Abstract
In this paper, an experimental study on the spalling behaviour and mechanical properties of Reactive Powder Concretes (RPCs) in high temperature are presented. The research program was established to evaluate the impact of low melting temperature polypropylene fibres PP on mechanical properties evolution with temperature but also to verify the effectiveness of their addition to prevent spalling. Three sets of RPC specimens were prepared for this study with different amount of PP fibres (no fibres, 1.0 kg/m 3 and 2.0 kg/m 3 ). The addition of PP fibres reduces the initial compressive strength of the RPC material by approx. 14% no significant influence on modulus of elasticity was observed. Addition of 1 kg/m 3 of PP fibres in RPC, seem not to give a sufficient protection against occurrence of spalling phenomenon. By adding 2 kg/m 3 of PP fibres the risk of spalling is significantly reduced.
Highlights
Reactive Powder Concrete (RPC) is a cement-based composite material in which the porosity is minimized by a low water to binder ratio, and its homogeneity is improved by the using fine aggregate
On the basis of the results presented and their analysis, the following conclusions can be drawn: - The addition of PP fibres added in the amount of 2.0 kg/m3 PP fibres allows to limit the spalling risk of RPC cementitious material
Spalling was efficiently limited even when the relatively high heating rate is applied 8 ◦C/min; - Lower amount of PP fibres 1 kg/m3 do not efficiently prevented spalling to occur; - The rate of weight loss results allowed to observe that higher amount of PP fibres allow easier water and gas evacuation
Summary
Reactive Powder Concrete (RPC) is a cement-based composite material in which the porosity is minimized by a low water to binder ratio, and its homogeneity is improved by the using fine aggregate. Water curing and low pressure steam cured RPCs spalled when heated with relatively slow heating rate of 1 ◦C/min These observations led to the conclusion that it is essential to incorporate polypropylene fibres in low w/c ratio cementitious materials at the mixing stage so providing a technological solution allowing the spalling risk to be reduced. This paper is a continuation of previous works of the authors on the influence high temperature on the behaviour of Reactive Powder Concrete (RPC). The goal of this investigation was to study the impact of the addition of PP fibres in the various amount on the mechanical properties of RPC. Composition Cement CEM I 52.5R Silica fume Ground quartz 0/0.20 mm Quartz sand 0/0.50 mm Superplasticiser Water Polypropylene Fibres (PP)
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