-tekhnologicheskikh faktorov na prochnostnye pokazateli betonov dlya in"ektirovaniya s dvukhstadiinym rasshireniem. Vestnik Dagestanskogo gosudarstvennogo tekhnicheskogo universiteta. Tekhnicheskie nauki. 2017; 44(1):150-161. [Zhil'nikova T.N., Koryanova Yu.I., Nesvetaev G.V. Impact of formula-technological factors on concrete strength indicators for injecting with two-stage expansion. Herald of Dagestan State Technical University. Technical Sciences. 2017;44(1):150-161. (In Russ.)]

15. Zhil'nikova T.N., Koryanova Yu.I., Nesvetaev G.V. Integral'nye pokazateli vliyaniya retsepturnotekhnologicheskikh faktorov na strukturoobrazovanie tsementnogo kamnya betonov dlya in"ektirovaniya s dvukhstadiinym rasshireniem. Vestnik Dagestanskogo gosudarstvennogo tekhnicheskogo universiteta. Tekhnicheskie nauki. 2016; 43(4):153-166. [Zhil'nikova T.N., Koryanova Yu.I., Nesvetaev G.V. Integral indicators of the influence of formula-technological factors on the cement matrix of concrete structure formation for injection with twostep expansion. Herald of Daghestan State Technical University. Technical Sciences. 2016; 43(4):153-166. (In Russ.)]

16. Nesvetaev G.V., Potapova Yu.I. Sostavy dlya in ektirovaniya s dvustadiinym rasshireniem. Naukovedenie. 2013; 3(16):128. Rezhim dostupa: http:// naukovedenie.ru/PDF/28trgsu313.pdf. [Nesvetaev G.V., Potapova Yu.I. Compositions for injection with two-stage expansion. Naukovedenie. 2013;3(16):128. Available at: http:// Naukovedenie.ru/PDF/28trgsu313.pdf. (In Russ.)]

17. Nesvetaev G.V., Koryanova Yu.I. Vliyanie uslovii tverdeniya betona s dvukhstadiinym rasshireniem na deformativno-prochnostnye pokazateli. Naukovedenie. 2015; 7(5):148. Rezhim dostupa: http:// naukovedenie.ru/PDF/129TVN515.pdf. [Nesvetaev G.V., Koryanova Yu.I. Effect of concrete hardening conditions with two-stage expansion on deformation-strength parameters. Naukovedenie. 2015; 7(5):148. Available at: http:// naukovedenie.ru/PDF/129TVN515.pdf. (In Russ.)]

18. Abukhanov A.Z. i dr. Aktual'nye problemy sovremennogo materialovedeniya. Groznyi, 2015. [Abukhanov A.Z. i dr. Relevant problems of modern materials science. Groznyi, 2015. (In Russ.)]

19. Bychkov M.V., Udodov S.A. Legkii samouplotnyayushchiisya beton kak effektivnyi konstruktsionnyi material. Naukovedenie. 2013; 4(17):41. Rezhim dostupa: http:// naukovedenie.ru/PDF/42TVN413.pdf. [Bychkov M.V., Udodov S.A. Light self-compacting concrete as an effective structural material. Naukovedenie. 2013;4(17):41. Available at: http:// naukovedenie.ru/PDF/42TVN413.pdf. (In Russ.)]

20. Murtazaev S.A.Yu., Salamanova M.Sh., Saidumov M.S., Elistratkin M.Yu. Samouplotnyayushchiesya betony s ispol'zovaniem modifikatorov i napolnitelei iz prirodnogo i tekhnogennogo syr'ya. Materialy Nauchnoprakticheskoi konferentsii k 85-letiyu zasluzhennogo deyatelya nauki RF, akademika RAASN, doktora tekhnicheskikh nauk Bazhenova Yuriya Mikhailovicha «Effektivnye stroitel'nye kompozity». Belgorodskii gosudarstvennyi tekhnologicheskii universitet im. V.G. Shukhova. 2015. C. 455-465. [Murtazaev S.A.Yu., Salamanova M.Sh., Saidumov M.S., Elistratkin M.Yu. Self-sealing concrete with the use of modifiers and fillers from natural and technogenic raw materials. Materials of the Scientific and Practical Conference devoted to the 85th anniversary of the Honored Scientist of the Russian Federation, Academician of RAASN, Doctor of Technical Sciences Bazhenov Yuri Mikhailovich «Effective Building Composites». Belgorod State Technological University named after V.G. Shukhov. 2015. C. 455-465. (In Russ.)]