Waste accounts for concrete and brick, 1999

Attention has been focused on concrete waste recently because in a certain period, PCB was used as an additive in concrete. PCB is considered to be one of the most harmful environmental toxins and is on the authorities priority list of environmental pollutants that are to be phased out by 2005. High concentrations of PCB in humans and animals have been associated with learning difficulties in children, increased risk of cancer and hormonal disturbances. In its report SFT - rapport 98 : 09 , the Norwegian Pollution Control Authority has estimated that there is around 80 tonnes of PCB in concrete in existing constructions. PCB was used as an additive in concrete and sealing compounds between 1960 and 1975. On the basis of the information recorded in the Ground Property, Address and Building Register (the GAB register) pertaining to the age of demolished buildings, it would appear that buildings built in a particular era are demolished relatively evenly over a long period of time. On the basis of this and the assumption that demolition activity is proportional to construction activity, we have calculated that in 1999 a little less than 1.5 tonnes of PCB was contained in concrete and brick waste (hereinafter “concrete waste”). In addition, it is likely that some PCB used in sealing compounds was also included in the concrete waste. By way of comparison, it has been suggested that 50 kg of PCB is included in discarded window frames every day.

At present, there are no special routines for the treatment of PCB in concrete. The regulation regarding PCB prohibits recycling of concrete containing PCB.

If these assumptions are correct and the rate of waste generation does not change significantly, PCB in buildings will have been phased out by around 2050. However, PCB will continue to have toxic effects for a long time after this.

Buildings are the main source of waste

Approx. 90 per cent of the total concrete waste is generated during construction, demolition and renovation of buildings, of which demolition is responsible for three quarters. There are no statistics on concrete waste from other types of constructions (bridges, quays, pipelines, curb stones, etc.). Against the background of communications from the Norwegian Public Roads Administration, the Port Authority, the Norwegian National Rail Administration and others, we have estimated that construction in these sectors produces approx. 30 000 tonnes of concrete waste, or about 3 per cent of the total concrete waste.

Concrete waste is also generated during the production of concrete products and ready-mix concrete. On the basis of production data, it has been estimated that this industry generates around 80 000 tonnes of production waste, which constitutes 7 per cent of the total quantity of concrete and brick waste in 1999.

Different types of pipes represent a large share of the concrete products in the constructed environment. We must assume that a considerable proportion of concrete pipes are replaced every year. However, much of the scrapped concrete is left in the ground and does not pass through the waste system. Statistics on the length of pipes made of different materials are not good enough to allow us to suggest a figure for the quantities of waste produced by replaced water and sewerage pipes. However, data in this area are being improved. New concrete pipes currently represent a little over 150 000 tonnes per year.

11 percent recycling

Concrete and brick waste can be crushed and used on site or delivered for recovery of materials to specialised recycling plants and some crushed stone producers. There are only a handful of specialised recycling plants in Norway that handle concrete and brick waste. In 1999, these plants recovered approx. 130 000 tonnes of concrete and brick. Increasingly, concrete from demolished buildings is being crushed using mobile crushing machines and reused on site, for example, for landfill. Whether the concrete in these cases is to be counted as waste or not is a point of discussion: traditionally, materials that are reused on site are not regarded as waste, but in this case, it may be included in the total figures, because it is not possible to distinguish it from other types of concrete waste using the method that is currently used to calculate the amount of building and construction waste generated.

Most from building works

It is difficult to provide an exact distribution of the origins of the concrete waste. Although over 90 per cent of concrete waste comes from buildings, this does not automatically entail that it is the building and construction industry that is responsible for the waste. If the contractor commits to dealing with the waste, then it must be regarded as waste from the construction industry; in the opposite case however, it ought more rightly to be regarded as waste from the developers industry. In these accounts, for the sake of simplicity, concrete from buildings is regarded as waste from the construction industry. On the basis of the industrial waste statistics , we would suggest that a little over 15 per cent of the concrete waste comes from industry.

More concrete expected

In the coming years, we can expect considerable quantities of concrete waste from the offshore industry. For example, in connection with the Ekofisk tank and the protective wall alone, approx. 470 000 tonnes of concrete waste are expected in the period 2003 to 2015. Concrete from offshore pipelines that are to be dismantled in the same period represents around 51 000 tonnes of concrete waste.

Approx. 70 per cent of the concrete waste is generated by demolition of buildings. Future quantities of concrete waste will therefore depend on the amount of demolition in the future. It is generally safe to assume that demolition is proportional to building activity, or a little lower. However, building activity is highly dependent on fluctuations in the economy in general, and it is therefore difficult to predict with any certainty future quantities of concrete waste, even if our assumption of proportionality holds true. There appears to be a fairly even distribution in the age of demolished buildings. Thus, changes in the use of concrete in buildings over time will not affect the quantities of concrete waste significantly.

Uncertainty regarding the figures

The figures quoted here have been taken from Statistics Norways waste accounts. This is based on a number of different sources of data and methods of calculation, and many of the figures are based on information provided directly by the waste producers and recycling facilities. It should be noted that some of the figures are extremely uncertain.