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This proposed standard is intended as a supplement to ACI Standard "Recommended Practice for Selecting Proportions for Concrete (ACI 613- 54)." The standard describes a procedure for proportioning concretes having slumps in the range of zero to I in. and consistencies below this range, for aggregates up to 11f2 in. maximum size. Suitable equipment for measuring such consistencies is described. Tables similar to those in ACI 613-54 are provided which, along with laboratory tests on physical properties of fine and coarse aggregate, yield information for obtaining concrete proportions for a trial mixture. Examples of the use of these tables, in conjunction with tables in ACI 613-54, are given. [ABSTRACT FROM AUTHOR]

To develop data on the factors affecting the durability of pretensioned concrete beams, 28 large beams containing pretensioning strands and 412 small companion specimens without pretensioning strands were fabricated. The concrete in 22 of the beams was air entrained; that in the other six was not. An appendix presents computations used in designing the beams. Some of the beams were subjected to laboratory tests, which indicated that the air-entrained beams showed less average camber and less midspan deflection, but the non-air-entrained beams withstood greater average flexural loads. A number of the auxiliary specimens were also tested in the laboratory to determine the strength, elastic, and plastic properties of the concrete. Some specimens were exposed to natural weathering. A few early results are noted. [ABSTRACT FROM AUTHOR]

Concretes made with water-reducing retarders showed improved freezethaw durability, primarily as a result of increased strength. Specimens made from constant slump, constant cement factor mixtures containing several agents at various dosage levels had higher flexural and compressive strengths than the control specimens. Flexural strengths at 7 and 28 days correlated significantly with durability factor. Microscopic studies indicated that there were minor differences between the air void systems of control and test concretes. In particular, spacing factors increased with retardation. This appeared to result from air entrainment by the water-reducing retarders and from bubble dissolution. [ABSTRACT FROM AUTHOR]

These specifications are a reference standard which the engineer or archi-tect may make applicable to any building project by citing them in the project specifications. Individual chapters or sections cannot be copied into project specifications since their meanings will be changed by taking them out of context. The specifications must be supplemented by designating or specifying individual project requirements. Four lists are provided listing places in these specifications and items that will require, or may require, specific treatment by the specification writer. The list of items requiring designation or specification are classed as: mandatory; additional mandatory, items designated or specified if the subject matter applies to the project; re-quirements at variance with these provisions; and requirements which are purely optional. [ABSTRACT FROM AUTHOR]

The durability and maintenance costs of concrete highway bridge decks are highly dependent upon the care exercised during the construction phase, including attendant activities during the preconstruction and postconstruction periods. Recommendations relatative to these periods are presented covering the areas of design considerations, inspection, preconstruction planning, falsework and formwork, reinforcement, concrete materials and properties, measuring and mixing, placing and consolidation, finishing, curing, postconstruction care, and the use of overlays. [ABSTRACT FROM AUTHOR]

Polymer latex modified mortars are portland cement mortars to which polymer latex emulsions have been added during mixing. Mechanical and durability properties of modified mortars, the ef-fects of curing history on modified mortars and latex films, and bond strength of modified mortar to plain mortar were studied. Significant improve-ments were observed in extensibility, bonding prop-erties, and durability of mortar. Hence, mortar modified by latex emulsion may be useful for sur-face coatings, pavement toppings, and patching of damaged concrete. Higher volume changes during wetting and drying, lower modulus of elasticity, and lower compressive strength were observed for modified mortars. Although continuous wet curing reduces the strength of modified mortars, subse-quent drying increases their strengths. For poly-vinyl acetate emulsions, this was partly explained by the performance of latex films in saturated lime solutions. [ABSTRACT FROM AUTHOR]

A logical framework is developed for the strength evaluation of existing concrete bridges. To establish estimates of the physical conditions of a structure, any distress present is taken into con-sideration by determining its cause and effect to date, and likely rate of progression. Using analyti-cal or analytical and experimental means, the strength of the structure can then be evaluated, and load ratings specified as a function of time. [ABSTRACT FROM AUTHOR]

Describes, with examples, two methods for selecting and adjusting proportions for normal weight concrete. One method is based on an estimated weight of the concrete per unit volume; the other is based on calculations of the absolute volume occupied by the concrete ingredients. The procedures take into consideration the requirements for placeability, consistency, strength, and durability. Example calculations are shown for both methods, including adjustments based on the characteristics of the first trial batch. [ABSTRACT FROM AUTHOR]

Quality of a concrete slab or floor is highly dependent on achieving a hard and durable surface which is plane and free of cracks. The properties that the surface has are determined by the quality of the concreting operations. Furthermore, timing of these concreting operations and finishing techniques is critical. Otherwise, undesirable changes occur at the wearing surface; these may lead to soft or dusting surfaces, permeable concrete, cracking, and poor durability. This recommended practice tells how to produce good quality floors and slabs for various classes of service, emphasizing such aspects of construction as site preparation, concreting materials, concrete mixture proportions, concreting, workmanship, and curing. Adequate supervision and inspection are required of all job operations including particularly those of finishing. [ABSTRACT FROM AUTHOR]

Describes the analysis, design, and construction of the variable depth floor slabs of the parking garage for the Chase Stone Center -- Colorado Springs, Colo. Column centers are 30 ft each way and columns are structural steel. A typical slab is cast in place 24 in. deep at the columns and 7 in. at the center lines of the square panels. The under-surface of the slab is a hyperbolic paraboloid with sections parallel to the center lines as straight lines in both directions which results in a "hypar slab." This system is easy to form and results in several other economies that make the system desirable for structures of this type. The elastic frame method was used for both the applied loads and for the effect of the prestressing forces. Calculations are described in detail. [ABSTRACT FROM AUTHOR]

An experimental investigation was carried out to determine the effects of different levels of compactive effort on the compressive strength, durability, and shrinkage of concrete over a range of workabilities. Results show that even when increase in water content alone is used to increase workability, at low levels of compactive effort comparable with those used in normal building construction, maximum strength may be achieved with high workability high water content concrete. [ABSTRACT FROM AUTHOR]

Quality of a concrete slab or floor is highly dependent on achieving a hard and durable surface which is plane and free of cracks. The properties that the surface has are determined by the quality of the concreting operations. Furthermore, timing of these concreting operations and finishing techniques is critical. Otherwise, undesirable changes occur at the wearing surface; these may lead to soft or dusting surfaces, permeable concrete, cracking, and poor durability. This recommended practice tells how to produce good quality floors and slabs for various classes of service, emphasizing such aspects of construction as site preparation, concreting materials, concrete mixture proportions, concreting, workmanship, and curing. Adequate supervision and inspection are required of all job operations including particularly those of finishing. [ABSTRACT FROM AUTHOR]

An experimental investigation was carried out to determine the resistance of popout formation in mortar. It was found that the required pressure to produce popouts on a concrete surface, from a spherically shaped particle near the surface, is directly proportional to the distance of the particle from the surface, and the tensile strength of the concrete, and inversely proportional to the size of the particle. [ABSTRACT FROM AUTHOR]

Test data covering improved, synthetically derived air-entraining admixtures for concrete are presented. The test data indicate that improved air-entraining admixtures can be formulated that overcome the loss in compressive strength usually associated with the incorporation of air into hydraulic cement mixes. Data comparing the most promising of the materials tested with two established commercial products are presented and show that the valuable compressive strength properties are retained even in the presence of grossly excessive amounts of admixture such as might inadvertently be used in the field. It is expected that products based on this new material will be generally available to the concrete industry in the near future. [ABSTRACT FROM AUTHOR]

A one-cycle freezing test, involving length measurements during freezing, is used in an attempt to establish limiting maximum water-cement ratios for concretes for different exposure conditions. Mortar prisms were cast from a series of mixes, (both air-entrained and non-air-entrained) covering a range of water-cement ratios from 0.40 to 0.70. After being moist cured for I month the prisms were then conditioned to various degrees of saturation (to simulate different exposure conditions) and subjected to the freezing test. Frost susceptibility of the various mixes was determined from the length change patterns produced in the freezing test. Critical degree of saturation was found to be approximately 90 percent. Air entrainment was found to provide protection up to a water-cement ratio of 0.58. [ABSTRACT FROM AUTHOR]

This guide summarizes the present state of the technology. It presents and interprets the data on lightweight aggregate concretes from many laboratory and field sources. These include the comprehensive studies at the University of Illinois in 1931, the parallel investigations by the U.S. Bureau of Reclamation and the National Bureau of Standards in 1949, numerous recent laboratory studies, accumulated experience resulting from greatly increased and successful use, and performance of structural lightweight aggregate concrete in service. The guide is intended for the architect, engineer, contractor, concrete producer, and student. It includes a definition of lightweight aggregate concrete for structural purposes; it discusses in condensed fashion the production methods and inherent properties of lightweight aggregates for structural concrete. This is followed by current practices on proportioning, mixing, transporting, placing; properties of hardened concrete; and finally, the design of structural concrete, with special reference to the 1963 ACI Building Code. [ABSTRACT FROM AUTHOR]

Two series of reinforced concrete beams were made and exposed to severe natural weathering at Treat Island, Maine. Variables under study were type of concrete, thickness of concrete cover over steel and tensile stress in the reinforcing steel, position of the steel, and type of steel used. Results after 15 winters of exposure of the first series of beams (Series A) indicated that the air-entrained beams were significantly more resistant to the weathering than the non-air-entrained beams, and that the beams with reinforcing steel having deformations conforming to ASTM Standard A 305 were more resistant to the weathering than those with reinforcing steel having old-style deforma-ions. These tests formed the basis for a change in Corps of Engineers practice in 1958 by which al-lowable steel stresses were increased from 18,000 to 20,000 psi (1260 to 1400 kg per sq cm). This change has resulted in a saving of cost in Corps of Engineers construction averaging $1.25 million per year since the change was made. Results after 12 winters of exposure of the second series of beams (Series B) indicated that more exposure is needed to produce deterioration sufficient to permit unambiguous conclusions. Exposure of both series of beams is continuing. [ABSTRACT FROM AUTHOR]

The resistance of concrete to chemical attack may often be enhanced or maximized by careful attention to concrete proportioning, mixing, placing, and curing procedures. However, in a number of situations concrete must be protected by barrier materials which prevent contact with the chemical agent. Materials available for protection have been classified here, and tables have been provided as a guide for protection against specific agents. Methods of application, with consideration for both effectiveness and safety, are discussed. The report is intended to serve as a guide prior to consultation with experts regarding the specific situation. [ABSTRACT FROM AUTHOR]

Recommendations are made for the design, manufacture, and erection of precast reinforced concrete floor and roof units having spans of 35 ft (II m) or less. Unit stress, ultimate strength, and a test method of strength design are recommended. Recommendations are made regarding bearing lengths, bar spacings, minimum reinforcement, and holes. Quality requirements and acceptance procedures are discussed. Prestressed concrete mem-bers are not covered in the report. [ABSTRACT FROM AUTHOR]

These specifications are a reference standard which the engineer or architect may make applicable to any building project by citing them in the project specifications. Individual chapters or sections should not be copied into project specifications since their meanings will be changed by taking them out of context. The specifications need to be supplemented by designating or specifying individual project requirements. Four lists are provided listing places in these specifications and items that will require, or may require, specific treatment by the specification writer. The list of items requiring designation or specification are classed as: mandatory; additional mandatory, items designated or specified if the subject matter applies to the project; requirements at variance with these provisions; and requirements which are purely optional. [ABSTRACT FROM AUTHOR]

Quality of a concrete slab or floor is highly dependent on achieving a hard and durable surface which is plane and free of cracks. The properties that the surface has are determined by the quality of the concreting operations. Furthermore, timing of these concreting operations and finishing techniques is critical. Otherwise, undesirable changes occur at the wearing surface; these may lead to soft or dusting surfaces, permeable concrete, cracking, and poor durability. To obtain a good floor, the project specifications must cover all aspects of site preparation, concreting materials, concrete mixture proportions, concreting, workmanship, and curing. Adequate supervision and inspection are required of all job operations including particularly those of finishing. [ABSTRACT FROM AUTHOR]

Set retarded concrete placed in a bridge deck and finished with conventional equipment exhibited a severe surface deterioration in the form of flaking several days after paving. Similar concrete placed in the approach slab on a granular subgrade did not flake. Laboratory and field investigations showed that the flaking was due to the formation of a weak plane immediately below the surface of the concrete and was closely connected with the bleeding characteristics of the mix. The solution was found in reducing the bleeding rate of the concrete by a change in the type of set retarding admixture. [ABSTRACT FROM AUTHOR]

Chemical and physical changes occurring in cotton cellulose when it is finished with N-methylol agents under varying degrees of cure are discussed. Resistance to acidic hydrolysis of the finish has been found to be an excellent method for establishing the degree of cure of a finish. Factors discussed include time and temperature of cure, reactant to catalyst ratio, type of catalyst, reactivity of the agent enhanced by the leaving group effect, functionality of the reactant, processing conditions, acid-base control, fabric weight, and fabric type, i.e., cotton and cotton-polyester fabrics. [ABSTRACT FROM PUBLISHER]

A new flame-retardant finish utilizing tris(hydroxymethyl)phosphine (THP), trimethylolmelamine (TMM), one and a half methylolurea (11/2 MU), and a mixed catalyst (MgCl2.6H 2O-citric acid) has been developed. The process con sisted of padding cotton fabrics through an aqueous solution containing 14.3% THP, 13.35% 11/2 MU, 4.45% TMM, 1% mixed catalyst, and 1% wetting agent.Sateen padded with 28% solids level solutions (exclusive of wetting agent and catalyst) and printcloth padded with 32% solids level solutions passed the vertical flame test after 50 launderings. Treated fabrics had good hand and appear ance. Losses in breaking strength were approximately 10% and tearing strength losses were of the same order of magni tude for wash-wear fabric. [ABSTRACT FROM PUBLISHER]

That washing causes fabrics to wear is an obvious fact. But "wear" is a general term which does not in itself provide much information. This paper reports the results of a study of the effects of repeated launderings on various physical properties of a variety of fabrics. Tests, which were performed both on open width fabrics and simulated cuffs, help to indicate how the fabric is degraded by repeated washing. [ABSTRACT FROM AUTHOR]

Bleeding can have far-reaching effects on the properties of concrete and it Is a phenomenon which has too often been ignored. This paper briefly discusses some of its important consequences with particular emphasis on tensile strength and deformational behavior, and suggests a method by which effects of bleeding on the internal structure of concrete may be studied. [ABSTRACT FROM AUTHOR]

These specifications are a reference standard which the engineer or architect may make applicable to any building project by citing them in the project specifications. Individual chapters or sections should not be copied into project specifications since their meanings will be changed by taking them out of context. The specifications need to be supplemented by designating or specifying individual project requirements. Four lists are provided listing places in these specifications and items that will require, or may require, specific treatment by the specification writer. The list of items requiring designation or specification are classed as: mandatory; additional mandatory, items designated or specified if the subject matter applies to the project; requirements at variance with these provisions; and requirements which are purely optional. [ABSTRACT FROM AUTHOR]

Quality of a concrete slab or floor is highly dependent on achieving a hard and durable surface which is plane and free of cracks. The properties that the surface has are determined by the quality of the concreting operations. Furthermore, timing of these concreting op-erations and finishing techniques is critical. Otherwise, undesirable changes occur at the wearing surface; these may lead to soft or dusting surfaces, permeable con-crete, cracking, and poor durability. This recommended practice tells how to produce good quality floors and slabs for various classes of service, emphasizing such aspects of construction as site preparation, concreting materials, concrete mixture proportions, concreting, workmanship, and curing. Adequate supervision and inspection are required of all job operations including particularly those of finishing. [ABSTRACT FROM AUTHOR]

Describes, with examples, two methods for selecting and adjusting proportions for normal weight concrete. One method is based on an estimated weight of the concrete per unit volume; the other is based on calculations of the absolute volume occupied by the concrete ingredients. The procedures take into consideration the requirements for placeability, consistency, strength, and durability. Example calcu-lations are shown for both methods, including adjustments based on the character-istics of the first trial batch. [ABSTRACT FROM AUTHOR]

Recommendations are made for the design, manufacture, and erection of precast reinforced concrete floor and roof units having spans of 35 ft (II m) or less. Unit stress, ultimate strength, and a test method of strength design are recommended. Recommendations are made regarding bearing lengths, bar spacings, minimum reinforcement, and holes. Quality requirements and acceptance procedures are discussed. Prestressed concrete members are not covered in the report. [ABSTRACT FROM AUTHOR]

This proposed standard is intended as a supplement to ACI Standard "Recommended Practice for Selecting Proportions for Concrete (ACI 613- 54)." The standard describes a procedure for proportioning concretes having slumps in the range of zero to I in. and consistencies below this range, for aggregates up to 11f2 in. maximum size. Suitable equipment for measuring such consistencies is described. Tables similar to those in ACI 613- 54 are provided which, along with laboratory tests on physical properties of fine and coarse aggregate, yield information for obtaining concrete proportions for a trial mixture. Examples of the use o·f these tables, in conjunction with tables in ACI 613-54, are given. [ABSTRACT FROM AUTHOR]