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Performance of high‑strength green concrete under the influence of curing methods, volcanic pumice dust, and hot weather

Zeyad Abdullah M., Magbool Hassan M., Amran Mugahed, Mijarsh M. J. A., Almalki Ali

Archives of Civil and Mechanical Engineering

2022

Vol. 22, no. 3

art. no. e134

This study aimed at examining the impact of concrete curing methods in hot-weather regions on the properties of high-strength green concrete (HSC), which is made from a local industrial waste by-product from the manufacture of light volcanic aggregates called volcanic pumice dust (VPD). The HSC properties are significantly affected by the curing methods, the ambient weather, and the alternative materials to cement. This study aimed to apply three curing methods in a hot-weather region, including the following: (1) the specimens were immersed in a water tank in laboratory conditions, (2) the specimens were cured by covering them with a wet burlap outdoors and spraying the burlap with water twice a day, and (3) the specimens were cured by spraying with water outdoor. Three VPD replacement rates are applied, namely 10%, 20%, and 30% cement mass replacements. In this study, slump tests were conducted and the water absorption, sorptivity, and compressive, indirect tensile, and flexural strengths were investigated to determine the HSC properties. The microstructure of the cement paste was evaluated through thermogravimetric analysis, scanning electron microscopy, and X-ray diffraction. The addition of VPD contributed to reducing the negative impact of hot weather on concrete and improving construction applications. All tests were conducted on hardened concrete at 7, 28, 90, and 180 curing ages. Furthermore, the compressive strength of the immersion curing methods using 10% of VPD surpassed 60 MPa at the 28-day curing age. The residual compressive strength was in the range of 85.6-98.2% when CC and SC were applied compared to IC for all replacement rates at a test age of 180 days. The HSC containing 30% of VPD showed low water sorptivity and water absorption in all curing methods.

Wpływ metody peklowania na stabilność przechowalnicza przetworów mięsnych

Krala L., Bagnowska A.

Chłodnictwo : organ Naczelnej Organizacji Technicznej

2012

R. 47, nr 3

40-43

Analizowano oddziaływanie zmodyfikowanego sposobu peklowania mięsa wieprzowego, przez zstąpienie azotanów(III) chitozanem, a-tokoferolem, batanina lub likopenem w różnych kombinacjach, na stabilność przechowalnicza (t = 2š1°C;T = 1,5 miesiąca) kiełbas parzonych. Mięso klasy l, 2a oraz 2b peklowano metodą na sucho oraz metoda na mokro. Gotowe kiełbasy parzono bez uprzedniego wędzenia. Badano liczbę Totox (TV), jako wskaźnik zaawansowania zmian oksydacyjnych, zawartość białek rozpuszczalnych, wodochłonność oraz parametry barwy w międzynarodowym systemie CIEL*a* b*. Obliczono parametry kinetyczne zmian badanych wskaźników oraz ustalono rzędowość reakcji. Ocena statystyczna uzyskanych wyników wykazała, że możliwe jest zastąpienie azotanów(III) w procesie peklowania mięsa przez chitozan i a-tokoferol. Taka modyfikacja procesu peklowania, oprócz zapewnienia lepszych walorów zdrowotnych kiełbas, znacznie poprawia ich stabilność przechowalnicza. Peklowanie na sucho daje bardziej stabilny produkt niż peklowanie zalewowe. Chitozan użyty w procesie peklowania surowców mięsnych w znacznie większym stopniu chroni kiełbasy przed zmianami denaturacyjnymi podczas chłodniczego przechowywania, niż a-tokoferol, betanina czy likopen.

The effect of modified method of pork meat curing, in which nitrates(IH) were replaced by various mixtures of chitosan, a-tocopherol, betanin or licopene on the storage stability (at t= 2š1°C; for T = 1.5 month) of boiled sausages was determined. Meat of classes l, 2a and 2b was subjected to dry and wet curing. Resulting sausages were boiled without previous smoking. The Totox value (TV) was estimated as a marker of intensity of oxidative changes. Soluble proteins concentration, water binding capacity, and color parameters in the international CIEL*a* b* system were also determined. Kinetic parameters of changes in these indices were calculated and reaction order was evaluated. Statistical analysis of experimental results revealed that the nitrates(III) could be replaced by chitosan and a-tocopherol. This modification of curing process increased the health-promoting properties of the sausages and considerably improved their stability during refrigerated storage. Products obtained by dry curing were more stable than those subjected to wet curing. Chitosan used in meat products curing was found to more efficiently protect them from changes caused by denaturation during refrigerated storage than a-tocopherol, betanin and licopene.