| dc.description.abstract |
In most African countries, supplementary cementitious materials (SCMs), such as silica
fume, slag, and fly ash, are scarce, creating a need for alternative low-clinker cement that
utilises locally abundant resources. Given the limited availability of SCMs, the development
of Limestone Calcined Clay Cement (LC3) has emerged as an attractive solution. LC3 is
a blended binder composed of ground limestone, calcined kaolinite clay, and ordinary
Portland cement clinker. This research assessed the mechanical and durability properties of
LC3 binders formulated using raw materials obtained from selected deposits in Tanzania.
Two samples of clay from the Pugu deposit were selected: Pugu hard clay (PH) and
Pugu soft clay (PS). Limestone and gypsum were sourced from Dar es Salaam. LC3
mixes containing 58% CEM I/42.5N were produced and used to make concrete with a
water/binder ratio of 0.4. Two control mixes were made, a mix with 100% Portland cement
CEM I/42.5 N and a mix with 100% Portland pozzolana CEM II/P-B 42.5 N. In addition,
four concrete mixes were designed for the study: LC3-PH, LC3-PS, CEM I + PH (CC-PH),
and CEM I + PS (CC-PS). The mechanical properties evaluated included compressive
strength, splitting tensile strength, and flexural strength, whilst durability performance
was assessed through sulfuric acid resistance, water sorptivity, and absorption. The results
demonstrated the superiority of LC3 concrete compared to CEM I and CEM II concretes.
For instance, the LC3-PS mix achieved a 90-day compressive strength of 63 ± 2.1 MPa,
compared with 62 ± 1.8 MPa for CEM I. Similarly, water absorption was 1.35% and 1.1%
for CEM I and LC3 concretes, respectively. Under sulfuric acid exposure, LC3 concrete
exhibited the lowest mass loss (1.6%) and strength loss (17.9%) compared with 2.4% and
23% for CEM I and 2.1% and 21% for CEM II, respectively. The enhanced performance of
LC3 concrete was attributed to its denser and more refined microstructure, which reduced
pore connectivity and improved resistance to the ingress of aggressive agents. |
en_US |