20/06/2016
Sub-standard microfine grout soil injection techniques and the wrong choice of microfine cementitious grout for the soil to be treated is becoming an increasing problem for builders and the piling stabilisation industry in Western Australia. The images below highlight what can go horribly wrong structurally. Lets cut to the chase here and discuss why this is happening.
There is an ill-informed perception among some engineers and builders that use of microfine cementitious grouts for soil permeation is a simple one. Whilst on the SURFACE its use and results appear to be uncomplicated the reality is, underground it is not. The varying soil types and environmental conditions, engineering design and actual outcome requirements, project time constraints, site access, adjoining structure surcharge loads and a myriad of microfine cementitious manufacturer products and additives are thrown into the MIX so how on EARTH is that simple? With all these variability's and any one of the following:
Lack of knowledge of how a particular product works in the actual ground conditions, including water/cement ratio's
Lack of a disciplined and recorded installation methodology and process log
Poor product selection choice and failure to use a proven/reputed product manufacture (i.e. unproven/untested Chinese or Indian product currently flooding the market)
Limited or no engineering expertise/knowledge in time tested and proven design methodology outcomes
Limited or no historical testing regimes of particular products in particular ground conditions
Careless introduction of unproven and untested components that incorrectly claim to improve the tensile and shear strength of a grout block structure resulting in Global Failure
Installation inexperience (unproven track record of project success with out failures or complications)
promote a potential scenario of catastrophic failure risking life and property, so why would you do that? Sometimes luck will play a part and the outcome will be sufficient to support what is there, temporarily. Just because the face of a grout block appears “ok” that's no guarantee that the rest of the grout structure is. Is the structure monolithic and consistent with the engineering design intent? In short, HOW SAFE IS IT!
Core sampling of a grout block to confirm actual pe*******on depths, a disciplined and recorded installation methodology and process logs, the use of volume flow meters, shear strength testing of core samples and the use of reputed and proven Microfine products goes along way in ensuring the installed grout structure meets acceptable engineering standards. As I've stated before there is no Australian Standard for the use of Microfine Cements and injection procedures. Worse still there are no licensing requirements for installing contractors in Western Australia! See: Industry Warning
For example, West Australia's reputed Microfine injection specialist companies know full well others are “short injecting” grout, particularly at the back of grout blocks, or where no excavation is to occur, to save on M3 grout volumes installed. There is also evidence to suggest reinforcing product is mistakenly introduced and claimed to strengthen the grout blocks design. This has been done without the necessary failure testing to confirm its stated advantages. As is the evidenced in the photos, there is no discipline in grout cover of the pushed in vertical steel rods at each grout injection location. It seems to indicate a total lack of understanding in engineering principals. The photos herein are a case in point.
In recent times there have been a number of avoidable failures by new players to the industry. The current economic climate in the WA construction industry is motivating builders to use contractors that produce substandard workmanship and use inferior microfine grout materials.
Differing soil conditions deliver differing aesthetic results but there can be no compromise to the monolithic mass grout block design outcomes. If an installer is a little unsure as to what is exactly going on underground during the injection process the rule is "INJECT MORE GROUT".
For over 25 years FONDEX has been injecting microfine grouts into West Australian soils. Over that time FONDEX has successfully completed thousands of projects without a single failure. Only a couple of its peers can boast similar results.
More than ever it is critical for the engineering and construction industry to take note and develop a strategy to limit this behaviour. And it's up to the leaders in the piling and stabilisation industry to actively educate them & expose these bad practices.
Fondex - Do it RIGHT or do it CHEAP. You choose!
