Construction Materials and Testing (LECTURE)

Construction materials have an important role to play in this modern age of technology. Although their most important use is in construction activities, no field of engineering is conceivable without their use. Therefore, the construction materials industry is an important contributor in national economy as it its output governs both the rate and quality of construction work.

At the end of the course, the students should be able to:

CLO1. Discuss relevant properties of common construction materials.

INTRODUCTION TO CONSTRUCTION MATERIALS AND TESTING

Construction material is an item, material or supply consumed or used in a construction project and incorporated in the constructed building or structure. On the other hand, material testing refers to the measurement of the characteristics and behavior of materials to be used in specifying the suitability of materials to various applications.

There are certain general factors which affect the choice of materials for a particular scheme. Perhaps the most important of these is the climatic background. Obviously, different materials and forms of construction have developed in different parts of the world as a result of climatic differences. Another factor is the economic aspect of the choice of materials. The rapid advance of constructional methods, the increasing introduction of mechanical tools and plants, and changes in the organisation of the building industry may appreciably influence the choice of materials.

Listed below are the construction materials widely used in the building industry:

AGGREGATES

A broad category of coarse to medium-grained particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Aggregates are the most mined materials in the world.

CONCRETE

Concrete is composed of cement, fine aggregates and coarse aggregates mixed with water which hardens with time.

CEMENT

A finely milled mineral powder, usually grey in colour. Mixed with water, cement serves as an adhesive to bind sand, gravel, and hard rock in concrete

WOOD

Wood pieces are machine-planed and cut into standard dimensions, such as 2”x4” and 2”x6,” so that their measurements can be accurately factored into building plans. It has been used as a building material for thousands of years.

CONCRETE HOLLOW BLOCKS

A type of concrete block used for building internal and external walls.

STEEL REINFORCEMENTS

Steel bars that are provided in combination with plain cement concrete to make it reinforced concrete.

BITUMEN

A black viscous mixture of hydrocarbons obtained naturally or as a residue from petroleum distillation. It is used for road surfacing and roofing

STANDARD SETTING AGENCIES

AMERICAN SOCIETY FOR TESTING AND MATERIALS (astm) INTERNATIONAL

A private organization that establishes specifications for materials and methods of construction accepted as standards throughout the United States.

AMERICAN ASSOCIATION OF STATE HIGHWAYS AND TRANSPORtATION OFFICIALS (aashto)

A standard setting body which publishes specifications, test protocols, and guidelines that are used in highway design and construction throughout the United States.

Listed below are some of the apparatus and equipment used in material testing

SIEVE SET

A device for separating wanted elements from unwanted materials or for characterizing the particle size distribution of a sample

BALANCE

Measures the mass of construction materials

SLUMP CONE

A metal mold with a top diameter of 4”, a bottom diameter of 8” and a height of 12”. It has a 2ft long bullet nosed metal. It is used for a slump test

VARIOUS MOULDS

It is used to measure the specific gravity of liquids.

HYDROMETER

Used to measure the specific gravity of liquids.

UNIVERSAL TESTING MACHINE

Designed that it is capable of exerting tensile, compressive or traverse stress on a specimen. Further, it can also determine ductility, cold bend and other properties. It consists of a loading unit and a control panel

CONCRETE MIXER

A device that homogeneously combines cement, aggregates, and water to form concrete. It can be mobile or stationary mixers

VIBRATOR

A mechanical device to generate vibrators

VICAT APPARATUS

Used to find out consistency and initial and final setting time of concrete.

ELECTRIC OVEN

Ovens for high-forced volume thermal convection applications. Typical sizes are from 1-32 cu. ft. with temperatures that can be over 340 degrees Celsius.

GENERAL PROPERTIES OF MATERIALS

The specific properties of construction materials serve as a basis for subdividing them into separate groups. Thus, the principal properties of construction materials predetermine their applications. Only a comprehensive knowledge of the properties of materials allows a rational choice of materials for specific service conditions.

CENG114 Module1 Part II (1).pdf

PHYSICAL PROPERTIES

Physical properties are those properties required to estimate the quality and condition of material without any external force.

MECHANICAL PROPERTIES

The mechanical properties of materials are determined by the application of external forces to them. These are very important properties that are responsible for the behavior of the material during its operation.

AGGREGATE TEST SAMPLING

Aggregates Test Sampling (1).pdf

what is an aggregate?

Aggregates are the materials basically used as filler with binding material in the production of mortar and concrete. They are derived from igneous, sedimentary and metamorphic rocks or manufactured from blast furnace slag, etc. Aggregates form the body of the concrete, reduce the shrinkage and effect economy. They occupy 70-80 per cent of the volume and have considerable influence on the properties of the concrete. It is therefore significantly important to obtain right type and quality of aggregates at site. They should be clean, hard, strong, durable and graded in size to achieve utmost economy from the paste.

According to size aggregates are classified as coarse aggregate or fine aggregate

Coarse Aggregate - Aggregate retained on 4.75 mm sieve are identified as coarse. They are obtained by natural disintegration or by artificial crushing of rocks. The maximum size of aggregate can be 80 mm. The size is governed by the thickness of section, spacing of reinforcement, clear cover, mixing, handling and placing methods. For economy the maximum size should be as large as possible but not more than one-fourth of the minimum thickness of the member. For reinforced sections the maximum size should be at least 5 mm less than the clear spacing between the reinforcement and also at least 5 mm less than the clear cover. Aggregate more than 20 mm size are seldom used for reinforced cement concrete structural members.

2.Fine Aggregate - Aggregate passing through 4.75 mm sieve are defined as fine. They may be natural sand—deposited by rivers, crushed stone sand—obtained by crushing stones and crushed gravel sand. The smallest size of fine aggregate (sand) is 0.06 mm. Depending upon the particle size, fine aggregates are described as fine, medium and coarse sands. On the basis of particle size distribution, the fine aggregates are classed into four zones; the grading zones being progressively finer from grading zone I to grading zone IV

SPECIFIC WEIGHT AND WATER ABSORPTION

specific weight

The bulk density or unit weight of an aggregate is the mass or weight of the aggregate required to fill a container of a specified unit volume. The volume referred to here is that occupied by both aggregates and the voids between aggregate particles.

Specific Weight and Water Absorption (1).pdf

The most common classification of aggregates on the basis of bulk specific gravity is lightweight, normal-weight, and heavyweight aggregates. In normal concrete the aggregate weighs 1,520 – 1,680 kg/m3, but occasionally designs require either lightweight or heavyweight concrete. Lightweight concrete contains aggregate that is natural or synthetic which weighs less than 1,100 kg/m3and heavyweight concrete contains aggregates that are natural or synthetic which weigh more than 2080 kg/m3.

WATER ABSORPTION

It is used to determine the amount of water absorbed under specified conditions. The water absorption test uses to find the water holding capacity of the aggregates.
The water is absorbed by the aggregates or stones in their pores known as water absorption. Usually, water absorption gives an idea about the strength of the aggregates. That aggregate has more water absorption and is usually unsuitable for the construction.

ABRASION, DENSITY, AND UNIFORMITY OF AGGREGATES

Abrasion, Density and Uniformity of Aggregates (1).pdf

Abrasion Test on Aggregates

It is the measure of Aggregate Toughness and abrasion resistance such as Crushing, Degradation and Disintegration. The aggregate used in surface course of the highway pavements are subjected to wearing due to movement of traffic.

DENSITY OF Aggregates

Gravel

Loose 1600 kg/m3

Undisturbed 1920-2160 kg/m3

Riprap 1280-1440 kg/m3

Granite 2630-2760 kg/m3

Brick Ballast 1200 kg/m3

2. Coarse Sand

Dry Clean 1540-1600 kg/m3

River 1840 kg/m3

Wet 1760-2000 kg/m3

3. Fine Sand

Dry Sand 1600 kg/m3

Saturated Sand 2080 kg/m3

UNIFORMITY OF Aggregates

Fine modulus (FM) is used to determine the degree of uniformity of the aggregate gradation. It is empirical number relating to the fineness of the aggregate. Fineness Modulus is defined as the sum of the cumulative percentages retained on a specific sieved divided by 100.

SYNCHRONOUS CLASSES CONDUCTED

Introduction and Familiarization with Apparatus.mp4

Properties of Materials Part2 .mp4

Properties of Materials Part1.mp4

Abrasion, Density and Uniformity of Aggregates.mp4

CLASSWORK:

Classwork #1 (CENG114)_BARTOLOME.pdf

Lab Report 3_BARTOLOME (1).pdf

REFLECTION:

The lectures and modules uploaded on this subject helped me understand the physical and mechanical properties of construction materials. Understanding the nature and properties enable us, especially civil engineers to perform incredible feats in the construction materials industry and advance them thereby pushing the boundaries of material science and ensure structural integrity that will last for a longer period. This is because civil engineers are often responsible for specifying, designing, and manufacturing the materials which structures are built with. Studies in construction materials are intended to make civil engineers aware of the fundamental properties of the materials they use. Also, this subject allowed me to realize the importance of making laboratory reports for every material test conducted. This is to ensure that the guidelines being set by standard-setting agencies are strictly followed. Lastly, I have learned that the equipment used in material testing are important for they provide the necessary information about the tested materials. Thus, the data collected during testing and the final test results can be very useful to engineers. It can be used to meet additional requirements for regulatory agencies, select appropriate materials for its end-application, verify the production process of materials, and evaluate if the material meets the minimum criteria or specifications that are set by ASTM or AASHTO standards.

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