Abstract

Weather conditions are the biggest influencers on the construction of the facilities and respecting the construction deadlines. The success of the construction of the facilities depends on several factors, including: temperature values, air currents, humidity, precipitation and similar. The most suitable temperature for work on a construction site is from 5 to 20° С. But work is not always done at weather when the mercury on the thermometer is among these numbers, especially when it comes to complex buildings.

To improve the working conditions of complex geotechnical structures, additives are applied to improve the properties of concrete. Additives are added before the concrete is installed and depending on the need, they can be in the form of: accelerators, retarders, plasticizers, aerators, antifreeze and others, and the amount depends of the final purpose. Accelerators are most widely used as additives. These additives affect the hydration process and improve the mechanical properties of concrete, achieve early strength, better adhesion, allow the installation of sprayed concrete on vertical and sloping surfaces, reduce repulsion and waste of the material. Additives are added before embedding the shotcrete where the amount of accelerators ranges from 3-10%, but the best results are achieved when this value is around 5%. From the analyzes, the values of compressive strength of sprayed concrete with a higher percentage of additives are higher in the first days. In the following days that value is dormant or has little growth. Whereas, in the case of sprayed concrete, which contains a smaller amount of accelerators, the opposite results are obtained, ie. the pressure strength in the first days behaves normally, and on the 28th day it has better results.

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