Archives for architectural concrete

In-situ retaining wall

3 Best Types of Concrete Retaining Wall

A Concrete Retaining wall can be described as a structure that retains the lateral pressure – usually formed due to soil. In simple terms, it is nothing but a wall that holds the soil on one side of it so the desired changes of the ground level elevation can be achieved. A difference of Elevation levels can be seen on the either side of the retaining wall in the illustration.  A basement wall, for instance, is a retaining wall.

Concrete Retaining wall

A Concrete Retaining wall

Retaining walls can be made up of materials like stone masonry, timber, steel etc. However, the most common material is concrete for retaining walls construction owing to its durability, adaptability and availability. It can be moulded in to any shape and size, can be ordered from concrete plants or made on the site – also called insitu concrete retaining walls.

 

Stripping the formwork off the commercial retaining walls.

Stripping the formwork off the walls.

Concrete retaining walls can be of different types based on their working methods and type of construction. These include, but are not limited to, Gravity Wall, Cantilever wall, Piling Wall and Anchored Wall. On a smaller scale of retaining walls, which is where smaller lateral loads are applied, block retaining wall and sleeper retaining wall – made of concrete retaining wall blocks and concrete retaining wall sleepers respectively – are also common.

Gravity Retaining Wall

A gravity retaining wall uses its self-weight to counter the lateral loads coming from soil. For this reason, the gravity walls are usually big and therefore heavier as compared to other retaining walls. It can be used for retaining walls as high as 3 metres.

 

Construction is pretty simple and can be done with plain concrete only. A proper drainage system should be provided to avoid the lateral pressure caused due to the water in soil.

Commercial Concreting

Although Concrete can be prepared on-site it is better to use the services of Commercial Concreting companies. The concrete provided is designed in a proper manner keeping the right amount of water, cement, fine and coarse aggregate along with any additives, if needed. They provide concrete based on Concrete’s compressive strength which is usually difficult to know when concrete is prepared on-site, unless very strict precautions are taken and a sample has already been checked in the lab.

 

 

Commercial Concreting makes the construction of concrete structures much easier and more reliable.

Cantilever Retaining Wall

A cantilever retaining wall, as the name suggests, is based on cantilever technique where a slab is put underground to support the stem (see illustration).

cantilever retaining wall

A cantilever retaining wall

Since the cantilever retaining wall is of a smaller section as compared to gravity walls, reinforcement is provided in normal conditions. Alternatively, Pre-cast concrete and Pre-stressed concrete can also be used for the construction. It can used for retaining walls up to 10 meters of height.

Construction, however, is not as simple as compared to gravity retaining walls. And, a suitable drainage system is provided to avoid to extra lateral pressure that would be caused due to the water available in soil.

Piled Retaining Wall

Piled retaining wall is nothing but reinforced concrete piles driven next to each other in the ground up to a certain depth that is enough to counter the lateral earth pressure. A gravel fill is usually provided for the drainage of water.

 

Sheet pile retaining walls are also used in a similar manner. These kind of piles can be used for the retaining walls which are up to 6 meters in height. The construction requires heavy machinery for the drilling or driving of piles in the ground. Construction is complex and therefore requires technical knowledge.

Anchored Retaining Wall

Anchored retaining walls are usually provided where a high retaining wall with a thin cross section is required. Wires or deep cable rods are driven deep sideways and then anchored by pouring concrete on to them. These tiebacks or anchors act against the sliding and over-turning of the retaining wall.

Similar to other methods, a drainage system is provided to avoid excess lateral pressure caused due to the water.

 

anchored retaining wall

Examples of anchored retaining wall

 

Gravity Retaining walls, Cantilever Retaining Wall and other described above are the kinds of retaining walls that are supposed to take high lateral loads. These kind of walls usually require an engineer and a technical team to design the retaining walls which would stand against sliding and over-turning failures.

Small retaining walls, usually up to 1.2 meters (4 feet), can be constructed and used on a private property with little expertise. All you’ll need is time and materials to construct these retaining walls. Such small retaining walls are constructed to hold back the garden soil and for other smaller lateral loads.

Concrete Block Retaining walls and Concrete Sleeper Retaining walls are possibly the best choices for such tasks.

Concrete Block Retaining Wall

A concrete block retaining wall is nothing but a set of concrete blocks stacked on top of each other. But, in order to make it a retaining wall that lasts for years and can take loads in a safe manner, some construction techniques should be utilized.

Concrete Block Retaining wall

A Concrete Block Retaining wall under construction.

 

In situ concrete stairs and block retaining walls.

In situ concrete stairs and block retaining walls.

Concrete Block Retaining Wall Construction

First of all, a trench of certain height should be dug and compacted. A layer of crushed stone base, 15 mm 20 mm stones in size, should be provided. This requires less compaction and is good for the drainage.

Concrete blocks, or hollow concrete blocks, are then stacked in the form of a masonry so that all the joints should not come in the same vertical line. This would allow the retaining walls to resist vertical loads as well.

Depending on the concrete blocks you are using, the can come up with butt joints or locking flange to avoid sliding of one block over the other.

The same stones that we used for the stone base can be provided on the back of retaining wall for the drainage of water to avoid extra water pressure.

 

 

Concrete Sleeper Retaining Wall

Concrete Sleeper Retaining wall is very similar to concrete block retaining wall. In this retaining wall, concrete sleepers are used instead of concrete blocks. A number of companies provide factory-made sleepers and vertical posts.

Concrete Sleeper Retaining Wall

An example of a concrete Sleeper Retaining Wall. – Photo Credit – Bunnings.

 

Concrete Sleeper Retaining Wall Construction

Site should be cleared and levelled. Measurements should be made and auger holes should be dug for a depth of around 1.4 meters for a retaining wall of 1 meter height. A deeper hole would be required in case the retaining wall is higher than 1 meter. The posts should then be concreted into the ground so they are secure. A Concrete of around 20MPa strength would do the job.

Once the concrete is hardened and posts are in their proper place, sleepers should be paced. Seal the back of sleepers with a plastic sheet or with a concrete layer. A perforated drainage pipe should be provided to run along the length of wall. A drainage material such as crushed stone of around 20 mm in size should be provided over the pipe.

 

drainage a wall.

Drainage for a concrete retaining wall.

 

After the placement of sleepers, one should wait for around 7 days for the concrete to gain strength after which it is okay to pour the backfill material.

 

 

 

Three Best Types of Concrete Retaining Walls

Since there are different uses for each Concrete Retaining Wall mentioned in this text, it is difficult to choose the best three types. However, if we grade them based on their simplicity of construction, we can enlist three.

  1. Concrete Block Retaining Wall
  2. Concrete Sleeper Retaining Wall
  3. Concrete Gravity Retaining Wall

Afore-mentioned retaining walls offer simple construction methods and can be constructed without any technical assistance, if their usage is limited to private properties and shorter heights of around 1.2 metres.

Related Landscaping Ideas from Red’s Landscaping and Civil

7 Great Reasons to choose Permeable Concrete

 

Concrete – 9 things you need to know for better concreting.

 

Melbourne Landscaper – Mill Park Leisure

 

7 things you need to know about exposed aggregate concrete paths

 

In-situ Concrete

 

© 2020 Reds Landscaping and Civil quality commercial landscaping Melbourne

 

References and Further Reading

 

About Civil

 

The Constructor

 

The Family Handymanre

 

Lowes – How to Build

 

Installation Guide

 

Trojan Sleeper Installation

 

Commercial Concrete

 

The Constructor

 

Icon Walls

 

The Bunnings Range.

 

Concrete Sleepers

 

 

 

 

 

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Permeable Concrete -

7 Great Reasons to choose Permeable Concrete

Permeable Concrete or pervious concrete is changing the way public spaces are landscaped.

Concrete is the second most consumed product in the world. And contrary to our belief, its usage is much wider than constructing buildings only. With recent developments in Concrete, it has become an important material for an array of usages. Permeable Concrete is a prime example of development in concrete industry. Although the material itself isn’t new, since it was first used in 1852, it has been attracting renewed attention.

What is Permeable Concrete?

Permeable Concrete is also known as Porous Concrete, Pervious Concrete, Gap Graded Concrete, No-Fines Concrete and Enhanced-Porosity Concrete. Permeable concrete, similar to Normal Concrete, uses a mix of Cement, Water and Coarse Aggregate with little or no sand (Fine Aggregate) in it. The resulting concrete has 15% to 25% voids which ensure a water flow rate of 480 in/hr or more. Although the higher porosity, and lack of mortar paste reduces the strength of pervious concrete as compared to the conventional one but it is sufficient for most of its uses.

 

What are the Applications of Permeable Concrete

Although Pavement Construction is the major application of Pervious Concrete since it reduces the stormwater runoff and adds to the surface water table. In fact, the usage of Permeable Concrete in Pavement Construction is considered as one of the Best Management Practices (BMP) by the Environment Protection Agency (EPA). The usage of Permeable Concrete in pavements and in other horizontal constructions, depending on the precipitation values of a certain region, can eliminate the need of retention ponds and other precipitation runoff storage facilities. This would result in a more efficient land use especially in urban areas where land is already expensive.

Permeable-Concrete

Figure 1 Pervious Concrete Pavement (Divya Bhavana et al., 2017)

 

Below are some of the many applications in modern landscaping;

  • Residential Roads and Driveways
  • Parking Lots
  • Pavements with low traffic volume
  • Tennis Courts
  • Sub-base for conventional concrete pavements
  • Artificial Reefs
  • Well Linings
  • Slope Stabilisation
  • Swimming Pool Decks
  • Pavement Edge Drains

Production of Pervious Concrete

Production of Permeable Concrete is very similar to Normal Concrete since it uses the same ingredients. However, the amount of ingredients differ. Pervious Concrete is also mix designed and therefore should be designed for the desired purpose.
A general guideline is enlisted in the table.
Table 1 Typical Mix Proportion for Pervious Concrete (Divya Bhavana et al., 2017)

 

Material Quantity (kg/cubic metre)
Cement 270 to 415
Aggregate (Coarse and Fine) 1190 to 1480
Water to Cement Ratio (by mass) 0.27 to 0.34
Aggregate to Cement Ratio (by mass) 4 to 4.5
Fine to Coarse Aggregate Ratio (by mass) 0 to 1

 

This typical guideline is for information only and therefore a trial mix should always be prepared and checked for the desired purpose. Apart from the usual materials, Supplementary Cementitious Materials (SCM) and chemical admixtures are also used as per their dosage mentioned by the manufactures.

Water to Cement Ratio

A lower water to cement ratio is used since higher water to cement ratios would affect the compressive strength of concrete. If desired for a purpose where compressive strength is of no importance, a higher water to cement ratio can be used.
Usage of Fine Aggregate would reduce the permeability of concrete and make it less porous, however the compressive strength would be improved.
Lightweight aggregate, recycled aggregate and other types of aggregate or other techniques like fly ash geopolymer concrete have also been utilized to make Permeable Concrete.

Characteristics of the Concrete

Although it is similar to Normal Concrete in terms of its ingredients, it has a plethora of characteristics that make this concrete different. Enlisted are some characteristics of Hardened and Green (Fresh) Permeable Concrete.
The Permeable Concrete has a textured surface after placement.
In-place densities are usually 1600 kg/m^3 to 2000 kg/m^3
Due to low or no mortar content, Permeable Concrete renders a lower slump value and a stiffer consistency. Slump values are usually less than 20 mm (0.75 inches).
In spite of higher void percentage the Permeable Concrete can render a compressive strength of 3.5 MPa to 28 MPa (500 psi to 4000 psi). Typical values are about 17 MPa (2500 psi).
No Darby, Trowel or Bullfloat is used since they tend to seal the surface of concrete.

Permeable Concrete -

I.Idro Drain – Heidelberg cement (Photo – Italcementi a division of Heidelberg cement.)

 

7 Benefits of using Pervious Concrete

Permeable Concrete is much more than a way to reduce the stormwater runoff in urban areas. Listed below are some benefits of using Permeable Concrete.
It reduces the pollution by allowing the water to percolate in the ground. The sand chemistry and biology are allowed to treat the water naturally.
Allowing the rainfall to percolate, it recharges ground water and aquifers.
It improves the land use especially in Urban Areas
The light color of Concrete and relatively open pore structure absorb and store less heat respectively when compared to Normal Concrete. This helps in lowering heat in urban areas.
It is difficult for trees planted in parking lots and sidewalks to grow in impervious concrete environments since it makes it difficult for water to reach the roots. Trees benefit from Permeable concrete and further reduce the heat in urban areas.
It eliminates the risk of ponding over the roads over a longer periods of time as observed in some developing countries after rainfall.
The pervious concrete can absorb the noise of the vehicles on the road creating a pleasant environment.
In rainy days, pervious concrete pavements do not have splashes which glisten at night and are dangerous for drivers.
As per recent researches, the permeable concrete can also be used for the purification of sea water.

 

 

Related Landscaping Ideas from Red’s Landscaping and Civil Melbourne

3 Best Types of Concrete Retaining Wall

 

Concrete – 9 things you need to know for better concreting.

 

7 things you need to know about exposed aggregate concrete paths

 

Concrete Architecture in Landscaping

 

In-situ Concrete

 

© 2020 Reds Landscaping and Civil quality commercial landscaping Melbourne

 

References and Further Reading

Draining Concrete Bike Path

 

Draining Outdoor Flooring

 

Paver reduce Pollutioni

 

Divya Bhavana, T., Koushik, S., Uday Mani Kumar, K., & Srinath, R. (2017). Pervious concrete pavement. In International Journal of Civil Engineering and Technology (Vol. 8, Issue 4). https://doi.org/10.3141/2113-02
Park, S. B., Lee, B., Lee, J., & Jang, Y. Il. (2010). A study on the seawater purification characteristics of water-permeable concrete using recycled aggregate. Resources, Conservation and Recycling, 54(10), 658–665. https://doi.org/10.1016/j.resconrec.2009.11.006
Yang, J., & Jiang, G. (2003). Experimental study on properties of pervious concrete pavement materials. Cement and Concrete Research, 33(3), 381–386. https://doi.org/10.1016/S0008-8846(02)00966-3

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Exposed aggregate Concrete Pathway

Concrete – 9 things you need to know for better concreting.

Concrete is without a doubt it is one of the most versatile used materials in landscape construction. From in situ concrete walls to pavers to fence posts it has a wide range of uses. What are the different types of concrete and its uses?  To properly decide on which mix to use, it is important to understand what it is and what factors affect its physical properties.

Architectural concrete construction

Reds Landscaping using a boom pump to pour architectural concrete walls

What is Concrete?

In technical terms, it is a structural material consisting of a hard, chemically inert particulate substance, known as aggregate that is bonded together by cement and water. It is a composite material as it consists of both a binder and a filler.

What is difference between concrete and cement?

The binder most commonly used is known as Portland Cement. This is a mixture of finely ground limestone (CaCO3) and shale or clay which has been combined together at around 1500℃. In this process, water and carbon dioxide are removed from the mixture (calcination), then calcium silicates are formed. A small amount of gypsum (CaSO4•2(H2O)) is added to regulate the setting.

Concrete with exposed aggregate.

The aggregate, that is the part of the mix made up of several smaller ingredients, will generally be the sand and gravel. The gravel itself will usually be hard stones of a certain size range. Fine aggregates are below about 10mm in size and are often used in small bags of cement mix or for smaller landscaping work. Larger stone aggregates range from 10 to 40mm in size and are commonly used in construction. It is the stone aggregates that give the mix its compressive strength. As the aggregate is around 70% of the mix, it provides much of the bulk and contributes to its dimensional stability. The rougher the surface of the aggregate and the greater the area in contact with the cement paste, the stronger a concrete will be.

River pebbles will not give your concrete the maximum compressive strength, but they do look great in exposed aggregate concrete.

Rounded particles like river pebbles or beach sand will result in lower strength than crushed aggregates. Larger size aggregates lead to relatively lower strength. Where extra strong mix is needed, a little less aggregate can be used.

Aggregate

Course aggregate.

Water

A key ingredient is of course the water. When the water is combined with the cement as paste is formed which binds the aggregate together. Concrete does not harden by drying out, it hardens by a chemical reaction know as hydration. In this reaction, compounds in the cement react with water molecules to form strong chemical bonds. Ideally, the water should be as pure as possible to prevent the occurrence of any side reactions which may weaken or interfere with the chemical reaction taking place. Even small quantities of organic soil compounds result in chemical reactions that seriously affect the strength. In Melbourne access to good quality water is not usually a problem.

 

 

Concrete Mixer

Loading the Concrete Mixer the correct materials in the correct ratios is essential for making strong concrete. The water needs to be as pure as possible.

The other important point for the landscaper is to get the ratio of water to cement correct. The ratio of water to cement is critical if strong concrete is required. If too much water is added, the strength of the mix will be reduced. Excess water above what is required for the chemical reaction will result in pores on the concrete which will reduce the strength especially the tensile strength. Too little will make the it difficult to work, to fill spaces, or create a good connection to the reinforcement. Accurate measurements and thorough mixing of the cement and water will help prevent these problems.

Concrete sets with a chemical reaction not by drying.

It is set by a chemical reaction and not by drying. This means that it will even will set under water. It is important to remember this fact during the curing stage. The two main hydration chemical reactions from the calcium silicates are as follows;
Tricalcium silicate + Water—>Calcium silicate hydrate+Calcium hydroxide + heat
2 Ca3SiO5 + 7 H2O —> 3 CaO.2SiO2.4H2O + 3 Ca(OH)2 + 173.6kJ
Dicalcium silicate + Water—>Calcium silicate hydrate + Calcium hydroxide + heat
2 Ca2SiO4 + 5 H2O—> 3 CaO.2SiO2.4H2O + Ca(OH)2 + 58.6 kJ

Exothermic reactions

Both of these reactions are exothermic, that is, they release heat. This heat will dissipate quickly in thin sections. In thicker sections, the internal temperature is transferred to the outside much more slowly. As the outer surface of the concrete will cool much more rapidly than the inner core, there can be a difference in reaction speed. This can lead to tensile stresses that can crack the surface as a result of this uncontrolled temperature difference across the cross section. For this reason, concrete should not be poured in very cold temperatures. In cases where thermal cracking does occur, it will be at early ages of curing. The heat can also cause moisture to evaporate from the surface of the concrete, making it weaker. This will be the case if there is insufficient water for the chemical reaction. For these reason excessively thick sections should be avoided in a single pour. Wooden formwork and damp hessian covers can help the curing process. Giving your concrete a very light spray of water as it is curing will often improve the strength.

 

What is the correct mix for concrete?

When mixing concrete for footings or foundations use a mix of 3 parts coarse or sharp sand and 3 parts aggregate with 1 part of a high quality cement.

History of concrete

What have the Romans ever done for us? The Romans are widely credited for the spread of building technologies including concrete throughout Europe. It was the Roman’ Empires’s engineering abilities that enabled them to built an enormous empire throughout Europe and through parts of North Africa and the Middle East. The concrete architecture of the Romans is famous amongst fans of history.

Durable Roman Concrete has lasted centuries.

The Roman  formula for quality concrete

It was know to the Romans as “opus caementicium”. Opus meaning a fortification, composition or a piece of work and caementicium meaning quarried or unhewn stone. The Romans developed their recipe in the third century BC. The ingredient the Romans used was volcanic dust known as pozzolana. This volcanic dust included fine particles of alumina and silica which created the chemical reaction enabling the setting. To this they added a mixture of lime or gypsum, brick or rock pieces and water. Usually the mix was a ratio of 1 part of lime for 3 parts of volcanic ash.

Concrete Pantheon Rome

The Pantheon in Rome was constructed entirely in concrete.

 

 

Concrete Dome of the Pantheon in Rome.

Concrete Dome of the Pantheon in Rome.

Roman Waterproof Concrete

Roman builders discovered that adding crushed terracotta to the mortar created a waterproof material which could be then be used with cisterns and other constructions exposed to rain or water. Recently, it has been found that the Roman mix used in seawall construction has better endurance to seawater than the modern stuff. This was mostly due to one of the minerals of the volcanic rock phillipsite, reacting with the seawater to form aluminous tobermorite which reinforced the concrete over time. After the fall of the Roman empire the technology for making concrete was lost for many years.

 

Assyrians Babylonians and Egyptians.

Among the ancient Assyrians and Babylonians, clay was often used as the bonding material. The Egyptians developed a substance more closely resembling modern concrete by using lime and gypsum as binders. Lime (calcium oxide), was derived from limestone, chalk, or (where available) oyster shells. (Pozzolans are actually a broad class of siliceous or siliceous and aluminous materials.)

Portland cement

In 1824 an English inventor, Joseph Aspdin, burned and ground together a mixture of limestone and clay. As the chemistry of concrete was not fully understood at the time, the proportions of the ingredients were developed by trial and error. This mixture, called Portland cement, has remained the dominant cementing agent used in concrete production. It is named Portland cement as it is an attempt to imitate the limestone from Portland in Dorset on the jurassic coast of England. Portland Limestone formed slowly over the last 150 million years or so as tiny grains of sediments and clays infused the limestone grew and compacted. This gives it both its unique physical properties when grown up for cement, but also its attractive appearance. Portland Limestone has been used in many of the iconic London buildings such as Saint Paul’s Cathedral and the palace of Westminster. As a building material Portland Limestone was popularised by architect Sir Christopher Wren.

Reinforced Concrete.

One of the drawbacks of concrete, despite its great compressive strength, is its lack of tensile strength. This is largely due to its natural porosity. Plain unreinforced concrete does not easily withstand stresses such as wind action, earthquakes, and vibrations and other bending forces and is therefore unsuitable in many structural applications. Low tensile strength also means low strength in bending or when used as a beam.

The Strength of Steel

Steel when compared with concrete has great tensile strength. The solution is to embed the steel into the concrete. This is usually achieved with the use of steel mesh reinforcement. The reinforcing steel, normally takes the form of rods, bars, or mesh. The reinforcement bars are often coined along the surface to give them a good connection to the concrete. The addition of tightly bound reinforcement bars makes the concrete section into a true composite beam. For this reason, the reinforcements must have good overlap.

Retaining wall footings.

Retaining wall footings with steel reinforcement.

 

 

Joseph Monier

Reinforced concrete is usually attributed to Joseph Monier, a Parisian gardener who made garden pots and tubs of concrete reinforced with iron mesh.This was patented in 1867. In reinforced concrete, the tensile strength of steel and the compressional strength of concrete render a member capable of sustaining heavy stresses of all kinds over considerable spans. Despite the strength of reinforced concrete, efforts should be make to minimise the loads on garden retains walls. This can be achieved by adequate agricultural drainage near the wall. It is important to remember that a cubic metre of water weighs a tonne. Plant selection near the retaining wall is also important plants should be chosen that do not have an invasive root system. For your existing trees, consider the use of a tree root barrier.

 

 

Related Landscaping information from Red’s Landscaping and Civil

Retaining Walls

 

In-situ

 

Exposed Aggregate

 

© 2020 Reds Landscaping and Civil quality commercial landscaping Melbourne

 

For more information on concrete

 

How to minimise thermal cracking

 

How it is made and the scientific principles.

 

The Pantheon in Rome

 

Cement Australia

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Tennis court repair Balwyn

Balwyn Landscaping – Commercial Project

Balwyn is an inner eastern suburb of Melbourne and lies in the northern part of the city of Boroondara. It was in this area that grazier John Gardiner settled near the point where Gardiners creek meets the Yarra River. The commercial editor of the Argus, Andrew Murray built house named Balwyn which gives the area its name.

 

How far is Balwyn from the Melbourne CBD?

Balwyn is only 10 kilometres from the Melbourne CBD and in an easterly direction. It was once serviced by the outer loop railway station at Deepdene.

 

Balwyn Community Centre

The Balwyn Community Centre at 412 Whitehorse Road Surrey Hills was upgraded to ensure it would continue to support the needs of the local Balwyn Community. As well as the upgrades to the buildings, there were landscaping works for the parkland, natural wetlands,  exposed aggregate concrete pathways and tennis courts.

Balwyn Community Centre Scope of works.

 

The hard landscaping for the Community Centre

The scope of work for this project included the following hard landscaping construction;

  • Plain, coloured and exposed aggregate concrete,
  • In-situ or poured in place concrete garden retaining walls,
  • Exposed aggregate concrete driveway crossovers,
  • Concrete upstands, edges, ramps stairs and landings.

 

The soft landscaping for Balwyn Community Centre

The scope of work for this project included the following soft landscaping installation;

 

  • The planting of advanced indigenous trees
  • The application of appropriate fertilizers
  • Lawn areas
  • The planting of native grasses and ornamental plants
  • Aggregate and Gravel
  • Imported top soil to Australian Standards
  • A sophisticated Irrigation System
  • Areas of mass planting
  • Mulched garden beds
  • Planting of Australian Native Shrubs
  • Garden edging.

Existing trees at the Community Centre

The existing tress on the site included the following;

  • Pin Oak (Quercus palustris),
  • River Red Gum (Eucalyptus camaldulensis) ,
  • Narrow leaved black Peppermint (Eucalyptus nicholii),
  • Lemon scented gum (Corymbia citriodora),
  • Prickly leaved Paperbark ( Melaleuca styphelioides)
  • Forest Oak (Allocasuarina torulosa),
  • Drooping She-oak (Allocasuarina verticilata)
  • Smooth Barked Apple ( Angophora Costata)

Nearly all of these existing trees were kept in the new landscape design.

 

Native Wetlands

Later in the project rehabilitation of native wetlands was added including a child proof fence.

 

Tennis Court Repairs and reconstruction

Part of the landscaping included repairs to a tennis court and the construction of another tennis court. A good sport surface must be stable, therefore the new tennis court was constructed with asphalt over 300 mm of roadbase.

Synthetic clay Tennis Court surface

A low maintenance synthetic clay tennis court surface was required to laid over the asphalt. Therefore, the surface chosen was Grassports Policlay. In addition to being low maintenance, Grassports Policlay is a fast draining low maintenance water free tennis surface resulting in the ideal surface for public tennis courts. A high quality sporting surface was required, therefore the asphalt surface was flattened rigorously in preparation. The very thick roadbase foundation will also help to maintain the stability of the playing surface. Root barriers we also installed to prevent invasive tree roots causing any unevenness to the playing surface.

 

Soft play surfaces

The soft play coloured surfaces in the landscape was required, so an EPDM wet pour rubber was chosen. In addition to its great colour range, EPDM is a synthetic rubber widely used in the automotive industry. Similarly, its mechanical properties make it ideal for this application. For instance, it has great UV stability, abrasion resistance, ozone resistance and it is water proof. So, the material used was Playkote which was installed as a rubber wet pour over SBR underlay. In addition to the added height, the SBR underlay makes the play surface a little softer.

 

Outdoor Gym Equipment

 

"Exercise

 

Environmentally Friendly Garden Furniture

Garden furniture including picnic tables, benches and seats were installed to add to the public amenity. In addition to the the amenity and aesthetic provided, recycled materials were also used. To this end, the material used was Enviroslat.  Enviroslat is an environmentally friendly low maintenance material produced from HDPE waste mixed with recycled cellulose. The recycled cellulose hardwood waste and rice husks.

Outdoor Furniture on Exposed aggregate concrete.

Outdoor Furniture on Exposed aggregate concrete. ACLA Consultants landscape architects.

 

Table Tennis Table

Table Tennis Table with bespoke surface treatment.

Table Tennis Table with bespoke surface treatment.

 

"<yoastmark

The finished Commercial landscaping Project

 

About the Community Centre  Commercial Landscaping Project

Landscape Architects: ACLA Consultants landscape architects.

 

Building Construction: CICG

 

Customer: City of Boroondara

 

Hume Global Learning Centre – Sunbury

 

 

© 2020 Reds Landscaping and Civil – Quality landscaping Melbourne

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Hanson Bokhara Exposed aggregate concrete.

7 things you need to know about exposed aggregate concrete paths

Exposed aggregate concrete is a great design solution for public spaces. The attractive durable not slip surface makes it an ideal choice for landscape architects. High traffic areas around public buildings often use this type of concrete path.

Exposed Aggregate Colours

The aggregates are available in a wide range of colours to suit your landscape design.  The available colours include red, brown, dark grey basalt, green quarts as well as black and white. In combination with this selection, the fine grain aggregates or sands are also available in a wide range of selections. The colour of these these fine aggregate will also be the more dominant when the surface is lightly abraded. However, more heavily abraded surfaces will result in more of the colour of the course aggregates showing.  This will result in a different appearance for the exposed aggregate concrete path. Coupled with this, the cement matrix can also have colour added. Always take these factors into account when selecting the aggregates and especially during the process of exposing the aggregates.

Exposing the aggregate

In addition to this, exposing the aggregate at a different concrete curing time can lead to different appearance. Similarly, this can result in colour differences for the same site for the same aggregate concrete pathway. To maintain quality, the landscaper must use a consistent approach to exposing the aggregates. As a rule of thumb, no more than 1/3 of the aggregate should be exposed.

 

 

 

The suitability of Exposed Aggregate Pathways

The landscape architect needs to also consider the use of the exposed aggregate concrete path when selecting the aggregate. Use a fine rounded aggregate for areas near swimming pools. For exposed aggregate concrete paths where water drainage is important, 19mm aggregates should be used.  Exposed aggregates of more than 20mm can be very difficult to transport using a concrete pump.

Exposed aggregate concrete strength

When rounded pebbles are used throughout the path, the path will be slightly less strong. This is because the matrix will not bond to the aggregate as tightly as it will with rough shaped aggregates.  Generally, the path should be at least 100mm thick N25 concrete. N25 means that the concrete will achieve a compressive strength of 25 mPa after 28 days.

Preventing Cracks

Even the strongest concrete will be weak in tension or bending and even properly cured concrete will have microcracks. Therefore, to minimise cracking steel reinforcement must be used. For pathways, this should be at least SL 72 using saddles to keep it in the top 1/3 of the concrete.  SL72 means that the bars are each 7mm in diameter with grids of 200mm. The path should be laid on 100mm thick class 3 roadbase , if it is for public spaces. If there is any possibility of a vehicle driving on the path, then the path needs to be built like an exposed aggregate concrete driveway. This will be the case with any vehicle crossovers in the path design. In these cases the concrete needs to be at lease 125mm thick N32 (32mPa) concrete with SL92 mesh laid on at least 100mm of class 2 roadbase.

Landscape design with exposed aggregate concrete

Outdoor Furniture on Exposed aggregate concrete.

Durable Outdoor Garden Furniture on Exposed aggregate concrete. ACLA Consultants landscape architects.

Using alternating concrete colour to break up large areas of concrete.

When the customer requirements call for a large expanse of exposed concrete, alternating contrasting colours can help to break up the appearance.  The public space at Balwyn Community Centre, Melbourne, used alternating exposed aggregate concrete of Hanson Bokhara with Hanson Galaxy. The artificial turf also helps to break the appearance of the large area of concrete and gives the area a more tranquil appearance. (ACLA Consultants landscape architects.)

Contrasting Exposed aggregate concrete

Creating some shade with a tree in the concreted area. The tree roots are protected with a slotted stainless steel grate. The lighter colour Hansen Galaxy forms a geometric pattern around the grate.(ACLA Consultants landscape architects.)

 

Drinking Fountain and exposed aggregate concrete.

Drinking Fountain and exposed aggregate concrete. Hanson Bokhara contrasts well with the natural concrete in-situ walls. (ACLA Consultants landscape architects.)

 

Hanson Bokhara Exposed aggregate concrete.

Exposed aggregate concrete is ideal for garden steps and stairs to help maintain grip. Recent sealing of the concrete makes it appear slightly darker. (ACLA Consultants landscape architects.)

 

Alternating exposed aggregate

Alternating exposed aggregate path.  Garden beds also break up the space. Sunbury Global Learning Centre.

 

Alternating decorative finish path

Alternating coloured path with centre native garden. Sunbury Global Learning Centre.

 

Entrance and Alternating decorative finish concrete path

Building entrance and Alternating exposed coloured path. Sunbury Global Learning Centre.

 

Concrete block garden retaining wall with coping next to the decorative finish concrete path.

Concrete block garden retaining wall with coping next to the alternating exposed coloured path. Sunbury Global Learning Centre. Hanson Bruthen and Hanson Galaxy.

 

Alternating colours of the concrete decorative finish entrance way.

The decorative finish of the alternating decorative finish of the entranceway looks striking when compared to the old concrete footpath in the foreground. Sunbury Global Learning Centre.

Frequently asked questions about Exposed Aggregate Concrete

Is Exposed aggregate concrete expensive?

Exposed aggregate will be more expensive than normal concrete solutions. It will  however, add more value and landscaping interest to your property. There is also extra labour in exposing the aggregate. Alternating colours is  also great way to break up the large expanses of concrete. It will similarly add to the cost, but will add great value to your property.

Should you seal Exposed Aggregate Concrete?

Sealing is essential for these paths. The high quality sealer we use helps to maintain the appearance of the coloured concrete by preventing stains getting into the pores of the concrete. The sealer also helps to prevent dust coming off the concrete.

Newly sealed paths at Balwyn Community Centre

 

 

Is Exposed Aggregate Concrete Durable?

It is important not to exposed too much of the aggregate during the water pressure cleaning part of the process. This is because exposing the aggregate excessively will result in it breaking loose from the matrix. Do not expose them more than 30%. The concrete we use for pathways is N25 with SL72 reinforcement over a thick layer of roadbase.

Residential Concreting Solutions

For residential concreting solutions a smaller version of the commercial landscaping concepts can be applied. In some cases it will be necessary to cart the aggregate mix in by wheelbarrow.

Exposed Aggregate Concrete Melbourne

Concrete Designs, textures and colours

Outwest Concrete have a great range of  aggregate colours available.

Colours and Textures available.

 

More information on decorative concretes

 

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Some more facts about Concrete Driveways

 

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In-situ concrete retaining wall and garden steps.

In-situ Concrete

In-situ Concrete, also known as insitu concrete, is an outstanding landscaping construction technique. In terms of long terms long term quality, robustness and longevity very few landscape construction techniques come close. To many people in-situ concrete is better know as landscaping architectural concrete and it is the point where landscaping, architecture and civil engineering all meet in landscape design. For the landscape design of public spaces, architectural concrete or in-situ concrete is a great choice for the severe use of our landscaped parks, gardens or commercial buildings. Some other names for in-situ concrete include “poured in place” concrete or “cast in place”  concrete”.

What is in-situ concrete?

In-Situ Concrete cast in place.

In-situ is concrete that as poured into formwork at the building site. When compared to pre-cast concrete, in-situ requires no crane or forklift to get it into position. In comparison with concrete block and rendered retaining walls, the very low porosity of sealed and vibed in-situ walls will ensure a quality finish for decades of use. With concrete block retaining walls, the blocks themselves will have some porosity which will allow moisture to creep under the rendered surface and may cause it to lift in a few years. In-situ concrete has the colour mixed in and the texture is provided by the formwork but it can be rendered if required.

In-situ Concrete pumped into the formwork.

In-situ Concrete pumped into the formwork through a boom.

In-Situ Concrete – strong connection to footings.

An additional advantage with in-situ  is it has a very strong and stable attachment to the very solid footings underneath. This is due to the reinforcement bars coming up from the footings and overlapping with the in-situ concrete steel reinforcement.  When compared with concrete block retaining walls, although the steel reinforcement runs up through the centre of the blocks, any voids in the concrete around the reinforcement can lead to corrosion of the reinforcement bars and concrete cancer. The homogeneity of the of the vibed in-situ walls also ensures a good attachment to the steel reinforcing bars and does not suffer the risk of a poor attachment of the core concrete to the inner void of the concrete blocks. Pre-cast concrete will usually require mechanical fixings to the footing. These fixings can corrode over time or can be ground off by vandals. Being securely attached to the footings is a big advantage of in-situ concrete. Newly constructed public spaces such as parks and gardens will often rely on these quality advantages of in-situ concrete.

Retaining wall footings.

Retaining wall footings with steel reinforcement protruding to give the retaining wall a strong connection to the footing. The reinforcement bars must be accurately placed.

Precast concrete versus in-situ in landscaping concrete architecture.

One of the advantages of precast concrete is that it is manufactured under controlled conditions in a factory. This ensures a consistent quality product. There can be a risk however of coloured concrete coming from different batches resulting in slightly different colours close together. The quality advantages of precast concrete can be matched by in-situ concrete with close attention to the details and quality control of the processes.

 

Quality in-situ concrete retaining walls, stairs and seating.

Commercial Retaining Walls Melbourne

Good quality in-situ concreting requires a lot of attention to the materials and the processes. In-situ concrete wall also need to consider the safety as well as the aesthetics of a public space or residential landscape construction project. A well constructed, quality, curved in-situ concrete wall will achieve both of these aims.

Stripping the formwork off the walls.

Stripping the formwork off the walls. Extra effort and attention to detail will result in a quality finish on the retaining walls.

Quality In-situ concreting footings.

Concrete sets by a chemical reaction and not by drying. The chemical reaction is ecothermic and water is part of the reaction. If there is a difference in temperature within the concrete or if the water evaporates quickly from the top surface, then cracking can be the result. Concrete footings should not be poured in freezing conditions or below 5 degrees. Fortunately, in Melbourne there are very few days when it is too cold to pour. In hot weather the concrete should not be poured during the hottest part of the day or in extremely hot weather. The top part of the footing can be kept moist with hessian or a light sprinkling of water to prevent the top layer of the footing being weaker.

Concrete reinforcement bars in the footings.

It is essential that the vertical bars coming out of the footing are located accurately. When the in-situ walls are poured, these bars need to be closed to the centre of the retaining wall with good overlap with the wall reinforcement. The concrete reinforcement within the footing should be encased within the concrete as much as possible to minimise the paths for moisture to get into the reinforcement.

 

Concrete footing design

If designing for in-situ concrete retaining walls, the concrete footing should be a suitable size for the wall, keeping in mind all of the loads on the wall including hydrostatic and mass of the wall. The design of the footings must be to Australian Standards.

 

Formwork for in-situ concrete retaining walls.

Quality in-situ walls require formwork that is smooth strong and flexible.  Any defect, imperfection of inaccuracy in the formwork will show up in the surface of the wall. The formwork needs to be strong enough to resist the weight of the wet concrete without bulging or deforming. Deflections in timer formwork will show up as ripples in the finished wall. A bulge in the formwork due to the hydrostatic load of the concrete will be a disaster when removing the formwork from the wall. The wall should be designed with a slight draft angle to make the removal easy without causing any damage to the retaining wall.

Strong supports for the formwork.

Strong supports for the formwork keep the wall dimensionally correct.

 

Accurately positioned formwork under construction.

Accurately positioned formwork under construction.

 

Pouring the concrete retaining walls.

Pouring the concrete retaining walls. Using the concrete vibrator to get a quality finish and good adhesion to the reinforcement.

 

 

Stripping the formwork after the concrete pour.

Stripping the formwork after the concrete pour. The formwork should be left on as long as possible to prevent the concrete drying excessively during curing. Taking the formwork off too early can result in microcracks in the concrete.

 

Stripping the formwork after the concrete pour

Stripping the formwork after the concrete pour and curing to show a quality result.

 

In-situ concrete steel reinforcement

The steel reinforcement bars must have a good overlap with the footing reinforcement bars and well encased within the concrete wall. Reinforcement to close to the surface may result in water ingress and concrete cancer.

 

Pouring the in-situ concrete.

The concrete walls should be poured in one go and definitely from the same batch of concrete.  Any interruption of the pour may show up as a line in the finished wall.  The freshly poured concrete should be thoroughly vibed to ensure there are no voids within the concrete especially on the outer surfaces or at the interface with the reinforcement.

The steel reinforcement within tin-situ also helps to prevent surface cracking. To minimise the surface cracks, we leave the formwork in place a little longer to keep the moisture in during curing. The concrete should then be given a light sprinkle of water once the formwork is removed as it is still curing. The concrete will not be fully cured for a few weeks so consider this before applying any excessive loads.

Landscape and Concrete Design

Landscape Design with in-situ walls.

In-situ walls give the landscape designer or the landscape architect enormous freedom to design shapes for retaining walls, seating  or concrete stairs that would be very difficult, if not impossible, using precast of other landscape construction techniques. In-situ walls can be designed into three dimensional shapes that would be impossible or expensive to do as Pre-cast. Curved retaining walls on an uneven landscape would be very difficult to achieve with any other landscape construction technique. Another advantage is the wide range of colours available.

In-situ concrete curved seating

In-situ concrete curved seating. Shapes like this are difficult with other landscape construction techniques.

 

Concrete stairs Cast in Place

Concrete stairs Cast in Place. This process is ideal for intricate or bespoke designs.

 

 

In-situ curved garden retaining wall.

Exposed aggregate path and in-situ curved garden retaining wall. Overflowing Australian native grasses in the garden bed soften the look of the concrete. The exposed aggregate path provides an attractive contrast to the wall and plants. It is also a safe non-slip cost-effective solution.

 

In-situ retaining wall and steps

In-situ retaining wall and steps

 

Curved In-Situ retaining wall.

Curved In-Situ retaining wall prior to the final touch up and surface treatment. The joins in the formwork will be visible until the concrete is ground back to an even join.

As the concrete is pumped in, damage to other landscaping structures can be avoided, making it  easier for the landscape project planner to  schedule the construction. These are important factors to consider when landscaping Melbourne public spaces.

In-Situ retaining wall.

A very straight In-Situ retaining wall.

 

In-situ retaining wall

Exposed aggregate pathway and in-situ retaining wall prior to filling and grinding by the concrete finisher. There will always be a few small voids to fill, but theses can be minimised with the vibe during the pour.

 

See also Concrete Architecture in Landscaping

 

Concrete For Landscape Design & Construction

 

© 2020 Reds Landscaping and Civil quality commercial landscaping Melbourne

 

 

More information on visual concrete for landscape design

Read more
Concrete Architecture

Concrete Architecture in Landscaping

Concrete architecture in landscaping is often seen of as a brutalist approach to landscape design. It is however possible to soften the design of concrete architecture with the use of landscape design techniques such as ponds or garden beds as well as using textiles such as cushions. The concrete architecture can also be softened with the use of naturalistic materials in the garden design such as timber or terracotta pots. The bringing together of cottage garden design with concrete architecture create a fusion of two very different garden design themes.

Garden Rocks

Naturalistic materials like these garden rocks help to soften the look of the in-situ concrete stairs.

Concrete Architecture design ideas

Concrete Designs

To see how to use concrete architecture in garden design, a visit to one of the bigger garden shows will help. Possibly the most famous of these shows is the annual Chelsea flower show held over 5 days in May each year. Unfortunately, there will be no show in 2020.  Due to the time constraints of a 5-day garden show, much of the concrete will be precast elsewhere and craned into place. To see examples of in-situ concrete, a visit to some of the recently constructed Melbourne public spaces such as Balwyn Community Centre or the Sunbury Global learning centre will provide some ideas.

Concrete Architecture

Concrete Architecture can be softened with garden plants and garden furniture. Sunken garden Chelsea Flower Show Gold Medal winner 2018. Kate Gould Gardens. Designed as a concept for a traditional square London West-End garden.

Concrete Designs

Precast Concrete Architecture

Formal blocks of stone and concrete with  foxgloves. Skin Deep. Garden designed by Robert Barker design. The blocks represent different human faces and skin conditions. Note the use of colour and texture in the concrete blocks. Plants were also chosen for form and texture.

 

Landscape design Ideas Urban Flow by Tonny Woods

An outdoor kitchen design using a concrete bench with cooktop, wooden paling fence and vertical kitchen garden. Urban Flow by Tony Woods combines bold landscape design with practical solutions.

 

Garden Pond. Landscape design idea

Garden Pond. Landscape design idea. A pond with overhanging flowers will soften the look of the garden.

 

Garden idea - Sunken Garden

Great colour coordination with the natural concrete colour with matching outdoor couches. Note how the cushions match the colours of the garden. Chelsea Flower Show 2018. Landscape design by Hay-Joung Hwang.

 

LG Eco-City Garden

The LG Eco-City Garden by Hay-Joung Hwang, represents one housing unit in a vertical forest. Note the use of coloured stone to provide a theme through the garden. The concrete has been softened with the use of soft furnishings, abundant lupins and a pond with concrete stepping stones.

 

Garden idea. Pond with concrete stepping stones.

Garden idea. Pond with concrete stepping stones. LG Eco-City Garden Chelsea Flower show 2018.

 

Curved Garden Seat garden design idea.

Curved garden seat with irregular stone paving. Design by Naomi Ferrett Cohen – Chelsea Flower show 2018.

Related Concrete Architecture and Landscaping Ideas from Red’s Landscaping

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© 2020 Reds Landscaping and Civil quality commercial landscaping Melbourne

Read more
Exposed aggregate Concrete Pathway

Landscaping Concrete

Landscaping Concrete needs to be the correct grade with the correct reinforcement for the job it is selected for. Otherwise cracking can occur. To properly decide on which mix to use, it is important to understand what it is and what factors affect its physical properties. There are many different grades of concrete available, so it important to pick the correct one for the job. Coupled with this there are different grades of steel reinforcement to choose from.

Pre-mixed Multipurpose Concrete for garden walls

 

Garden Paving

Bending stresses are not normally a problem with garden paving when a properly prepared sub base has been created. Steel reinforcement will however, help to prevent cracks opening in the pavement.

Generally, the path should be at least 100mm thick N25 concrete. N25 means that the concrete will achieve a compressive strength of 25 mPa after 28 days. If you are in a part of Melbourne with a reactive clay soil, you need to ensure there is sufficient thickness of roadbase under the paving to cope with the expansion and contraction of the soil.

Preventing Cracks in landscaping concrete.

Even the strongest concrete will be weak in tension or bending and even properly cured concrete will have microcracks. Therefore, to minimise cracking steel reinforcement must be used. For pathways, this should be at least SL 72 using saddles to keep it in the top 1/3 of the concrete.  SL72 means that the bars are each 7mm in diameter with grids of 200mm. The path should be laid on 100mm thick class 3 roadbase , if it is for public spaces. If there is any possibility of a vehicle driving on the path, then the path needs to be built like an exposed aggregate concrete driveway. This will be the case with any vehicle crossovers in the path design. In these cases the concrete needs to be at lease 125mm thick N32 (32mPa) concrete with SL92 mesh laid on at least 100mm of class 2 roadbase.

Landscaping concrete. Steel reinforcement helps to prevent large cracks opening up in your concrete.

For paving, the steel mesh should be placed about 30mm from the top surface. When reinforcement steel is placed too near the surface, it can corrode. Expansion results as steel is converted to iron oxide through corrosion. This expansion can crack the concrete surface and accelerate the concrete cancer.

Concrete block garden retaining wall with coping next to the alternating exposed aggregate path.

Concrete block garden retaining wall with coping next to the alternating exposed aggregate path.

When the crack is caused by corroding steel, corrosion is typically visible at the slab surface. In the case of retaining walls, the wall is in effect a cantilever beam with the soil applying pressure to the wall. Steel reinforcement will help increase bending strength of the wall.

Melbourne Landscaper - Concrete in-situ steps Mill Park Leisure centre.

Melbourne Landscaper – Concrete in-situ steps Mill Park Leisure centre.

Architectural Landscaping Concrete in Melbourne

Modern concrete is now available with an enormous range of colours and textures. There are some available that can mimic the appearance of stone, but at a much lower cost to the landscaper. There are also some techniques by landscape architects to break up a large expanse of concrete by using alternating contrasting colours.

Exposed aggregate Concrete Pathway

Exposed aggregate Concrete Pathway using alternating coloured concrete. The appearance is also softened by the mulched garden bed with plantings of native grasses. These architectural concreting techniques provide a very cost effective solution but maintain the aesthetic appeal.

Related Concrete information from Red’s Landscaping and Civil

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Contact us

For help with the design  and development or your landscaping ideas, contact one of our experienced Landscape Gardeners.

We can help with small garden design all the way up to  Commercial Landscape design.

Our specialities include fast growing screening plants, plant health and horticulture, garden lighting  and in-situ concreting.

By Callum O’Brien – Landscaper Melbourne

 

 

© 2020 Reds Landscaping and Civil quality commercial landscaping Melbourne

 

For more information on concrete

 

How to minimise thermal cracking

 

How it is made and the scientific principles.

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