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cause discoloration. Factors found to influence discoloration are: the use of calcium chloride, variation in cement alkali content, delayed hydration of the cement paste, admixtures, hardtroweled surfaces, inadequate or inappropriate HOW to Avoid Discoloration? 1. Calcium chloride in concrete can cause concrete discoloration.
May 12, 2015· The calcium chloride test, long considered the standard for testing concrete moisture vapor emissions, has been in use since the 1940s. This test produces a moisture vapor emissions rate (MVER), which is a reading of how much moisture content is released from 1000 square feet of concrete slab over a 24hour period.
Toprated concrete pros and industry associations we consulted say that calcium chloride, especially if added in amounts that approach 2 percent of the cement weight, can cause a mottled, blotchy surface. They say the discoloration is probably just an aesthetic issue, not a sign of weakness in the slab.
The American Concrete Institute Committee 306 has suggested procedures to achieve a quality product in adverse conditions. The use of calcium chloride assists in reaching the concrete''s desired strength by accelerating the cement''s hydration. Calcium Chloride is the most costeffective accelerator for today''s modern concrete.
Mar 29, 2018· Discoloration. There is no one single factor that causes concrete discoloration. Uneven concrete color can be caused by a number of factors. Calcium chloride admixtures, cement alkalies, wonky curing, and other things beyond the finisher''s control can all factor into a slab''s color. Hardtroweling can even contribute to concrete discoloration.
Sep 28, 2014· Paula, adding calcium chloride to readymix concrete can cause all sorts of issues. It''s an additive that''s used to speed up the hydration chemical reaction in the concrete so the concrete transform from a plastic material to a solid faster in colder weather.
Acceptable Use of Calcium Chloride in Concrete ASCC Position Statement #31 ACI 31808, "Building Code Requirements for Structural Concrete," with some exceptions, allows calcium chloride as an accelerating admixture for castinplace concrete. But many specifications prohibit its use. This is unfortunate because calcium
Sep 28, 2018· Pinghung Chen / Getty Images Concrete should be of one color if you are using the correct batch and materials from the Ready, concrete discoloration could occur if there are sudden changes to the cement material, if the finishing operations are rushed or if calcium chloride .
Concrete degradation may have various can be damaged by fire, aggregate expansion, sea water effects, bacterial corrosion, calcium leaching, physical damage and chemical damage (from carbonatation, chlorides, sulfates and nondistilled water).This process adversely affects concrete exposed to these damaging stimuli.
Types and Causes of Concrete Deterioration Fig. 4. Deicing salts are a major cause of corrosion of reinforcing steel in concrete. (55807) Table 2. Maximum Chloride Ion Content of Concrete (ACI 318) Maximum Type of Member Cl* Prestressed concrete Reinforced concrete exposed to chloride in service Reinforced concrete that will be dry
Calcium chloride in concrete is a primary cause of concrete discoloration. The chances for discoloration are much less if calcium chloride or chloridebearing chemical admixtures are not used. The type, kind, and condition of formwork can influence surface color. Forms with different rates of absorption will cause surfaces with different shades ...
Causes Of Grey Concrete Discoloration Calcium Chloride. Gray (or grey) mottling discoloration is due to high amounts of calcium chloride added to a plaster mix, and or late, hard and dry troweling. This issue has nothing to do with the water chemistry or the way the pool was originally started .
by mixing Liquiblack with gray cement. Plain Concrete ... is the number 1 cause of dark spots or blotchy appearance of the surface of a concrete slab. Specifically, discoloration will almost certainly occur with late or hard troweling. ... sand or applying water can cause blotchiness. Calcium chloride will darken any cementitious material so ...
CIP 23 Discoloration ... Calcium chloride in concrete is a primary cause of concrete discoloration. The chances for discoloration are much less if calcium chloride or chloridebearing chemical admixtures are not used. 3. The type, kind, and condition of formwork can in
Take a look at the common causes of concrete discoloration, including inconsistent materials, adding water at the jobsite, adding calcium chloride and more.
(a) Ovarall View, Concrete in foreground contained calcium chloride, that in back did not. [b) Closeup of surface. Fig, I A Driveway with Gross Color Contrast and Mottling Discoloration. Development Laborofories, Sepfember 1966 35
Dec 08, 2017· Research by ACI and PCA has documented discoloration problems with improper concrete flat work. The cause/effect is virtually the same as with pool plaster because both plaster and concrete contain a significant amount of Portland cement. (Concrete Slab Surface Defects: Causes, Prevention, Repair – Portland Cement Association 2001).
Jun 04, 2014· Gray (also spelled "grey") or darkened blotchy or streaky discoloration of pool plaster (cement flatwork) is known to be caused by several improper plastering practices, including the addition of calcium chloride to the mix (even less than 2%), late hard or dry troweling, and sometimes a cement material issue can lead to this problem.
Sep 17, 2010· Gray (or grey) mottling discoloration which occasionally occurs in plaster swimming pools may also occasionally occur on other cement flatwork, including things like driveways and sidewalks. According to the American Concrete Institute and the Portland Cement Association, adding calcium chloride and troweling concrete too late when the surface is hard are two factors that can cause .
Factors found to cause discoloration include: the use of flake form of calcium chloride that may not completely dissolve, variation in cement 1. Calcium chloride in concrete can cause discoloration. Flake or pelletized calcium chloride, when not mixed uniformly, discolors more than liquid calcium chloride.
Apr 13, 2011· Discoloration of new Concrete (color, light, cost, slab) User Name: ... most of the concrete has dried to a light whitish grey but the discolorations are a darker gray. ... It was broomed the same day it was poured, so maybe this is a clue that they used calcium chloride (I was originally told they''d come back the next day to broom.) ...
Much care must be taken in applying acid to Portland cement products. The acid will attack, not only the calcium carbonate and calcium sulfate efflorescence, but also other calcium compounds to produce calcium salts such as calcium chloride. It is, therefore, very important to neutralize the acid before it can attack other compounds.
Calcium chloride in concrete is a primary cause of concrete discoloration. The chances for discoloration are much less if calcium chloride or chloridebearing chemical admixtures are not used. The type, kind, and condition of formwork can influence surface color.
Contributing further to efflorescence with cold weather pours is the use of calcium chloride to accelerate the set time. High slump concrete and the addition of calcium chloride are major contributors to efflorescence. Secondary efflorescence is often described as water coming from underneath the slab or water that is introduced from the surface.
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