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Portland cement plaster mix12/9/2023 The combinations of cementitious materials and aggregates shown in Table 2 have proven to provide satisfactory performance. Properly proportioned mixtures can be recognized by their workability, ease of application, adhesiveness to the base, and resistance to sagging. If necessary, larger aggregate may be added to obtain the desired appearance. Uniform gradation produces plaster that is easier to apply. As a starting point, all aggregates for finish-coat plaster should be below a No. Various sizes and shapes can be evaluated with test panels to obtain special textures or finishes. Recommendations for gradation of the sand to be used in the base coat are listed in Table 1.Īggregates used for finish coats need not comply with the gradation requirements of ASTM C897. Types I, II, III, and their air-entrained counterparts IA, IIA, IIIAĪggregates used in plaster should conform to the chemical and physical requirements of ASTM C897, Standard Specification for Aggregate For Job-Mixed Portland Cement Plasters (ref. Types IP, IP(M), IS, IS(M), and their air-entrained counterparts IP-A, IP(M)-A, IS-A, IS(M)-A CementĬement should comply to one of the following product specifications:īlended hydraulic cement -ASTM C595 (ref. 3) includes specifications for materials for use in plaster. Standard Specification for Application of Portland Cement-Based Plaster, ASTM C926 (ref. Each must be evaluated on its ability to provide serviceability, durability, and satisfactory appearance. Of primary importance to the performance of the finished surface is the selection and use of proper materials. Since block is manufactured of the same cementitious material as that in the plaster, the two have a natural affinity. Concrete masonry, however, provides an excellent base for plaster without the need for reinforcement. While plaster may be used as an interior or exterior finish for most building materials, some type of metal reinforcement or mechanical keying system is usually required to effectively attach the plaster to the substrate. It can be applied either by hand or machine in two or three coats, although two-coat applications are more typical when plaster is applied to newly constructed concrete masonry. When freshly mixed, plaster is a pliable, easily workable material. They both describe a combination of cement and aggregate mixed with a suitable amount of water to form a plastic mixture that will adhere to a surface and preserve the texture imposed on it. The terms cement plaster and cement stucco are used interchangeably. Portland cement-based plaster has many useful applications: as a moisture resistant coating for concrete masonry walls as an interior wall finish in residential and commercial structures and as an exterior architectural treatment for buildings of all types.
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