Cement bonded articles are coated on their surface in orderto avoid ef?orescence and to attain an aesthetic appearance.In the course of time the coating is exposed to Weatheringthrough atmospheric conditions. While With strong sun exposure in the summer the temperature on the surface mayincrease up to about 80° C., With frost the temperature candecrease to —30° C. in Winter. The attack by cycles of freeZingand thaWing, as Well as by acid rain, is particularly critical.Various coating compositions are knoWn in the art as usefulfor protecting cement bonded articles from Weathering.Among these, silica-based coating compositions may in particular be cited.US. Pat. No. 2,956,958 discloses a silica dispersion usefulfor coating a substrate such as glass. This dispersion containsamorphous silica particles in the proportion by Weight of (a) one part of particles having a diameter larger than 50 nm andan average diameter D from 50 to 150 nm; (b) from 0 to 0.07part ofparticles from 0.25 D to 0.4 D nm in diameter; and (c)from 0.04 to (0.4-x) part of particles 4 to 0.25 D nm indiameter Where x is the parts by Weight of portion (b). Thedispersion does not contain any polymer.US. Pat. No. 3,895,956 discloses a Water permeabilityreducing inorganic coating slurry composition useful forcoating construction surfaces. The composition contains5-700 parts by Weight of an inorganic ?ller; 0.1-30 parts byWeight of a Water sWellable magnesium silicate and/or bentonite; 0.1 -50 parts by Weight of a Water-repellent (alkali alkylsiliconate, inorganic poWder coated With alkali alkyl siliconate or fatty acid); 0.01-10 parts by Weight of a viscosityimprover (monovalent alkali metal, ammonium or amine saltof a polyacrylic acid having a degree of polymeriZation of atleast 2000, polyethyleneoxide of 500,000 molecular Weight, or Water soluble cellulose derivative); and 100 parts by Weightof a silica sol containing a silica component ranging from3-50 Wt % and at least one alkali component, Wherein themole ratio of SiO2 to M2O is greater than 4 (M20 being analkali metal oxide, ammonium hemihydrate, an amine hemihydrate, guanidine hemihydrate or hydraZine hemihydrate).