Rebuild Los Angeles With Ultra High Strength Concrete and UHPC Domes Where Possible

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Los Angeles could have to rebuild over 30% of the city. California has fires, earthquakes, high winds and other risks.

Replacing hundreds of billions in residential and commercial buildings and roads is an opportunity to enable a shift to Ultra-high performance concrete and making key structures like hospitals, fire departments into UHPC concrete domes.

The 2001 world trade center disaster made the Freedom tower out of ultra-high performance cement.

This new rebuilding is an opportunity for the Federal and California government to finish some key materials analysis and testing for mass production of ultra high performance cement. We have learned a lot about cement and we can make the buildings 10-100 times stronger. Why rebuild with flimsy material that we know cannot withstand fires and earthquakes?

We can select the material that with volume usage could be about the same cost as current wood construction. It would be good for high rises and other towers and has been used for them already.

3D printing of cement can make for complex structures with interesting architecture.

Ultra-high Performance Concrete

Ultra-high performance concrete (UHPC) is an enhanced fibrous and cementitious concrete with high compressive strength (120–250 MPa) particle packing density (0.825–0.855, tensile strength (15–20 MPa) and extraordinary durability. UHPC has 300 times the ductility and energy absorption of high performance concrete (HPC) and three to sixteen times the compressive strength of regular concrete. About $500 million of the billions spent on the Freedom Tower was the UHPC concrete. It has stronger material than the old Minute Man nuclear silos. The large amount of UHPC has moved it into the mainstream higher end option for skyscrapers, bridges and roads.

A 3000 square foot dome house using UHPC would only need about 40 cubic meters of material for a highly bomb resistant structure. This only need $120,000 worth of UHPC material. IF the efforts to develop low-cost UHPC are successful then the cost of UHPC for such a building would drop to $30,000. The high strength material could replace larger amounts of regular concrete.

UHPC mixes cost $2500–$3000 per cubic meter compared to $170 per cubic meter for ordinary concrete. There are low cost UHPC.

Ultra-high performance concrete mixes cost $360-650 per cubic yard and have compressive strength from 22,500 PSI to 29000 PSI. There are proprietary makers of stronger concrete with costs of $2000 per cubic yard. There have been test blocks of concrete with strengths of 60000 PSI. Regular concrete is usually at 3000-5000 PSI compressive strength.

There is currently a trend to simplify low-cost UHPC production methods by substituting affordable local resources for expensive components such as cement, steel fiber, and silica powder. In addition, UHPC consisting of silica sand with a maximum particle size of 500 μm, GGBS, and steel fibers of 13 mm in length can be utilized to augment already existing RC beams.

Portable bridge deck panels can be made from the upgraded lightweight UHPC. 3D printing is a promising technique in a variety of fields, including the concrete industry. Theoretically, it is simple and quick to construct a complicated three-dimensional structure utilizing concrete extrusion via a printing machine.

Cement Monolithic Dome Houses Meet FEMA Standard of Near Absolute Fire Protection

Monolithic Domes meet FEMA standards for providing near-absolute protection and have a proven ability to survive tornadoes, hurricanes, earthquakes, most manmade disasters, fire, termites and rot.

Monolithic Domes are constructed using:

Concrete: A non-combustible material that can withstand high temperatures
Steel reinforcement: Adds structural integrity during fire exposure
Polyurethane foam insulation: While foam is combustible, it’s protected by the concrete shell

Design Features

Seamless structure: The dome shape eliminates weak points where fire could penetrate
Minimal exposed wood: Reduces flammable materials in the structure

Fire Resistance Performance

Monolithic Domes can withstand fire exposure for several hours
They meet FEMA standards for “near-absolute protection”
Some cement dome homes have survived wildfires that destroyed surrounding structures

Additional Fire-Resistant Measures
To further enhance fire resistance:

Use fire-resistant doors and windows
Install fire-resistant vents with metal mesh screening
Construct decks and exterior features with fire-resistant materials
Apply fire-resistant coatings to the exterior

Here is link to the FEMA guide on safe rooms for Tornadoes and Hurricanes

Protection Levels

FEMA’s primary standard for near-absolute protection is focused on safe rooms designed for extreme wind events. These include:

Monolithic Dome safe rooms
Reinforced concrete safe rooms
ICF (Insulated Concrete Form) safe rooms
Prefabricated safe rooms (meeting specific criteria)

These structures are designed to meet the criteria outlined in FEMA P-361: Safe Rooms for Tornadoes and Hurricanes.

FEMA Protection Levels
FEMA doesn’t use a specific rating system for protection levels across all hazards. Instead, they provide guidelines for different types of hazard-resistant construction:

Wind Resistance: FEMA P-361 outlines criteria for “near-absolute protection” from extreme winds.
Flood Resistance: FEMA provides guidelines for flood-resistant design and construction in ASCE 24-14.
Seismic Design: While FEMA provides guidelines, seismic design is primarily governed by building codes based on ASCE 7 standards.
Fire Resistance: Fire resistance is typically addressed through local building codes rather than specific FEMA standards.

The Cost to Make a Building Fire Resistant Would be More Than Committing to Ultra-high Strength Concrete for Better Protection

The cost to make a 2,500 sq ft home more fire resistant.

Roof replacement with asphalt shingles: $8,125 – $13,750
Fiber cement siding installation: $11,750 – $21,250
Additional measures (eaves, vents, etc.): Approximately $2,000 – $5,000

Total estimated cost: $21,875 – $40,000

Fiber Cement Siding
Fiber cement siding is one of the most cost-effective fire-resistant options. It typically comes with a Class A Fire Rating and offers durability against weather and pests

Enclosed Eaves and Soffits
Enclosing eaves and soffits with fire-resistant materials can prevent embers from entering the attic space

Fire-Resistant Vents and Screens
Installing 1/8″ steel mesh screens on vents can help prevent embers from entering the home.

14 thoughts on “Rebuild Los Angeles With Ultra High Strength Concrete and UHPC Domes Where Possible”

  1. Thank you for posting this great article. For those concerned about spalling, in our practical experience—over 50 years building Monolithic Domes, and seeing them withstand everything nature and man can throw at them—it just isn’t an issue. It can happen now and again, but it’s a cosmetic matter.
    Please see: https://monolithicdome.com/burning-legacy-how-vista-dhome-defied-an-inferno
    And
    https://www.monolithic.org/foam/foam-fire-hazard-and-fire-barrier

  4. What do the great Fire of Chicago, the San Francisco earthquake, and hurricane Katrina have in common? They all took out older buildings and construction now considered dated in design. Through attrition, we’ll see replacement homes built with sealed eaves and vents, the primary sources of home to home fire spread. There’s a reason modular homes have been built like this for years—most of them get placed on rural or remote land, areas prone to fires.

    • Ultra-high performance concrete (UHPC) can be fire-resistant when designed and mixed properly:

      Mix design
      UHPC’s dense microstructure can cause explosive spalling when exposed to high temperatures. To prevent this, the mix design should allow water vapor pressures to dissipate.

      Fibers
      Synthetic fibers like polypropylene (PP) can improve UHPC’s fire resistance and prevent spalling. Flame-retardant polymer (SFRP) fibers can also help prevent spalling and reduce strength loss

    • A moving brush fire is just that, moving. Once it consumes the fuel in and around the house, it’s moved on. There isn’t enough time to superheat the concrete and achieve failure. Piling 500 chords of fire wood against the wall is another (highly unlikely) other issue.

  7. Fireproof roofing, fine vent screens and painting all exposed wood with intumescent paint, and fire buffer zone around a house should be enough.

  8. Vents need to be fire vent screens with intumescent paint which expands in heat to block embers.
    In any case, short of UHPC concrete, an adjacent firestorm can penetrate. But protecting from embers and removing adjacent vegetation and wood fences, etc goes a long way.
    Roof sprinklers connected to pool pump with heat sensors and battery backup is another strategy used to protect against embers, but high winds can reduce its effectiveness.
    Cement board siding or stucco helps. A self adhering fire resistant underlayment under asphalt shingles is required in high fire zones in California.

  9. The key is not solely materials but expertise. The best Seismic/ Disaster Structural Engineers are japanese and mediterranean (italian?) with methods and systems requiring expensive concepts like dislocating/damping the ground from the building and proper allocation of mass in the building. Fire is expensive but having a multi-day panic room and a property cistern means saving essentials. We are past typical concrete if you want to resist wind-blown fires. Of course, having functional community water supplies and sufficient competent staff works everywhere in the modern world since a few generatrions ago. Totally Avoidable CA Tragedy.

    • I really doubt it was avoidable. Burn enough houses, and you’ll lose too much water through the broken house pipes. Fan the fire with 100 MPH winds, and you’ll get dozens or hundreds of houses burning at once. Houses can be engineered to withstand hurricanes, but not F5 tornadoes. This was a tornado. It would be nice if we had infinite firefighting resources, but we don’t.

  10. There’s not enough workforce with experience working with these materials.

    Residential properties in the US are mostly built by labor with no formal training or certifications. You have one crew lead plus whoever was at the Home Depot that morning.

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