Types Of Rocks And Their Mechanical Properties For Construction

Igneous Rocks

1. Three basic kinds of rock

Rocks are naturally occurring coherent aggregate minerals in a combination of one of more minerals. Rocks can also be described as the aggregate constituents or basic solid constituent of earth and it generally categorized into three different classes based on their formation processes. The three main classes of rocks are sedimentary rocks, igneous rocks and metamorphic rocks.  

Igneous rocks – These are the rocks that are formed from the solidified magma. The texture of these rocks is determined by the cooling rate of the hot magma. For instance, igneous rocks with large crystals are formed from slowly cooling magma while those with fine-grained crystals are through quickly cooling magma. Igneous rocks are composed of a silicon-oxygen mixture fortified with potash and soda. Example of igneous rocks include diabase, diorite, and granite which is extensively used in building construction and statues.

Sedimentary Rocks – Are rocks formed from the fragments of the preexisting rocks or from particles precipitation materials from water that accumulate into layers over time to form a solid rock. Chemical weathering reaches the earth’s surface, hardening exposed sediments, resulting in sedimentary rocks. Examples include limestone, and sandstone are the main types used in construction projects.

Metamorphic rocks – These are rocks that are formed when existing rocks change to other forms due to pressure, heat, or active fluids such as mineral laden (hot) water. When igneous or sedimentary rocks are subjected to either heat or pressure over time they might transform to metamorphic rocks. Examples include Manhattan Schist, gneiss and slate.

1. The usage of the rocks in building construction.

• Igneous rocks, premium pillars, and buildings are granite, an igneous rock found on the continental crust.
• Sedimentary rocks; one of the numerous raw goods used in a building is sand, which is contained in sedimentary rocks.Sand is used to making strong slabs and build critical infrastructure such as roadways. Further, sorting and classification are always done by researchers to obtain the best quality of sedimentary rocks (sand) (Siebach et al., 2017).
• Metamorphic rocks are the most substantial rocks on the planet. Quartz is one of these materials, and it’s utilized to build permanent rails that are both strong and indestructible.

Heating crystals at extreme temperatures to become molten and cooling them; they produce other substance as per the Bowen reaction sequence. As a result, weathering properties of rocks may be noticed, as metamorphic minerals dissolve when heated to high temperatures, while igneous rocks develop during the cooling phase. The Bowen reaction series also illustrates how high temperatures affect rock formation. Mafic minerals, including iron and magnesium, are produced at high temperatures. In contrast, felsic minerals, which contain silicon and oxygen and are formed at low temperatures, are included. The chemical disintegration of rocks on the earth’s surface is referred to as weathering qualities of rocks. Consequently, the weathering processes and Bowen’s reaction series are linked since they create warmth, essential for change.

• As a foundation for a road

Rocks’ mechanical qualities offer a sturdy and robust foundation for road construction. These mechanical properties enable high-mechanical-property rocks to be used to build long-term structures such as roadways.

• As a structural element

The requirement for construction rocks and the density and hardness of rocks used in building construction is determined by the mechanical properties of rocks. These features also impact how long rocks will last and how they will degrade over time when weathering chemicals break down.

• It may be used as a concrete aggregate.

Concrete’s mechanical qualities influence how strong it can be. Mechanical aggregate features improve the strength of concrete. On the other hand, understanding how the mechanical properties of rocks aggregate can help you estimate and determine the strength of existing concrete.

• As construction materials

The mechanical properties of building stones determine material characteristics such as density, hardness, and strength. As a result of weathering, the durability of building stones deteriorates with time. As a consequence, building stones must be stable and long-lasting.

Sedimentary Rocks

Dirt is used to make the bulk of construction materials, such as cement. Furthermore, the soil is essential for obtaining construction materials such as roofs, furniture, and timbers. On the other hand, materials like soil and rocks play a vital role in dam building. Dam builders must use durable materials like sand soil to keep dams on large bodies of water in place. Water may now flow into and through the dam. On the other hand, the connection between soil and dam is undeniably strong.

In contrast to quarry materials, which are intact and discontinuous, the rock mass is often continuous, and robust building rocks are utilized in engineering extractions.

Compared to quarry materials, the strength of rock mass tends to deteriorate with time. Furthermore, if a rock mass breaks apart, its power is significantly affected. However, quarry materials are constantly discontinuous and maintain their strength. The strength of rock mass is high compared to the same materials obtained directly from quarry because rock materials are more intact with discontinuities thus represent hard pieces of drill core. Due to these reasons, rocks and stones are preferred in the foundation construction of medium and high-rise structures. Quarry materials are majorly the by-products released from crushing and cutting processes therefore are fine particles and can alternatively use in construction but not in applications that require higher strength like foundation construction.

Rock-quality designation is a rough measure used in the determination of core recovery percentage of rock chunks. It is useful in the strength analysis on rocks, especially in the evaluation of the degree of fracture or jointing in rock mass, expressed in percentage of the drill core. It also enable geologists to assess the soundness of the rock as well as establishing the various damages the rock endured during weathering processes.  

RQD is an important test in construction as it is often used to evaluate the critical parameters of rocks such as quality of rocks, depth and degree of weathering, zones of fracturing and weakness therefore informing the area of application in the construction project.  

 The solution with the highest strength, in this example, quarry materials, should extend perpendicularly, whereas the rock mass with the lowest strength should stretch parallel.

Because they entail random dispersion of rocks from tunnel block connections, discontinuities in the rock form are among the most critical challenges in excavating (Ashcroft & Munro 1978). Discontinuities may appear when rock masses are separated into distinct portions by ordering and bedding joints in diverse directions (Armstrong 1978). In addition, rock block instability may result in rock mass discontinuities (Rock mass characterization 2014).

Brownfield refers to land, site, property that had been in use once for industrial purposes but was vacated and now remain or lie idle and mostly considered hazardous due to presence of concentration of hazardous chemicals. In other words, brownfields site is a real property, redevelopment, the expansion or a complicated reuse characterized by presence of pollutants, hazardous substances or contaminants. The difference between brownfield sites and other sites is the safety concerns.

Metamorphic Rocks

A brownfield site is an abandoned building or piece of land that humans do not utilize because it contains harmful pollutants that might spread infectious diseases if they encounter people.  In addition, the other locations differ from brownfield sites and are therefore utilized for commercial purposes, for example, to house industrial projects and constructions. However, some barriers hinder the redevelopment of these fields in developing countries, for instance, lack of technology (Ahmad et al. 2019).

• First and foremost, you should be aware that a brownfield site has previously been populated and contaminated, which may impact your health.

You’ll need to get your hands on a brownfield ground calculator. 

This calculator will aid you in determining the amount of risk and the potential losses associated with certain risks.

• A survey of other land sites will be more superficial since, unlike brownfield sites, these areas have not been occupied and hence are not contaminated.

The ground calculator will not be relevant or required in this situation.

A touched soil sample absences the original soil features, rendering it impossible for personnel to return it to its original location. Also, untouched soil samples are easier to get, and samplers can acquire them at any time since they know where to look.

Collecting disturbed soil samples is simple since there are on specified locations; however, collecting undisturbed soil samples is more difficult because they are acquired from a specific site (origin).

Engineers can more easily determine the composition and strength of undisturbed soil samples, making it simpler to identify brownfield sites; it is not present in disturbed soil samples.

• The engineers will first dig a 400mm deep hole using drill rig equipment to remove the earth.
• Then a sample of dirt is extracted by the sampler from the hole and placed in a
• hygienic, moistened container, which they will transport to the lab for analysis.
• Then the sample will be kept in a freezer for 24 hours in the laboratory.
• The engineer will study the composition of soil particles after the freezing procedure using a microscope.
• Finally, when the findings are available, the engineer will record them.

An important aspect of undisturbed soil samples is that after in-situ tests, they often retain their mechanical properties and structural integrity and also exhibit higher rates of recovery from the sampler. However, the challenge with this test is the collection of undisturbed soil sample, in some cases the undisturbed soil samples can be obtained at the top and bottom of the sample length. Undisturbed soil tests are most preferred by engineers as it allows the evaluation of several geotechnical properties like compressibility, strength, fracture and permeability among other properties. Tools like long split-spoon, pitch barrel and piston samplers are often used in the collection of the undisturbed soil samples.

The Classification Of Soil Is Wide And Is Often Considered On The Basis Of Chemical And Physical Properties Their Horizons Other Parameters Or Properties Used in classification of soils are soil texture, color, and soil structure. Soil are broadly classified as Sandy, Clay, loam and Silt soil.

Soils are classed based on the size and texture of the soil particles. 

• Clay soil- it is damp soil made containing microscopic particles.
• Sandy soil- contains rough textures and particles and visible particles. They also consist of small particles of weathered rocks. It is has the lowest nutrient content and poor water holding capacity, thus does not support agriculture
• Silt soil- have both properties of sand and clay soil. However, silt has finer and smaller particles than sandy soil and it has better water holding capacity than sand. It is most fertile soil thus can support agriculture.
• Loam soil – It is generally a combination of silt, clay and sand soil hence it is a combination of the benefits of the three types of soils. It’s more suitable for farming because of high nutrient contents and water holding ability.

During the categorization process, plasticity is utilized to increase the compressibility of each soil particle. Engineers also use plasticity to assess how much water a soil can store and how that water will drain.

Plasticity or plastic limits of soil sample is measured by rolling out a thread of the course or fine soil on a non-porous flat surface and the laboratory procedure of the plasticity evaluation is outlined the ASTM D 4318. However, precaution is given when the soil to be tested has moisture content it is recommended that the soil samples be dried by heating over hot plate for few minutes before subjecting to plasticity tests. It is worth to note that as the moisture content in the soil sample reduces or falls in due to heating effect, the thread begins to disjoint at larger diameters.

In situ soil sampling uses the same processes as undisturbed soil sampling. The engineer dug the hole using drilling equipment to gather the in-depth sandy soil with a shear strength of roughly 3.0g/cm. Also, the soil is clean and pollution-free due to its big particles; next, they’ll add some water and close the sample container entirely. Engineers will provide detailed examples of the outcomes of the sample obtained after inspections and laboratory tests.

Mechanical Properties of Rocks for Construction

The benefits of in-situ testing and laboratory testing.

Situ testing has many advantages because researchers have developed adverse procedures, making the testing too easy (Yihdego 2016). Also, it makes it simpler for samplers since they will save energy and time if they know where to get certain soil samples.  In addition, situ testing motivates engineers to do additional tests, which is simple since samples may be collected anywhere, they wish. In situ testing improves efficiency and accountability by requiring less time to gather samples from their source. Further, when a certain kind of soil is readily accessible, it is highly straightforward for engineers to collect significant samples for laboratory testing.

The advantage of laboratory soil test is on the accuracy and the reliability of the results obtained. For instance, due to the use of high quality and high precision equipment and tools thus giving the more accurate outcomes compared to the in-situ test methods. However, the challenge with this methods is that the technology keeps evolving and when new technique or machine is introduced the practical knowledge on how to handle and operate becomes a challenge.

Another advantage or reasons for considering in-situ testing method on samples it allows continuous evaluation of the soil profile in stratigraphy for the geotechnical properties of the sample can be easily obtained. The in-situ tests can also be conducted on soils samples that are either difficult or impossible to sample without the aid of expensive specialized tools and approaches. And lastly large volume of soil samples can be tested for various properties concurrently unlike in laboratory test where one test has to complete to leave way for another test.  

An individual needs two to three cups of soil to do a soil test. Small sample size may provide erroneous findings and include avoidable mistakes. On the other hand, the excessive sample size might introduce hazards, leading to uncertainty.

1. In situ sample.

• Soil moisture content

Divide the soil sample into two half to assess the moisture content. Then put one of the halves in a plastic bag. Then bind it with a thread and lay it in the sunlight for approximately 8 hours till it becomes simple to carry than the initial one. After completing the technique, you will see water droplets inside the plastic bag. The quantity of water a researcher collects throughout the experiment is utilized to define the soil’s moisture content.

• Bulk density

It refers to how much weight is contained in a given amount of soil. The measuring unit is G/cm. The bulk density is high in the sand because it is buried deeply.

• Specific gravity

The metric assists in determining the soil’s quality. A researcher needs a clean and dry density bottle. 15gm of completely dry soil and 5-10 ml of water is added into the density bottle then the soil is allowed to absorb the liquid thoroughly. Take the bottle outside after some time has elapsed and weighed it.

A cone penetrometer test procedure may be used to analyze the geotechnical and shear strength properties of a certain kind of soil in situ. It is an experimental method for determining materials’ density and shear strength in situ. In a laboratory environment, shear strength is also tested. A lab test is conducted by organizing numerous samples taken from in situ sites to decrease the doubts and mistakes if shear strength testing is done straight. Though shear strength testing is more advantageous, there are still a few downsides, especially for those who perform the test.

• When evaluating the shear strength of sandy soil, for example, samplers find it difficult to regulate or eliminate undesired water owing to its poor drainage qualities, which may contribute to errors in sample findings.

Rock Quality Designation (RQD)

 Laboratory testing is one of the easiest methods for assessing soil compressibility. On the other hand, limited compression testing performed by samplers may be more accurate and timely. The sample is placed in a sealed cylinder to improve the stress of unsettled compression strength, which raises water heights in the soil samples and allows the sampler to produce conclusions more rapidly. Almost everything improves its functional features as time passes. It may also be seen in the sample testing methods. Initially, a sampler may make a mistake, but practice will make the results more faultless and precise. Furthermore, obtaining exact results from the limited compression test takes along. Consequently, there is a high link between the test methodologies for determining soil compressibility and time, which is maintained.

The purpose of this testing is to enable engineers to identify, distinguish, and classify natural components in various kinds of uninterrupted soil samples based on their quality. Further, incorporation of parametric and non-parametric models makes the test more efficient (Farias González & Araujo et al. 2018). Also, more crucially, they behave when exposed to fluid substances during geotechnical activities.

The liquid limit is assessed when the researcher can distinguish between different soil kinds depending on how they respond to a specific quantity of water. Although, salinity affects the liquid limit of soils (Ying et al. 2010). The researcher can use the water limit machine to identify the quantity of liquid while doing the tests. The wet plastic soil is rolled out frequently when the plastic limit is reached during the trial. The presence of moistures in plastic soil is characterized as the plastic limit. Every test, however, must have a result, whether it is the best or the worst. The engineer seeks to ascertain whether the soil’s nature will change by measuring liquid and plastic restrictions because a considerable volume of water might create unexpected outcomes at the end of your testing procedures.

3.46-10.58=-7.12; therefore,

 -7.12*100=-712%

-712/3.46=-206%

-6.85/3.86*100= -177.5%

-7.3/4.49*100= -163%

-8.03/3.94*100=-204%

-4.64/5.93*100 =-78.25%

Liquid limit

15/25=0.6

0.6^0.121 =0.94

0.94* (-206%) =-1.9364

19/25=0.76

0.76^0.121 =0.97

0.97*-177.5% =-1.72175

21/25=0.84

0.84^0.121=0.98

0.98*-163%=-1.5974

26/25=1.04

1.04^0.121=1.004; 1.004*-204%=-2.0502

19/25=0.76

0.76^0.121=0.97

0.97*(-177.5%) =-1.72175

Plastic Limit

3.34/10.58=036; 0.36*100=36%

3.86/10.71=0.36; 0.36*100=36%

4.49/11.79*100= 38%

3.9/11.97*100=33%

5.93/10.57*100=56%

Cone penetration (mm)	Moisture content (g)	Mass of dry soil (g)	Moisture %	Liquid Limit	Plastic limit
15	3.46	10.58	-206%	-1.9364	36%
19	3.86	10.71	-177.5%	-1.72175	36%
21	4.49	11.79	-163%	-1.5974	38%
26	3.94	11.97	-204%	-2.0502	33%
31	5.93	10.57	-78.25%	-0.8060	56%

The repeatability and reliability of the liquid limit are less than the plastic limit. The researcher has a high chance of making errors when determining the liquid limit than the plastic limit.

Produce design proposals to address geotechnical problems related to embankments, bridge and road foundations for a given site. 

1.Construction of embarkments, bridge and road foundations require maximum strength and this can be attained through use of high strength materials, proper construction techniques, machines and equipment. The organization and coordination of these items also requires proper planning among other logistic arrangements. Therefore before staring on these projects the contractor has to make logistic arrangement on how to acquire the best materials, required equipment and machines and how they are supplied to site on time before the commencement of construction projects.

1. The study of sea levels rise and fall in reaction to the sun and moon and earth’s revolution is known as tides. High tides will keep the logistic areas dry by making them less flexible. The earth’s circles and objects may get lost over time. When high waves and strong winds coincide, however, aquatic animals are more likely to be injured, perhaps leading to the death of a huge number of them. High tides may create widespread destruction, such as floods, killing many people and restricting the flow of goods that depend on water transportation.

At the most significant tides, engineers will be limited in their capacity to apply geotechnical ideas to technological issues. As a consequence, engineers will be unable to resist using these concepts. These concepts are essential since they verify and acquire in situ environmental repercussions. Furthermore, geotechnical ideas are used even at the greatest tides. Engineers may use these notions to determine how much water the planet can hold within a specific range.

Hydrographic surveys are done by the surveyor because of high tides that cause water to rise. The survey enables the engineers to develop realistic measures to lessen destruction, especially for those who live near water bodies.

Foundation layers are built by engineers using strong materials, especially when developing residences near beaches and bridges. In addition, strong and durable concrete is made from sand soil to resist destruction from a major flood. Engineers should also choose corrosion-resistant steel materials to avoid excessive wear and tear and, as a consequence, massive damage. Furthermore, strong and dramatic fixtures and structures will emerge from a sturdy base.

Reference List

Ahmad, N., Zhu, Y., Shafait, Z., Sahibzada, U. F., & Waheed, A. (2019). Critical barriers to Brownfield redevelopment in developing countries: The case of Pakistan. Journal of Cleaner Production, 212, 1193-1209.Available from:

<https://doi.org/10.1016/j.jclepro.2018.12.061> [12 December 2021]

Armstrong, R. L. (1978). Undefined. New Zealand Journal of Geology and Geophysics, 21(6), 685-698. Available from :<

https://doi.org/10.1080/00288306.1978.10425199> [12 December 2021]

Ashcroft, W. A., & Munro, M. (1978). The structure of the eastern part of the Insch mafic intrusion Aberdeenshire. Scottish Journal of Geology, 14(1), 55-79. Available from:  <https://doi.org/10.1144/sjg14010055> [12 December 2021]

González Farias, I., Araujo, W., & Ruiz, G. (2018). Prediction of California bearing ratio from index properties of soils using parametric and non-parametric models. Geotechnical and Geological Engineering, 36(6), 3485-3498. Available from:  

<https://doi.org/10.1007/s10706-018-0548-1> [12 December 2021]

Rock mass characterization. (2014). Rock Engineering and Rock Mechanics: Structures in and on Rock Masses, 379-506. Available from: <https://doi.org/10.1201/b16955-6> [12 December 2021]

Siebach, K. L., Baker, M. B., Grotzinger, J. P., McLennan, S. M., Gellert, R., Thompson, L. M., & Hurowitz, J. A. (2017). Sorting out compositional trends in sedimentary rocks of the Bradbury group (Aeolis Palus), Gale crater, Mars. Journal of Geophysical Research: Planets, 122(2), 295-328. Available from:  

<https://doi.org/10.1002/2016je005195> [12 December 2021]

Yihdego, Y. (2016). Hydraulic in situ testing for mining and engineering design: Packer test procedure, preparation, analysis, and interpretation. Geotechnical and Geological Engineering, 35(1), 29-44. Available from :

< https://doi.org/10.1007/s10706-016-0112-9  >

Ying, Z., Cui, Y., Duc, M., Benahmed, N., Bessaies-Bey, H., & Chen, B. (2020). Salinity effect on the liquid limit of soils. Acta Geotechnica, 16(4), 1101-1111. Available from: <https://doi.org/10.1007/s11440-020-01092-7>