The Properties of Composites with Recycled Cement Mortar Used as a Supplementary Cementitious Material

Abstract

The process of recycling concrete rubble is accompanied by the formation of a large amount of fine fraction, which cannot be reused as aggregate. The results of research on the possibility of using recycled cement mortar (RCM), obtained during concrete recycling, as a cementitious supplementary material, are presented. The experimental research was carried out on the basis of two variables determining the recycling process: X 1 -temperature (range of variation 288-712 • C) and X 2 -time (range of variation 30-90 min) of thermal treatment of concrete rubble. The experiment included 10 series of new composites made with RCMs subjected to different variants of thermal treatment, and two additional control series. The best treatment parameters were determined based on the assessment of selected physical and mechanical properties of the new cement composites, as well as the analysis of characteristics and microstructure of RCM. The test results showed that proper thermal treatment of concrete rubble makes it possible to obtain a high-quality fine fraction, which has the properties of an active addition and can be used as a partial replacement for cement in mortars and concretes.

Influence of the Treatment Temperature on the Microstructure and Hydration Behavior of Thermoactivated Recycled Cement

“…Some authors simply concentrated on a single treatment temperature [ 5 , 6 ] and others approached only a few properties, namely the fresh behavior and the mechanical strength [ 4 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. Other studies were dedicated to the incorporation of varying percentages of RC in mortars and concrete [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. Furthermore, results reported in the literature are contradictory, reflecting the lack of knowledge of these poorly explored new binders [ 1 ].…”

Special Issue: Supplementary Cementitious Materials in Concrete, Part I

“…properties of modified cement matrix composites reinforced with fibers [14,[18][19][20]; • application of new types of supplementary cementitious materials [13,16,[21][22][23][24][25][26][27][28]; • characterization of various types of modified cement based materials [18,21,23,[25][26][27][28][29][30][31].…”

“…The issues of the original research papers and stat-of-the art reviews published in this Special Issue of Materials, and coming from over 45 international universities and scientific centres, can be divided as follows: permeability and diffusivity, which are directly related to the quality of concrete and to the durability in various aggressive environments [ 13 , 14 , 15 , 16 , 17 ]; properties of modified cement matrix composites reinforced with fibers [ 14 , 18 , 19 , 20 ]; application of new types of supplementary cementitious materials [ 13 , 16 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]; characterization of various types of modified cement based materials [ 18 , 21 , 23 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. …”

Mechanical Characterisation and Shrinkage of Thermoactivated Recycled Cement Concrete

“…In recent years, the attention has shifted towards the production of recycled cement (RC) with rehydration capacity through thermal activation [1,4]. In this still relatively unexplored domain, studies have mostly focused on the microstructure and rehydration behaviour of RC [5][6][7][8][9][10], as well as the mechanical characterisation of cement pastes and mortars produced with this binder [11][12][13][14][15][16][17][18]. RC pastes have been reported to achieve compressive strengths of up to 32 MPa at 28 days [7], though generally presenting high water demand and low setting times [4,6].…”

“…Kalinowska-Wichrowska et al [15] investigated the influence of the treatment temperature and residence period on the mechanical strength of mortars with 25% RC obtained from the cement fraction of waste mortar. The authors found that the incorporation of RC treated at 650 • C for 80 min led to the highest compressive strength.…”