Concrete mix designs is best defined as a process in selecting suitable ingredients, which is cement, aggregate, sand and water, and determining their relative proportions to give the required strength, workability and durability.  The mix designs, which is a performance specification stating required strength and minimum cement content but leaving the grading and details of the concrete mix design to be work out.

Objective of Concrete Mix Design

Concrete Mixer – Drum type 140L

Two main objectives for concrete mix design:

• To determine the proportions of concrete mix constituents of; Cement, Fine aggregate (or normally Sand), Coarse aggregate, and Water.
• To produce concrete of the specified properties.
• To produce a satisfactory of end product, such as beam, column or slab as economically as possible.

Theory of Mix Designs

The Process of Concrete Mix Design
The method of concrete mix design applied here is in accordance to the method published by the Department of Environment, United Kingdom (in year 1988).

There are two categories of initial information required:

1. Specified variables; the values that are usually found in specifications.
2. Additional information, the values normally available from the material supplier.

Reference data consists of published figures and tables is required to determine the design values including;

• Mix parameters such as target mean strength, water-cement ratio and concrete density.
• Unit proportions such as the weight of materials.

The design process can be divided into 5 primary stages. Each stage deals with a particular aspect of the concrete mix design:

Stage 1: Determining the Free Water/ Cement Ratio
i) Specify the required characteristic strength at a specified age, f_c
ii) Calculate the margin, M.

M = k x s     ….. [ F1 ]

where;
k = A value appropriate to the defect percentage permitted below the characteristic strength.  [ k = 1.64 for 5 % defect ]
s = The standard deviation (obtained from CCS 1).

CCS 1: Approximate compressive strength (N/mm2) of concrete mixes made with a free-water/cement ratio of 0.5

iii) Calculate the target mean strength, f_m

f_m =   f_c + M     ….. [ F2 ]

where;
f_m = Target mean strength
f_c = The specified characteristic strength

iv) Given the type of cement and aggregate, use the table of CCS 1 to obtain the compressive strength, at the specified age that corresponds to a free water/cement ratio of 0.5.

CCS 4: Relationship between compressive strength and free-water/ cement ratio.

v) In figure CCS 4, follow the ‘starting line’ to locate the curve which passes through the point (the compressive strength for water/cement ratio of 0.5). To obtain the required curve representing the strength, it is necessary to interpolate between the two curves in the figure. At the target mean strength draw horizontal line crossing the curve. From this point the required free water/cement ratio can be determined.

Stage 2: Determining the Free-Water Content

CCS 2: Approximate free-water contents (kg/m3) required to give various levels of workability.

Given the Concrete Slump or Vebe time, determine the free water content from table CCS 2.

Stage 3: Determining the Cement Content

Cement Content = Free Water Content / Free-water or Cement Ratio     ….. [ F3 ]

The resulting value should be checked against any maximum or minimum value that may be specified. If the calculated cement content from F3 is below a specified minimum, this minimum value must be adopted resulting in a reduced water/cement ratio and hence a higher strength than the target mean strength. If the calculated cement content is higher than a specified maximum, then the specified strength and workability simultaneously be met with the selected materials; try to change the type of cement, the type and maximum size of the aggregate.

Stage 4: Determining the Total Aggregate Content

This stage required the estimate of the density of fully compacted concrete which is obtained from figure CCS 5. This value depends upon the free-water content and the relative density of the combined aggregate in the saturated surface-dry condition. If no information is available regarding the relative density of the aggregate, an approximation can be made by assuming a value of 2.6 for un-crushed aggregate and 2.7 for crushed aggregate.

CCS 5: Estimated wet density of fully compacted concrete.

With the estimate of the density of the concrete the total aggregate content is calculated using equation F4:

Total Aggregate Content = D – C – W     ….. [ F4 ]

where;
D = The wet density of concrete ( in kg/m³)
C = The cement content (in kg/m³)
W = The free-water content (in kg/m³)

Stage 5: Determining of The Fine and Coarse Aggregate Contents

This stage involves deciding how much of the total aggregate should consist of materials smaller than 5 mm, i.e. the sand or fine aggregate content. The figure CCS 6 shows recommended values for the proportion of fine aggregate depending on the maximum size of aggregate, the workability level, the grading of the fine aggregate (defined by the percentage passing a 600 μm sieve) and the free-water/ cement ratio. The best proportion of fines to use in a given concrete mix design will depend on the shape of the particular aggregate, the grading and the usage of the concrete.

CCS 6: Recommended proportions of fine aggregate according to percentage passing a 600 μm sieve.

The final calculation, equation F5, to determine the fine and coarse aggregate is made using the proportion of fine aggregate obtained from figure CCS 6 and the total aggregate content derived from Stage 4.

Fine Aggregate Content = Total Aggregate Content x Proportion of Fines ….. [ F5 ]

Coarse Aggregate Content = Total Aggregate Content – Fine Aggregate

Procedures of Design Mixing

Production of Trial Mix Design

1. The volume of mix, which needs to make three cubes of size 100 mm is calculated. The volume of mix is sufficient to produce 3 numbers of cube and to carry out the concrete slump test.
2. The volume of mix is multiplied with the constituent contents obtained from the concrete mix design process to get the batch weights for the trial mix.
3. The mixing of concrete is according to the procedures given in laboratory guidelines.
4. Firstly, cement, fine and course aggregate are mixed in a mixer for 1 minute.
5. Then, water added and the cement, fine and course aggregate and water mixed approximately for another 1 minute.
6. When the mix is ready, the tests on mix are proceeding.

Slump Test apparatus for Concrete Workability

Tests on Trial Mix Design

1. The slump tests are conducted to determine the workability of fresh concrete.
2. Concrete is placed and compacted in three layers by a tamping rod with 25 times, in a firmly held slump cone. On the removal of the cone, the difference in height between the uppermost part of the slumped concrete and the upturned cone is recorded in mm as the slump.
3. Three cubes are prepared in 100 mm x 100 mm each. The cubes are cured before testing. The procedures for making and curing are as given in laboratory guidelines. Thinly coat the interior surfaces of the assembled mould with mould oil to prevent adhesion of concrete. Each mould filled with two layers of concrete, each layer tamped 25 times with a 25 mm square steel rod. The top surface finished with a trowel and the date of manufacturing is recorded in the surface of the concrete. The cubes are stored undisturbed for 24 hours at a temperature of 18 to 22⁰C and a relative humidity of not less than 90 %. The concrete all are covered with wet gunny sacks. After 24 hours, the mould is striped and the cubes are cured further by immersing them in water at temperature 19 to 21^oC until the testing date.
4. Compressive strength tests are conducted on the cubes at the age of 7 days. Then, the mean compressive strengths are calculated.

The Calculations

Here is one example of calculation from one of the concrete mix design obtained from the laboratory. We have to fill in all particulars in the concrete mix design form with some calculations…

CCS 3: Relationship between standard deviation and characteristic strength.

Firstly, we specified 30 N/mm² at 7 days for the characteristic strength. Then, we obtained the standard deviation, s from the figure CCS 3. So, s = 8 N/mm².

From the formula F1, k = 1.64 for 5 % defect. The margin, M is calculated as below:
M = k x s = 1.64 x 8 = 13.12 N/mm²

With the formula F2, target mean strength,  f_m is calculated as below:
Target mean strength, f_m = f_c + M
= 30 + 13.12 = 43.12 N/mm²

The type of cement is Ordinary Portland Cement (OPC). For the fine and course aggregate, the laboratory’s fine aggregate is un-crushed and for coarse aggregate is crushed before producing concrete.

Then, we obtain the free-water/ cement ratio from table CCS 1. For OPC ( 7 days ) using crushed aggregate, water/cement ratio = 36 N/mm².

After that, from the figure CCS 4, the curve for 42 N/mm² at 0.5 free-water ratio is plotted and obtained the free-water ratio is 0.45 at the target mean strength 43.12 N/mm².

Next, we specified the slump test for slump about 20 mm and the maximum aggregate size we used in laboratory is 10 mm. For the specified above, we can obtained the free-water content from table CCS 2 at slump 10 – 30 mm and maximum size aggregate 10 mm, the approximate free-water content for the un-crushed aggregates is 180 kg/m³ and for the crushed aggregates is 205 kg/m³. Because of the coarse and fine aggregates of different types are used, the free-water content is estimated by the expression:

Free-water Content, W
= ²/₃ W_f + ¹/₃ W_c
= (²/₃ x 180) + (¹/₃ x 205)
= 188.33 kg/m³

where,
W_f = Free-water content appropriate to type of fine aggregate
W_c = Free-water content appropriate to type of coarse aggregate

Cement content also can obtained from the calculation with the expression at F3:
Cement Content, C = Free Water Content / Free-water or Cement Ratio
= 188.33 / 0.45 = 418.52 kg/m³

We assumed that the relative density of aggregate (SDD) is 2.7. Then, from the figure CCS 5 with the free-water content 188.33 kg/m³, obtained that concrete density is 2450 kg/m³. The total aggregate content can be calculated by:

Total Aggregate Content = D – C – W
= 2450 – 418.52 – 188.33 = 1843.15 kg/m³

The percentage passing 600 μm sieve for the grading of fine aggregate is about 60 %. The proportion of the fine aggregate can be obtained from the figure CCS 6, which is 38 %. Then, the fine and course aggregate content can be obtained by calculation:

Fine Aggregate Content
= Total Aggregate Content x Proportion of Fines
= 1868.74 x 0.38 = 700.40 kg/m³

Coarse Aggregate Content = Total Aggregate Content – Fine Aggregate
= 1843.15 – 700.40 = 1142.75 kg/m³

The quantity per m³ can be obtained, which is;
Cement                                       = 418.52 kg
Water                                          =  188.33 kg
Fine aggregate                        =  700.40 kg
Coarse aggregate (10 mm)  =  1142.75 kg

The volume of trial mix for 3 cubes
= [(0.1 x 0.1 x 0.1) x 3] + [25% contingencies of trial mix volume]
= 0.006 + 0.00075
= 0.00375 m³

The quantities of trial mix = 0.00375 m³, in which is;
Cement                                      = 1.57 kg
Water                                         = 0.71 kg
Fine aggregate                       = 2.61 kg
Coarse aggregate (10 mm) = 4.29 kg

The Results of Mix Design

Slump Test = True Slump of 55 mm…

All the 3 concrete cubes produced were then cured for 7 days. After that, the compressive cube test is carried out. The results are as follows:

For cubes after 7 days of curing, compressive strength should not be less than 2/3 target mean strength.
= 2/3 × 43.12 = 28.75 N/mm² < 33.9 N/mm²

After 7 days of curing, the compressive strength of concrete cubes produced by the mix design method pass the specific strength requirements.

Discussions Upon Concrete Mix Designs

Although our compressive strength passes the specific requirements, we still identified several factors which contribute to the lacking of compressive strength of concrete mixes produced in the experiment. However, the main factor is the condition of aggregates whether it is exposed to sunlight or rainfall.

When the free water/cement ration is high, workability of concrete is improved. However, excessive water causes “honey-comb” effect in the concrete produced. The concrete cubes become porous, and hence its compressive strength is well below the design value. Other possible reasons include over compaction, improper mixing methods and some calculation errors.

Few suggestion upon several steps to avoid the problems previously faced:

• All the raw materials, which is cement, aggregates, and sand should be protected from precipitation or other elements which may affect its physical properties.
• The quantity of ingredients may be adjusted if necessary, theoretical values are not always suitable.  For example, if the aggregates are wet or saturated, less amount of water should be added, vice versa.
• Compaction should be done carefully, as either under or over-compaction will bring significant negative effect on the concrete produced.

The Conclusion

1. By using the concrete mix design method, we have calculated the quantities of all ingredients, that is water, cement, fine and coarse aggregate according to specified proportion.
2. The concrete produced did not fulfill the compressive strength requirements due to several reasons.  Furthermore, some steps mentioned above should be taken into consideration to overcome this problem.

Standard reference for the concrete mix design is as accordance to British Standard;
BS 5328: 1981 : Methods of Specifying Concrete including Ready-Mixed Concrete

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• The Facts About Concrete

For classification of soil for engineering purposes, we oath to know the distribution of the grain sizes in any given soil mass especially the one obtain from the construction site or burrow pits. Particle size distribution test, also know as sieve analysis test is a method used to determine the grain (granular) size distribution of soil samples.

The sieves are normally made of woven wires with square openings and steel body frame. It has different numbers which respect to the opening sizes. BS Sieve Aperture and ASTM Sieve Aperture sizes are mostly the same especially from 4.75 mm to 63 μm, and slightly different from 75 mm to 6.3 mm.

The Objective and Scope of Test

Stack of Sieve

The objective of this test is to determines the relative proportions of different granular sizes as they are passing through certain sieve sizes. Thus, the percentage of sand, gravel, silt and clay can be obtained from the sieve analysis test.

The sieve analysis (grain size analysis) is widely used in classification of soils. The data obtained from grain size distribution curves is used in the design of filters for earth dams and to determine suitability of soil for road/highway construction, embankment fill of dam, airport runway/taxiway, etc. The information that we obtained from sieving test could be used to predict soil water movement although permeability tests are more generally used.

The Technical Standards
The sieve analysis of soil test is accordance to ASTM D-422 (American Society for Testing and Materials) or BS 1377: Part 2 1990 (British Standards) as both are the most widely used technical standards in construction. The dry sieving of soil is the simplest and cheapest method among others.

The Required Apparatus

Sieve Analysis Apparatus: A) Sieve aperture sizes, B) Dry oven, C) Sieve shaker, D) Mortar & Tray, E) Rubber pestle, [F) Balance

• Stack of Sieve Aperture sizes (including the cover and pan)
• Electronic Balance (decimal reading to 0.01 g)
• Rubber pestle, mortar (for crushing the soil if lumped), and brush
• Mechanical sieve vibrator (shaker)
• Oven Dry (thermostatically controlled temperature)

The Test Procedure / Method
Here is how we going to do it:

1. Take out the dried soil samples from the oven dry and weighs about 500 g (normal amount used for any soil samples the greatest particle size of which is 4.75 mm).
2. The dried soil particles should be first crush (in lumped) using the rubber pestle and mortar.
3. Determine the mass of sample accurately and label as W_total (in g).
4. Then prepare a stack of sieve aperture sizes with larger opening sizes of sieve at the top (having lower number) and down to the last one with smaller opening sizes (having higher number). Not forgetting the sieve pan underneath and cover on top.
5. Weigh all sieves and the pan separately if necessary (mostly neglected).
6. Pour the soil slowly into the stack of sieves from the top and place the cover, put the stack onto the sieve shaker (vibrator), tighten the clamps, adjust the time within 5 to 10 minutes and turn it on…shake it baby…
7. When times out, take it out and measure the mass of each sieve aperture + retained soil inside, from the top sieve until the pan. This procedure should be done carefully…one by one…
8. Record down the weight in the result sheet and ready for calculation and plotting of graph.

The Calculations
Both calculation methods taken into account with an example of test sheet result:-

Calculation following BS 1377: Part 2 1990:

Calculation following ASTM D-422:

The Results Documentation
Draw graph of log sieve size vs % finer. The graph is known as grading curve. Corresponding to 10%, 30% and 60% finer, obtain diameters from graph these are D10, D30, D60, using these obtain Cc and Cu which further represent how well the soil is graded i.e whether the soil is well-graded, gap-graded or poorly graded.

The Graphs
Graph for BS 1377: Part 2 1990:

British Standard Sieve Sizes

Graph for ASTM D-422:

US Standard Sieve Sizes

Referring to the graph;
Uniformity Coefficient, C_u = D₆₀ / D₁₀ = 0.9 / 0.16 = 5.625

Coefficient of Gradation, C_c = (D₃₀)² / (D₆₀ x D₁₀) = (0.37)² / (0.9 x 0.16) = 0.95

Things to Remember

A few thing remember during the sieve analysis testing:

• Make sure the sieve aperture in dry condition and properly cleaned from any particles by poke them out using brush before commencing the test.
• Make sure to double check the stack of sieve aperture sizes arrangement in order before shaking begins.
• Make sure the balance have an adequate battery for a long run (if lots of soil sample to be test).
• The sieve shaker should be in good condition as well for a long run.
• The oven-dry and the balance calibration certificate still valid (haven’t due yet) for an accurate results.
• Do not shake the soil sample with the shaker for too long as the finer particles could easily lost. For more accurate results especially doing some research or independent lab test, manual approach is recommended.

The sieve analysis of soil test above is applicable not only to soil samples but can be tested upon aggregate, cement, and sand samples. The procedure would be the same as well as the calculation method and the graph plotting. The particle distribution test would eventually allows the grading of soil particles. Happy testing…

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• Phase Relationships of Soil
• How to Test Moisture Content of Soil
• 7 Info You Should Know About Soil.
• Introductory to Laboratory Testing of Soil

Moisture content (or water content) of soils measurement, both in the natural state and under defined test conditions could offer us an extremely useful information of classifying cohesive soils and of assessing their engineering properties. The moisture content of a soil is the characteristic which is most frequently determined, and applies to all types of soil.

The standard method for determining moisture content of soils is the oven-drying method, and it is the procedure recommended for soil laboratory testing. The technical standards that commonly used for testing in construction are BS1337: Part 2 1990 and ASTM D2216. It depends on contract specification upon the method to be used and I normally used the British Standards, but the procedures are mostly similar for both standards.

Water content of soil is defined as:

Test Method as accordance to BS1337: Part 2 1990;

Test Apparatus

Apparatus: Sample container, Electronic Balance and Oven-Dry

Basically only three apparatus required:

• Sample container(s) for putting soil samples.
• Electronic balance (readable until 0.01g) for sample weighing.
• Thermostatically controlled drying oven, maintained temperature at 105 to 110^oC.

Test Procedures

1. Weigh the container (an empty one) and record the weight – label as M1.
2. Select the soil sample for testing and put it in the container.
3. Weigh the soil together with the container, and record the weight again – label as M2.
4. Then put it in the oven and turn it on for drying for 24 hours to obtain a constant weight of dry soil sample.
5. Lastly weigh the dry samples (plus container) and record the last reading – label as M3.

The Calculations

• Mass of empty container           = M1
• Mass of wet soil + container     = M2
• Mass of dry soil + container     = M3
• Mass of moisture loss in soil     = M2 – M3
• Mass of dry soil                              = M3 – M1

Moisture content,

The Result Sheet
An example of test results:

Example of calculation, taking the container no. A1:
w = [(52.68 - 47.17) / (47.17 - 15.53)] x 100 % = 17.41 %
Average = (17.42 + 18.59 + 17.68) / 3 = 17.89 % of moisture content
Reported moisture content = 18 %

Things to Remember

• The soil samples took from the selected burrow pits or location should be test for its moisture content.
• Make sure to use dry container before putting the sample and enough for testing.
• Make sure the balance have an adequate battery for a long run (if lots of soil sample to be test).
• The oven-dry and the balance calibration certificate still valid (haven’t due yet) for an accurate results.

An Additional Info
The approximate mass of soil sample required for each main sample:

• Homogeneous clays and silts = 30 g (weigh to 0.01 g)
• Medium-grained soils = 300 g (weigh to 0.1 g)
• Coarse-grained (stony) soils = 3,000 g or 3 kg (weigh to 1 g)

Typical values of water content in a Saturated State:

• Loose uniform sand = 25 to 30 %
• Dense uniform sand = 12 to 16 %
• Loose angular-grained silty sand = 25 %
• Dense angular-grained silty sand = 15 %
• Stiff clay = 20 %
• Soft clay = 30 to 50 %
• Soft organic clay = 80 to 130 %
• Glacial till = 10 %

And that’s all about testing of soil moisture content pretty simple test that we could run. This is the first test that shall be conduct first upon the ‘fresh’ soil samples obtained from the site. There are other kinds of test but this is the most popular ones. Happy testing…

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• Phase Relationships of Soil
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• 7 Info You Should Know About Soil.
• Introductory to Laboratory Testing of Soil

Among all of material used for construction, soil stand as one of the most interesting yet complex material to study by testing via field or laboratory. The common knowledge of us as the Earth dwellers is that we are living on its surface and it is a must for understanding the 30% ground mass of our world. In engineering especially at construction site, almost all the man-made structures supported and in direct contact with our ground.

Soil has been the oldest construction material used by humankind, and is also the most plentiful. The youngest discipline of civil engineering, soil mechanics covers the investigation, description, classification, testing and analysis of soils to determine its inter-relation with structures built in or upon it, or built with it.

Soil in Site Investigation

Purposes of Soil Testing

The physical properties of soils are usually determined by carrying out tests on samples of soil in the laboratory, obtained from the selected site or burrow pits. These tests shall be divided into two main categories:

• Firstly the classification tests, which will indicates the general type of soil and the engineering category to which it will belong.
• Secondly, tests for the assessment of engineering properties, such as shear strength, compressibility and permeability.

The parameters determined from laboratory tests, taken together with descriptive data related to the soil example through observation; which required by soil engineers for many reasons. The more usual applications are as follows:

• The acquired data from classification tests are applied to the identification of soil strata (profile) when the subsurface conditions of a site are being investigated through the process called site investigation.
• Other test data enable the soil engineering properties to be qualified in numerical terms, which can then be used as the basic of analysis on which the recommendations os the investigation report are based.
• Test data maybe used for the confirmation of assumptions which have been based on the previous experience and engineering judgments.
• The acceptance criteria of a soil used in construction can be drawn up in the light of available test results (most probably after the operation events).
• Laboratory tests are needed as part of the control measures which later be applied in construction of earthworks (cut and fill) or excavation works, especially for ensuring that the design criteria are met.
• The findings of site investigation can be supplemented by further testing as construction proceeds, as, for instance, when new ground is being opened up.

Advantages of Laboratory Testing

During the field operations known as site investigation as prime importance for any construction projects, where the studies of the geology and history of the site, subsurface exploration and in-situ testing. The determination of the ground characteristics by in-situ testing can be take into account of large-scale, such as soil fabric, structure and discontinuities of strata, which cannot be represented in small laboratory specimens. Nevertheless the measurement of soil properties by means of laboratory tests offers a number of advantages, as follows:

• Full control of the test conditions, including boundary conditions, can be exercised,
• Control cab be also exercised over the choice of material which is to be tested,
• Laboratory testing generally permits a greater degree of accuracy of measurements than doing it on field (at in-situ),
• A test can be conduct under conditions which are similar to, or which differ from, those prevailing in-situ, as maybe appropriate,
• Any changes in conditions can be stimulated, as it will most likely to occur during or after completion of construction,
• Tests can be carried out on soils which have been broken down and reconstituted, or processed in the other ways.

The Scope of Soil Laboratory Testing

The General Applications

During the past decades of evaluating the properties of soil from reliable test procedures has led to a closer understanding of the nature and probable behavior of soils as civil engineering number one materials. Some of the resulting benefits in the realm of civil engineering construction have been:

• Reduction of uncertainties in the analysis of foundations and earthworks,
• Economies in design due to the use of lower factors of safety,
• Exploitation of difficult and complex sites,
• Erection of structures and below ground level construction which would not have been feasible without this essential knowledge,
• Increased economy in the use of soils as construction materials, examples like in earth dams and embankment fills of roads, and so forth.

In soil testing, as in all laboratory work, it is necessary to take measurements of different kinds and to record it. Instruments used for making measurements of various kind are listed first. We will cover a lot more in another session of soil laboratory testing and until then take care…

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• Phase Relationships of Soil
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• 7 Info You Should Know About Soil.

The basic materials used in civil engineering application or in construction projects are aggregate, Portland cement, concrete, timber or wood, reinforced metal or steel, structural clay (brick), bitumen and polymer. The common properties of engineering or construction materials are physical, mechanical and chemical properties.

Purpose of Testing Materials
Every materials shall be tested before using it in any construction works. Reasoning of testing construction materials as follows:

• Required for any construction project at preliminary stage, on-going progress works, at completion stage, and during maintenance period.
• To make sure the cost-effective in utilizing materials and factor of safety guaranteed upon test achievement.
• Testing specification and guidelines are met as accordance to technical standards requirements; example technical manuals like British Standard or ASTM.
• Testing of construction materials becomes one of project benchmark in terms of quality control assurance.
• To make sure the durability and longevity of the constructed structures could be achieved and maintain.
• To prevent any possible damage or defect to the structure at early stage before completion.
• And so forth…

Materials Physical Properties

Physical Test of Materials

Density – Defined as an objects mass (property) per unit volume or physical property of matter; solid, liquid and gas. Compaction would be soil and bitumen usual testing method whereby optimum moisture content and maximum dry density as an outcome of test. Density also becomes timber or wood an important property.

Porosity – A measure or percentage of the void spaces (pore volumes) in a material such as soil, aggregate, concrete, and etc. There are several methods can be employed to measure porosity; namely as water evaporation, direct methods, gas expansion, mercury intrusion porosimetry, and optical methods.

Moisture Content – Materials contained certain percentage or quantity of water inside; materials such as soil, aggregate, timber and bitumen. The commonly used method to determine it is based on removing soil moisture by oven-drying a soil sample until the weight remains constant.

Specific Gravity – Defined as a substance comparison (ratio) of its density to that of water or relative density with respect to water. It can be measure within three general forms – in liquids, solids and gases form. It can theoretically be used to describe any type of matter, but in practice it’s typically used only for liquids (measurement using a hydrometer) and dimensionless unit.

Permeability – A capacity or ability measurement of a porous material for transmitting a fluid. Materials like aggregate and soil which having a certain cross-section and thickness under given pressure, measured using Darcy’s Law or by empirical derived formulas. It can be measure by using constant head method for soil (with water) or determination of the coefficient of specific permeability for the flow of air through rocks.

Texture and Color – Texture, the distinctive physical composition or structure of substances, especially with respect to the size, shape, and arrangement of its structures. This can be done by simply using our hands via touching whereby soft or hard as a result. Color on the other hand, means the visual perceptual property corresponding in our natural judgment to the categories called green, blue, red, yellow,  and so forth.

Shape and Size – Shape defines as the characteristic surface configuration of an object (an outline or contour) and size defines as the physical dimensions, proportions, magnitude, or extent of an object. Grading of aggregate by sieve analysis method refers to the process of dividing a sample of aggregate into fractions of same particle size. Shapes of aggregate could be rough textured, angular, or elongated.

Soundness – It refers to the ability of the cement paste to retain its volume after setting, and is related to the presence of excessive amounts of free lime or magnesia in the cement or supplementary cementitious material. Soundness of cement is determined by Le-Chatelier method.

Materials Mechanical Properties

Mechanical Test of Materials

Compressive Strength – Defines as the capacity of a material to withstand axially directed pushing forces whereby the material will crushed when the limit of compressive strength is reached. The mechanical test measuring the maximum amount of compressive load a material can bear before fracturing. The test piece, usually in the form of a cube, prism, or cylinder, is compressed between the platen of a compression-testing machine by a gradually applied load. Materials used for testing are normally aggregate, cement, concrete, timber, brick, and etc.

Brittle – A material is brittle if it is liable to fracture when subjected to stress and has little tendency to deform (or strain) before fracture. This fracture would absorb relatively little energy, even in materials of high strength, and usually makes a snapping ‘pop’ sound especially tested against metal or steel.

Ductility – The ductility of a metal is the property that allows it to be stretched or otherwise changed in shape without breaking and to retain the changed shape after the load has been removed. The ductility of a metal can be determined from the tensile test and it is done by determining the percent of elongation.

Materials Chemical Properties

Chemical Test of Materials

Chemical Reaction – Process which respect to the reaction of two or more elements together results in the formation of a chemical bond between atoms and the formation of a chemical compound. Water is the key ingredient, which when mixed with cement, forms a paste that binds the aggregate together whereas causes the hardening of concrete through a process called hydration. Hydration is a chemical reaction in which the major compounds in cement form chemical bonds with water molecules and become hydrates or hydration products.

Chemical Composition – Defines as the unit cell of any substance will contain one or integral multiple of chemical formula units and the formulas of minerals are based on the relationship to unit cell volume and the positions of atoms within the unit cell.s an example, the composition of cement is varied depending on the application which typically contains C3S (Tricalcium silicate),  C2S (Dicalcium silicate), C3A (Tricalcium aluminate), and C4AF (Tetracalcium aluminoferrite).

Natural Attributes – The natural attributes of materials also important in chemical properties – acid, alkali, or neutral.

In conclusion, testing construction materials is a must for every civil engineering projects and the results we obtained from the experiments shall becomes the construction index guidelines.

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• No Relevant Materials Yet…