Self Compacting Concrete

  SELF COMPACTING CONCRETE

Self-consolidating concrete is a highly flowable type of concrete that spreads into the form without the need for mechanical vibration. Self-compacting concrete is a non-segregating concrete that is placed by means of its own weight. The importance of self-compacting concrete is that maintains all concrete’s durability and characteristics, meeting expected performance requirements.

In certain instances the addition of superplasticizers and viscosity modifier are added to the mix, reducing bleeding and segregation.

 Concrete that segregates loses strength and results in honeycombed areas next to the formwork. A well designed SCC mix does not segregate, has high deformability and excellent stability characteristics

Self-Compacting Concrete Properties

Self-compacting concrete produces resistance to segregation by using mineral fillers or fines and using special admixtures. Self-consolidating concrete is required to flow and fill special forms under its own weight, it shall be flowable enough to pass through highly reinforced areas, and must be able to avoid aggregate segregation. This type of concrete must meet special project requirements in terms of placement and flow.

Self-compacting concrete with a similar water cement or cement binder ratio will usually have a slightly higher strength compared with traditional vibrated concrete, due to the lack of vibration giving an improved interface between the aggregate and hardened paste.

The concrete mix of SCC must be placed at a relatively higher velocity than that of regular concrete. Self-compacting concrete has been placed at heights taller than 5 meters without aggregate segregation. It can also be used in areas with normal and congested reinforcement, with aggregates as large as 2 inches.

Self-Compacting Concrete Uses

Self-compacting concrete has been used in bridges and even on pre-cast sections. One of the most remarkable projects built using self-compacting concrete is the Akashi-KaikyoSuspension Bridge. In this project, the SCC was mixed on-site and pumped through a piping system to the specified point, located 200 meters away. On this particular project, the construction time was reduced from 2.5 years to 2 years. This type of concrete is ideal to be used in the following applications:

• Drilled shafts
• Columns
• Earth retaining systems
• Areas with high concentration of rebar and pipes/conduits

Self Compacting Concrete Benefits

Using self-compacting concrete produce several benefits and advantages over regular concrete. Some of those benefits are:

• Improved constructability.
• Labor reduction.
• Bond to reinforcing steel.
• Improved structural Integrity.
• Accelerates project schedules.
• Reduces skilled labor.
• Flows into complex forms.
• Reduces equipment wear.
• Minimizes voids on highly reinforced areas.
• Produces superior surface finishes.
• Superior strength and durability.
• Allows for easier pumping procedure.
• Fast placement without vibration or mechanical consolidation.
• Lowering noise level produced by mechanical vibrators.

•  Produces a uniform surface.
• Allows for innovative architectural features.
• It is recommended for deep sections or long-span applications.
• Produces a wider variety of placement techniques.

Factors Affecting Self Compacting Concrete

Using self-compacting concrete must not be used indiscriminately. These factors can affect the behavior and performance of self-compacting concrete:

• Hot weather.
• Long haul distances can reduce flowability of self-compacting concrete.
• Delays on job site could affect the concrete mix design performance.

• Job site water addition to Self-Compacting Concrete may not always yield the expected increase in flowability and could cause stability problems.

What Is Civil Engineering?

Civil Engineers

Following is everything you need to know about a career as a civil engineer with lots of details. As a first step, take a look at some of the following jobs, which are real jobs with real employers. You will be able to see the very real job career requirements for employers who are actively hiring. The link will open in a new tab so that you can come back to this page to continue reading about the career.

What Civil Engineers Do

Civil engineers conceive, design, build, supervise, operate, construct and maintain infrastructure projects and systems in the public and private sector, including roads, buildings, airports, tunnels, dams, bridges, and systems for water supply and sewage treatment. Many civil engineers work in planning, design, construction, research, and education.

Duties of Civil Engineers

Civil engineers typically do the following:

• Analyze long range plans, survey reports, maps, and other data to plan and design projects
• Consider construction costs, government regulations, potential environmental hazards, and other factors during the planning and risk-analysis stages of a project
• Compile and submit permit applications to local, state, and federal agencies, verifying that projects comply with various regulations
• Oversee and analyze the results of soil testing to determine the adequacy and strength of foundations
• Analyze the results of tests on building materials, such as concrete, wood, asphalt, or steel, for use in particular projects
• Prepare cost estimates for materials, equipment, or labor to determine a project's economic feasibility
• Use design software to plan and design transportation systems, hydraulic systems, and structures in line with industry and government standards
• Perform or oversee surveying operations to establish building locations, site layouts, reference points, grades, and elevations to guide construction
• Manage the repair, maintenance, and replacement of public and private infrastructure

Civil engineers also must present their findings to the public on topics such as bid proposals, environmental impact statements, or property descriptions.

Many civil engineers hold supervisory or administrative positions ranging from supervisor of a construction site to city engineer, public works director, and city manager. As supervisors, they are tasked with ensuring that safe work practices are followed at construction sites.

Other civil engineers work in design, construction, research, and teaching. Civil engineers work with others on projects and may be assisted by civil engineering technicians.

Civil engineers prepare permit documents for work on projects in renewable energy. They verify that the projects will comply with federal, state, and local requirements. These engineers conduct structural analyses for large-scale photovoltaic, or solar energy, projects. They also evaluate the ability of solar array support structures and buildings to tolerate stresses from wind, seismic activity, and other sources. For large-scale wind projects, civil engineers often prepare roadbeds to handle large trucks that haul in the turbines.

Civil engineers work on complex projects, and they can achieve job satisfaction in seeing the project reach completion. They usually specialize in one of several areas.

Construction engineers manage construction projects, ensuring that they are scheduled and built in accordance with plans and specifications. These engineers typically are responsible for the design and safety of temporary structures used during construction. They may also oversee budgetary, time-management, and communications aspects of a project.

Geotechnical engineers work to make sure that foundations for built objects ranging from streets and buildings to runways and dams, are solid. They focus on how structures built by civil engineers, such as buildings and tunnels, interact with the earth (including soil and rock). In addition, they design and plan for slopes, retaining walls, and tunnels.

Structural engineers design and assess major projects, such as buildings, bridges, or dams, to ensure their strength and durability.

Transportation engineers plan, design, operate, and maintain everyday systems, such as streets and highways, but they also plan larger projects, such as airports, ship ports, mass transit systems, and harbors.

The work of civil engineers is closely related to the work of environmental engineers.

How to Become a Civil Engineer

Civil engineers need a bachelor's degree. They typically need a graduate degree and a license for promotion to senior positions. Although licensure requirements vary from state to state, civil engineers usually must be licensed if they provide services directly to the public.

Education for Civil Engineers

Civil engineers need a bachelor's degree in civil engineering, in one of its specialties, or in civil engineering technology. Programs in civil engineering and civil engineering technology include coursework in math, statistics, engineering mechanics and systems, and fluid dynamics, depending on the specialty. Courses include a mix of traditional classroom learning, work in laboratories, and fieldwork. Programs may include cooperative programs, also known as co-ops, in which students gain work experience while pursuing a degree.

Important Qualities for Civil Engineers

Decisionmaking skills. Civil engineers often balance multiple and frequently conflicting objectives, such as determining the feasibility of plans with regard to financial costs and safety concerns. Urban and regional planners often look to civil engineers for advice on these issues. Civil engineers must be able to make good decisions based on best practices, their own technical knowledge, and their own experience.

Leadership skills. Civil engineers take ultimate responsibility for the projects that they manage or research that they perform. Therefore, they must be able to lead planners, surveyors, construction managers, civil engineering technicians, civil engineering technologists, and others in implementing their project plan.

Math skills. Civil engineers use the principles of calculus, trigonometry, and other advanced topics in mathematics for analysis, design, and troubleshooting in their work.

Organizational skills. Only licensed civil engineers can sign the design documents for infrastructure projects. This requirement makes it imperative that civil engineers be able to monitor and evaluate the work at the jobsite as a project progresses. That way, they can ensure compliance with the design documents. Civil engineers also often manage several projects at the same time, and thus must be able to balance time needs and to effectively allocate resources.

Problem-solving skills. Civil engineers work at the highest level of the planning, design, construction, and operation of multifaceted projects or research. The many variables involved require that they possess the ability to identify and evaluate complex problems. They must be able to then use their skill and training to develop cost-effective, safe, and efficient solutions.

Speaking skills. Civil engineers must present reports and plans to audiences of people with a wide range of backgrounds and technical knowledge. This requires the ability to speak clearly and to converse with people in various settings, and to translate engineering and scientific information into easy-to-understand concepts.

Writing skills. Civil engineers must be able to communicate with others, such as architects, landscape architects, urban and regional planners. They also must be able to explain projects to elected officials and citizens. Civil engineers must be able to write reports that are clear, concise, and understandable to those with little or no technical or scientific background.

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