1. Prepared by:
ShahrulAfifi B Zakaria.
Nur Muhammad Kamil B Mohd Izhari.
2. Preparing Wet Concrete.
What is concrete?
- Concrete is product consist of
cement, sand and coarse aggregates
and water which is there are mix
together in required proportion (ratio).
Cement Sand Coarse Water
Aggregate
(gravel)
3. Preparing Wet Concrete.
Water /Cement Ratio.
For normal mix, the amount of mixture for
cement, sand, and course aggregate is measured
by ratio of weight or ratio of volume.
However, ratio of weight is most preferable. For
example, a mixture of 1: 2 : 4 means 1 part of
cement, 2 parts of fine aggregate and 4 part of
coarse aggregate.
In addition, other examples of concrete mixture
proportion used to produce the required strength of
concrete are 1: 3 : 6 , 1 : 1.5 : 3 and 1 : 4 : 8.
Water use in concrete mixture is based on
water/cement ratio which is it is a ratio of weight of
water to weight of cement. The chemical reaction
between cement and water causes concrete to
harden.
4. Preparing Wet Concrete.
Mix the cement with Pour clean water on Mix the mixture with
sand the mixture. the scoop.
Concrete are ready Mix the mixture with Add course aggregate
5. Concrete Test
Devide into 2 Test:-
i. Slump Test
ii. Cube Test.
Concrete Slump Test is a one of test that
usually conducted to measure
workability of fresh concrete.
Concrete Cube Test is a test conducted
to determine the strength of concrete.
6. Slump Test
Equipment And Material.
Frustum Steel Rod
Base Plate Steel Ruler
7. Slump Test
Procedures:
i. Place frustum on the base plate.
ii. Fill the wet concrete mixture in the cone in three
equal layers.
iii. Compact each layer 25 times using compacting
steel rod and the top surface is struck off by
means of a sawing and rolling motion of the
tamping rod.
iv. The cone is slowly lifted and observed the slump.
v. Invert the frustum and place it close to the
collapsed concrete.
vi. Measure and record the slump and type of slump.
vii. The slump can be measured as shown in the
figure.
8. Slump Test
Result.
-There are three types of slumps that can happen, which are
true slump, shear slump, and collapse slump as shown in figure
below.
Quality concrete is concrete which experiences true slump. True
slump happens because of its cohesiveness and rich mixes.
Rich mix is a mixture that has more cement content.
The shear slump happens due to inadequate mix. Inadequate
mix means a mixture which has less cement. Shear slump show
lack of cohesiveness in the concrete mix.
The collapse slump shows that the mix is too wet and produces
low quality concrete.
9. Cube Test
Instrument And Material.
Concrete cube mould of size Cube Mould
150mm or 100mm. It is used for
aggregate size of not greater than
40mm and 25mm. Cube mould for
test must be made from steel or
cast iron with smooth inner
surface. Every mould must have
steel plate to support and to Steel Rod
prevent leakage.
Compacting steel rod with 16mm
diameter and 600mm long.
Compression test machine.
Compression
10. Cube Test
Procedures.
Mould and base plate must be clean and applied with
oil to prevent concrete from sticking to the side of the
cube. Base plate is attached to the mould by using bolt
and nut.
Fill the cube with concrete in three layers.
Every layer must be compacted for 25 times. This
process is carried out systematically and compaction
is done uniformly to all surfaces of the concrete.
Compaction can also be conducted using machine.
The surface of concrete must be smoothen so it will
has the same level with the upper side of the mould.
Cubes which are made at construction site must be
covered with plastic cover for a period of 24 hours
before the moulds can be dismantled.
After remoulded, the concrete cubes are submerged in
water for curing.
Compression strength test must be carried out for
concrete at age 7, 14, and 28 days by using
compression test machine.
11. Cube Test
Result.
- The Strength value of each
cube must be recorded and
compared with the targeted
strength value. The
purpose of carrying out
concrete test on 7th day
and the 14th day is to
predict whether the
concrete could archive the
targeted 28th day strength.
In general, concrete would
have acquired 70%
strength on the 7th day.
12. Reference
Yusop Bin Paal, Werdah Binti Abdul
Halim, Sarifah Binti Daud. (Pengajian
Kejuruteraan Awam Tingkatan 4),DBP
Kuala Lumpur,2005.
Google Image Search.
http://en.wikipedia.org/wiki/Concrete_slu
mp_test.
Thank You.