The flexural strength and fracture toughness of reactive powder concrete in response to changing fibre size and pre‐setting pressure

Abstract

A B S T R A C T In this study, steel fibre mixtures having different compositions of fibres with various sizes were used in reactive powder concrete. The mixture composition, which would present the best performance during the flexural tests, was determined. Pre-setting pressure tests at six different magnitudes (0,5,10, 15,20, 25 MPa) were conducted on the freshly prepared reactive powder concrete mixture having the determined mixture composition. The 30-mm-long steel fibres mixed at a ratio of 4.5% provided the highest flexure strength and the fracture toughness during these tests. The highest pre-setting pressure was attained at 25 MPa and the flexural strength of the sample increased by 117% reaching 28.07 MPa at that pre-setting pressure. Ctrl = Control JSF-14 = Japan Standard L = Long LVDT = Linear Variable Differential Transformer M = Medium PC = Portland cement Q. Powder = Quartz powder Q. Sand = Quartz sand RPC = Reactive powder concrete S = Small SF = Silica fume SP = Super-plasticiser TCMA = Turkish Cement Manufacturers' Association TL = Turkish Liras TS = Turkish Standards Institute Z = Zero I N T R O D U C T I O NReactive powder concrete (RPC) is manufactured by a different method of production through hot curing than that of ordinary concrete. The aggregates were replaced by micro-sized particles and the particle distribution was arranged in such a way to enable the minCorrespondence: M.İpek.

Effect of pre-setting pressure applied flexure strength and fracture toughness of new SIFCON+RPC composite during setting phase

“…When presetting pressure reached to 15 MPa, unit weight value increased by 12% compared to the replicate sample. In a previously performed study, it was stated that 20-25% of mixture water went out and relative pressed density increased more than 2% in a 50 MPa pre-setting pressure during experiment [1,5,15,16]. Compared to this study, the results show similarity with each other.…”

“…Pre-setting pressure is applied for minimizing the adverse effects of autogenous shrinkage as well as removing water and air in the SIFCON and RPC. SIF-CON and RPC are needed to setting under pressure for minimizing the adverse effects of autogenous shrinkage during the setting phase [1,5,15,16]. Moreover, the sample was expanded due to pushing of the pressed grains to each other.…”

“…Also, we used the mixture ratios, which were chosen in previous works within the literature [1,3,5,15,16,[22][23][24][25][26][27]. By using these theories, 24 different mixtures including without fiber were prepared.…”

“…Fiber ratios and mixture techniques used in the study were obtained from studies, which were previously conducted by some studies [5,15,16]. SIFCON was filled up to the lower half of mold and RPC was filled to the rest part of the mold for producing test samples.…”

“…Increasing adherence is directly connected to paste cohesion, maximum grain diameter, granulometry, fiber geometry and surface roughness. Additionally, increasing adherence is also connected to pre-setting pressure [1,5,15,16]. A strong, non-porous adherence is formed between paste and fiber by minimizing pores among grains and removing excess water used for workability owing to pre-setting pressure.…”