Purpose and scope
This guide presents state-of-the-art information relative to the construction of slab-on-ground and suspended-slab floors for industrial, commercial, and institutional buildings. It is applicable to the construction of normalweight and structural lightweight concrete floors and slabs made with conventional portland and blended cements. Slabs specifically intended for the containment of liquids are beyond the scope of this document.
The design of slabs-on-ground should conform to the recommendations of ACI 360R. Refer to ACI 223 for procedures for the design and construction of shrinkagecompensating concrete slabs-on-ground. The design of suspended floors should conform to requirements of ACI 318 and ACI 421.1R. See Section 1.2 for relevant work by these and other committees.
This guide identifies the various classes of floors as to
• Use;
• Design details as they apply to construction;
• Necessary site preparation; and
• Type of concrete and related materials.
In general, the characteristics of the concrete slab surface and the performance of joints have a powerful impact on the serviceability of floors and other slabs. Because the eventual success of a concrete floor installation depends on the mixture proportions and floor finishing techniques used, considerable attention is given to critical aspects of achieving the desired finishes and the required floor surface tolerances. This guide emphasizes choosing and proportioning of materials, design details, proper construction methods, and workmanship.
Prebid meeting—While this guide does provide a reasonable overview of concrete floor construction, it should be emphasized that every project is unique; circumstances can dictate departures from the recommendations contained herein. Accordingly, contractors and suppliers are urged to make a thorough review of contract documents before bid preparation.
The best forum for such a review is the prebid meeting. This meeting offers bidders an opportunity to ask questions and clarify their understanding of contract documents before submitting their bids. A prebid meeting also provides the owner and the owner's designer an opportunity to clarify intent where documents are unclear and to respond to last-minute questions in a manner that provides bidders an opportunity to be equally responsive to the contract documents.
Preconstruction meeting—Construction of any slabon- ground or suspended floor or slab involves the coordinated efforts of many subcontractors and material suppliers. It is strongly recommended that the designer require a preconstruction meeting to be held to establish and to coordinate procedures that will enable key participants to produce the best possible product under the anticipated field conditions. This meeting should be attended by responsible representatives of organizations and material suppliers directly involved with either the design or construction of floors.
The preconstruction meeting should confirm and document the responsibilities and anticipated interaction of key participants involved in floor slab construction. Following is a list of agenda items appropriate for such a meeting; many of the items are those for which responsibility should be clearly established in the contract documents. The following list is not necessarily all-inclusive:
Site preparation;
Grades for drainage, if any;
Work associated with installation of auxiliary materials, such as vapor barriers, vapor retarders, edge insulation, electrical conduit, mechanical sleeves, drains, and embedded plates;
Class of floor;
Floor thickness;
Reinforcement, when required;
Construction tolerances: base (rough and fine grading), forms, slab thickness, surface configuration, and floor flatness and levelness requirements (including how and when measured);
Joints and load-transfer mechanism;
Materials: cements, fine aggregate, coarse aggregate, water, and admixtures (usually by reference to applicable ASTM standards);
Special aggregates, admixtures, or monolithic surface treatments, where applicable;
Concrete specifications, to include the following:
Compressive strength, flexural strength, or both, and finishability (Section 6.2);
Minimum cementitious material content, if applicable (Table 6.2);
Maximum size, grading, and type of coarse aggregate;
Grading and type of fine aggregate;
Combined aggregate grading;
Air content of concrete, if applicable (Section 6.2.7);
Slump of concrete (Section 6.2.5);
Water-cement ratio (w/c) or water-cementitious material ratio (w/cm); and
Preplacement soaking requirement for lightweight aggregates.
Measuring, mixing, and placing procedures (usually by reference to specifications or recommended practices);
Strikeoff method;
Recommended finishing methods and tools, where required;
Coordination of floor finish requirements with those required for floor coverings such as vinyl, ceramic tile, or wood that are to be applied directly to the floor;
Curing procedures, length of curing, necessary protection, and time before opening slabs for traffic (ACI 308R);
Testing and inspection requirements; and
Acceptance criteria and remedial measures to be used, if required.
Additional issues specific to suspended slab construction are as follows:
Form tolerances and preplacement quality assurance survey procedures for cast-in-place construction;
Erection tolerances and preplacement quality assurance survey procedures for composite slab construction (see ANSI/ASCE 3 and ANSI/ASCE 9 [Section 12.1]);
Form stripping procedures, if applicable; and
Items listed in Section 3.3 that are appropriate to the structural system(s) used for the project.
Quality assurance—Adequate provisions should be made to ensure that the constructed product meets or exceeds the requirements of the project documents. Toward this end, quality control procedures should be established and maintained throughout the entire construction process.
The quality of a completed concrete slab depends on the skill of individuals who place, finish, and test the material. As an aid to ensuring a high-quality finished product, the specifier or owner should consider requiring the use of prequalified concrete contractors, concrete suppliers, accredited testing laboratories, and concrete finishers who have had their proficiency and experience evaluated through an independent third-party certification program. ACI has developed programs to train and certify concrete flatwork finishers and concrete inspectors and testing technicians throughout the United States, Mexico, and Canada.