Can I Use Mortar Mix For Stucco

They are concretes of a sort, masonry mortar and stucco, that is. They both contain portland cement and aggregates, just then they dissever into distinct compositions and purposes. Concrete, to all kinds of structures; masonry mortar, mainly in joints and equally parging for brick, cake (physical masonry units, or CMU), and rock structure; and stucco in its primary role every bit wall coverings.

Concrete needs to be placed and molded to shape, which is done by restraining its potential fluid movement, using forms and so restraint against gravity is along the bottom and sides. When initially placed, masonry mortar is restrained in joints by flanking overlying, underlying, or adjacent masonry units, but non along front end, back, and all sides. Masonry mortar needs to have "fat" to retain its shape, support overlying masonry units, and not "flow" laterally the moment it is loaded past the weight of overlying masonry units. Stucco for walls also needs "fat" so it can defy gravity and hang in place, which is also true for parging mortar when practical to the behind of walls. The "fat" is obtained using hydrated lime or relatively high levels (e.g. 14%) of air-entrainment (both taboos for physical) also provide h2o retention needed for cement hydration.

Hydration of portland cement provides their master strength. Physical strength correlates mainly to water-cement ratio and to attainment of as much portland cement hydration as the water-cement ratio will permit—under the circumstances of its curing surroundings. On the other hand, although cement hydration is important to mortar and stucco, equally, if non more important, is the "fat" that allows them to accommodate masonry units placed on their surfaces (mortar), and to stay in place. An boosted need is to maximize strength past retaining water that can so rapidly depart into absorptive flanking masonry units or from forepart and rear evaporative articulation surfaces. Concrete doesn't need that assistance. Water-retention of mortar and stucco is important, and is a belongings imparted by their constituents.

Piffling recognized is the relationship of specified mortar compressive strength in standards (which are determined in the laboratory under strictly controlled water content, component batch weights, and moist curing) to in-place field forcefulness. Portland cement will continue to hydrate as long every bit water is available. Purposeful curing does that for concrete. Mortar and stucco do that, as best they can, past retaining mix water, thus, the need for water retention by the mortar and stucco.

Later, when atmospheric carbon dioxide causes a trounce of carbonation products to envelop cement particles, hydration stops—permanently. Considering of the relative thinness of mortar and stucco, and their invariably high-water contents that increase permeability to atmospheric carbon dioxide, carbonation more readily happens to stymie later force development, which does not occur to concrete. Likewise field masonry mortar, for example, tin can undergo retemperings for up to two and a half hours, according to usual specifications, and there is no numerical limit on the amount of initial water and tempering water that can be used. So in-place field mortars cannot exist expected to reproduce strengths of laboratory-prepared exam mortars.

The initial chemic properties of concrete, mortar, and stucco are similar; that is, they each maintain a loftier pH, never less than the pH of a saturated calcium hydroxide (Ca(OH)2) solution, 12.4 to 12.5. Atmospheric carbonation of concrete affects only its pare, whereas, with time, it usually deeply penetrates mortar and stucco, and thus drops the pH chop-chop. Carbonation results in shrinkage, and also creates sensitivity to corrosion of embedded reinforcement, which unremarkably is galvanized to resist corrosion. Not so for concrete considering if reinforcing steel is buried deeply enough, the high pH maintained protects information technology from corroding. All of the in a higher place assumes the chloride nemesis is not present.

Some major differences between these are: (1) restrictions on water content of concrete versus an near cavalier freedom for mortar and stucco; equally long as their "fat" is retained; (2) physical slump versus the bricklayer's "artfulness" in decision-making "fatness" of mortar and stucco; (3) prolonged cement hydration for concrete and an virtually guaranteed cessation of hydration over a relatively short catamenia for mortar and stucco; (4) carbonation, express to the concrete "skin" but throughout mortar and stucco; and (v) better field strength control for concrete versus mortar and stucco.

William Hime is a principal with Wiss, Janney, Elstner Associates and began working as a chemist at PCA 54 years ago.

Bernard Erlin is president of The Erlin Co. (TEC), Latrobe, Pa., and has been involved with all aspects of physical for more than 48 years.