Civil Engineering | Assignment

Civil Engineering
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1. Introduction
1.1 slump test
slump test is conducted to determine the fluidity or the degree of mobility of concrete.
Commonly, it can be stated to as the consistency of concrete. Consistency of concrete is
determined by factors such as surface texture of aggregates, use of admixtures, water cement
ratio, mix proportions as well as sizing of the constituent aggregates. In addition to the slump
value it shows the concrete feature. It is called true slump if the concrete slumps uniformly. It
is called shear slump if one half of the cone slides down.
1.2 compressive strength test.
To determine the cube compressive strengths, cubes of 150 mm sizes were tested at 28 days
cure as per the standards of ACI which requires use of cylinder of height 300 mm and
diameter 150 mm. the results of this test are identified as the characteristic compressive
strength of the concrete sample and is based with not exceeding 5 % f the test results.
1.3 splitting tensile strength test.
This test is key determinant on understanding failure of concrete by means of cracking, that
is the strength of the said concrete to resist tensile forces within it. Concrete is weak in
tension hence the need for reinforcement in structural works. Determine the maximum tensile
strength of a given concrete is key so as to effectively design against any failures that may
result when the resulting tensions is more than the tensile strength of concrete.
1.4 flexural test on concrete.
Concrete flexural test is an indirect evaluation of the concrete splitting tensile strength.
Flexural test evaluates the capacity of unreinforced slab or beam to resist bending. It is
expressed as modulus of rupture MR in psi or MPa.
2. Experimental method/ procedure.
Manufacture of concrete
Concrete is manufactured from a mixture of cement as binder material, coarse aggregates
(gravel) and fine aggregates(sand). Chemical additives such as plasticizers could be added in
some mixes to impart other properties such as increased strengths.

Concrete testing
To test concrete, aspects of compressive strength, tensile strength and flexural strength are tested
for hardened concrete. For fresh concrete, slump test is carried out to evaluate the consistency or
workability of concrete. The following procedures describe these tests;
Mix proportions
Mix proportions implies the ratio of cement, sand and aggregates by weights
For example, for group one: cement: sand: aggregates ratio is
10.5
10.5 = 10
10.5 = 23.2
10.5 which translates ¿1:0.95:2.2 as shown in the table
2.1 Slump test procedure.
See figure 2.1 (a) and (b).
 The mould is
kept damp
and clean
with no
excess
moisture on
its surface.
Position the mould in a smooth non-absorbent, horizontal, and rigid surface
devoid of any shock or vibration.
 The mold is held firmly in place and a scoop is used to fill the mould in three
layers of concrete.
 Each layer is sufficiently tampered upon placement with 25 strokes of
tamping rod to ensure uniform distribution of the test concrete mix over the
cross-section layer. This should be done carefully such that the tamping road
doesn’t not strike the surface below and that it is not excessively conducted.
 Heap the concrete on top of the mould before tampering the uppermost layer.
Groups cement: sand: aggregates simplified mix ratio
1 10.5:10:23.2 1:0.95:2.2
2 10:10.5:23.2 1:1.05:2
3 9.1:11.1:23.6 1:1.0:2.6
4 8.2:11.7:23.8 1:1.5:3
5 7.6:12.7:23.5 1:1.67:3.1
6 6.9:14.4:23.4 1:2:3.4
7 7:14.4:23.4 1: 2:3.3
8 6.5:15.5:22.2 1:2.4:3.4
9 6.6:15.1:21.7 1:2.3:3.3
10 4.5:12.9:22 1:2.9:4.9

 upon sufficient tamping of the top layer, strike off the concrete level with the
mould edge with a rolling and sawing motion of the tamping device. While
still maintaining the mould down, any concrete that have fallen onto the
surface is carefully cleaned.
 Remove the mould from the entire concrete by carefully, vertically and slowly
raising in in such a manner that minimum torsional and lateral movement is
impacted on the concrete.
 Immediately after removing the mould, by use of a rule measure the height of
the mould and that of the highest point of the sample.
Figure 2.1 a) slump test procedure.