Cosmicrete

概要 Overview §01

Cosmicrete is cement that’s been whipped full of tiny, stable bubbles — producing a block that weighs less than half its conventional equivalent while outperforming R-6 foam board for insulation.

The secret ingredient is xanthan gum — a thickener from your local grocery store. It neutralizes cement’s aggressive water absorption long enough for dish soap to generate and stabilize bubbles directly inside the mix. No foam machine. No pre-generated foam. Just stir and watch it expand.

材料 Ingredients §02

Ingredient	Amount	Notes
Xanthan Gum キサンタンガム	15g	Grocery store / bulk online. The key ingredient.
Dawn Ultra Dish Soap 食器用洗剤	60 ml	¼ cup. Match top ingredients — see reference below.
Water 水	1 litre	Room temperature.
Rubbing Alcohol 消毒用アルコール	Splash	Mouthwash also works. For pre-wetting xanthan.
Portland Cement ポルトランドセメント	2 parts	By volume, to 1 part gel base.

Dawn Ultra — Reference Ingredients

Sodium Lauryl Sulfate Alkyldimethylamine Oxide Alcohol Denat. C9-11 Pareth-8 Colorants Deceth-8 Fragrances Methylisothiazolinone PEI-14 Phenoxyethanol PPG-26 Sodium Chloride Water

Highlighted surfactants are what generate and stabilize bubbles. When substituting another brand, verify these are present.

手順 Instructions §03

▶ PART 01 // GEL BASE — ゲルベース

Pre-wet the Xanthan

キサンタンガムの予備加水

Add 15g of xanthan gum to a large container. Add a small splash of rubbing alcohol (or mouthwash) and stir into a paste. This prevents clumping when water is added later.

Add Dish Soap

洗剤を追加

Stir in 60ml (¼ cup) of Dawn Ultra dish soap until combined with the xanthan slurry.

Add Water & Wait

水を加えて待機

Pour in 1 litre of water and stir. Leave to sit for 5–10 minutes until the mixture thickens into a gel. This is your Cosmicrete base.

Why it works: The hydrated xanthan slows cement’s water absorption, protecting the soap’s bubble-forming ability inside the hostile alkaline environment.

▶ PART 02 // MIX & POUR — 混合と注型

Suit Up

保護具装着

Put on your dust mask before opening the cement.

⚠ Dry cement dust is hazardous. Wear a mask throughout mixing.

Combine Gel + Cement

ゲルとセメントの混合

Combine 1 part gel base to 2 parts dry Portland cement by volume. It will look too dry at first — keep mixing. Bubbles form automatically as you work.

Stir to Target Density

目標密度まで撸拌

This is your only variable. Keep stirring and watch it expand. Draw marks on your container to hit the same density batch after batch.

Pro move: Mark your container at two points — your preferred density line, and the “bubble pop” limit for open-cell foam.

Pour Immediately

すぐに注型

Pour into your mold. Cosmicrete holds its shape like stiff meringue and is far easier to work with than regular concrete.

密度 vs 特性 Stir Time vs Properties §03a

Short Stir短時間撸拌

STRENGTH

INSULATION

~35% air

Long Stir長時間撸拌

STRENGTH

INSULATION

~75% air

Past Limit限界超過

OPEN-CELL (bubbles pop at surface)

Filter

混合方法 Mixing Methods §04

🥄

By Hand

手動撸拌

Spatula or paint stick. Works fine for small batches. Most effort, full control.

→ Up to 75% air

⚙

Drill + Paddle

ドリル＋パドル

Best for 5-gallon bucket batches. Fast, consistent, and achieves maximum foam density.

→ Up to 75% air

🔄

Cement Mixer

セメントミキサー

Viable at scale with standard equipment. Mix gets too light to tumble properly at higher densities.

→ ~50% air

クイックリファレンス Quick Reference §05

REF_001

▶ TRANSMISSION_COSMICRETE_v1.0

// GEL BASE (per 1 litre water)
15g   xanthan gum
      + splash alcohol  → stir into paste
60ml  Dawn Ultra dish soap  → stir in
1L    water               → stir in
      wait 5–10 min       → gel forms

// MIX
1 pt  gel base
2 pt  dry Portland cement  (by volume)
      mix until desired expansion
      pour immediately

// CURE
      cover with damp cloth day 0
      keep damp            days 1–5
      75% strength         ~7 days
      full strength        28 days