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M.E.T.T.S. - Consulting Engineers > R&D Projects > Deactivation of Landmines by Passive Degradation

The Deactivation of Landmines by Passive Degradation


Dr. Michael C. Clarke, M.E.T.T.S. Pty. Ltd., Sydney, Australia


Colonel Rod McKinnon, Royal Australian Engineers

As presented at the PARARI Ordnance Conference, March 1995, Canberra, Australia


From the middle 1970's to the present, landmines have become a weapon of choice for armies and insurgent groups for many conflicts in the third world. The landmines are sometimes aimed at vehicles or tanks, but more commonly at personnel. Anti-personnel mines are small, and are not designed to kill directly. They are designed to cause severe and lasting injuries, that have an on-going economic consequence for society to which the maimed return.

Many modern anti-personnel mines are of simple and cheap construction. These mines are often constructed of plastic with little metal content, and are virtually undetectable by magnetic or electronic means. An estimated one hundred million have been spread over sixty two countries1. An example of a plastic mine is the butterfly mine as shown in the photograph. Such mines have a very long life and are attractive to children2; they are soft and look like a toy. By squeezing the thicker side several times, a child will release the firing pin, thus removing the playing hand.

Propositions for the total banning of landmines have been put forward by both national and private organisations. In the very best of worlds mines would never have been invented, and no problem would exist. In our present world, the acceleration of insurgencies and examples of irregular warfare, will only see more use of landmines in the future. Conventions to ban their manufacture, export and use will be ignored by countries and groups who through lack of cash, military and civil discipline, and morals, will see the landmine as a 'fair' weapon.

Some nations that wish to use landmines for border security, have expressed the desire to have mines that have indefinite active lives. Unfortunately mines that are laid as permanent features of a border boundary, can still 'migrate' through water and ground movement, causing casualties amongst those who live in border regions, and amongst border guards responsible for border security. Whether it be in a war or border situation, emphasising the advantage of having a mine with an 'inactive laid by date' is the best answer to future problems caused by their use.


The aim of this paper is to outline an option for the passive deactivation of landmines through the incorporation of degradable bio-plastic components.


The combined effect of direct fire weapons (tanks) and indirect fire weapons (artillery), natural terrain, and man-made or artificial obstacles provides a commander with an effective and efficient means of restricting an enemy's manoeuvre capability. Mines are one form of artificial obstacle which may be employed to enhance the effectiveness of other weapons across the spectrum of military operations. In conventional warfare, landmines are considered an integral part of a co-ordinate military plan. However they must be considered as an element of available combat power, and not viewed in isolation.

Mines can be grouped in two broad types, anti tank/vehicle and anti-personnel. Anti -tank mines are designed to inflict damage to armoured and soft skin vehicles while anti-personnel mines are intended to inflict casualties to personnel. Mines of both types can be employed individually, or in quantities to form minefields.

Mines/minefields are designed to create delay, supplement other obstacles, deny the enemy the use of ground, channel the enemy into areas where direct and indirect fire weapons may be used to optimum effect, provide protection to unit positions, vital assets and infrastructure and degrade the enemy's morale.

When employed in accordance with the principals of conventional warfare where classical contemporary military doctrine prevails and trained, disciplined soldiers are engaged, mines do not present a hazard to non-combatants as minefields are recorded and marked to facilitate later clearance. In contrast, the use of mines in civil war, insurgency and counter insurgency operations, by forces who ignore the conventions of the Law of Armed Conflict, have produced the serious dilemma now confronting the international community.


Mines generally consist of five parts. These are:
· a firing mechanism or other device, which sets off the detonator or igniter charge,
· a detonator or igniter charge,
· a booster charge which may either be attached to the fuse/igniter or be part of the main charge,
· a main charge in a container, which actually forms the body of the mine and
· the outer casing which contains all the parts listed above and may be made of wood, plastic, metal or other material. A general design of a simple mine, is presented in Figure 1.

The aim of the firing mechanism is twofold. Firstly to prevent the mine from exploding before it is acted upon by the type of influence to which the firing mechanism is designed to respond, and to ensure immediate detonation when the mine is actuated. Simpler types of firing mechanisms, which are most commonly found, may be activated by mechanical means such as pressure, pressure release etc. More complicated mechanisms often include electric systems that are activated by sound(acoustic), magnetic influences from a passing vehicle, radio frequencies or vibrations (seismic).

Many modern mines are designed to self-neutralise after a predetermined or pre-selected period of time. The self destruction or self-neutralisation process relies on mechanical, electrical or electro-chemical (including battery exhaustion) systems which as yet have not proven 100 percent reliable.

The detection of mines in indiscriminately laid minefields is a slow process. Despite advances in technology, manpower intensive have proven to be the only way of providing a reasonable guarantee of success in those effected countries. Given that the types of mines likely to be used in civil wars, insurgency or counter insurgency operations will be of cheap, unsophisticated variety, and that a total ban on manufacture is unlikely to be achieved, one possibility is to provide the manufacturers of these mines with simple, cheap, easily incorporated neutralising mechanisms.


The creation of a passive system for disarming landmines is considered as tan option for ensuring that such weapons have a destructive life that will end when their use as a weapon is no longer desired. The passive system should be such that it will not significantly add to the cost of manufacture. A process where landmines degrade so that they are incapable of detonation is being proposed. Biologically activated degradation is considered the best means of achieving that end.

Some conceptual points for consideration are:

· The inclusion of (or manufacture from) degradable material (or mechanism) in landmines to allow for their degradation over time, once laid in a war situation,

· Such weapons would be rendered harmless, after a period that would be considered reasonable for civilian reoccupation,

· The inclusion of bio-degradable plastic (or other mechanism/material) would be such that as the material degraded, the weapon would be rendered harmless. This could be achieved by allowing air, water and micro-organisms to enter the mine and rot the explosive, deactivate the firing mechanism and/or destroy the casing. In electrically detonated mechanisms, the invasion of water etc could be used to short-circuit the battery,

· Landmines produced in such a way, would have a 'natural' laid life, that would be defined by a time median and a distribution,

· Allowance would need to be made for local climatic conditions when estimating the active life of the weapon in a particular area,

· The systems developed would be suitable for inclusion in 'cheap' mines that do not contain a timed self-destruct mechanism, or as a back-up (an inexpensive redundant inclusion) in mines that contain more sophisticated self-destruct mechanisms and

· Stable storage of such mines would be ensured by using methods developed for food preservation. These methods could include vacuum packaging, of packaging with dry nitrogen.


Using bio-degradable or corrosive decay systems, precise deactivation times would not be achievable. However general mine deactivation periods could be achieved, where civilian reoccupation could be allowed with 'reasonable safety' after that period. (The safety of all individuals, in all situations, could not be guaranteed, but the terrible circumstances that exist in Angola and Cambodia would be largely avoided.)

Where the degradation of the explosive is the means of deactivation, then deactivation would depend on a number of factors. These would include;

1. Explosive Composition. Some explosives have considerable resistance to non explosive decomposition. Others, particularly those based on ammonium nitrate, tend to degrade much faster. Standards may need to be devised for the decomposition characteristics of landmine explosives. (Ammonium nitrate based explosives, are cheap to produce, can be made very powerful depending on what additives are included in the composition and can have short or long 'shelf-lives'.),

2. The degree of contact between the atmosphere (including microbes) and the explosive and

3. The climatic and physical conditions under which the mine is laid. Exposure to sunlight, the range of temperatures and the rate of change of temperature, exposure to water and the composition of the water, the immediate presence of organic material, the depth of burial and degree of exposure to the elements etc will all effect the viability of the landmines.

For deactivation that depends on the destruction of the detonating mechanism, the resistance of that mechanism to corrosion would be the governing factor. For electronic mines, the ability of moisture to enter the mine and discharge the battery, would be crucial.


In the figures included with this presentation some concepts for mine deactivation are presented. These are based principally on bio-degradable plastic incorporation, but may also include the incorporation of corrodible metal sections in mines (zinc/magnesium plugs in metal cased mines), or fine capillary tubes in other mines. Figures 1 and 2, show the basics of the incorporation of the bio-degradable material or capillary tube. Figures 3 to 7, show specific examples of personnel and anti-vehicle mines that include passive degradation features. Figures 8 and 9 show more advanced use of bio-degradable plastic.


It seems likely that the UN Convention on Inhumane Weapons will come up with new rules for landmines. The rules are likely to state that mines will be detectable (by metal detectors or possible radiation and or chemical emissions) and have automatic destruction mechanisms. The Convention rules have however been ignored in the past, and will be ignored in the future.

Given that landmines are cheap weapons, often used by very unsophisticated and under-funded armies, accurate mapping is unlikely during a war and detection is awkward after war has passed an area. The hope that such armies will use 'better' self-destructing weapons is unlikely, since the cost of such weapons will be significantly higher than the simple units. A minimalist approach is more likely to be followed than a comprehensive set of rules requiring expensive compliance.

The incorporation of bio-degradable (or similar) self deactivation mechanisms at minimum cost, would be preferable in such situations. Local troops would not have to set a destruction mechanism (or be tempted to not set that mechanism).

For the leaders of warring parties, the use of self deactivating mines would have the attraction that the land that their people are fighting over would be useful at some future date, and that this return to usefulness would be achieved without the huge cost on mine clearance.


Standards for such mines would need to be written. Deactivation times would need to be established for various climatic and ground conditions. Considerable research on mine design and bio-plastic degradability (and climatic variation) will be required to turn this scheme into a workable proposal. The chemical engineering profession would make a significant contribution to such research.

Bio-degradable plastics are made from materials that include, modified corn and potato starches ('the monomers'), to which are added fillers, plasticising agents and stabilisers3 & 4. Their properties range from thermoplastic to thermosetting. They can be used for cladding and structural purposes, depending on the composition of the 'monomer'. For incorporation into landmines, structural material would probably be used, although the incorporation of a degradable membrane inside a mine may also achieve the desired degree of degradability - Figure 8.

The inclusion of starch consuming yeast into a mine, contained in capsules that would be ruptured when the mine is laid, may be one way of achieving predictable deactivation times. The inclusion of live yeast however could be challenged in terms of international conventions on the use of biological agents5&6 in warfare. To avoid such a challenge, the yeast would need to be of a type that has no pathological properties; for example, brewer's yeast.

Figure 9, shows a mine with a case made from bio-plastic. The cost of this mine would be significantly higher than one made from conventional plastic, since the bio-plastic monomers are up to six times the price of conventional material. Also, to make this mine a reality, additional research would need to be carried out on the physical properties of the case during detonation.


It should be possible to incorporate inexpensive passive deactivation systems into landmines. The incorporation of bio-plastic into landmines would be a means of achieving that goal.

Accurate deactivation times could not be guaranteed. However any development that gives reasonable certainty that landmines will be deactivated over some defined period, will be welcome.

Research into degradability of bio-plastics, as well as the best means of incorporating that material into mines, will be needed. Once that initial research has been carried out, development work can be undertaken to, design mines, find the most suitable explosive, assess deactivation periods and develop standards for manufacturing. Finally international marketing (including the use of political and moral pressure) will be needed to ensure their use; as against landmines with no deactivation mechanism.

Recent Developments: The Pentagon looks to Non-Persistant Landmines, 2004

ABC News: Saturday, February 28, 2004. 9:00am (AEDT)

Story: Fury mounts over US landmine U-turn

"The United States has abandoned a sweeping land mine prohibition envisioned by the Clinton administration in a move that has angered humanitarian groups. The new policy allows the use of sophisticated or "smart" land mines that can be automatically defused within days, marking a retreat from the pledge to ban all land mines by 2006 if the Pentagon is able to develop alternatives.

It would ban after 2010 "dumb" mines that cannot self-destruct and pose a risk long after battlefields return to peaceful use. The United States, which has refused to sign on to a global land mine treaty, has long been criticized for its mine policies."

NB. The development of landmines that self destruct or degrade should be a priority. The question is: 'can the Pentagon develop suitable self-destruction and/or self-degradation systems for landmines that maintains their weapons capability, whilst preventing civilian carnage?'


1. Landmines and (the) Expanding Global Arms Trade Industry.
Human Rights Council of Australia

2. Seeds of War. Louise Williams and Warren Osmond.
SMH February 26, 1994

3. NOVON Polymers. Technical information produced by Warner-Lambert, Pharmaceuticals.

4. The Starch Industry. J. W. Knight., Pergamon Press. Oxford, 1969.

5. Protocol II of the Inhumane Weapons Convention, 1980

6. Geneva Convention

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