Effect of Slurry Coating Modified Methods on Water Absorption of Recycled Coarse Aggregate

Abstract

Water absorption rate of the recycled coarse aggregate is higher than the natural ones. Until now, there is no test method to record the instantaneous value of the water absorption although this could help us to understand the recycled coarse aggregate better. This paper developed a new device that can record the water absorption continuously and calculate the water absorption rate automatically. The water absorption curve from 0 min to 60 min can be plotted smoothly. The performances of modified recycled coarse aggregate and concretes with recycled coarse aggregate have also been studied. The result shows that the water absorption rate increases fast and about 90% water has been absorbed during the first 10 min. The slurry of silicon nitride with 500 nm particle size can reduce the 10 min water absorption rate of the recycled coarse aggregate from above 4.5% to below 2.5%. A recycled coarse aggregate wrapped with wet slurry is better than the ones wrapped with dry slurry shell for the slump of concrete. Compared to the concrete without any recycled coarse aggregate, the compressive strength and the splitting tensile strength of the concrete with recycled coarse aggregate modified by fresh cement slurry have been increased by more than 20%.

An Experimental Study on Strengthening Recycled Aggregates Considering Dry Mixing before Slurry Coating

“…However, the water-absorption rate W is increased when cement slurry is used for strengthening. The results correspond well with those in the literature, where the PVA solution and WG can reduce the water-absorption rate [20,25], while CS can increase the water-absorption rate [13]. It can be attributed to the different strengthening mechanisms for the three kinds of coating solutions.…”

“…At present, the main strengthening methods of recycled aggregates include the mechanical grinding and shaping method, removing adhesive mortar with water or acid solution, carbonization curing treatment, strengthening with an organic solvent or inorganic slurry, mixing with mineral fines, etc. [1,10,13]. In the mechanical grinding and shaping method, horizontal or vertical eccentric grinding equipment is utilized to remove impurities and old mortar at the aggregate interface and change the shape of the edges and corners of the aggregates [14,15].…”

Laboratory evaluation of a complex treatment technology for reducing water absorption of the pavement subbase aggregate from the blast-furnace slag

“…The issues of reducing water absorption of the construction and building materials are considered in a large number of papers [30][31][32][33][34][35][36][37][38][39][40]. To reduce water absorption of materials, various researchers suggest methods such as the use of nano-TiO2-modified recycled coarse aggregate [30], using the air entraining agent (for mortars) [31], slurry coating modified methods (for recycled coarse aggregate) [32], silane emulsion impregnation [33], cement-silica fume slurry coating method [34], compression casting method (to reduce water absorption properties of concrete) [35], impregnation with spent technical fluids [36], selective crushing [1], enrichment in heavy media [37], jigging [38], porosity enrichment on the friction classifier [39], etc. There is also a known method for reducing water absorption of liquid BFS , including pouring it with a thin layer for faster solidification [40].…”

Study on the Properties of Concrete with Different Admixtures in Acid Corrosive Environment

“…Many scholars have systematically studied the durability of concrete and obtained lots of great progress and rich engineering experience and which put forward a feasible method to improve the durability of concrete [1]. Coating is a main method to enhance the durability of the concrete [4]. While, brush with anticorrosive paint is not a practical method because the pile foundation is under ground.…”