{"id":5578,"date":"2026-05-07T05:52:42","date_gmt":"2026-05-07T05:52:42","guid":{"rendered":"https:\/\/taiguo-steamboiler.com\/?p=5578"},"modified":"2026-05-07T05:52:42","modified_gmt":"2026-05-07T05:52:42","slug":"lightweight-concrete","status":"publish","type":"post","link":"https:\/\/taiguo-steamboiler.com\/es\/blog\/lightweight-concrete\/","title":{"rendered":"Concreto ligero: los 6 tipos comparados (celular, CAA, agregado, espuma)"},"content":{"rendered":"
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Six different concretes share the lightweight concrete (LWC) label \u2014 anything from a 320 kg\/m\u00b3 insulating roof fill up to an 1840 kg\/m\u00b3 structural floor deck (90\u2013115 pcf). Pick the wrong one and a project either fails inspection or runs roughly 30% over budget. This guide stacks all six recognised types side-by-side: density, strength, cost, governing code. There’s a four-question decision tree at the end and a wide reference matrix you can save and come back to.<\/p>\n

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\ud83d\udcd0 Definition (Featured Snippet)<\/strong><\/p>\n

Lightweight concrete is concrete with an oven-dry density at or below 1850 kg\/m\u00b3 (115 lb\/ft\u00b3), per ACI 213R-14<\/a>. Six recognised types make up the family: autoclaved aerated (AAC), cellular lightweight (CLC), foamed, lightweight aggregate (LWAC), perlite\/vermiculite insulating, and no-fines.<\/p>\n<\/div>\n

Quick Specs: The 6 Types of Lightweight Concrete<\/h2>\n

\"Quick<\/p>\n

These six differ in production method, density range, and what they’re built to do. Headline numbers below come from NRMCA CIP 36<\/a>, ACI 213R, ASTM C1693<\/a>, and the Perlite Institute<\/a>. Use this card to shortlist; specs per type follow.<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n
Type<\/th>\nDensity (kg\/m\u00b3)<\/th>\nCompressive Strength<\/th>\nPrimary Use<\/th>\n<\/tr>\n<\/thead>\n
AAC (Autoclaved Aerated)<\/td>\n300\u2013800<\/td>\n2\u20137 MPa<\/td>\nWalls, panels, masonry blocks<\/td>\n<\/tr>\n
Cellular (CLC)<\/td>\n300\u20131800<\/td>\n1\u201310 MPa<\/td>\nGeotechnical fill, void fill, sub-base<\/td>\n<\/tr>\n
Foamed<\/td>\n400\u20131600<\/td>\n1\u201310 MPa (up to 25 at 1400)<\/td>\nInsulating fill, lightweight slabs<\/td>\n<\/tr>\n
LWAC (Structural Aggregate)<\/td>\n1440\u20131840<\/td>\n17\u201340 MPa<\/td>\nFloors, bridge decks, precast<\/td>\n<\/tr>\n
Perlite \/ Vermiculite Insulating<\/td>\n320\u2013800<\/td>\n<1.5 MPa<\/td>\nRoof decks, fire-rated assemblies<\/td>\n<\/tr>\n
No-Fines<\/td>\n1600\u20131900<\/td>\n5\u201320 MPa<\/td>\nWall infill, drainage, heritage retrofit<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

What Is Lightweight Concrete? Definition and Density Threshold<\/h2>\n

\"What<\/p>\n

Lightweight concrete is structural concrete with an air-dried density not more than 115 lb\/ft\u00b3 (1850 kg\/m\u00b3), per ACI 213R-14<\/a>. Normal weight concrete (also called standard concrete or normal-weight concrete) sits between 2,300 and 2,400 kg\/m\u00b3 \u2014 so a switch to lightweight cuts roughly 25\u201335% of the weight off whatever you’re casting. That’s where the engineering case starts. A reinforced concrete slab built with lightweight aggregate transfers less design load to columns and footings, which can mean smaller rebar quantities and shallower foundations \u2014 and a measurable reduction in cost savings on long-span structures.<\/p>\n

One cross-border definitional gap is worth flagging. ACI 213R caps structural lightweight concrete at 1,850 kg\/m\u00b3. Eurocode 2 Part 1-1<\/a> draws the line at 2,200 kg\/m\u00b3 for material specified as LC, with at least part of the aggregate below 2,000 kg\/m\u00b3. So a mix that’s “lightweight” on a London tender might not qualify on a US ACI-governed project. Specifiers working internationally need to call it out on the cover sheet.<\/p>\n

What is the difference between normal concrete and lightweight concrete?<\/h3>\n

Aggregate choice is the core difference. Normal concrete uses crushed natural stone or gravel near 2,650 kg\/m\u00b3 in particle density. Lightweight concrete swaps in a lower-density aggregate \u2014 expanded shale, expanded clay, expanded slate, pumice, fly-ash pellets, perlite, or vermiculite \u2014 or removes mass altogether by trapping air through foam injection or autoclave gas-formation. Net effect: reduced weight, often high thermal insulation values, and a slower drying curve. The pore structure of the resulting low-density mixture (whether porous from entrained air, foamed, or aggregate-derived) is what produces both benefits. Lightweight slabs can take two to three times as long to reach equilibrium moisture, which matters for finished-floor schedules.<\/p>\n

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Three density classes (per ACI 213R)<\/strong><\/p>\n

    \n
  1. Insulating<\/strong> <800 kg\/m\u00b3 \u2014 non-structural, thermal performance only<\/li>\n
  2. Structural-insulating<\/strong> 800\u20131,350 kg\/m\u00b3 \u2014 moderate strength, partial insulation duty<\/li>\n
  3. Structural<\/strong> 1,350\u20131,850 kg\/m\u00b3 \u2014 load-bearing, \u226517 MPa minimum at 28 days<\/li>\n<\/ol>\n<\/div>\n

    Type 1: Autoclaved Aerated Concrete (AAC)<\/h2>\n

    \"Type<\/p>\n

    AAC \u2014 autoclaved aerated concrete \u2014 is a precast concrete product based on calcium silicate hydrates. Manufacture starts with a cement-lime-sand-fly-ash slurry into which aluminum powder is dosed; hydrogen gas reaction expands the mass during pre-curing, the green cake is cut to size, and the units are cured in a saturated-steam autoclave. AAC was first commercially produced in Sweden in 1923, per the Concrete Centre<\/a>, and now ships on every continent as masonry blocks, reinforced wall panels, and lintels.<\/p>\n

    Autoclave processing is the hard requirement that separates AAC from the other aerated concretes. Without that high-pressure steam cure, the calcium silicate hydrate phase that gives AAC its dimensional stability simply does not form. A typical cycle runs 8 to 14 hours at 180\u2013200 \u00b0C and 10\u201312 bar of saturated steam, inside large pressure vessels supplied by specialised industrial autoclave manufacturers<\/a>. Density classes per ASTM C1693<\/a> run 300, 400, 500, 600, 700, and 800 kg\/m\u00b3, with compressive strengths from about 2 to 7 MPa.<\/p>\n

    Is AAC concrete waterproof?<\/h3>\n

    AAC is not waterproof. It is highly porous \u2014 that porosity is exactly what gives the material its R-value (an 8-inch AAC wall delivers roughly R-8 to R-10, per the International Masonry Institute<\/a>). Crack control reinforcement still applies the same as any reinforced concrete element: AAC’s low tensile strength means it cannot resist shear or shrinkage cracking on its own. Wet AAC takes on water by capillary action through the same pore network that gives the material its fire rating advantage. In service, AAC walls need a render, paint, or cladding to control moisture; below grade, AAC needs membrane waterproofing the same as any other masonry.<\/p>\n

    \n

    \ud83d\udcd0 Engineering Note \u2014 AAC Production Cycle<\/strong><\/p>\n

    A standard AAC plant runs the autoclave at 180\u2013200 \u00b0C and 1.0\u20131.2 MPa saturated steam for 8\u201314 hours after the green cake has been cut. This cycle drives quartz sand and lime to react into tobermorite, the crystalline phase that locks the porous structure into the cured product. Hydration of the cement paste continues during the steam cycle, locking pore geometry and final density. Plants typically need 600\u20131200 kW of steam capacity per autoclave depending on cake volume; cycle compliance is the single largest contributor to consistent compressive strength batch-to-batch.<\/p>\n<\/div>\n

    “AAC’s specific weight of around 500 kg\/m\u00b3 \u2014 about a quarter of dense concrete \u2014 combined with thermal conductivity values between 0.08 and 0.16 W\/mK, allows roughly 30% savings on heating and cooling loads when used as the building envelope.”<\/p>\n

    \u2014 Aircrete Europe technical bulletin<\/cite><\/p><\/blockquote>\n

    Type 2: Cellular Lightweight Concrete (CLC)<\/h2>\n

    \"Type<\/p>\n

    CLC is a cementitious slurry into which preformed foam \u2014 or, less commonly, foam generated inline \u2014 is folded to create a stable matrix of entrained air cells. The result is a low-density concrete mix that cures without high-pressure steam. CLC and AAC look similar in cross-section but the production routes don’t overlap. CLC cures at ambient temperature, in formwork or directly in place, with no autoclave needed. That single difference shapes how each material gets used. AAC is a factory-produced precast block; CLC is a job-site or ready-mix product. That’s why CLC dominates fill applications while AAC dominates walls.<\/p>\n

    CLC’s current growth segment is geotechnical fill. Iowa State’s Institute for Transportation<\/a> has published a working guide for state DOTs that covers CLC use in highway embankments over weak soils, abutment backfill, and abandoned-pipe grouting. Densities run from roughly 400 kg\/m\u00b3 for ultra-light fill to 1800 kg\/m\u00b3 for structural variants. Compressive strengths track with density: a 400 kg\/m\u00b3 mix delivers about 1 MPa, and 1600 kg\/m\u00b3 approaches 10 MPa.<\/p>\n

    \n
    \u26a0\ufe0f<\/span> Common Mistake: Conflating CLC with AAC<\/strong><\/div>\n

    A lot of contractor-facing material lumps “aerated concrete,” “cellular concrete,” and “AAC” into one bucket. They are not the same. AAC requires autoclave processing and ships as cured precast blocks; CLC cures in place at ambient temperature and is generally placed wet. If a spec calls for AAC and the supplier delivers CLC, the strength curves and dimensional tolerances won’t match \u2014 and the AAC manufacturer’s fire-rating documentation won’t transfer.<\/p>\n<\/div>\n

    Type 3: Foam Concrete (Foamed Concrete)<\/h2>\n

    \"Type<\/p>\n

    Foamed concrete is closely related to CLC, and the two terms are sometimes used interchangeably. The practical distinction most engineers draw: “foam concrete” describes any cement-based mix where stable foam has been folded in; CLC is the structured-application label for foam concrete used in fills where engineered density and strength are part of the spec. UK readers may also see “foamed concrete” used for road-trench reinstatement and culvert filling.<\/p>\n

    Foam dosing is the key control variable. A surfactant or protein-based foaming agent is dosed at roughly 0.5 to 1.5% by weight, with the foam volume making up 20 to 75% of the final mix. Per the Foamed Concrete UK<\/a> reference, “the strength of foamed concrete is generally accepted as being between 1 and 10 N\/mm\u00b2, though strengths up to 25 N\/mm\u00b2 at 1400 kg\/m\u00b3 have been produced.” Water-cement ratios published in the Iowa State LCC guide range from 0.45 to 0.80 \u2014 much higher than structural concrete because the slurry has to remain fluid enough to disperse the foam without collapse. The dry density of the placed material decreases sharply as foam volume rises, which directly reduces tensile strength and durability.<\/p>\n

    Can you pump lightweight concrete?<\/h3>\n

    Foam concrete and lightweight aggregate concrete can both be pumped, but the rules differ. Foam concrete is typically pumped at low pressure through dedicated foam-concrete units that protect the cell structure; high pressure or excessive bends will collapse foam and raise the placed density. Pumpable lightweight aggregate mixes are usually designed with natural sand replacing the lightweight fines \u2014 plus an admixture \u2014 to keep workability up and avoid segregation. Over-vibration is the classic failure mode. It drives the lightweight aggregate to float and the cement paste to settle, which is why a flowing mix with minimum vibration is the safer pumping route.<\/p>\n

    \n
    \ud83d\udca1<\/span> Field Note: Volume Loss on Site<\/strong><\/div>\n

    Engineers placing foam concrete on flat roofs sometimes report material consumption 20 to 40% above the calculated geometric volume. Causes include some combination of cell loss during pumping, settlement-related compaction during placement, and underestimated substrate slope variation. Order foam concrete with a 15% contingency and stage placement so a missed truck doesn’t hold the trade behind it.<\/p>\n<\/div>\n

    Type 4: Lightweight Aggregate Concrete (LWAC) \u2014 Structural Lightweight<\/h2>\n

    \"Type<\/p>\n

    LWAC is the structural workhorse of the family. Replace the dense crushed stone with expanded shale, expanded clay, or expanded slate (the ESCS group, covered by ASTM C330<\/a>), or with sintered fly-ash pellets, and the resulting lightweight structural concrete can hit 17 to 40 MPa at 28 days (cylinder strength) while running 1440 to 1840 kg\/m\u00b3 in place. ESCSI \u2014 the Expanded Shale, Clay and Slate Institute<\/a> \u2014 publishes case studies showing structural efficiency gains in floor systems and bridge decks where the strength-to-weight ratio matters more than absolute strength.<\/p>\n

    One useful sub-distinction inside LWAC: “all-lightweight” mixes use lightweight aggregate for both coarse and fine portions. Densities run lowest, but pumpability and finishability take a hit. “Sand-lightweight” mixes use lightweight coarse aggregate plus normal-weight sand, which is the dominant choice for bridge decks and metal deck floors because it keeps modulus and shrinkage closer to normal weight concrete values while still cutting dead load. FHWA’s Lightweight Concrete Bridge Design Primer<\/a> covers the design adjustments needed for tensile strength, shear, and modulus of elasticity, all of which run lower than equivalent normal-weight concrete at the same compressive strength.<\/p>\n

    Internal curing is one of the underdocumented benefits of LWC mix design. Pre-soaked lightweight aggregate releases water back into the paste during hydration, reducing autogenous shrinkage cracking. NYSDOT bridge-deck monitoring programs show measurably better long-term durability where this mechanism is in play \u2014 a finding that’s starting to drive specification of LWAC even on projects where dead-load reduction isn’t the primary concern.<\/p>\n

    Type 5: Perlite and Vermiculite Insulating Concrete<\/h2>\n

    \"Type<\/p>\n

    Perlite and vermiculite are the insulating-only members of the family. They use volcanic glass (perlite) or mica-derived layered silicate (vermiculite) that has been heat-expanded to 4 to 20 times its raw volume, creating an aggregate with very low particle density and a closed-cell or layered air structure. Resulting concrete runs 320 to 800 kg\/m\u00b3 with compressive strength typically below 1.5 MPa \u2014 well outside structural territory.<\/p>\n

    Roof decks are the standard application \u2014 typically as a low-density screed under the membrane in commercial concrete construction. Per the Perlite Institute<\/a> roof-deck reference, U-values for typical perlite roof concrete start around 0.21 Btu\/h\u00b7ft\u00b2\u00b7\u00b0F and improve to roughly 0.12 Btu\/h\u00b7ft\u00b2\u00b7\u00b0F at 4-inch thickness. Minimum R-value for lightweight insulating concrete in city specifications is generally R-1.4 per inch, per the San Diego MWWD specs<\/a>. Vermiculite concrete behaves similarly, with marginally higher R-value per inch but lower compressive strength.<\/p>\n

    \n
    \u26a0\ufe0f<\/span> Important: Perlite Concrete Is Not Structural<\/strong><\/div>\n

    A recurring field error is using a perlite or vermiculite mix in load-paths that need real strength \u2014 for example, casting it as a lightweight slab where structural framing was assumed. With compressive strength under 1.5 MPa, it will not carry imposed loads. Perlite\/vermiculite concrete sits in the build-up between the structural deck and the membrane, never in the deck itself.<\/p>\n<\/div>\n

    Type 6: No-Fines Concrete<\/h2>\n

    \"Type<\/p>\n

    No-fines concrete is the oldest type on this list. The mix omits fine aggregate entirely \u2014 cement, water, and uniform-graded coarse aggregate only \u2014 leaving a porous structure with large interconnected voids. Density lands between roughly 1600 and 1900 kg\/m\u00b3 depending on coarse-aggregate gradation, and compressive strength runs 5 to 20 MPa.<\/p>\n

    George Wimpey used the technique at scale in the United Kingdom after World War II, producing an estimated 300,000 Wimpey No-Fines<\/a> houses between 1946 and 1976. Many are still in service. A Coventry Society review (October 2025)<\/a> documents continued occupancy and maintenance challenges in those housing stocks today. Modern no-fines work is rarer, but the technique persists in specific niches \u2014 pervious-pavement adjacency for stormwater control, drainage layers under slabs, and infill walls where low shrinkage and reduced thermal bridging are valued. Anyone working on heritage retrofit in postwar UK housing will encounter it. Engineers consult building code provisions and local environmental factors before committing to no-fines reuse, since modern climatic and durability standards demand documentation that 1940s-era construction did not produce.<\/p>\n

    Side-by-Side Decision Matrix: All 6 Types Plus Normal Concrete<\/h2>\n

    \"Side-by-Side<\/p>\n

    This matrix cross-references density, 28-day strength, thermal R-value, relative cost, production method, governing standard, and best\/worst-case use. It’s the article’s quick-reference card \u2014 most readers will save it and ignore everything else. Cost figures are relative indices benchmarked against normal-weight concrete = 1.0 (US ready-mix as of Q1 2026); they shift with regional aggregate availability and freight.<\/p>\n

    \n\n\n\n\n\n\n\n\n\n\n\n
    Type<\/th>\nDensity (kg\/m\u00b3)<\/th>\n28-day Strength (MPa)<\/th>\nThermal R \/ inch<\/th>\nRelative Cost<\/th>\nProduction<\/th>\nStandard<\/th>\nBest For<\/th>\nWorst For<\/th>\n<\/tr>\n<\/thead>\n
    AAC<\/td>\n300\u2013800<\/td>\n2\u20137<\/td>\n~1.25<\/td>\n2.0\u20133.0\u00d7<\/td>\nAutoclave precast<\/td>\nASTM C1693<\/td>\nWalls, panels, fire-rated assemblies<\/td>\nSlabs taking heavy point loads<\/td>\n<\/tr>\n
    CLC<\/td>\n300\u20131800<\/td>\n1\u201310<\/td>\n~0.8<\/td>\n0.6\u20131.2\u00d7<\/td>\nIn-place ambient cure<\/td>\nACI 523.3R<\/td>\nGeotech fill, embankment, pipe grouting<\/td>\nVisible architectural finishes<\/td>\n<\/tr>\n
    Foamed<\/td>\n400\u20131600<\/td>\n1\u201310 (25 max)<\/td>\n~0.7<\/td>\n0.7\u20131.3\u00d7<\/td>\nIn-place foamed<\/td>\nNo formal ASTM<\/td>\nInsulating fill, void fill, road trench<\/td>\nHigh-pressure pumping over distance<\/td>\n<\/tr>\n
    LWAC<\/td>\n1440\u20131840<\/td>\n17\u201340<\/td>\n~0.3<\/td>\n1.2\u20131.8\u00d7<\/td>\nReady-mix<\/td>\nACI 213R, ASTM C330<\/td>\nFloors, bridge decks, precast<\/td>\nCost-driven small projects<\/td>\n<\/tr>\n
    Perlite\/Vermiculite<\/td>\n320\u2013800<\/td>\n<1.5<\/td>\n1.0\u20131.4<\/td>\n1.5\u20132.5\u00d7<\/td>\nSite-mixed<\/td>\nASTM C495, C332<\/td>\nRoof decks, fire-rated build-ups<\/td>\nAny structural load path<\/td>\n<\/tr>\n
    No-Fines<\/td>\n1600\u20131900<\/td>\n5\u201320<\/td>\n~0.4<\/td>\n0.8\u20131.2\u00d7<\/td>\nReady-mix or site<\/td>\nNo US standard, BS practice<\/td>\nDrainage, heritage retrofit<\/td>\nModern code-driven structural design<\/td>\n<\/tr>\n
    Normal Weight<\/strong><\/td>\n2300\u20132400<\/td>\n20\u201380<\/td>\n~0.1<\/td>\n1.0\u00d7<\/strong><\/td>\nReady-mix<\/td>\nACI 318<\/td>\nGeneral structural use<\/td>\nWeight-sensitive retrofits<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
    \n
    \n

    \u2714 Lightweight Concrete Advantages<\/strong><\/p>\n