Expando Articles

Energex - Removal Of A Concrete Slab

John Rothwell Director of No Blast Pty Ltd - Tuesday, August 05, 2014

When I was contacted by Adam Philippini, the Construction Coordination Officer for Energex (an Australian energy provider) to remove a concrete plinth from their basement yard, I knew that Expando Explosive Mortar was the perfect solution for the job.


The concrete plinth needing removal was being used as a base for a transformer, the slab itself was approximately 1 metre thick by 3 metres wide and 10 metres long.


Given the location and size of the plinth, removal was not going to be a straight forward demolition job, this is one of the reasons that Expando was an excellent choice.


The slab was between two buildings where there could be no vibrations, minimal dust and no airborne concrete chips, this mean that traditional demolition methods such as  pounding the concrete with an evacuator was not an option.


After researching alternative solutions, Energex decided to use the unique non explosive demolition method that Expando Expansive Mortar provides, it was also chosen due to the cost saving provided over other demolition options.


To carry out the concrete demolition, Energex loaded Expando SCA-2 into holes drilled 38mm wide, approximately 450mm apart and around 850mm deep. 

The chemical started to crack the slab early on the second day after application, the weather was warm which helps with a quicker concrete burst.


To further speed the process and to ensure the reinforcing was cut, Energex decided to run diamond saw cuts along the slab, as you can see however in the images below, these cuts were not necessary as the job was completed entirely by the chemical expansion.


Expando Expansive Mortar ensured a safe and effective means of demolishing the concrete slab, with none of the usual concerns that need to be considered with demolition in a busy area.


Energex have been very happy with the result and will continue to use Expando in future jobs. 

Tunnelling a horizontal shaft through Sydney Sandstone

John Rothwell Director of No Blast Pty Ltd - Monday, October 31, 2011

We are now involved in a small residential tunneling project in North Sydney. The owner is in his early 70s and knows that in the future the 38 steps from his gate to his door are going to become a really big obstacle. The project is to cut a tunnel through the rear of the garage under the front lawn and then under the existing lounge room, where a small elevator shaft will connect the vertical shaft to the horizontal tunnel under the front lawn. The project has been a hobby for the former mining engineer.

Due to the cost and time taken to excavate the first five meters of the tunnel we have been engaged to help. The challenge has been to fill horizontal and vertical holes using the chemical Expando. We initially used a grout pump to fill the horizontal holes but the cost of hiring was too expensive for this residential job so we came up with an alternative method.

We have been filling long skinny bags with the chemical Expando and forcing the bags into the horizontal holes using a PBC pipe and Timber ream it has had the same effect as if we had poured it into the holes from the top.

We are now far enough under the house that we can start cutting in the vertical shaft .Holes have been drilled up from the lower tunnel and as we remove the rock from the top we can simply drop it down the hole to be cleaned out through the garage. 

(Click on the images to make them larger)

Reduce construction vibration with Expando

John Rothwell Director of No Blast Pty Ltd - Saturday, September 03, 2011

 

As the building and construction industry faces escalating urban density, natural environmental concerns and proximity to cultural heritage areas such as schools and hospitals, controlling construction vibration can be a nightmare.

Complaints from neighbours, council restrictions, crippling project budgets, and damage to adjacent buildings are some of the common impacts from vibration issues.

Now an innovative product called Expando has provided a solution for these difficult sites. Expando – a non-toxic expansive mortar is the ideal solution to crack rocks and concrete without the headache of vibration issues typical of traditional demolition and rock removal methods.

Expando is a non explosive demolition agent with an impressive 14,000 PSI expansive strength that will simplify the process of cutting and breaking rocks or concrete and takes the risk out of difficult excavation, trenching or demolition work.

By using Expando, you can save thousands of dollars and achieve your demolition objectives without having to hire expensive experts or specialised equipment like excavators, jackhammers, concrete saws or use explosive blasting.

Why is vibration an important issue?

Construction vibration levels are set by regulatory authorities such as each state’s Environment Protection Authority (EPA), Standards Australia and local councils*.

The need for such regulation arises as construction equipment (including pile drivers, jackhammers, dump trucks, dozers, excavators and concrete saws) can operate in very close proximity to residential and commercial premises, sometimes for extended daily hours and for some projects, in excess of two to three years. If vibrations are a potential problem, councils may require a dilapidation report on neighbouring properties as part of DA approval.

If vibration levels from construction are too high, then people residing or working nearby may take action or involve councils to restrict construction activities, especially if it can be demonstrated that levels exceed acceptable limits set by relevant standards and regulations. As such, construction vibration can threaten a project's schedule and budget if not adequately addressed.


Vibration – Some of the impacts


Neighbour Complaints due to Human Disturbance

Vibration can potentially impact on an individual’s quality of life or work efficiency. This is especially true for project sites within close proximity to residential or cultural heritage areas such as schools and hospitals.

The vibration criteria for human disturbance tends to be more stringent than for effects on building contents and building structural damage. The table below shows vibration limits for normal construction activities to protect human comfort based on NSW EPA's guidelines. These human comfort limits are intended to minimise annoyance and are below levels required for the prevention of structural damage to buildings (because people can feel vibration at lower levels than what is required to cause damage to buildings and contents)and as such, are considered suitable for use in general assessments.


Table 1 – NSW EPA Vibration Limits to Protect Human Comfort (rms)*

Place

Time

Continuous Vibration

Intermittent Vibration

Residential

Day

0.2mm/s

6.0mm/s

 

Night

0.14mm/s

2.0mm/s

Offices

Day

0.4mm/s

12.7mm/s

 

Night

0.4mm/s

12.7mm/s

Workshops

Day

0.8mm/s

12.7mm/s

 

Night

0.8mm/s

12.7mm/s


Below are some commonly used indicative minimum buffer distances to avoid human discomfort during the day. However, please note that as vibration level depends on many factors and is site specific, these should be used as a general guide only.


Table 2: Suggested Minimum Bugger Distances to Avoid Human Discomfort*

Activity/ Equipment Type

Min. Distance

Rock breaker  (small – large)

5m – 15m

Pulverisor 30 tonne

4m

Bulldozers

5m

Vibratory rollers (light – heavy)

5m – 25m

Truck movements

10m

Sheet piling

50m


Structural damage to buildings

Construction in dense urban settings can result in damage to adjacent structures. Even the most careful planning and implementation can result in damage if adjacent buildings are fragile or especially susceptible to vibration due to demolition and other construction activities.

Currently no Australian Standard exists for assessment of building damage caused by vibrational, however as a guide, the German standard DIN 4150 - Part 3 Structural vibration in buildings – Effects on Structures provides “safe limits” up to which no damage due to vibration effects has been observed for particular classes of buildings.


Table 3: Minimum Safe Limits of Vibration to Reduce Likelihood of Building Damage (rms)*

Building Type

Intermittent Vibration

Commercial & Industrial

20mm/s

Dwellings

5mm/s

Sensitive Structures (eg. historical with preserve orders, etc)

3mm/s


British Standard BS7385: Part 2 Evaluation and measurement of vibration in buildings also sets standards for assessing the likelihood of building damage from vibration.


Reduce construction vibration – Buy Expando today

When construction vibration is an issue for demolition and excavation work in residential settings or sites within close proximity to cultural heritage areas such as schools and hospitals, Expando is the ideal solution for you.
Expando is a non explosive demolition agent that cracks rocks and concrete without the need for blasting or heavy equipment like excavators, jackhammers or concrete saws.

Buy Expando now via our secure online shop, delivered anywhere around Australia. For more information on Expando expansive mortar please contact us.