Abstract:
In construction industry, sand is a major raw material besides water, cement, gravel and steel. The quality of sand is vital
in development of firm structures in construction. Thus, for construction industry to remain competitive, it is critical to develop
efficient sand screening technologies that produce high quality sand while reducing labour cost. Therefore, the main objective of
this research paper was to assess sand sieving technologies used in construction industry in Kenya and to design and evaluate
performance operation of the sand screening machine that would help improve the efficiency and quality of sand while lowering
the overall construction cost. The specific objectives were to design sand screening machine and to investigate the effect of moisture
and sieve sizes on screening time. Experiments were conducted on semi-automatic machine driven by motor to determine fine sand
produced at different moisture levels and time consumed. The machine designed consist a motor, sieve, shaft, steel hollow tubes,
flat steel bars, sheet metal plates, hinges, eccentric sheaves, and angle bars. The study found that screening raw sand of 10 kg using
a designed semi-automatic machine with a sieve of 3mm x 3mm and densities 1442 kg/m3
, 1602 kg/m3
, 1682 kg/m3
, 1922 kg/m3
and 2082 kg/m3 were found to produce 8.1kg, 6.8kg, 6.1kg, 4.1kg and 2.8kg respectively with sieving time of 24s, 26s, 27s, 30s
and 32s respectively. Designed semi-automatic sand sieving machine displayed a labour reduction cost of 66% leading to savings
of Ksh. 39,600 per month. In addition, the output of the machine screening dry sand (1442 kg/m3
) 8 hours per day was found to be
9,720 kg. In conclusion, low density sand and optimal sieve size results to high efficiency and significant labour cost savings. The
study recommends the use of sand with low density (dry) and adoption of semi-automatic screening machine technologies in
construction industry in order to attain Kenya’s affordable housing programme
