Portland cement mortars and concretes, modified by the addition of silica fume (sf) or by styrene-butadiene (s-b) latexes, have beenand are being used as overlays for bridge and parking-garage decks.The overlays are used both in repair of old construction and in newconstruction. The primary reason for the incorporation of either admixture in overlays is to improve permeability resistance of the mortar or concrete to deicing salts. The latter cause corrosion of reinforcing steel, which in turn leads to deterioration of the deck. Sf is widely used to produce high compressive strength concrete. Laboratory work is described that examines the combined use of silica fumeand s-b latex. The results indicate that the combined use of sf ands-b latex yields mortars and concretes that have superior properties to those using one or the other of the admixtures. This work also indicates that the two admixtures can be combined into one, which means that current equipment for placing latex-modified mortars or concretes could be used without modification. This paper appears in transportation research record no. 1301, Factors affecting properties and performance of pavements and bridges 1991.
Samenvatting