Composites Based on Alternative Raw Materials at High Temperature Conditions

Jiří Bydžovský,Tomáš Melichar,Ámos Dufka

doi:10.3311/ppci.9820

Jiří Bydžovský, Tomáš Melichar + Show 1 more

Open Access

https://doi.org/10.3311/ppci.9820

Copy DOI

Abstract

This paper presents newly developed polymer-cement composites.The primary binder (cement) was partially substituted byuse of blast-furnace slag and high-temperature fly ash. A lightweightaggregate – agloporite (grain size in range 1–2 mm) wasused among other components. This porous aggregate is producedfrom energy by-products (fly ash). Attention was focusedon the behavior of the composites when exposed to elevatedtemperatures (400 °C–1,000°C). The influence of several differentmethods of temperature decrease was assessed – slow(in furnace 1°C/min) and rapid (laboratory ambient 22°C andwater bath 18°C). Specific dimensional changes were determined,including strength characteristics and bulk density.Structural deterioration and microstructural changes of selectedspecimens were investigated by analytical techniques (SEM andCT). Compressive and bending tensile strength changed variouslydepending on temperature changes, including severalcooling conditions. Deterioration reactions (especially cracks)which were formed in investigated composite structures correspondedwith results of physico-mechanical testing. That wasconfirmed by using the CT and SEM.The fact that the agloporite has a positive effect on thermalresistance of developed polymer-cement composites wasproved. Almost no cracks or other failures were identified (byusing CT and SEM) in interfacial transition zones of agloporiteafter thermal stress. This indicates very good bond adhesionbetween the matrix and the porous aggregates during extremetemperature conditions (in case of different cooling methods).

Highlights

The research presented in this paper is focused on new repair mortars development
5 Conclusions The results of the investigations presented in this paper show that with alternative raw materials (35% of cement substituted by high temperature fly ash / blast furnace slag, high proportion of porous sintered fly ash based aggregates) it is possible make a composite material with high resistance to extreme temperatures
Computer tomography (CT) analysis showed that porous aggregate – agloporite with particle size in range of 1 – 2mm, contributes positively on thermal resistance of analyzed mortars

Summary

Introduction

The research presented in this paper is focused on new repair mortars development. These mortars are based on alternative raw materials. A non-traditional laboratory technique (computational tomography – CT) was used for assessing changes in mortar structure. Selected important information pertaining to this issue is described below (suitable alternative raw materials, cooling methods, use of CT, etc.). Extreme temperature-resistant repair mortars should be used when a possibility of increased risk of accidental circumstances such as fire exists. Such mortars must fulfill certain demands concerning fire resistance of those elements repaired with the mortar. Good interaction between mortar and the repaired element must be achieved during thermal stress and subsequent cooling (extinguishing fire)

Results

Discussion

Conclusion