Effect of high temperatures on cement composite materials in concrete structures

Abstract

Concrete is flexible construction material, which is utilized in various technological applications for underground structures and reinforcement of mine works (adits, tunnels etc.). In such applications, concrete has many functions -static function, water-tightness, gas-tightness, resistance to action of aggressive waters as well as durability. In case of railroad and road tunnel constructions, there is another important problem: influence of high temperatures on concrete lining during wildfire. The paper focuses on analysis of behavior of cement composite material (concrete) exposed to high temperatures. Several possibilities of increasing resistance of cement composites to high temperatures are proposed as well as recommendation for reduction of damage on structures exposed to high temperature.

Influence of Climate Change on the Lifecycle of Construction Projects at Gaza Strip

“…Thus, the temperature change affects the curing process directly due to the relation between water and temperature. Many studies confirm this issue and its effects such as [22], [15], [19] and [20]. In addition, the temperature affects the painting works and safety of work.…”

Possibilities of observation of behaviour of concrete- and cement-based composite materials exposed to high temperatures

“…2,3 The experiment aimed to observe the behaviour of several concrete mixtures over longer period and slightly reduced heating with the focus on the surface damage caused by heat and spalling.…”

Behaviour of cement composites with lightweight and heavyweight aggregates at high temperatures

“…For example, quartz aggregate at the temperature of 573 °C and pressure 0.1 MPa increases its volume by as much as 4.7 %, carbonaceous aggregate decomposes CaCO 3 approximately about 800 °C (depending on the composition of aggregates) to CaO and CO 2 , moreover, when CaO from the aggregate is cooled down, it can hydrate again and increase its volume by as much as 40 %. Based on this knowledge, the efforts aimed at using an aggregate with low thermal expansion and low thermal deformation, as is recommended in literature [9], [10], [11], [12]. Mineralogical composition and internal texture also affect the physical and mechanical properties of rocks which may also have an impact on thermal behaviour of natural aggregates [13].…”

“…Water gradually releases; first the free water leaves through capillaries, then the chemically bound water. However, if mastic cement is heated in an enclosed and humid environment (so-called internal autoclaving) hydrothermal reaction can occur, which can cause considerable changes of the microstructure both physically and chemically [4], [10].…”