WATER ABSORPTION KINETIC OF RECYCLED SAND DURING MORTAR MIXING

Author(s): Assia Djerbi, Aiman Yacoub, Teddy Fen-Chong
Paper category: Proceedings
Book title: IV International Conference Progress of Recycling in the Built Environment
Editor(s): Isabel M. Martins, Carina Ulsen, Yury Villagran
ISBN:
e-ISBN: Isabel M. Martins, Carina Ulsen, Yury Villagran
Publisher: RILEM Publications SARL
Publication year: 2018
Pages: 430-437
Total Pages: 08
Language : English

Abstract: Use of recycled concrete aggregates (RCA) as construction and building materials has not yet
spread out. One of the reasons lies in porosity: a given RCA is more porous than its natural
aggregate because of the presence of the attached old cement paste. This higher porosity causes
inadequate mixing due to increase in both RCA water absorption and water exchange between
RCA and new cement paste. It is thus necessary to quantify the weight fraction of in-pore water,
which is usually done through the so-called water absorption coefficient (WAC), and to
decrease this potential water exchange by pre-saturating the RCA. This paper aims to
investigate mortar mixes made of recycled sand (RS). It puts forward a new vacuum-based
method combined with an evaporation method to measure the WAC, which permits saturating
the RS fully and confirming that the standard method (NF EN 1097-6) largely underestimates
the WAC. A new experimental approach is used to follow the absorption kinetics of the RS by
immersing them into a limestone filler, which allows better reproduction of mixing mortar since
aggregates are added into cement paste and not into water. Last, it is shown that adequately pre-
saturating the RS can improve the mortar consistency.

Online publication : 2018
Publication type : full_text
Public price (Euros) : 0.00