what is the inside chemical happening when cement motar dries and gets hard?
819524
From the start of the first reference (many more can be found with a simple web search).\n\n"Concrete is made of cement, aggregate, and water mixed together to form a paste. The aggregate is usually a filler material composed of inert ingredients such as sand, rocks, and underworld crime figures1 (for Hoover Dam, just sand and rocks). Usually concrete is about 70% aggregate. Using an appropriate amount of aggregate makes the cost of concrete much cheaper without sacrificing too much strength."
518090
What you are observing is the oxidation and weathering of a rock. The outside of the rock is exposed to the elements and gets bleached out, the inside is protected by the outer layers.
744760
I use water at work that is so pure it is at 10 MegaOhms of resistance (this is extremely pure). It falls on the bare concrete all the time. Nothing has ever happened, be it stains, etching, or pitting. I've seen it eat right through the rough spots on metal when it is heated to steam, but never concrete. Of course, I do realize that the concrete has been sealed with a polymer of some sort. But there are places where we've dropped things that have chipped the concrete. The water was fallen in those specific places, and even flooded across them. Nothing.\n\nNow water that pure CAN be erosive and it is an extreme solvent. You wouldn't believe how fast things dissolve in water that pure. It will rust metal faster than you've ever seen and it will break welds and springs in a steam system. This I've personally witnessesd.
40729
It's probably ethyl chloride. See link below for more info.
314656
When you blow into it , you actually blow in carbon-di-oxide which reacts with limewater making it chalky.The reaction is as follows-\n\nLimewater + Carbon-di-oxide ----- Calcium Carbonate
49182
90% of cement (by wieght) is made up of four compounds, that mixed with water hydrate to create new compounds that form the hardened cement in concrete.
983191
Depends what medium is eroding it.\nI think you're looking for the hardness scale.
973045
Concrete, as it cures, forms a complex and insoluble "crystalline" structure.  Crystalline materials such as this have atoms that are more or less "locked" in place by the kinds of chemical bonds that formed during the curing process.  Since the atoms are more or less fixed in space relative to one another, they can't slip and slide to dissipate stresses.  So, when a large enough force is applied, the strong chemical bonds finally break and a "brittle fracture" occurs.  One observes concrete shatter, creating splinters and dust, and the material is described as brittle.
478009
it comes from moving around. because of the heat you do not have enough mucous to keep it lubricated while in motion. Without that protection, the insides become brittle and subject to breakge. Much in the same way a hose on a car would become brittle with age and heat.
1054682
It "fizzes".  When you put acid on CaCO3 it reacts to release CO2 gas:\n\nCaCO3 + 2H+(aq)  -> Ca2+(aq) + H2O + CO2(g)
583415
Apparently these pellets (for example, Damp Rid) are calcium chloride (see ref.), a well-known dehumidification and ice-melting compound. So you get a water solution of calcium chloride, which is sort of oily feeling to the touch. Other than being pretty corrosive to metals (like salt water) it's not particularly dangerous, but obviously it's not for internal consumption. Incidentally you can heat the solution and any half-dissolved wet pellets for reuse when dry.
945741
Due to the fact that this salt is found as a hydrated salt (first Na2SO4.10H20 and then as Na2SO4.7H2O, so, with the increase of temperature it looses moisture (water)). When the Na2SO4.10H2O is heated the solution of this compound decreases because a solid phase and a liquid phase are formed after the initial heating.
11530
It's known as "grout".  It may feel gritty because it contains sand.
910954
Concrete---\n\n\n\nConcrete is a construction material that consists, in its most common form, of Portland cement, construction aggregate (generally gravel and sand) and water.\n\nConcrete does not solidify from drying after mixing and placement; the water reacts with the cement in a chemical process known as hydration. This water is absorbed by the cement, which hardens, bonding the other components together and eventually creating a stone-like material.\n\nConcrete is used more than any other man made material on the planet[1]. It is used to make pavements, building structures, foundations, motorways/roads, overpasses, parking structures, brick/block walls and footings for gates, fences and poles.\n\nAs of 2005 about six billion cubic meters of concrete are made each year, which equals one cubic meter for every person on Earth. Concrete powers a US$35 billion industry which employs over two million workers in the United States alone. Over 55,000 miles of freeways and highways in America are made of this material. The People's Republic of China currently consumes 40% of world cement production.\n\n\n\nFOR MORE INFO\nUSE THIS LINK--\n\nhttp://en.wikipedia.org/wiki/Concrete\n\nHOPE THIS HELPS
358563
an ongoing process....\n\nthe hardening begins before laying and continues after laying...\n\nlike a baby's head...
49380
Cement is made from gypsum, shale or clay, and limestone. The term "cement" is most often used to refer to Portland cement. Portland cement, when mixed with sand, gravel, and water, makes concrete.\nTo make cement, clay, shale and limestone is ground to a powder and baked in a kiln. The baked mixture forms clods (clinkers), which are then ground up and mixed with gypsum. Although the terms cement and concrete often are used interchangeably, cement is actually an ingredient of concrete.
877043
That would be calcium phosphate.  It has a very high compressive strength.