Main constituent of cement

Recycled crushed sand

At present, DIN EN 197-1 does not define recycled fine aggregates (crushed sands) as main constituent of cement. Cements with ground crushed sand as main constituent are subject to an approval. Apart from technical verifications of the properties in accordance with DIN EN 196-1 and/or DIN EN 197-1 and durability tests carried out on concrete, crushed sands also have to comply with the parameters of eluate and solid matters relevant to the environment.

The investigations within the “R concrete” research project ( aimed at the development of guidelines on the use of crushed sands for the production of cement (called “R cement” in the context of the project). The majority of R cements was manufactured in the laboratory by mixing of 90 and/or 70 wt.-% of CEM I 42.5 R and 52.5 R, respectively, by 10 and/or 30 wt.-% of ground crushed sand. In large-scale plant tests, R cement was manufactured by combined grinding of clinker, crushed sand, and sulphate agent. The crushed sand used originated from crushed concrete, recycled brick and roof tile material, track ballast and railroad sleepers. The R cements corresponded to the strength classes of 42.5 N up to 52.5 R. The assessment criteria regarding the durability of the concretes being relevant for approval were met by using the cements containing up to 10 wt.-% of crushed sand. In addition, the crushed sands complied with the requirements in terms of environmental analysis according to DIN 4226-101.

When considering all results obtained with R cement within the project as a whole, it can be determined that these cements containing up to 30 % of crushed sand at least could be used for concrete of interior components. However, a continuous, consistent material flow of the corresponding quality between processing industry and cement plant would be a precondition.

Related articles:

Issue 2017-03

Concrete mix and products including recycled porcelain

(10) US 2017/0015587 Al (22) 27.09.2016 (57) A concrete mix for use in forming molded concrete end products is disclosed. The concrete mix includes treated porcelain kernels, cement and sand. The...

Issue 2016-03

High-strength concrete


Issue 2012-09

Permeable concrete

(10) WO 2012/089944 A1 (22) 31.08.2011 (43) 05.07.2012 (71) LAFARGE [FR/FR]; 61 Rue des Belles Feuilles, F-75116 Paris (FR). (57) The present invention relates to a permeable concrete comprising, in...

Issue 2014-11 Holcim (Schweiz) AG

Concrete as versatile building material in material cycles

Holcim (Schweiz) AG has been organizing the concrete conference at ETA Zurich for twenty years now. Therefore, this year‘s conference attended by more than 230 visitors was characterized by the...

Issue 2020-02 Requirements on recycling

Using recycled materials in the concrete products industry in line with applicable standards

Approvals for the new development of raw materials operations are rarely, if at all, obtained, and difficult and lengthy approval procedures have to be allowed for the extension of existing...