cementgebundene

The term cementgebundene is used in German-speaking civil engineering to refer to materials or construction layers in which cement acts as the binding agent that holds aggregates together. This encompasses cement-stabilized soils, cement-bound base and subbase layers used in road and rail construction, as well as cementitious mortars and composites.

Composition and production: The typical mix consists of Portland cement, water, and aggregates such as sand and gravel or crushed stone. Additives such as fly ash, slag, pozzolans or plasticizers may be used to improve workability, setting, or durability. The material is prepared, laid in layers, compacted to a specified density, and cured to gain strength.

Properties: After curing, cementgebundene layers exhibit high compressive strength, good stiffness, and low permeability, reducing water ingress and frost damage. They stiffen subgrades and distribute loads more evenly. Potential drawbacks include shrinkage cracking with inadequate curing, sensitivity to sustained high moisture, and higher energy and CO2 emissions associated with cement production.

Applications: The main uses are cement-stabilized road bases and subbases, airport and industrial pavements, railway track beds, stabilization of soft soils for building foundations, and cementitious mortars and screeds used in construction.

Standards and evaluation: Quality control involves tests such as unconfined compressive strength, modulus of elasticity, and permeability, as well as compaction tests for in-situ layers. Specifications vary by country; in German-speaking regions the terms Zementstabilisierung or cementgebundene Bauweisen are commonly used.

Environmental considerations: Reducing cement content through supplementary cementitious materials, recycling aggregates, and optimizing mix design can lower the carbon footprint of cementgebundene construction.