‘Marinet Special’ on Alternative Aggregate to Marine Sand : Interim Progress Report

In September 2015 Marinet published its Report Marine Aggregate Extraction — The Need to Dredge : Fact or Fiction?

This Report is based on work undertaken by a Marinet Member, Kayasand, which features the substitute sand manufacturing process developed by Kemco, Japan, and validated for use in this country via a study by Cardiff University with financial support from the Welsh Assembly.

This ‘manufactured sand’ is derived from quarry waste and involves a carefully controlled, technologically-driven crushing process where unused waste quarry rocks are converted into ‘manufactured sand’. This sand is able to replace wholly (100%) marine-sourced sand.

It is therefore a hugely important process. Not only does it increase the economic return and viability of land quarries, maximising the use of their resources, but it also relieves the marine environment of a process which dredges the seabed, causing severe injury to marine habitats and species and fish spawning and nursery grounds.

In Japan, the Kemco/Kayasand process is now widely employed. It is accepted by the construction industry as proven technology for the manufacture of concrete, is economically viable, and has greatly relieved pressure on the dredging of Japan’s seas for virgin sand.

Marinet asks the question — is it not time for this technology to be adopted in the UK?

We have addressed this question broadly — to government, to the regulators and conservation agencies, and to the industry. We report here both on the replies we have received to date, and on the central issues on which we are trying to focus future debate.

The replies we have received so far feature: The Minister at Defra, the CEO at the regulator of marine aggregate dredging (Marine Management Organisation), the CEO at the principal Conservation Agency (Natural England), and the Director of the industry’s trade association (British Marine Aggregate Producers Association — BMAPA). The full text of these replies, and our response to them, can be seen at the bottom of this page.

Of particular note so far is the failure, indeed avoidance, of the replies to address the question of the desirability and viability of the alternative to marine-source sand — ‘manufactured sand’ from waste quarry rock. The only reply that has addressed this question is the one from the industry’s trade association (BMAPA) which questions the technical competence of the process and whether it is economically viable.

On the question of technical competence, it would appear that none of our respondents have seriously read the study by Cardiff University. Here the technical evaluation of the process states clearly:

“An extensive Cardiff University led laboratory programme, together with information from literature and input from industrial project partners, form the basis for the evaluation of the primary aim of this project which was to examine the potential for Kayasand to completely replace natural sand in concrete.

“The results obtained from the laboratory testing of a range of samples collected for this project provide additional data on grading characteristics and pre-and post-processing physical properties of the Kayasand product.

“Four different rock types were considered in the present study: gritstone (sandstone), limestone, basalt and granite and all appear to varying extents in the geology of South Wales. In order to evaluate the use of Kayasand in concrete a suite of physical characterisation tests were performed which were used to identify the effect of the physical sand properties on the fresh and hardened properties of concrete.

“Mix proportions were established for each individual rock type and a w/c (water/cement) ratio selected to achieve a fresh concrete slump of 50-90mm.

“Additional laboratory tests were performed in order to observe the performance of the various Kayasand concrete mixes with the use of plasticisers at a fixed water/cement (w/c) ratio. These mixes allowed the potential for cement savings to be addressed.

“The test results demonstrate that with appropriate adjustment to the mix proportions it is possible to replace marine sand in concrete with 100% Kayasand with no detrimental effects on the development of workability as measured by the slump test, compressive or tensile strength.

“Moreover, there was no apparent relationship between fines content and 28-day compressive strength in any of the Kayasand concretes. This suggests that there are no negative effects of higher fines contents on the compressive strength for the given mix compositions and range of fines contents investigated in the study.

“An increase in the fines content of the Kayasand mixes generally resulted in a small reduction in the slump of the mix, however only 1 of the 16 Kayasand mixes fell outside of the S2 slump range with some evidence of the fines acting as lubricants in Kayasand concretes with medium fines contents.”

And, in its conclusion the study by Cardiff University states:

“The aim of this study was to explore the use of Kayasand as a complete replacement for natural sand in concrete mixes.

“The results shown in Section 5 prove that while great care is required to ensure that the mix design used is appropriate for the type and properties of the feed material, it is feasible to produce workable concretes with satisfactory 28 day compressive and flexural strengths using Kayasand as a complete replacement for natural marine dredged sand in concrete.”

So it is clear that, from a technical perspective, the Kayasand/Kemco manufactured sand process works using waste quarry rocks; and, works across all rock types — sandstone, limestone, basalt and granite. As a result, waste rocks from every type of quarry are available. This represents a considerable under-used resource and, in all likelihood, this resource matches marine-sourced sand in terms of the quantity that is available.

It is true that the industry trade association, BMAPA, challenges this. However it is to be noted that the Cardiff study was broadly based, and included industrial partners in its technical assessment. It is also a fact that the building and construction industry in Japan, which uses the process widely, does not share the technical reservations which BMAPA voices.

Of course, it can be argued that BMAPA has a vested interest. Its members have, with encouragement from successive UK governments, invested heavily in infrastructure involving marine-sourced sand — dredging vessels, port and storage facilities, and a general ‘mind-set’ supported by on-side environmental consultants which argues that marine sand is preferable to quarry sand. Thus when BMAPA says that ‘manufactured sand’ from waste quarry rocks is “prohibitively expensive” it is effectively saying that it has developed a huge capital investment in marine facilities, rather than land-based facilities, which it cannot afford to abandon.

So as Marinet sees matters, the industry is turning a blind eye to a technical process which works. It is investing its capital heavily in its preferred source (the seabed), and is underplaying the adverse impact on the undersea marine environment because it is easy to do so — the public cannot exactly ‘go there’ to see and witness the damage. Of course, damage to the coastline and beaches from which sand is eroded and drawn down to the excavation areas is far more evident, but once again the industry seeks to absolve itself through technical arguments involving counter balancing offshore currents and other scapegoats, such the consequences of climate change which results in more frequent and more intense storms, and sea level rise.

The impact of dredging upon marine habitats and species, and upon endangered fish spawning and nursery grounds, is similarly dismissed by the industry and its supporters in government. The fact that the “death cull” of marine life at dredging site is near total is not denied. However the industry asserts that the area it dredges is very small relative to the area of the seabed as a whole, and that recolonisation at dredged sites by marine life occurs relatively rapidly.

What this argument ignores, and what conservation organisation mandated to protect the seabed sometimes forget, is that the sites chosen for dredging are often unique and, if not unique, certainly rare and at a premium. Sand and gravel sites are ancient river valleys, formed during the last Ice Age, which are now stranded out at sea as sea levels and topography have changed with time. They are filled with fluvial material — sand and gravel — and it is this sand and gravel, in the particular combination and blend found in these submerged ancient river valleys, which provides unique and rare habitat for complex marine ecosystems which have taken hundreds of years to establish, and which fish of many species require for successful breeding. Yet government has allowed the dredging companies to come along, to espy this blend of sand and gravel with a commercial eye and, after obtaining a licence from a compliant regulator, to be permitted to suck it all up into the holds of their dredging vessels. Almost everything in a dredging vessel’s path dies, and the physical habitat is not just wrecked but removed, almost entirely and permanently. Recolonisation does occur — nature abhors a vacuum – but the ecological complexity is lost, and the sophisticated needs of the various species of fish that have bred there for years are trashed. Once there was diversity and fecundity, and now there is a desert. For species at the top of the food chain, such as fish, this means starvation.

Dredging occurs not just in these ancient river valleys formed during the last Ice Age, but also over large areas of offshore sand banks. These sand banks, although appearing physically to the untrained eye like the rolling dunes of a terrestrial desert, are actually rich in marine life — or once were, until ravaged by the dredgers and the fisherman’s version of the dredger — the trawler. On these dunes live, if allowed, complex ecological communities built around reef creating species, such as mussels and oysters and the various species of sand worm. Alas, the dredgers’ suction pipes pass over the surface of the sand banks, killing and destroying these communities of mussels, oysters and worms, and in their place is left a literal desert — a collapsed ecological community where only opportunistic species now live — like the wild plants that seed in the soil once an ancient forest is felled. Life, yes . . . . but only a pale version of what was there before. And, once again, fish spawning and nursery grounds are obliterated.

Vast amounts of sand have been removed from these sites, million of tonnes per annum in total. In some cases, the sand banks have lost a quarter of more of their original bulk. It is said that a land-based quarry is a scar on the landscape. Yes, but do not doubt that the same happens at sea, if not more so.

Also the offshore wave regime changes because of all of this excavation. The seabed is lowered, which in turn creates a greater depth of sea. Thus when a storm arrives the waves are stronger and higher because their character is intensified in deeper water compared to shallower water, and along the adjacent coast the erosive forces are increased as this changed wave regime arrives on the beaches. Counting the cost is an expensive business and, ironically, the aggregate dredging companies are now paid by the government, and hence the tax payer, to suck more sand from the seabed to pump onto the denuded beaches  This, euphemistically, is termed “beach recharge.” Many view it as adding insult to injury.

Dredging for sand and gravel, although unseen to the human eye, is not a neutral force. It is a practice with enormous consequences, most of which are negative when viewed from the perspective of life in the sea.

So why, when we have a huge under-used — in fact, unused — resource of waste rocks sitting around in land quarries, are we insisting, first, in ignoring this resource and the incremental value it confers upon the investment made by the aggregate company when it established the quarry in the first place? And secondly, why are we ignoring a technology that can create a manufactured sand to the highest quality which, if invested in and deployed, would forestall the immense damage now inflicted upon the seabed?

The time has come for the industry, for government, and for conservation agencies charged with protection of our seas and their life, to examine the Kayasand/Kemco with a professional, financial and moral eye.

The time has come for change — and it is change that is not unrealistic or born of idealism, but change that creates new economic value for the aggregate industry, change that enables the government to be the custodian of our future, and change that would be celebrated by all the species living in the sea.

It is time to act, as the modern term has it, sustainably. When will all the players associated with this industry do just that?

Responses (in pdf format) so far to:


The Fisheries Minister, Department for Environment, Food and Rural Affairs.


The Director, BMAPA, British Marine Aggregate Producers Association.


Chairman, Natural England, Statutory Nature Conservation Agency.


Chair of EFRA Committee, House of Commons Environment, Food and Rural Affairs Committee.


Chief Executive, MMO, Marine Management Organisation (the licence regulator).


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