Hypertufa is an anthropic rock

Anthropic rock

Anthropic rock is rock that is made, modified and moved by humans. Concrete is the most widely-known example of this. The new category has been proposed to recognise that man-made rocks are likely to last for long periods of Earth's future geological time, and will be important in humanity's...

 made from various aggregates

Aggregate (composite)

Aggregate is the component of a composite material that resists compressive stress and provides bulk to the composite material. For efficient filling, aggregate should be much smaller than the finished item, but have a wide variety of sizes...

 bonded together using Portland cement

Portland cement

Portland cement is the most common type of cement in general use around the world because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout...

.

Hypertufa is intended as a manufactured substitute for natural tufa

Tufa

Tufa is a variety of limestone, formed by the precipitation of carbonate minerals from ambient temperature water bodies. Geothermally heated hot-springs sometimes produce similar carbonate deposits known as travertine...

, which is a slowly precipitated

Precipitation (chemistry)

Precipitation is the formation of a solid in a solution or inside anothersolid during a chemical reaction or by diffusion in a solid. When the reaction occurs in a liquid, the solid formed is called the precipitate, or when compacted by a centrifuge, a pellet. The liquid remaining above the solid...

 limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 rock; being very porous

Porosity

Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%...

, it is favorable for plant growth.

Hypertufa is popular for making garden ornaments, pots and land forms. Hypertufa is relatively light compared with terracotta or traditional concrete

Concrete

Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

 and can withstand harsh winters, at least down to -30 C.

Hypertufa was invented for use in alpine gardens

Alpinum

An alpinum is a botanical garden specialized in the collection and cultivation of alpine plants growing naturally at high altitudes around the world, such as in the Caucasus, Pyrenees, Rocky Mountains, Alps and Himalayas....

. Alpine gardeners formerly used antique animal watering troughs, which became rare and expensive.

Composition

Aggregates

Aggregate (composite)

Aggregate is the component of a composite material that resists compressive stress and provides bulk to the composite material. For efficient filling, aggregate should be much smaller than the finished item, but have a wide variety of sizes...

 are generally Sphagnum

Sphagnum

Sphagnum is a genus of between 151 and 350 species of mosses commonly called peat moss, due to its prevalence in peat bogs and mires. A distinction is made between sphagnum moss, the live moss growing on top of a peat bog on one hand, and sphagnum peat moss or sphagnum peat on the other, the...

(peat moss), sand, and perlite

Perlite

Perlite is an amorphous volcanic glass that has a relatively high water content, typically formed by the hydration of obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently...

 or vermiculite

Vermiculite

Vermiculite is a natural mineral that expands with the application of heat. The expansion process is called exfoliation and it is routinely accomplished in purpose-designed commercial furnaces. Vermiculite is formed by weathering or hydrothermal alteration of biotite or phlogopite...

. Hypertufa made with the classic proportions for mortar

Mortar (masonry)

Mortar is a workable paste used to bind construction blocks together and fill the gaps between them. The blocks may be stone, brick, cinder blocks, etc. Mortar becomes hard when it sets, resulting in a rigid aggregate structure. Modern mortars are typically made from a mixture of sand, a binder...

 (1 part cement

Cement

In the most general sense of the word, a cement is a binder, a substance that sets and hardens independently, and can bind other materials together. The word "cement" traces to the Romans, who used the term opus caementicium to describe masonry resembling modern concrete that was made from crushed...

: 3 parts aggregate) has a composition of

• 3 parts Type I Portland cement
  Portland cement
  Portland cement is the most common type of cement in general use around the world because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout...
  
  
• 4 parts Sphagnum
• 5 parts perlite

or 3 parts cement: 9 parts aggregate

To increase structural strength and longevity, polymer fibers

Synthetic fiber

Synthetic fibers are the result of extensive research by scientists to improve on naturally occurring animal and plant fibers. In general, synthetic fibers are created by forcing, usually through extrusion, fiber forming materials through holes into the air, forming a thread...

, liquid acrylic, and fiberglass

Fiberglass

Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...

 may be incorporated into the mixture. Powdered concrete dyes (in small amounts) tint the hypertufa to resemble natural rock.

External links

• Gardenweb forum discussing Hypertufa techniques
• Blue Fox Farm - All Rustic, All Day Long, Hypertufa Projects.
• Making hypertufa garden ornaments tutorial
• Hypertufa Trough (Planter) Project Thorough how-to instructions for a successful trough project.
• Drought Smart Plants Hypertufa What to plant in your finished project.
• Four Hypertufa Recipes & Mixing Guidelines Step-by-step directions to properly make hypertufa.
• Het bouwen van een alpentuin example of a Dutch rock garden using hypertufa.