2 research outputs found
The influence of cement fineness on the structural characteristics of normal concrete
This research presents the influence of cement fineness on the structural characteristics
of normal concrete. The cement was divided into different fineness zones (150 μm – 7 5μm, 75 μm
– 45 μm and 45 μm – 0 μm). Thirty (30 Nos.) cement mortar cubes, 54 Nos. of 150 x 150 x 150
mm concrete cubes and 36 Nos. of 150 x 300 mm cylinder specimens were cast, cured by
immersion and tested at 3, 7, 14, 21, 28 and 45 days. A concrete mix ratio of 1:2:4 (Cement: Fine
aggregate: Coarse aggregate) with water/cement ratio of 0.5 was used. The results reveal that an
increase in the fineness of cement particle led to an increase in workability. The setting times
(initial and final setting time) reduces progressively as the cement fineness is increased from
175mins (initial setting time) for sizes 150 μm – 75 μm to an initial setting time of 140mins for
sizes 45μm - 0μm. The final setting time also reduces from 300 mins to 240 mins as the cement
fineness is increased. The tensile and compressive strengths recorded an increase due to the
increase in cement within the concrete matrix. It was concluded that the finer the cement particle
the greater the concrete strength
A comparative study on the strength characteristics of Grade 25 and Grade 30 rice husk ash blended cement concrete
Rice husk ash (RHA) is an agricultural waste which is a pozzolanic material that can be
blended with cement in producing concrete. This research presents investigation carried out on the
comparative strength characteristics of concrete produced with grade 25 and grade 30 cement
blended concrete using a replacement level of 10% rice husk ash as substitute. Two mix ratios (1:2:4
and 1:1.12:3.01) were used. A total of 60 cube size of 150mm were cast, tested and their mechanical
properties determined. The RHA was made in the laboratory by burning the husk obtained from Ifo
in Ogun State Nigeria using an Electric furnace, with the temperatures of the furnace at about 700°C.
The results showed that the compressive strength at 28 days decreased as the percentage replacement
of Portland Limestone cement (PLC) with RHA increased from 0% to 10% respectively with
compressive strengths of 29.78 N/mm2 to 21.56 N/mm2 for grade 25 concrete and 32.12 N/mm2 to
26.82 N/mm2 for grade 30 concrete. It was concluded that RHA replacement in concrete can be used
for the production of concrete for light structural works in the development of sustainable and green
structures