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What Is Grasscrete? Types of Grasscrete

Introduction

Grasscrete is manufactured by a simple process by pouring concrete over styrene void formers. It is thus a cast on site cellular reinforced concrete system with void created by formers.

Former is fundamentally equipment or a mould that forms voids in the concrete, which can be filled later with a variety of porous materials such as stone, gravel or vegetation.

Grasscrete is one of the pavements methods where instead of the plain paving surface, vegetation or grass is grown on the surface, which gives an appealing look to pavements or driveways.

Grasscrete consists of a reinforced cellular cast on-site concrete on that one can grow natural grass by filling those voids with either soil or stones. These voids are created with the help of plastic formers (generally called moulds).

This type of pavement is widely adopted in major cities and modern designs because of its aesthetically appealing and environmentally favorable.

Types Of Grasscrete

Stone Filled Grasscrete
Partially Concealed Grasscrete
Concealed Grasscrete

1. Stone Filled Grasscrete

As the name suggests, in stone-filled grasscrete instead of soil, crushed stones are filled between the concrete. These crushed stones’ size comes in a range of 1/2 inches to 3/4 inches.

Generally, the draining capacity of stone-filled grasscrete rates up to 480 inches per hour with 100% water retention. The main reason to consider this one is that it is considered a low-maintenance design, and it is best suited for traffic sustained areas and provides max percolation rates.

This type of Grasscrete is ideal if you are looking for considerably a low maintenance design. Stone filled Grasscrete is perfect for sustained traffic areas. Furthermore, it provides maximum percolation rates. It is both functional and environment friendly.

This grasscrete type is used for:

Military Installations
Access Roads
Vehicle Parking
Fire and Emergency Access

2. Partially Concealed Grasscrete

In this type of grasscrete, the vegetation or the grass is placed parallel to the concrete. Usually, concrete with a thickness of 51/2″ is provided along with a half-inch space to protect the root alongside the vegetation.

Partially concealed grasscrete is eco-friendly and pleasing in appearance. It is most suited for sustained traffic areas.

This grasscrete type is used for:

Road Shoulders
Access Roads
Driveways
Fire and Emergency Access
Vehicle Parking

3. Concealed Grasscrete

In concealed grasscrete, a layer of soil with linch thickness is laid on the concrete. While the concert below has a depth of five and a half inches.

The vegetation or the grass laid on the soil surface. These types of grasscrete are best suited for low-traffic areas.

This grasscrete type is used for:

Medians
Low traffic access roads
Overflow vehicle parking
Fire and emergency access

Advantages Of Grasscrete

There are various advantages, including Economical, Structural, and Environmental benefits.

1. Economical Advantages

Longer Lifecycle:

Grasscrete has a longer lifecycle in comparison to the other conventional impervious paving systems. In fact, Grasscrete has installations that go back in time as far as 1974 that is still in place today.

Reduces Costly Infrastructure;

One of the unique properties of Grasscrete is that, it allows natural water infiltration. And it is also established that treating stormwater is not a practical solution but is also regulated by a number of agencies. Thus, the need for expensive stormwater infrastructure such as curbs, gutters and underground piping can be reduced or even eliminated in some cases.

Low Maintenance Costs:

The most viable option associated with low maintenance cost is the stone filled Grasscrete. It is also the most widely used Grasscrete. Clogging of the voids in areas having slope less than 1% is not typical although, these voids can be cleaned out easily.

2. Environmental Benefits of Grasscrete:

Increases Green Space and Reduces Heat Island Effect:

Heat islands are nothing but the built up areas that are hotter than the nearby rural areas. The visually appealing green space/vegetation reduces the heat Island effect, thereby creating a comfortable, attractive and a calming parking area for the use of vehicles. This is how Grasscrete allows a barren vehicular area transform into a green urban oasis.

Uses Recycled Materials:

The use of recycled material is encouraged in Grasscrete right from the manufacturing process of the concrete mix to fill the voids and the sub base layers. Grasscrete maintains its environmental focus by utilizing the recycled materials to its 100% capacity.

Infiltration of Storm Water:

Grasscrete not only maintains the natural equilibrium of the groundwater recharge but also significantly reduces the runoff. Infiltration of the stormwater in Grasscrete is at about the same rate as any other ordinary lawn located in the same area.

Innovative Bridge Design Handbook – Conctruction Rehabilitation and Maintenance Free PDF

Integrating new materials, innovative construction practices, and research from a wide
variety of other innovative engineering and scientific fields (such as aerospace engineering,
materials engineering, and so on), bridge engineering represents the highest
intellectual pursuit of the construction and structural engineering fields. Moreover, as
the demand for new and retrofitted infrastructure is increasing worldwide, the interest
in the bridge engineering field—from both the economic and political points of
view—is also increasing to a remarkable extent.

This book is the culmination of 10years of challenging work, which began when I
discovered that a comprehensive work on the state of the art of bridges—including
theory, design, construction, research and development (R&D), and innovation—
was not present in the existing literature. I hadn’t found any existing manuals with
useful content on the market, as these usually include a lot of content without precise
answers to the most pressing questions relating to the everyday experience in the theory
and practice of bridge engineering and design. I realized I wanted to create an
innovative reference book that could be updated as innovations were made in the field.
This culminated in the first edition of this book.

I initially tried to make a monograph on the matter on my own, spending some
years to research books and articles during my doctoral and postdoctoral studies on
bridge engineering. I then realized that many of my colleagues, including prominent
academicians and engineers from around the world, had the same idea and sought to
write an innovative monograph on bridge engineering and design—not a manual, but a
reference book in which students, academics, and engineers could find useful information
on bridge engineering topics from not merely an academic perspective but also
including research and work in the industry. The preparation of this book has been
very intensive, with thousands of communications passing between the other authors
and myself.

After 5 years, we realized that so much progress in bridge and structural engineering
had been made that a second edition was needed.
I hope that this final work has successfully expressed our thoughts and goals. All
the chapters in this book have been “built” (this term captures the fatigue and the challenges
the contributors overcame while preparing every chapter) and presented by
leading experts in the specific area discussed—engineers and academics who have
very soundly researched their findings. If you are searching for the best design and
research handbook in this area, you can find everything you need to know about bridge
design, engineering, construction, and R&D here in this text.

Download Link

Types and Applications of Fly Ash in Construction

Since wide scale coal firing for power generation began in the1920s, many millions of tons of ash and related by-products have been generated. The current annual production of coal ash world-wide is estimated around 600 million tones, with fly ash constituting about 500 million tones at 75–80% of the total ash produced.

Thus, the amount of coal waste (fly ash), released by factories and thermal power plants has been increasing throughout the world, and the disposal of the large amount of fly ash has become a serious environmental problem. The present day utilization of ash on worldwide basis varied widely from a minimum of 3% to a maximum of 57%, yet the world average only amounts to 16% of the total ash.

Fly ash is generally grey in color, abrasive, mostly alkaline, and refractory in nature. Pozzolans, which are siliceous or siliceous and aluminous materials that together with water and calcium hydroxide form cementitious products at ambient temperatures,are also admixtures.

Fly ash from pulverized coal combustion is categorized as such a pozzolan. Fly ash also contains different essential elements, including both macro nutrients P, K, Ca, Mg and micro nutrients Zn, Fe, Cu, Mn, B, and Mo for plant growth. The geotechnical properties of fly ash (e.g., specific gravity, permeability,internal angular friction, and consolidation characteristics) make it suitable for use in construction of roads and embankments, structural fill etc.

The pozzolanic properties of the ash, including its lime binding capacity makes it useful for the manufacture of cement, building materials concrete and concrete-admixed products.

Fly Ash Types :

There are two common types of fly ash: Class F and Class C.

Class F fly ash contain particles covered in a kind of melted glass. This greatly reduces the risk of expansion due to sulfate attack, which may occur in fertilized soils or near coastal areas. Class F is generally low-calcium and has a carbon content less than 5 percent but sometimes as high as 10 percent.

Class C fly ash is also resistant to expansion from chemical attack. It has a higher percentage of calcium oxide than Class F and is more commonly used for structural concrete. Class C fly ash is typically composed of high-calcium fly ashes with a carbon content of less than 2 percent.

Currently, more than 50 percent of the concrete placed in the U.S. contains fly ash.2 Dosage rates vary depending on the type of fly ash and its reactivity level. Typically, Class F fly ash is used at dosages of 15 to 25 percent by mass of cementitious material, while Class C fly ash is used at dosages of 15 to 40 percent.3

Fly Ash Applications :

Utilization of fly ash appears to be technically feasible in the cement industry. There are essentially three applications for fly ash in cement

(1) replacement of cement in Portland cement concrete

(2) pozzolanic material in the production of pozzolanic cements

(3) set retardant ingredient with cement as a replacement of gypsum

Cement is the most cost and energy intensive component of concrete. The unit cost of concrete is reduced by partial replacement of cement with fly ash.

The utilization of fly ash is partly based on economic grounds as pozzolana for partial replacement of cement, and partly because of its beneficial effects, such as, lower water demand for similar workability, reduced bleeding, and lower evolution of heat.

It has been used particularly in mass concrete applications and large volume placement to control expansion due to heat of hydration and also helps in reducing cracking at early ages.

The major drawback of fibre reinforced concrete is its low workability. To overcome this shortcoming, a material is needed, which can improve the workability without comprising strength.

The use of fly ash in concrete enhances the workability of concrete and being widely recommended as partial replacement of cement. This also reduces the cost of construction. Fly ash concrete provides much strong and stable protective cover to the steel against natural weathering action.

What is better steel or concrete?

Construction projects require many decisions. A key decision is to find the most effective option, as well as determining which process could produce ideal results.

Take a look at this breakdown. This example weighs the pros and cons of Structural Steel versus Concrete.

Costs

Structural Steel: A large majority of all steel manufactured today comes from recycled materials; A992 steel. This recycling usage makes the material much cheaper when compared to other materials. Although the price of steel can fluctuate, it typically remains a less expensive option compared to reinforced concrete.

Concrete: A large cost benefit to concrete is the fact that its price remains relatively consistent. On the other hand, concrete also requires ongoing maintenance and repairs, meaning added costs throughout its lifetime. Supply-and-demand may also impact the availability of concrete. Even though it can be poured and worked with directly onsite, the process to completion can be lengthy and could accrue higher labor costs.

Strength

Structural Steel: Structural steel is extremely strong, stiff, tough, and ductile; making it one of the leading materials used in commercial and industrial building construction.

Concrete: Concrete is a composite material consisting of cement, sand, gravel and water. It has a relatively high compressive strength, but lacks tensile strength. Concrete must be reinforced with steel rebar to increase a structure’s tensile capacity, ductility and elasticity.

Fire Resistance

Structural Steel: Steel is inherently a non-combustible material. However, when heated to extreme temperatures, it’s strength can be significantly compromised. Therefore, the IBC requires steel to be covered in additional fire resistant materials to improve safety.

Concrete: The composition of concrete makes it naturally fire resistant and in line with all International Building Codes (IBC). When concrete is used for building construction, many of the other components used in construction are not fire resistant. Professionals should adhere to all safety codes when in the building process to prevent complications within the overall structure.

Sustainability

Structural Steel: Structural steel is nearly 100% recyclable as well as 90% of all Structural Steel used today is created from recycled steel. Due to its long lifespan, steel can be used as well as adapted multiple times with little to no compromise to its structural integrity. When manufactured, fabricated and treated properly, structural steel will have a minimal impact on the environment.

Concrete: The elements within concrete are natural to our environment, reducing the harm to our world. Concrete may be crushed and used in future mixtures. This type of recycling can reduce a presence of concrete in landfills.

Versatility

Structural Steel: Steel is a flexible material that can be fabricated into a wide array of designs for endless applications. The strength-to-weight ratio of steel is much higher when compared to other affordable building materials. Steel also offers many different aesthetic options that different materials, such as concrete, cannot compete with.

Concrete: Although concrete can be molded into many different shapes, it does face some limitations when it comes to floor-to-floor construction heights and long, open spans.

Corrosion

Structural Steel: Steel may corrode when it comes into contact with water. If left without proper care, it could affect the safety and security of a structure. Professionals should care for the steel with such processes such as water-resistant seals and paint care. Fire-resistant features may be included when water-resisting seals are applied.

Concrete: With proper construction and care, reinforced concrete is water resistant and will not corrode. However, it’s important to note that the steel reinforcement inside should never be exposed. If exposed, the steel becomes compromised and can easily corrode, compromising the strength of the structure.

Reference : blog.swantonweld.com

What is a two-way slab?

A Two-Way Slab “TWS” is simply a slab carrying loads in both directions (length and width) to its supports (Beams or Columns). This is because it’s length to width ratio is (Long/Short) not big enough for loads to travel in the short direction only (width).

Theoretically speaking:

Loads are lazy, they travel in the shortest path possible, they like to spend the least effort.

Slabs have 4 supports to transfer its loads to (2 in each direction).

Slab: A structural element that has large width and length compared to its thickness. Designed to carry whatever loads the building is meant to carry, and transfer it to its the supporting elements.
Loads: Slab’s own weight, Slab covering and finish, live loads (people, furniture, machines…etc) etc.
Supports: Beams or Columns that the Slab is resting on at its 4 edges (could be on . The slab transfers its loads to the supports > Supports transfer its loads to the foundations on the ground > Foundations transfer all these loads to the grounds below the building.

That being said, let’s assume a (10 x 2) Rectangular Slab (width=2m and length=10m) the ratio is large enough (Long/Short = 10/2 = 5) in this case all the loads will travel much faster through the Short Direction which is the 2m width to the nearest supports.

This makes a One Way Slab “OWS”. On this slab loads will not travel in the Long Direction (the 10m length). The slab will carry 100% of the loads to half of its supports through one direction only. (supports on the other direction will not receive any loads from the slab, therefore these slabs can have 2 supports only at the short direction).

The Length is larger than Double the Width (Long/Short > 2)
100% of the Loads Travel in the Short Direction only.
Only the 2 Supports on this Short Direction will carry the slab and 100% of its the loads.
We need Reinforcement (steel bars or other) in this direction only to resist the straining actions caused by loads traveling through this direction to the supports.
We will study and design based on one direction only.
Slab thickness is design based on short direction only.

Now assume a (5 x 5) Square Slab with ratio (Long/Short = 5/5 =1), in this case loads will travel in both directions equally, since Long=Short they will spend almost equal effort. Each direction will carry 50% of the loads to its supports.

This makes a Two Way Slab “TWS”. In this case all 4 supports are working and they receive almost equal loads from the slab. (The Slab must be supported from all directions).

The Length is equal to the Width (Long/Short = 1)
Loads Travel in Both Directions. 50% of the total loads through each direction.
All supports (2 pairs in each direction) will carry half of the slab and its loads.
We need equal reinforcement in both directions.
We will study two directions, but since they are equal, we can design one direction and apply the same to the other.
Slab thickness is design based on either direction, since they are equal.

If we have something in between the above two cases, assume a (4×6) Rectangular slab (width=4m, length=6m) Which direction will the loads travel through?

The ratio is (Long/Short = 6/4 = 1.5) which is smaller than double the width (1.5 < 2) which means this a “TWS” as well.

The number we compare to the length to width ratio (2) might be different depending on the Application and the Code we are following (which is based on studies and experiments), but here we assume that the breakpoint is the length being over or under double the width.

So this is also a “TWS” where we predict loads travel in both directions, but will each direction carry 50% of the loads? We know that one direction is shorter than the other, therefore more of our loads will prefer to travel through the easier-shorter direction, and less will travel through the longer direction. Supports will receive a percentage of the Slab loads based on the distance it has to travel.

The Length is smaller than Double the Width (Long/Short <2)
Loads Travel in Both Directions. The short direction transfers a larger percentage of the loads, the long direction transfers a smaller percentage of the loads.
All support (2 pairs in each direction) will carry the slab, but each pair will receive different percentage of the loads.
We need more reinforcement in the short direction (larger percentage of loads > larger bending moment) than we need in the long direction (smaller percentage of loads > smaller bending moment)
We will study and design each direction separately (different loads, different bending moments, different reinforcement)
Slab thickness is designed based on the worst case, the larger straining actions we calculate from the Short or Long direction (most probably the short direction)

Bio-bricks made from human urine could be environmentally friendly future of architecture

University of Cape Town researcher Suzanne Lambert has created a zero-waste building material made with human urine, which hardens at room temperature, as an alternative to environmentally taxing kiln-fired bricks.

Lambert, a masters student in civil engineering, used recovered human waste and living bacteria to make the bricks, which can be fabricated in different sizes, shapes and strengths.

She believes the bio-bricks could be a real alternative to traditional bricks, which are heated at temperatures of more than 1,000 degree Celsius, producing huge carbon dioxide emissions.

“I see so much potential for the process’s application in the real world,” said Lambert. “I can’t wait for when the world is ready for it.”

The bio-bricks have been developed by a researcher at the University of Cape Town

The process utilised is called microbial carbonate precipitation, which Lambert’s supervisor at the University of Cape Town (UCT), Dyllon Randall, likens to “the way seashells are formed”.

Human urine, loose sand and a bacteria that produces the enzyme urease are combined in a brick-shaped mould. The urease triggers a chemical reaction, breaking down the urea in urine, while producing calcium carbonate — aka limestone, the main component of cement.

This solidifies the bricks, and the longer they’re left in their moulds, the stronger they get.

The bricks are created with human urine, loose sand and bacteria

“If a client wanted a brick stronger than a 40 per cent limestone brick, you would allow the bacteria to make the solid stronger by ‘growing’ it for longer,” said Randall.

“The longer you allow the little bacteria to make the cement, the stronger the product is going to be. We can optimise that process.”

Lambert builds on previous work, and particularly credits the foundational research by Jules Henze, a Swiss student who spent four months working with Randall on this concept in 2017. Testing was conducted with the help of UCT civil engineering honours student Vukheta Mukhari.

In contrast to previous efforts, Lambert’s product is the first of its kind to be brick shaped, and also the first to use human urine instead of a synthetic compound.

Designed as an environmentally friendly alternative to traditional bricks, the bio-bricks harden at room temperature

This was important to the UCT team, who wanted the bricks to be part of a holistic waste recycling effort. The bio-brick process creates nitrogen and potassium — good for fertiliser — as by-products, and is ultimately zero-waste with 100 per cent of the urine converted into something useful.

“No-one’s looked at it in terms of that entire cycle and the potential to recover multiple valuable products,” said Randall. “The next question is how to do that in an optimised way so that profit can be created from urine.”

Urine is collected using a special fertiliser-producing urinal. Randall says there are hurdles to scaling up the idea — such as how to collect from people who don’t use urinals — but fortunately, another of his masters students is working on the transport logistics of urine collection and treatment.

Engineers around the world have turned their attention to bricks that are grown rather than manufactured in an attempt to lower the carbon footprint of construction.

A MoMA PS1 gallery pavilion by The Living in 2014 featured towers built from bricks that were grown from corn stalks and mushrooms.

Mushroom mycelium is a perhaps the most celebrated of these bio-materials, featuring in experimental structures like the MycoTree exhibited at the Seoul Biennale of Architecture and Urbanism and the Shell Mycelium pavilion in India.

Source : https://www.dezeen.com