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UDC 691
THE INFLUENCE OF A DRY, HOT CLIMATE ON THE RHEOLOGICAL
PROPERTIES OF CONCRETE MIXTURES BASED ON LOW-WATER-
CONSUMPTION CEMENTS
Yusupov H.V.
- t.u., Professor, SamGASU, Samarkand
Pulatova Z.U.
- Doctoral student, SamGASU, Samarkand
Annotation:
The influence of extreme climatic conditions (high temperatures and low humidity)
on mobility, persistence, setting speed and evaporation of moisture in concrete mixtures is
investigated. Patterns of changes in rheological parameters in hot climates have been
established. Recommendations on the adaptation of mixtures for hot regions are given.
Keywords:
concrete mix, rheological properties, dry climate, hot climate, mobility,
preservation.
Аннотация:
Исследуется влияние экстремальных климатических условий (высоких
температур и низкой влажности) на подвижность, сохраняемость, скорость схватывания
и испарение влаги в бетонных смесях. Установлены закономерности изменения
реологических параметров в условиях жаркого климата. Даны рекомендации по
адаптации смесей для жарких регионов.
Ключевые слова:
бетонная смесь, реотехнологические свойства, сухой климат, жаркий
климат, подвижность, сохраняемость.
The dry, hot climate is typical for many regions of Central Asia and the Middle East. The main
climatic features are high air temperature (over 35-40 °C) and low relative humidity (<30%).
Under such conditions, the rate of evaporation of moisture from the concrete mixture increases
sharply, which leads to a deterioration in its technological properties, a decrease in the strength
and durability of structures.
Cements of low water consumption (LW) have the ability to form concrete with less mixing
water, which improves the water-cement ratio and allows for high strength. However, in a dry
climate, the efficiency of the central heating system can also be reduced due to premature
evaporation of moisture and accelerated setting.
The purpose of this study is to analyze the influence of climatic factors on the
rheotechnological characteristics of CNG-based concrete mixtures and to develop
recommendations for improving their resistance to external climatic influences.
Research methodology.
Assume the following initial conditions:
Air temperature: +40 °C;
Relative humidity: 20 %;
Cement: PC 500-D0 with low water consumption;
In/Out: 0.35;
Additive: superplasticizer 1% by weight of cement;
Initial mobility: 22 cm (according to the draft of the cone);
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Weight of one batch: 20 kg
1. Mobility of the concrete mix (cone sediment) = 22 cm.
According to experience, at a temperature of +40 °C and 20% humidity, mobility decreases by
~30% in the first 30 minutes due to moisture evaporation and the onset of hydration.
Mobility along the cone sediment
Table 1
Time
Expected mobility (cone draft), cm
0 min
22
30 min
15,4 (−30%)
60 min
10,5 (−52%)
90 min
6,6 (−70%)
We consider the retention coefficient as the ratio of mobility to the initial one:
R
r
=
S
t
S
0
Время
St (см)
R
r
30 мин
15,4
0,70
60 мин
10,5
0,48
90 мин
6,6
0,30
The beginning and end of setting (according to the Vic device). Standard value (GOST 310.3–
76 for PC):
Start: no earlier than 45 minutes
End: no later than 600 min
At a temperature of +40 °C, hydration accelerates:
Setting time: t
h
= t
n0
−Δt
climate
≈ 90-25 = 65 min
End of grasping: tk = 180-40 = 140 min
The loss of water due to evaporation (by weight) is determined by the following formula (SNiP
3.03.01-87):
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ΔW=E
⋅
A
⋅
t
Here:
E — evaporation rate (g/m2·h): at +40 °C and 20% humidity ≈ 250 g/m2·h
A — open area: 0.1 m2 (for the tray)
t — time, hour
In 1 hour:
ΔW=250 * 0,1 * 1 = 25 g water
For a mixture weighing 20 kg with a moisture content of 7% (1400 g of water):
25
14 00
∗ 100% = 1,79%
(that is, almost 2% of water is lost in one hour.).
Conclusion.
In a dry, hot climate, concrete mixtures based on cements with low water
consumption are subject to rapid evaporation of moisture and accelerated setting, which
requires adjustments to the composition and concreting technology. The use of modern
chemical additives, technological techniques and protective measures makes it possible to
effectively adapt such mixtures to extreme climatic conditions and ensure high quality and
durability of concrete.
List of literature:
1. GOST 10181-2014. Concrete mixes. Test methods. Moscow: Standartinform, 2015.
2. Sheindlin A.E., Gusev V.F. Influence of temperature on the structure and properties of
cement stone // Building materials. 2020. No.5.
3. Rashitov K.M., Juraev S.B. Technological aspects of concreting in a hot climate // Bulletin of
Construction Science. – 2021.
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RESEARCH & DEVELOPMENT
SJIF 2019: 5.222 2020: 5.552 2021: 5.637 2022:5.479 2023:6.563 2024: 7,805
eISSN :2394-6334 https://www.ijmrd.in/index.php/imjrd Volume 12, issue 06 (2025)
547
4. Neville A.M. Properties of concrete. London: Pearson Education, 2011.
5. AISI 305 R20. A guide to concreting in hot weather. – American Institute of Concrete, 2020.
6. GOST 7473-2010. Concrete mixes. Technical specifications.
7. SNiP 3.03.01-87. Load-bearing and enclosing structures.
8. AVI 305 R20. A guide to concreting in hot weather.
