[Standard Specs] [Introduction] [Physical Properties] [Structural Lt. Wt. Concrete] [Bridge Decking] [Pumping] [Masonry] [Thermal Insulation] [Sound Absorption] [Fire Resistance] [Lightweight Fill] [Other Uses]

Standard Specifications

• Standard Specification for Structural Concrete
• Concrete Masonry Specification
• Lightweight Concrete Information Sheet

The following is a standard specification which has been incorporated in a number of job specifications.

Structural Concrete

Scope

These specifications apply to cast-in-place lightweight concrete wherever shown on the plans. They are intended to supplement the specifications for standard normal weight concrete

1. Materials - Cement: The cement shall be Portland Cement, Type I or II conforming to ASTM Designation: C 150, "Standard Specifications for Portland Cement". When deemed necessary and approved in writing by the Engineer, Type lIl, Portland Cement conforming to ASTM C 150 may be used.

   Aggregate: All lightweight aggregate shall be a rotary kiln expanded shale. The aggregate shall be NORLITE or equal as approved by Architect and conform to ASTM Designation: C 330. The maximum size of the coarse aggregate shall be 3/4 inch and the gradation requirements shall conform to ASTM C 330 and the unit weight of the dry loose aggregate shall conform to those values given in Table II, ASTM C 330.

   Water: Mixing water shall be clean and free from injurious amounts of oils, acids, alkalis, organic materials or other deleterious substances, such as would render it unfit for drinking.

   Admixtures: An approved type of air-entraining agent consisting of neutralized visol resin or a commercial AE agent conforming to ASTM designation: C 260, "Standard Specifications for AirEntraining Admixtures for Concrete"; and an option for the use of a water reducing admixture, conforming with the requirements of Standard Specification for Chemical Admixtures for Concrete, ASTM Designation: C 494

2. Concrete- Materials shall be proportioned in such a manner as to produce a concrete providing a compressive strength at 28 days of..... psi and weighing not more than..... pcf plastic weight and..... pcf air dry weight.

   Concrete shall be mixed with the minimum slump

   necessary to afford proper consistency for efficient mixing, handling, placing and finishing. The maximum slump shall be..... in. with a tolerance of 1 1/2 in. ±1.

   The air content shall be 5% ± 1% as determined by ASTM Designation: C 173, "Standard Method of Test for Air/Content of Freshly Mixed Concrete by the Volumetric Method"

3. Control - The control of the concrete shall be under the supervision of a competent representative of the architect/engineer.

   The unit weight of the wet concrete and the slump shall be measured at frequent intervals - 50 yards or fraction thereof.

   Four control compressive test cylinders, or more if deemed necessary, will be taken from each pour - 100 yards or fraction thereof. Samples of the concrete shall be taken in accordance with ASTM Designation: C 172 and compression test cylinders made and cured according to ASTM Designation: C 31. Test specimens are to be tested in a reputable testing laboratory, and are to be cured in accordance with Section 7 (b), ASTM C 31. Two of the cylinders are to be tested at an age of 7 days and two at 28 days.

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Concrete Masonry Specification

All aggregates shall be a rotary kiln expanded shale lightweight aggregate. It shall be NORLITE or equal as approved by architect and conform with ASTM Designation: C 331 "Lightweight Aggregate for Concrete Masonry Units". The term Norlite applies to lightweight aggregates produced by the Norlite Corporation, Cohoes, New York. The weight of Norlite concrete from which the masonry units are made shall not exceed 105 lb. per cu. ft. when measured in accordance with provisions of ASTM Designations: C 140 "Sampling and Testing Concrete Masonry Units".

All concrete masonry units shall conform with the following ASTM Designations:

• C 55 "Concrete Building Brick"
• C 90 "Hollow Load-Bearing Concrete Masonry Units"
• C 129 "Hollow Non-Load-Bearing Concrete Masonry Units"
• C 145 "Solid Load-Bearing Concrete Masonry Units"

Masonry units shall be stacked on planks off the ground, and in wet weather shall be covered to keep dry. Mortar shall comply with ASTM Designation: C 270 "Mortar for Unit Masonry" either Property Specifications or Proportion Specifications except that type O and K mortars shall not be permitted.

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The following is a list of often specified test methods and practices:

Specifications

American Society For Testing Materials

1. ASTM Designation: C 94, Specifications for Ready-Mixed Concrete
2. ASTM Designation: C 150, Specifications for Portland Cement
3. ASTM Designation: C 205, Specifications for Portland BlastFurnace Slag Cement
4. ASTM Designation: C 340, Specifications for Portland-Pozzolan Cement
5. ASTM Designation: C 330, Specifications for Lightweight Aggregates for Structural Concrete
6. ASTM Designation: C 260, Specifications for AirEntraining Admixtures for Concrete
7. ASTM Designation: C 143, Method of Test for Slump of Portland Cement Concrete
8. ASTM Designation: C 172, Method of Sampling Fresh Concrete
9. ASTM Designation: C 173, Method of Test for Air Content of Freshly Mixed Concrete by the Volumetric Method
10. ASTM Designation: C 138, Method of Test for Weight per Cubic Foot, Yield, and Air Content (Gravimetric) of Concrete
11. ASTM Designation: C 31, Method of Making and Curing Concrete Compression and Flexure Test Specimens in the Field
12. ASTM Designation: C 39, Method of Test for Compressive Strength of Molded Concrete Cylinders
13. ASTM Designation: C567, Test for Unit Weight of Structural Lightweight Concrete.
14. ASTM Designation: C331, Specification for Lightweight Aggregates for Concrete Masonry Units.

American Concrete Institute

1. ACI Standard 613A, Recommended Practice for Selecting Proportions for Structural Lightweight Concrete
2. ACI Standard 604, Recommended Practice for Winter Concreting
3. ACI Standard 605, Recommended Practice for Hot Weather Concreting
4. ACI Manual of Concrete Inspection
5. ACI Committee Report 213, Guide for Structural Lightweight Aggregate Concrete

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EXPANDED SHALE CLAY AND SLATE INSTITUTE-SALT LAKE CITY, UTAH 84117

This Guide Specification has been prepared to supplement the Architect-Engineer's standard concrete specifications where structural lightweight concrete is to be used. PART I - GENERAL 1.1 REFERENCE STANDARDS 1.1.1 AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM). C31, Standard Method of Making and Curing Concrete Test Specimens in the Field. C33, Standard Specification for Concrete Aggregates. C39, Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens. C94, Standard Specification for Ready-Mixed Concrete. C138, Standard Test Method for Unit Weight, Yield, and Air Content (Gravimetric) of Concrete. C143, Standard Test Method for Slump of Portland Cement Concrete. C150, Standard Specification for Portland Cement C172, Standard Method of Sampling Fresh Concrete. C173, Standard Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method. C260, Standard Specification for Air-Entraining Admixtures for Concrete. C330, Standard Specification for Lightweight Aggregates for Structural Concrete. C494, Standard of Specification for Chemical Admixtures for Concrete. C567, Standard Test Method for Unit Weight of Structural Lightweight Concrete. C595, Standard Specification for Blended Hydraulic Cements. C618, Standard Specification for Fly Ash and Raw or Calcined Natural Pozzolan for use as a Mineral Admixture in Portland Cement Concrete. 1.1.2 AMERICAN CONCRETE INSTITUTE (ACI). ACI 211.2 Standard Practice for Selecting Proportions for Structural Lightweight Concrete. ACI 301 Specifications for Structural Concrete for Buildings. ACI 318 Building Code Requirements for Reinforced Concrete. 1.2 PERFORMANCE 1.2.1 Except as modified or exceeded by these specifications all cast in place structural lightweight concrete work shall conform to ACI 301. 1.3 STORAGE OF MATERIALS 1.3.1 Cement: Store in weather tight enclosures and protect against dampness, contamination and warehouse set in accordance with ACI 318. 1.3.2 Aggregates: Each gradation of lightweight aggregate as supplied, shall be stockpiled in separate bins or piles. Storage shall minimize segregation and prevent contamination. PART 2—PRODUCTS	COMMENTS These Guide Specifications have been prepared following the 16 Division Format of the Construction Specifications Institute, Section 03313 Concrete. These comments are intended to help the Architect-Engineer set down limits in his specifications and to so write them that he can obtain the quality of structural lightweight concrete required by the design in an economical manner. The Standards that are listed under Reference Standards are the ones quoted in the specification. In the Appendix there is a list of ACl publications that will be of assistance to the Architect-Engineer when preparing his concrete specifications.
2. I MATERIALS	2.1 MATERIALS Hereinafter when the term "expanded shale" is used, it is understood to include expanded shale, clay or slate produced by the rotary kiln method
2.1.1 CEMENT: ASTM C150 or C595. Air-entraining cement will not be permitted. 2.1.1.1 FLY ASH: Shall meet ASTM C618. 2.1.2 AGGREGATE: Expanded shale, clay or slate produced by the rotary kiln method and shall conform to ASTM C330. Natural sand shall conform to ASTM C33. 2.1.3 MIXING WATER: Clean and free from injurious amounts of oils, acids, alkalis, organic materials or other deleterious substances, in accordance with ACI 318. 2.1.4 ADMIXTURES 2.1.4.1 AIR-ENTRAINING AGENTS: ASTM C260.	2.1.1 The effect and comparability of various combinations of cement, fly ash and/or admixtures is generally the same in expanded shale lightweight concrete as in normal weight concrete.
2.1.4.2 WATER REDUCING ADMIXTURES: ASTM C494. Admixtures may be used, provided they have a proven satisfactory performance record with structural concrete and are approved by the ArchitectEngineer. Admixtures shall be used in accordance with the manufacturer's recommendations.	2.1.4.2 Consistent with comment 2.1.1, high range water reducing admixtures have demonstrated satisfactory performance with expanded shale lightweight concretes. You should consult the lightweight aggregate producer in your area for specific information concerning the performance of his aggregate with high range water reducing admixtures.
2.1.4.3 ACCELERATING ADMIXTURE: ASTM C494. Admixtures may be used only with the approval of the Architect-Engineer. 2.1.4.4 RETARDING ADMIXTURE: ASTM C494. Admixtures may be used only with the approval of the Architect-Engineer.
2.2 CONCRETE PROPERTIES	2.2 CONCRETE PROPERTIES The requirements of this paragraph as well as those of 2.2.5 should be repeated in the specifications if more than one type of concrete is required by the design.
2.2.1 Materials shall be proportioned to produce concrete with a minimum compressive strength of____ psi (____ Mpa) at 28 days.	2.2.1 Expanded shale aggregate has been used in lightweight concrete for practically every type of structural application. It has been furnished at all compressive strength levels common to construction practice today, including high strength of 5000 and 6000 psi (34.4 - 41.4 MPa) or more when required
2.2.2 Materials shall be proportioned to produce concrete with a maximum air dried density of _pcf (_kg/m3) at ___days age, as determined by ASTM C567.	2.2.2 The weight of this concrete will range from 80 to 115 pcf (1280 to /840 kg/m3) depending upon the strength, air content, aggregate density and mix proportions. The 28 day density is normally from 3 to 8 pcf less than the fresh density of the concrete as placed. The amount of weight loss in curing is primarily affected by the moisture content of the lightweight aggregate when it is batched. Also, expanded shale lightweight concrete will gain strength and lose weight even after the classical 28 day requirement. This is due to the absorbed moisture, and is especially significant in pumped lightweight concrete. The concrete may gain 500-1000 psi (3.4-7 MPa) and may lose 2% or more in density, in a period between 28 and 98 days, at which time it approaches density equilibrium. If the design conditions will allow extending the time for strength and/or unit weight requirements, it will allow a more economical mix to be used. Consult the lightweight aggregate producer in your area for specific information relating to his aggregate.
2.2.3 Concrete shall be delivered at the minimum slump necessary for efficient mixing, placing and finishing. The maximum slump shall be ___in. (___mm) with a tolerance of ± 1 in. (±25 mm).	2.2.3 The Architect-Engineer should require that the mix be designed for the specified compressive strength and unit weight with a slump which will enable the concrete to be placed and finished efficiently and economically. This slump should be specified. If the concrete is to be placed by pumping, certain considerations such as presaturation of lightweight aggregates, use of admixtures and minimum cement content may be necessary. The Aggregate Producer can supply the Architect–Engineer recommended mixes for special placing conditions. The workability of structural lightweight concrete is comparable with that of normal weight concrete having 1 to 2 in. (25 to 50 mm) greater slump. Shape and dimensions of forms, placement of reinforcement and other specified job conditions vary. However, the following are generally satisfactory; for slabs and beams 3 to 5 in. (80 to 130 mm). For columns and walls 2 to 4 in. (50 to 100 mm).
2.2.4 The air content shall be percent by volume with a tolerance of ± 2 percent.	2.2.4 Air-entrainment in structural lightweight concrete, as in normal weight concrete, improves durability, workability and reduces bleeding. Generally the aggregate producer recommends air entrainment to achieve workability with minimum slump. For durability, 5 to 8 percent air is required; for workability, 4 to 6 percent is generally satisfactory. The Architect-Engineer should specify the amount of air content required for the most economical mix and for the specific application.
2.2.5 The Contractor shall furnish the mix design for the strength and unit weight of concrete specified. The mix design shall be prepared by a qualified testing laboratory and may be based upon the recommendations of the aggregate producer. The mix design shall be subject to the approval of the Architect-Engineer.	2.2.5 In establishing batch proportions, trial mixes should produce concrete with an average compressive strength higher than specified in 2.2.1. The aggregate producer generally follows one of the procedures that are outlined in ACI 211.2, Recommended Practice for Selecting Proportions for Structural Lightweight Concrete. The degree of over design required depends on variability of test results. See AC1318, Building Code Requirements for Reinforced Concrete, Section 4.4. It is recommended that the Architect-Engineer obtain from the aggregate producer a recommended economical cement content, slump, air content and unit weight for the strength of concrete required by the structural design and for the finishing qualities desired.
2.2.6 The Concrete shall be batched and mixed in accordance with ASTM C94.	2.2.6 In designing structural lightweight concrete mixtures, the question is often raised regarding the effect of aggregate absorption. Prewetting requirements in specifications to provide for this characteristic of the aggregate often lead to difficulty in control. Consequently, these specifications do not contain prewetting requirements. The mix and the control of the mix proportions should be established and maintained by the producer's quality control personnel or a qualified laboratory based upon the recommendations of the aggregate producer. With this approach, the variations that exist in batching arrangements, ready-mixed plant layouts, weather, as well as in aggregate properties, can be taken into account to produce the most efficient and economical procedure.
PART 3 — CONTROL 3.1 FIELD CONTROL 3.1.1 The control of the concrete shall be under the supervision of the Architect–Engineer. 3.1.2 Samples of concrete shall be obtained in accordance with ASTM C172, and shall be transported to a place on the site where tests can be made and cylinders stored without being disturbed for the first 24 hours. In addition, if the concrete is placed by pumping, samples shall be obtained from the end of the pump discharge line.
3.1.3 Compressive strength specimens shall be made in accordance with ASTM C31, with the exception that the curing requirement for the test specimens shall be 7 days of moist curing followed by 21 days of air drying. as detailed in ASTM C330. Section 8.1.1 for each of the following conditions: 3.1.3.1 Each day's placing; 3.1.3.2 Each type of concrete; 3.1.3.3 Each change of supplier or source; 3.1.3.4 Each 150 cu. yd. (m3) of concrete and fraction thereof. 3.1.4 Compressive strength specimens shall be tested in accordance with ASTM C39.	3.1.3 The modified curing cycle for lightweight concrete is reasonable due to the large amount of absorbed water in lightweight aggregate concretes as compared to normal weight concretes. This curing cycle is standard practice for the expanded shale industry, and is recognized in ASTM C330.
3.1.5 Unit weight. slump and air content of fresh concrete shall be determined from each batch of concrete sampled for compressive strength tests. Fresh unit weight, slump and air content shall be determined by ASTM C138, C143, and C173 respectively. The fresh unit weight of the concrete shall not exceed the design weight plus the weight loss factor determined from project trial mixes by ASTM C567.	3.1.5 The unit weight, slump and air content determinations at intervals specified enable the Architect-Engineer to maintain uniformity in the concrete mixture. As long as there is no appreciable change in the unit weight, i.e., not more than 2 pcf (32 kg/m3) variation from the established fresh unit weight, there is reasonable certainty that the correct proportions are being batched. Variations greater than 2 pcf (32 kg/m3) indicate that some change has taken place in air content, weight of aggregate or batch weights, thereby resulting in a variation of yield. When this occurs, proper adjustments in the mix should be made at once to bring concrete quality back to that specified

Appendix

The following is a list of ACI publications that will be of assistance to the Architect–Engineer when preparing specifications for the use of structural lightweight aggregate concrete.

• ACI 211.2 Recommended Practice for Selecting Proportions for Structural Lightweight Concrete.
• ACI 212.2R Guide for Use of Admixtures in Concrete.
• ACI 213R Guide for Structural Lightweight Concrete.
• ACI 301 Specifications for Structural Concrete for Buildings.
• ACI 302 Recommended Practice for Measuring, Mixing Transporting and Placing Concrete.
• ACI 305R Hot Weather Concreting.
• ACI 306R Cold Weather Concreting.
• ACI 318 Building Code Requirements for Reinforced Concrete.
• ACI 347 Recommended Practice for Concrete Formwork.
• SP-2 ACI Manual of Concrete Inspection, ACI Committee 311

EXPANDED SHALE CLAY AND SLATE INSTITUTE Salt lake City, Utah 84117. 20852

Copyright, 1961, Expanded Shale Clay and Slate Institute

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Copyright 1998, Norlite Corporation, all rights reserved.