Lightweight foamed cement, cement board, and methods for making same

A method of providing a lightweight cementitious product comprising:

• mixing a cementitious foamed mixture comprising
• 65-75 wt. % hydraulic cementitious reactive powder,
• 20-35 wt. % water
• 0.05-1 wt. surfactant as a foaming agent;
• 0.1 to 1.0 wt. % polyvinyl alcohol as a foam stabilizing agent;
• 0-0.5 wt. % a retarder selected from the group consisting of citric acid, alkali metal salt of citric acid,
• 0.15-1.0 wt. % superplasticizer;
• at least one member selected from the group consisting of aggregate and filler, wherein a weight ratio of total aggregate and filler to hydraulic cementitious reactive powder is 0 to 0.5:1, wherein all aggregate and filler of the cementitious foamed mixture is only lightweight non-porous aggregate and lightweight non-porous filler,
• wherein the lightweight non-porous aggregate and lightweight non-porous filler have a particle density of less than or equal to 40 lbs/cubic foot,
• wherein the lightweight non-porous filler and the lightweight non-porous aggregate have an open porosity of at most 0.10;
• water, wherein the foamed mixture weight ratio of water to hydraulic cementitious reactive powder is 0.3 to 0.5:1;
• and
• air in the form of foam bubbles with diameter in the range of 50 to 200 μm, wherein the foamed mixture has air volume content of 20 to 55 volume %;
• wherein the hydraulic cementitious reactive powder comprises in % by weight relative to the weight of the hydraulic cementitious reactive powder:
• 75 to 95% Portland cement,
• 0 to 21% high alumina cement, (also known as calcium aluminate cement),
• 0 to 10% calcium sulfate, and
• 0 to 25 pozzolanic material;
• casting the cementitious foamed mixture and leaving the cast mixture to set to form the lightweight cementitious product,
• wherein the set cementitious foamed mixture has, measured 14 days after casting, a nominal density of 45-60 pounds per cubic foot and a nail pull value of greater than 90 pounds-force;
• wherein the set cementitious foamed mixture has a compressive strength, measured 7 days after casting of 500 psi to about 5000 psi.