An Initial Analysis of the Effect of Gypsum Plaster in Recycled Fine Aggregates from C&D Wastes

Title: An Initial Analysis of the Effect of Gypsum Plaster in Recycled Fine Aggregates from C&D Wastes
Author(s): Aguiar
Paper category : conference
Book title: International RILEM Conference on the Use of Recycled Materials in Building and Structures
Editor(s): E. Vázquez, Ch. F. Hendriks and G.M.T. Janssen
Print-ISBN: 2-912143-52-7
e-ISBN: 2912143756
Publisher: RILEM Publications SARL
Publication year: 2004
Pages: 493 - 502
Total Pages: 10
Nb references: 23
Language: English

Abstract: For one type of recycling unit a study was made of the use of recycled sands containing
gypsum plaster impurities as mortar for laying masonry. Such mortars, when in contact with
moisture, can cause the outset of delayed ettringite and affect the performance of the masonry
depending on the porosity of the materials used. Materials characteristic of the region of the
recycling plant produced 4 recycled sands (0% up to 0,5% of theoretical sulfate
contamination). The mortars were produced with a cement content around 220 kg/m 3 ,
including a reference mortar of cement, lime and quartz sand.
The materials quantities used, density and consistency of mortars in the plastic state; and in
the hardened state at 63 days of age, the compressive strength, flexural modulus, static and
dynamic modulus of elasticity, water absorption and apparent porosity are described in this
paper. In between the 63rd and 175th days the mortars were submitted to 8 cycles of 7 days at
> 95% R.U., alternating for 7 days at 40 o C. At the end of 8 cycles there was dimensional
change and loss of tensile and compressive strength in all mortars studied. Analysis of the
microstructure will confirm if such alterations can be associated to delayed ettringite.

Online publication: 2004-09-29
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2912143756.055