|Wachira, Jackson M.
|A Thesis Submitted In Partial Fulfilment for the Degree of Masters of Science in Chemistry of Kenyatta University.
|This thesis reports the results of a study aimed at making low cost cement from
some agricultural and industrial wastes. The utilization of these wastes would
avail an economical and environmentally friendlier waste disposal methods and
cheap cementing material. The cement made was based on the materials whose
pozzolanic reaction was investigated.
The materials tested for pozzolanicity included rice husks ash (RHA) from wastes
of rice milling factories, spent bleaching earth (SBE) from oil processing factories
and broken bricks (BB) from clay products manufacturers. Natural pozzolana
(Ptuff) used for making East African Portland pozzolana cement was tested for
comparative purposes. Heat content of rice husks (RH) and spent bleaching earth
(SBE) was found to be adequate for activation of silica and alumina in the
pozzolanic materials. Only a little kerosene was necessary for ignition. Acetylene
lime sludge (ALS) from acetylene manufacturing industry and commercial
hydrated lime (CHL) were used for the pozzolana-hydrated lime reaction.
Pozzolanic activity of the materials with commercial hydrated lime (CHL) in
different ratios was investigated on the pozzolanic materials separately. A blended
calcined mix and a calcined blended raw mix of the materials was similarly tested.
The results showed that the test materials were active pozzolanas. AI: 2 ratio of
the pozzolanic material: CHL gave the best results. The 1: 2 ratio now using ALS
was also investigated on the materials. ALS showed a superior performance than
CHL with all the pozzolanic materials under test. Calcined blended raw mix
exhibited a better performance than the blended calcined mix.
The test materials were then singly interground in different proportions with
laboratory made ordinary Portland cement (OPC) as per the Kenya Standard (KS)
02 1263 of 1993  for cement tests. The resulting mixtures were then assessed
using the same standard. The results showed that up to 25 percent replacement of
the cement with the pozzolanic materials under test met the standard
Calcined blended raw mix was interground with ALS and OPC from Bamburi
Cement Factory in different percentages. The resulting products were subjected to
the Kenya Standard . Up to 45 percent replacement of the OPC with the
material under test met the standard requirements, while higher percent
replacements failed. A rough financial estimate suggested a running cost saving of
up to 20 percent per tonne of PPC
|Pozzolana based Cement
|Agricultural Waste Materials
|Low Cost Pozzolana based Cement from Industrial and Agricultural Waste Materials