This process involves addition of some chemical like
cement, lime or gypsum in agglomeration stage. This induces bonding property in
the material. The green pellets are then cured in pressurised saturated steam
at a temperature of 1400C. This process helps in reducing bonding material in
pellet formation and curing time (Bijen, 1986). But the strength and durability
properties does not show much difference compared to normal curing (Manikandan
and Ramamurthy, 2008).
It is the process of normal water curing at ordinary
room temperature (Bijen, 1986). This process helps avoiding energy utilization.
Niyazi Ugur Kockal et al. says that cold bonded aggregate shows poor properties
compared to sintered aggregates (Niyazi Ugur Kockal and Turan Ozturan, 2011). But in contrary, Manikandan et al.
(2008) says when curing time is increased, the aggregate properties are
comparable with autoclaving and steam curing.
There also researcher to implement geopolymerisation
process bonding during agglomeration by granulation of manufactured aggregates
(Gomathi, 2014). Geopolimerisation is an inorganic polycondensation reaction
which is yielding three-dimensional zeolitic framework to produce geopolymer
cement (Razak, 2014). The hardening mechanism of geopolymeration process is
when the aluminium and silicate oxides in any raw material react with alkali
polysilicates. The physical and mechanical properties of the geopolymer
artificial aggregate are also affected by the molarities and quantity of the
alkaline activator use.
The geopolymer fly ash shows an increase in strength
after exposing to 100000C (Abdullah, 2012). The porosity of the
artificial aggregate is decreasing after the heat treatment is increasing
(Ruzaid, 2013). The source materials also had a huge role in geopolymer
properties according to the reactivity and chemical composition. Lower
compressive strength can be seen in cold bond geopolymer artificial aggregate
using only fly ash show compared with the geopolymer lightweight aggregate
blends with ground granulated blast slag and rice husk ash (Bui, 2012).