TITLE:
Substitution of Kasila Group Basalt with the Archean Man Gneiss in Asphalt and Hydraulic Concrete Mix Design (Sierra Leone)
AUTHORS:
Ibrahima Sow, Ibrahima Khalil Cisse
KEYWORDS:
Gneiss, Basalt, Asphalt Concrete, Hydraulic Concrete, Marshall, Duriez, Diametric Compression
JOURNAL NAME:
Open Journal of Civil Engineering,
Vol.9 No.4,
October
29,
2019
ABSTRACT: The
study of the performances of the Archean of Man gneiss aggregates with the
addition of filler to replace the basalt of Kasila group in the asphalt and concrete mix design of southern Sierra Leone is presented in this document. The goal is to compare the results of the asphalt and concrete
mix design with gneiss and basalt aggregate. The applied methods and design used are 1) Volumetric design and Marshall method for the
asphalt, 2) French Dreux-Gorisse Method for the concrete. We added 2% of gneissic filler and 2% portland cement
type 42.5 R to the
asphalt hot mix with the gneiss aggregates to follow the criteria variation. The Marshall, the
diametric compression and the Duriez tests require us to perform four different types of mix
design. The
four mix designs meet the requirements but F2 and F4 give the best mechanical
properties. F2
(gneiss + 2% filler) and F4 (basalt)
have many similarities from which we can conclude their interchangeability. F2 gives 5255 of optimal
bitumen content. In regards to hydraulic
concrete, the results of the compressive strength test (cement content 350 kg CMI 42.5 R/m3) with the
gneiss and basalt aggregates are respectively 40 MPa and 45 MPa at 28 days curing: these values are greater than
35 MPa
required by the technical specifications. The use of the Super Fluid ® Thermoplast 120
admixture, to increase the concrete compressive strength, is justified by the
requirement of a minimum of 80% Rc28 at 24 hours. For both types of
concrete, we have at 24 hours, 34 and 35 MPa which are higher than the minimum
of 32 MPa (in
24 h).
These results meet the requirements of the technical specifications.