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Groundwater Control and Dewatering Techniques for Successful Construction Projects

The construction of certain structures might require excavation below the water table. When this occurs, it is important to control the groundwater, which could affect the construction project. It is important to control the water in order to complete the project and ensure safer working conditions.

 

Groundwater control refers to the process used to control and provide reductions in water levels for structures that must extend below the groundwater level.

 

The most commonly used process in achieving this is referred to as dewatering. The effectiveness of dewatering systems, however,  is largely dependent on factors such as ground conditions (soil penetrability, stability, etc.), and water level.

 

Dewatering includes the following techniques

 

a.  Sump pumping

Sump pumping is a basic method which involves digging a sump to collect groundwater and pumping the water out. This method of groundwater control is mostly used during minor excavation projects and it can be economical, but quite time-consuming to deal with.

b.  Wellpoint systems

Wellpoint systems consist of a number of small-diameter wells (horizontal or vertical), which are dug into the ground and connected with a header pipe to a wellpoint pump. The water is drawn out from the ground using a vacuum/ suction created by the wellpoint pump.

Wellpoint systems are used to reduce groundwater levels. It is a versatile groundwater control method and helps to ensure secure working conditions during the excavation process. It is also swift to set up.

c.  Siphon draining

Siphon draining involves pumping water by gravity along siphon pipes, quite similar to the process of sucking on a straw to draw out a liquid . It is most often used where there are unsteady slopes.

d.  Deep well systems

Deep well systems are often used in situations where the excavation depth surpasses the maximum levels for a wellpoint system and there is a need for a  large quantity of water to be extracted.

These systems consist of several drilled wells, with each using a borehole pump that can be operated while underwater.

e.  Ejector systems

Ejector systems operated on similar principles as well systems. They are based on wells which reduce the groundwater level to ensure safe working conditions and they enable water to be drawn out of deeper levels in the ground. Ejectors make use of air in the wells to suction water out of the soil.

f.  Vacuum wells

Vacuum wells are a reorientated type of the deep well method and they have similar operational uses as deep wells. However, there is an expectation- the submersible/ underwater pumps used in the deep well systems are supported by vacuum pumps positioned above the ground in this case.

The implementation of a vacuum pump is useful in helping to draw out water better from fine-grained soil- an action that cannot be implemented by a submersible/ underwater pump alone.

For dewatering to be successful, it must be done suitably and by experts. At Geophas Resources, we take the time to guide you through each groundwater control technique, with the aim of selecting the most suitable option for your construction project(s).

 

For more information, please visit https://geophaseresources.com/ or our office, located at 13 Olufunmilola Okikiolu St, Allen, Ikeja.

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Eight Reasons Why Buildings Collapse Frequently in Nigeria

Over the past years, news updates have been filled with stories of buildings collapsing in different parts of Nigeria at an alarming rate.  Structures which were once standing tall, have been reduced to rubble and ruins.

 

These incidents have raised serious concerns over the safety of residents and homeowners. According to the Nigerian Building and Road Research Institute in a report by the BBC, 199 people died in four Nigerian collapsed buildings between 2014 and 2016.

 

We’ll be identifying some significant reasons for the collapse of buildings and solutions to them.

 

a.  Quality of Building Materials

Substandard building materials are not strong enough to keep buildings standing for long. However, many contractors and building personnel, in a bid to save costs or outsmart their clients, often use counterfeit and low-grade building materials, which could eventually fail and lead to collapse.

 

Moreover, testing facilities aren’t adequate or readily available to determine the quality and strength of materials such as steel reinforcement bars and concretes, which are very vital in building processes.

 

b.  Failure to Conduct Soil Investigation and Tests

Soil tests are a fundamental practice in building construction. Soil tests let the builders determine the soil strata and its bearing capacity. These tests determine the type of foundation to be used in the construction. Failure to conduct soil tests could result in building collapse.

 

c.  Incompetent Building Contractors

Hiring Inexperienced and ill-equipped contractors could be detrimental to the construction of a building. These contractors might defy standard building principles, leading to poor construction and eventual collapse.

 

Furthermore,  it is the duty of building contractors to carry out their operations in line with the specifications and blueprints of architects and engineers, so if they fail to do so, it could spell doom for the construction project.

 

d.  Illegal Alterations to Existing Structures

It’s a common practice to make ‘adjustments’ and ‘additions’ that defy the original structure of buildings in Nigeria. These include adding an extra storey (which could increase the pressure on the foundation). Another example is changing the function of a building. (e.g changing the first floor of a home residence to a business unit or factory, which might involve the use of heavy equipment and machinery, weakening the structure in the process) .

 

Some alterations require permission and approvals from designated authorities to be regarded as legal.

 

e.  Natural Forces

Natural occurrences such as earthquakes, floods and heavy storms could cause a building to collapse. Many reported cases of collapsed buildings have been caused by natural disasters.

 

f.  Absence of Monitoring, Inspection and Supervision of Construction Works

Construction works are to be properly monitored and inspected by professionals and government officials. In many cases, these officials fail to do so, and such negligence could lead to building collapse.

 

 

 

What Can Be Done to Avoid Building Collapse?

 

  1. Building experts must uphold professional ethics and work in accordance with standard industry procedures and policies, always.
  2. Adequate supervision and monitoring of construction works must be mandated by concerned authorities, to ensure that they are done in accordance with the established regulations.
  3. Construction industry professionals must deploy the geophysical survey data in their building designs.
  4. The general public must be adequately informed and sensitized on the importance of engaging trusted professionals and experts in construction works to avoid collapse and ensure safety.
  5. All necessary tests, such as soil tests and environmental impact assessment must be made compulsory and adhered to, before the commencement of construction works.

 

Geophase Resources Limited boasts a team of highly-trained experts who uphold all industry values to engage in construction projects that are in accordance with necessary policies.

 

Interested in our services? Contact us: https://geophaseresources.com/ or visit our office, located at 13 Olufunmilola Okikiolu St, Allen, Ikeja.

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Five Types of Concrete Quality Tests

Concrete refers to a composite material that is essentially composed of elements such as cement, aggregates ( such as sand and gravel) joined together by water. The mixing proportions of the materials determine the strength and quality of the concrete.

 

Concrete is a requisite component of the construction process, therefore, it is important to subject it to quality tests to determine its condition.

 

Here are six important tests that help to determine the quality of fresh and hardened concrete:

 

a.  Water Permeability Test

A water permeability test is taken to ascertain the durability of the concrete and its resistance against water under hydrostatic pressure.

 

This type of test is taken from substructures concrete elements such as foundations, concrete water tank, retaining wall etc.

 

b.  Slump Test

Slump tests are taken to determine the workability and consistency of concrete. These tests are carried out from batch to batch to check the consistent quality of concrete during construction work.

 

 Factors such as moisture content, particle size distribution, air content and temperature could influence a slump test.

c.  Compressive Strength Test

Compression strength refers to the ability of a material to carry a compressive load without cracking or fracturing. A compression strength test, therefore, is a method used to measure the highest amount of compressive load a material can support.

 

The Compressive strength of concrete is dependent on constituents such as the cement strength, water-cement ratio, etc. The test is usually implemented on a cube, prism or cylinder.

 

d.  Rapid Chloride Ion Penetration Test

Similar to the Water Permeability Test, the  Rapid Chloride Ion Penetration Test is carried out to determine the durability of concrete. The test assesses the resistance of a concrete sample to the penetration of chloride ions.

 

e.  Air Content

Air entrainment is a significant component of concrete mixtures that are exposed to freezing and thawing environments, as it helps to ensure that the concrete is durable.

To measure the air content in fresh concrete, as well as the variation in the volume of concrete with a change in pressure, it is important to conduct an air contest test.

 

 

f.  Unit Weight

A unit weight test is done to measure the air content of a concrete mix and confirm that the volume of concrete is in accordance with the approved project mix plan. It is important to help you verify that you have the volume of concrete you requested.

 

At Geophase Resources Limites, we prioritise quality control and assurance, including standard concrete tests.

 

Interested in our services? Contact us: https://geophaseresources.com/ or visit our office, located at 13 Olufunmilola Okikiolu St, Allen, Ikeja.

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Erosion Control in Construction: What It Is and Why It Is Important

One of the significant threats to infrastructure is erosion. Erosion, in simple terms,  is defined as a geological process in which the extreme impact of natural forces (such as water and wind) and man-made forces, leads to the deterioration of earth surfaces.

 

Erosion is common in Nigeria and has ravaged homes, roads and other infrastructure for years.

 

What Is Erosion Control?

Erosion control refers to the measures that are taken to control and limit the risk of erosion. It involves practices that are aimed at preventing its occurrence in construction, agriculture and more.

 

Why Is It Important?

A publication in the International Journal of Erosion Control Engineering states that ‘Erosion is arguably the single most serious natural hazard in Nigeria, affecting nearly every part of the country but more aggressive in the southeastern part where it has killed people, torn roads in shreds, destroyed homes, schools, farmlands, and displaced poor people’.

 

Erosion is a factor that is detrimental to not just infrastructure, but individuals and inhabitants, as well.

 

Erosion Control in Construction

 

Erosion control plays a vital role in areas such as construction work, as it helps to ensure the preservation and protection of structures, as well as reducing the environmental impact of a construction project on the surrounding area. It involves innovative techniques such as the following:

 

a.  Observation of  the Construction Site

It’s very important to observe the construction site for any issues or potential risks. Doing this will enable construction officials to plan accordingly.

 

b.  Geotextiles

Geotextiles are absorbent materials that are used in, drainage, filtration, reinforcement, sealing, and protection, amongst others. These factors often influence the type of geotextile to be used. Geotextiles help in drainage, filtration and soil stability in construction projects.

 

c.  Riprap

Riprap refers to an erosion-proof layer of large stones interlocked together to act as a barrier to protect slopes, riverbeds and soil. Ripraps are often placed over geotextile to ensure that the soil does not ‘pipe’ or move through the riprap.

 

d.  Drainage Channels

Drainage channels such as the French Drain are useful in controlling erosion. The French Drain is a system that includes underground piping (known as a drain tile) that serves as a conduit for surface and groundwater to flow out. The drain tile may also be made penetrable to enable water to trickle into the soil below the tile, while excess water moves to the exit point.

 

e.  Mechanically Stabilized Earth (MSE) Walls

A Mechanically Stabilized Earth (MSE) refers to a compound solid structure that is made up of facing elements, soil mass and reinforcement. MSE walls are more effective than the conventional retaining walls and they are easier to install.

 

Geophase Resources involves innovative solutions and expertise to deliver excellent erosion control practices and other environmental consulting services. Visit https://geophaseresources.com/ or our office, located at 13 Olufunmilola Okikiolu St, Allen, Ikeja.