Laterlite Lightweight Fill Above Underground Structures Aggregates
LIGHTWEIGHT FILL ABOVE UNDERGROUND STRUCTURES AGGREGATES
LIGHTWEIGHT FILL ABOVE UNDERGROUND STRUCTURES AGGREGATES
Traditional aggregates used as fill above underground structures (tunnels, parking garages, etc.) impose a high permanent load that restricts the possibilities of re-using the existing structures and requires new structural elements to be oversized to take the extra load.
information
BRAND
Laterlite
PRODUCT TYPE
Aggregates
REUSABLE & RECYCLABLE
It is 100% reusable and recyclable.
DETAIL
The construction of lightweight fills and embankments on underground structures with Laterlite Expanded Clay drastically reduces the weight of the fill layers, and its high strength enables maximum flexibility in how the spaces above are used.
MATERAIL
Clay & Concrete
FEATURE
Lightweight
LOADING
Reduced dead loading on the below-ground structure
ADVANTAGES
-Simplicity of construction -Can be laid to deep thicknesses -Greater freedom for modifying and re-using any existing structure -Maximum freedom in the use of the spaces above, including by vehicles -Economy of construction in new-build structural elements (which can be slimmer) -Freedom from risk in case of fire (expanded clay is a 100% mineral material)
WATER ABSORPTION AND DRAINAGE
-Laterlite Expanded Clay is an inert, vitrifi ed, dimensionally stable material whose volume remains unchanged in contact with water. -When the inter-granular voids (i.e. the voids between the granules, which interconnect with one another) are immersed in water they immediately become saturated; the intra-granular pores (the voids within each granule) only fi ll more slowly with water by capillary action, and some of them will never become saturated.
-In accordance with European Standard EN 13055-2 (par. 4.8), the coeffi cient of water absorption of expanded clay is determined by immersing a dry sample in water for 24 hours. Comparison of its weight before and after the test (of the drained material) gives the quantity of water that has been absorbed by the granules (this will vary, depending on the grain size).
-The excellent drainage capacity of expanded clay is due to this network of intergranular pores, whilst the water absorption is due to the intra-granular pores. -For design purposes, the coeffi cient of water absorption of Laterlite Expanded Clay can be conservatively considered as always less than 25% by weight. Laterlite Expanded Clay is also available in the special Laterlite Plus dry hydrophobic variant, which maintains its extremely low coeffi cient of water absorption over time.
LATERLITE EXPANDED CLAY
-Laterlite Expanded Clay is a granular lightweight aggregate that is obtained by subjecting special natural clays to a thermal expansion and vitrifi cation (clinkerisation) process at 1200°C. -The granules have a lightweight internal cellular structure with good insulating properties. This is enclosed within a compact, strong external shell that provides an excellent weight/strength ratio, making the product suitable for a wide range of geotechnical, infrastructure, and construction applications. -Laterlite Expanded Clay is also a durable and incombustible material that is fi re and frost resistant, thermally insulating, and sound-absorbent.
SUSTAINABILITY
-Laterlite Expanded Clay, as well as the rest of our range, are manufactured using the Best Available Technology (BAT) that uses natural resources effi ciently, obtaining more than 5 m³ of expanded clay from 1 m³ of our abundant natural local clay. We operate an environmental management system that complies with voluntary international standard ISO 14001:2004, and Health and Safety Management Best Practice that meets British Standard BS OHSAS 18001.
-Whilst we are continuing to reduce emissions from our manufacturing plants, for some time we have also been implementing a long-term programme of further development to make them more energy-effi cient. At all of our factories we have replaced fossil fuels with alternative recycled combustibles and/or biomass, whilst a signifi cant part of the electrical energy we use is now generated on site from renewable sources.
-Laterlite is a partner member of the CASA CLIMA energy certifi cation agency and is actively involved in promoting energy effi ciency as a member of the Green Building Council for Italy: promoting the retention and upgrading of existing buildings and encouraging sustainability throughout the construction Industry supply chain. Most of our products are certifi ed by ANABICEA, the Italian Accreditation Institute, for use in sustainable construction.
MECHANICAL CHARACTERISTICS
ANGLE OF INTERNAL FRICTION
The angle of friction of unbounded expanded clay is obtained from triaxial tests by varying the lateral confi ning pressure of the aggregate and its degree of compaction.
For design purposes, with a confi ning pressure of 200 kPa (which is typical of the most important geotechnical applications), a value of approximately 40° can be assumed.
SURFACE STIFFNESS OF EMBANKMENTS – PLATE LOADING TESTS
-The surface stiffness of expanded clay embankments is determined by plate load testing. The stiffness values obtainable will depend on the technical solution chosen, the grain size of the expanded clay, and the degree of compaction. -The various methods for constructing an embankment are described in detail in Section 2. In general these include a fi nishing layer to distribute the loading.
-The graph shows the trend of the modulus of deformation Md as a function of the relative density, for an 80 cm thick layer of type 0/30 expanded clay fi nished with 20 cm of granular mix.
-If necessary, an asymptotic value of Md = 200 Kg/cm2 can be considered for design purposes, which corresponds to a degree of compaction of the aggregate that is easy to attain using ordinary ground-compacting machinery (plate vibrators, compaction rollers) -Values for the modulus of deformation Md as a function of the compaction of individual layers and different granulometries of Laterlite Expanded Clay are available by request.
DETAIL
CONSTRUCTION OF EMBANKMENTS/FILLS
Depending on the technical and economical constraints, expanded clay embankments and fills can be constructed in the following ways :
- 1. Embankments/fi lls consisting of expanded clay only
- 2. Embankments/fi lls consisting of alternating layers of expanded clay and granular mix (of gravel or rockfi ll)
- 3. Embankments/fi lls in expanded clay bound with cement
1. EMBANKMENTS/FI LLS CONSISTING OF EXPANDED CLAY ONLY
-Average density after completion : 400 - 600 kg/m3 -The surface of the expanded clay is compacted directly by multiple passes with a vibrating plate compactor (typical weight 50-140 kg, width 50-80 cm, contact stress < 5 kN/m2, frequency 75-100 Hz) or a tracked vehicle (excavator, shovel, bulldozer - Contact stress < 50 kN/m2) The number of passes required will depend on the thickness of the layers and the machine used
-A geotextile separation layer (if required) is laid in contact with the founding ground -Expanded clay is laid to a thickness that is variable depending on the means of compaction used
2. EMBANKMENTS/FI LLS CONSISTING OF ALTERNATING LAYERS OF EXPANDED CLAY AND GRANULAR MIX
-Average density after completion : 600 - 1200 kg/m3 -The thickness of each layer can be varied depending on the design requirements -A geotextile separation layer (if required) is laid in contact with the founding ground.
-A geotextile separation layer is laid. -A layer of granular mix is laid to a thickness of at least 10 cm. -A fi rst layer of expanded clay is laid to a thickness of 20 - 100 cm
- The top of the granular mix layer is compacted using a vibrating roller, typically weight 15-50 kN. -The total thickness of each sandwich of clay + granular mix must not exceed 120 cm. The fi nal layer of granular mix, on which the fi nishing layers will be placed, must be at least 30 cm thick
3. EMBANKMENTS/FI LLS IN EXPANDED CLAY BOUND WITH CEMENT
-Densities ranging from 500 - 800 kg/m3 and strengths from 1 - 4 MPa, depending on the type of expanded clay and the quantity of cement used. -To increase the stiffness of fi lls or embankments or to resolve problems of lateral containment, or to deal with other requirements, they can be constructed using cemented expanded clay (permeable concrete – open pore structure). -Each layer must not be more than 50 cm thick and compaction must be carried out with a plate vibrator
CEMENTED EXPANDED CLAY CAN BE MANUFACTURED IN VARIOUS WAYS :
-Continuous on-site manufacture : expanded clay is delivered to site in tanker trucks equipped with suitable pumping gear. At the same time a cement slurry is manufactured on site using suitable machinery, and continuously injected into the pump hose as the expanded clay is delivered. The mixing takes place at this stage -Off-site manufacture in a batching plant, with delivery in concrete mixer trucks
- On-site mixing (if small quantities are required)
-Using bulk expanded clay and cement.
-Using bagged premixes (Latermix Cem Classic or Maxi).
