Expanded clay aggregate

<h2 id="history">History</h2>
<p>LECA was developed about 1917 in <a href="/facts/Kansas_City,_Missouri/N8GxbWWR">Kansas City, Missouri</a>, to the production in a <a href="/facts/Rotary_kiln/T8Meq7T0">rotary kiln</a> of a patented expanded <a href="/facts/Aggregate_(composite)/dKfhlNIw">aggregate</a> known as Haydite which was used in the construction of <a href="/facts/SS_Selma_(1919)/gdGrYPSn">SS Selma</a>, an ocean-going ship launched in 1919. Following in the USA was the development of a series of aggregates known as Gravelite, <a href="/facts/Perlite/X0vFLpzj">Perlite</a>, Rocklite, etc. In <a href="/facts/Europe/DTAtrKfh">Europe</a>, LECA commenced in <a href="/facts/Denmark/KVtykzsw">Denmark</a>, <a href="/facts/Germany/paluuWBX">Germany</a>, <a href="/facts/Netherlands/y8xn5stT">Netherlands</a>, and UK.
</p>
<h2 id="characteristics">Characteristics</h2>

<p>LECA is usually produced in different sizes and densities from 0.1 millimetres (0.004 in) up to 25 millimetres (1.0 in), commonly 0–4 mm, 4–10 mm, 10–25 mm and densities of 250, 280, 330, and 510 kg/m3. LECA <i>boulder</i> is the biggest size of LECA with 100–500 mm size and 500 kg/m3 density.
</p><p>Some characteristics of LECA are lightness, <a href="/facts/Thermal_insulation/j7tVT4uv">thermal insulation</a> by low <a href="/facts/Thermal_conductivity/qWnSG3nQ">thermal conductivity coefficient</a> (as low as 0.097 W/mK<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a>), soundproofing by high <a href="/facts/Soundproofing/hKbTnCMq">acoustic insulation</a>, <a href="/facts/Hydraulic_conductivity/XMBD4Xdb">moisture impermeability</a>, being <a href="/facts/Compressibility/eePznleN">incompressible</a> under permanent <a href="/facts/Pressure/eyc37GRG">pressure</a> and <a href="/facts/Gravity/bqAN7DdQ">gravity</a> loads, not <a href="/facts/Decomposition/6Bve4pgl">decomposing</a> in severe conditions, fire resistance, a <a href="/facts/PH/RnSv8D7y">pH</a> of nearly 7, <a href="/facts/Freezing/0kNr25SF">freezing</a> and <a href="/facts/Melting/zhhDBo5V">melting</a> resistance, easy movement and transportation, lightweight backfill and finishing, reduction of construction dead load and <a href="/facts/Earthquake/NGjIzagw">earthquake</a> lateral load, being perfect <a href="/facts/Substrate_(biology)/EBDd458H">sweet soil</a> for plants, and as a material for <a href="/facts/Drainage/thEd3nfB">drainage</a> and <a href="/facts/Filtration/x4no9XQy">filtration</a>.
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<h2 id="uses">Uses</h2>
<p>Common uses are in <a href="/facts/Concrete_masonry_unit/kpnN48EV">concrete blocks</a>, <a href="/facts/Concrete_slab/YkVygvIp">concrete slabs</a>, geotechnical fillings, <a href="/facts/Autoclaved_aerated_concrete/Cz4c906D">lightweight concrete</a>, water treatment, <a href="/facts/Hydroponics/g96g3ypl">hydroponics</a>, <a href="/facts/Aquaponics/XmpbM2HB">aquaponics</a> and <a href="/facts/Hydroculture/g96g3ypl">hydroculture</a>.
</p>

<p>LECA is a versatile material and is utilized in an increasing number of applications. In the <a href="/facts/Construction_industry/58eqDhy9">construction industry</a>, it is used extensively in the production of lightweight concrete, blocks and precast or incast structural elements (panels, partitions, <a href="/facts/Brick/2CBPgDIK">bricks</a> and light <a href="/facts/Tile/vk9El8Ty">tiles</a>). LECA used in structural backfill against <a href="/facts/Foundation_(engineering)/ACVkQsDy">foundations</a>, <a href="/facts/Retaining_wall/BNqSyXeS">retaining walls</a>, <a href="/facts/Abutment/QzGxGmDq">bridge abutments</a> etc., in addition, it can reduce earth pressure by 75% compared with conventional materials, and also increases ground stability while reducing settlement and <a href="/facts/Landslide/sXSzA31e">land deformation</a>. LECA can drain the surface water and groundwater to control groundwater pressure. LECA grout can be used for flooring (finishing) and roofing with thermal and <a href="/facts/Soundproofing/hKbTnCMq">sound insulation</a>.
</p><p>LECA is also used in water treatment facilities for the filtration and <a href="/facts/Water_purification/rguCGW3q">purification</a> of municipal <a href="/facts/Wastewater/g6Bn8xvT">wastewater</a> and <a href="/facts/Drinking_water/FmSJcKGG">drinking water</a> as well as in other filtering processes, including those for dealing with <a href="/facts/Industrial_wastewater_treatment/401ph19H">industrial wastewater</a> and <a href="/facts/Fish_farming/PA6EKo97">fish farms</a>.
</p><p>LECA has many uses in <a href="/facts/Horticulture/m8qBLuT3">horticulture</a>, <a href="/facts/Agriculture/TGztqzJs">agriculture</a>, and <a href="/facts/Landscape/pU9HneR0">landscapes</a>. Using LECA helps to alter <a href="/facts/Soil_mechanics/WfVDFMAW">soil mechanics</a>. Using LECA provides <a href="https://www.futuregarden.co.uk/expert-advice/top-tips-for-making-the-most-out-of-clay-balls/">many benefits across horticulture</a>. It's commonly used as a growing medium in <a href="/facts/Hydroponics/g96g3ypl">hydroponics</a> systems since blended with other <a href="/facts/Growth_medium/97IMkpFP">growing mediums</a> such as <a href="/facts/Soil/5Ddpr3QM">soil</a> and <a href="/facts/Peat/F0kJcsLt">peat</a>, it can improve compaction resistance, and <a href="/facts/Drainage/thEd3nfB">drainage</a>, retain water during periods of <a href="/facts/Drought/LVW0rfuV">drought</a>, insulate roots during <a href="/facts/Frost/0zan2Azj">frost</a>, and provide roots with increased <a href="/facts/Oxygen/acyn6o8r">oxygen</a> levels promoting very vigorous growth. LECA can be mixed with heavy soil to improve its aeration and drainage.
</p><p>In the horticultural practice of <a href="/facts/Hydroponics/g96g3ypl">hydroponics</a>, LECA is a favored medium for growing plants within; the round shape  provides excellent aeration at the root level, while the LECA clay pieces themselves become saturated with water and plant food, thus giving the roots a consistent supply of both. So-called semi-hydroponics or passive hydroponics (also called "semi-hydro") is a popular, simplified method of hydroponics, most commonly utilized for houseplants and tropical species. A plant is potted in solely LECA (preferably in a container with multiple air holes on the sides and bottom, like an orchid pot) and placed into a second, sealed container, in which a "nutrient reservoir" of water and plant food is maintained. Only the very bottom of the pot needs to touch this reservoir; the LECA, being porous by nature, gradually wicks moisture and nutrients up and becomes saturated, allowing the plant to feed and drink at a consistent rate. 
</p><p>One of the main differences between semi-hydroponics and more advanced hydroponics is the nutrients and water--whether they are consistently being delivered or whether they are sitting beneath each plant, gradually needing to be replaced before evaporating or becoming stagnant. Other differences are elements such as the facilities, the equipment, the types of plants being grown and why, and the consistency of water and nutrient delivery. Hydroponics is often favored by farmers and growers of edible crops on a larger scale. LECA can be used successfully in these settings. Semi-hydroponics is much more popular with individual plant collectors, bearing in mind the need to flush out and replenish the plants' nutrient reservoirs periodically (approx. every 7-10 days); more advanced systems provide constantly flowing, filtered, nutrient-enhanced water over the plants' roots, which typically drains into another reservoir for recycling and reusing.
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<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Perlite/X0vFLpzj">Perlite</a></li>
<li><a href="/facts/Aggregate_(composite)/dKfhlNIw">Aggregate (composite)</a></li>
<li><a href="/facts/Vermiculite/NDeQ8QQR">Vermiculite</a></li></ul>

<ul><li>Tor Arne, Hammer; Klaas van Breugel; Steinar Helland; Ivar Holand; Magne Maage; Jan P. G. Mijnsbergen; Edda Lilja Sveinsdóttir (2000). "Economic Design and Construction with Structural Lightweight Aggregate Concrete". <i>Materials for Buildings and Structures</i>. EUROMAT 99. Vol. 6. p. 18. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1002%2F3527606211.ch3">10.1002/3527606211.ch3</a>. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 3527301259.</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>"Geotechnical Fill". Norlite Lightweight Aggregate. Archived from the original on 2015-05-24. Retrieved 2015-05-24. <a href="https://web.archive.org/web/20150524095524/http://www.norliteagg.com/geotech/insulation.asp" target="_blank">https://web.archive.org/web/20150524095524/http://www.norliteagg.com/geotech/insulation.asp</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
</ol>

Expanded clay aggregate open-in-new

Expanded clay aggregate