§ 143-23. Plain and reinforced concrete.

A. 

General. Concrete used on any type of construction shall be as specified on the final plans approved by the Board. Materials used shall conform with Section 700 of the New York State Department of Transportation Standard Specifications.

B. 

Mixing, placing and testing concrete. Mixing, placing and testing of concrete shall conform with the latest edition of the New York State Department of Transportation Standard Specifications.

C. 

Quality of concrete.

(1) 

Class of concrete. Concrete installed in various structures or units shall be one of the three classes defined in the following subsections. The class to be installed shall be as specified in the subdivision final approval.

(a) 

Class I: 4,000 pounds per square inch at 28 days.

(b) 

Class II: 3,000 pounds per square inch at 28 days.

(c) 

Class III: 2,500 pounds per square inch at 28 days.

(2) 

Water-cement ratio.

(a) 

All concrete shall be proportioned on the basis of the "water-cement ratio," which is defined as the ratio of the total quantity of water in the mixture, including the surface water carried by the aggregate, to the quantity of cement. The ratio is expressed in United States gallons, eight and one-third (8 1/3) pounds to the gallon, per ninety-four-pound sack of cement.

(b) 

Concrete that is subject to freezing temperatures while wet shall have a water-cement ratio not exceeding six gallons per bag and shall contain entrained air.

(3) 

Concrete proportions and consistency.

(a) 

The proportions of the concrete shall produce a mixture that will work readily, with the placement method used, into the corners and angles of the forms and around reinforcement. Neither segregation of materials in the mixture nor the collection of excess free water on the surface shall be permitted.

(b) 

The slump of concrete shall be the minimum that is practicable. When vibrators are used to consolidate the concrete, the slump shall not exceed four inches, otherwise the slump shall not exceed six inches.

(c) 

The methods of measuring the concrete materials shall be such that the proportions can be accurately controlled and easily checked. Measurement of materials for ready-mixed concrete shall conform to Specifications for Ready-Mixed Concrete (ASTM C94).

D. 

Tests on concrete.

(1) 

Sampling. As the work progresses, concrete shall be sampled in accordance with the American Society for Testing and Materials Method of Sampling Fresh Concrete (ASTM C172).

(2) 

Slump test. Slump tests shall be made according to American Society for Testing and Materials Method of Test for Slump of Portland Cement Concrete (ASTM C143).

(3) 

Compression test.

(a) 

Compression test specimens shall be made and cured according to American Society for Testing and Materials Method of Making and Curing Concrete Compression and Flexture Test Specimens in the Field (ASTM C31). Not fewer than three specimens shall be made for each test at each age nor less than one test for each 150 cubic yard of concrete of each class. At least one test per day shall be made of each class of concrete used that day.

(b) 

Specimens shall be taken by the owner or his representative under the direction of the Town and the tests made by a laboratory approved by the Town. The cost of transportation to the laboratory and of testing the concrete cylinders shall be borne by the owner. The owner shall furnish two copies of all test results to the Town.

(c) 

Additional specimens cured under job conditions may be required when, in the opinion of the Town, there is a possibility of the surrounding air temperature falling below 40º F. or rising above 90º F.

(d) 

The standard age of test specimens shall be 28 days, but seven-day specimens may be used, provided that the relationship between the seven- and twenty-eight-day strengths of the concrete is established by test for the materials and proportions used.

(e) 

If, after testing, the average strength of test cylinders is found to be more than 10% below the required strength, the Town may elect either to permit such concrete to remain in place and require the owner to forfeit from his performance bond an amount agreeable to both the owner and the Town or require the owner, at his own expense, to remove the concrete area deficient in the specified strength and replace it with concrete of satisfactory quality.

E. 

Mixing and placing concrete.

(1) 

Preparation of equipment and place of deposit.

(a) 

Before placement, all equipment for mixing and transporting the concrete shall be cleaned and all debris and ice shall be removed from the places to be occupied by the concrete. Forms and subbase shall be thoroughly wetted (except in freezing weather) or oiled. The reinforcement shall be thoroughly cleaned of ice, dirt, rust, scale or other coatings.

(b) 

Standing water shall be removed from the place of deposit before concrete is placed unless otherwise permitted by the Town. All laitance and other unsound materials shall be removed from hardened concrete before additional concrete is added.

(2) 

Mixing of concrete.

(a) 

For job-mixed concrete, the mixer shall be rotated at a speed recommended by the manufacturer. Each batch of one cubic yard or less shall be mixed for at least one minute after all materials are in the mixer. The mixing time shall be increased 15 seconds for each additional cubic yard or part thereof. The entire batch shall be discharged before the mixer is recharged.

(b) 

Ready-mixed concrete shall be mixed and delivered in accordance with Specifications for Ready-Mixed Concrete (ASTM C94).

(3) 

Conveying of concrete.

(a) 

Concrete shall be conveyed from the mixer to the place of final deposit by methods that will prevent separation or loss of materials.

(b) 

Equipment for chuting, pumping and pneumatically conveying concrete shall be of such size and design as to achieve a practically continuous flow of concrete at the delivery and without separation of materials.

(4) 

Placing of concrete.

(a) 

Concrete shall be deposited as nearly as practicable in its final position to avoid segregation due to rehandling or flowing. The placing of concrete shall be carried on at such rate that concrete is at all times plastic and flows readily into the spaces between the bars. No concrete that has partially hardened or been contaminated by foreign material shall be deposited on the work, nor shall retempered concrete be used.

(b) 

When concreting is once started, it shall be carried on as a continuous operation until concreting of the panel or section is completed. When construction joints are necessary, they shall be made in accordance with accepted practice or as approved by the Board.

(c) 

All concrete shall be thoroughly consolidated by suitable means during placement. It shall be thoroughly worked around reinforcement and embedded fixtures and into the corners of the forms. Tools used shall be such that they will not cause segregation of aggregates.

(5) 

Curing of concrete. Provisions shall be made for maintaining concrete in a moist condition for a period of at least five days after placement. For high-early-strength concretes, however, moist curing shall be provided for at least the first two days when concrete and air temperatures are above 50º F.; longer periods of curing shall be required when temperatures are below 50º F.

(6) 

Cold-weather concreting.

(a) 

Adequate equipment shall be provided for heating concrete materials and protecting concrete during freezing or near-freezing weather. No frozen materials or materials containing snow or ice shall be used in the concrete.

(b) 

All reinforcement, forms, fillers and ground with which the concrete is to come in contact shall be free from snow and ice. Whenever the temperature of the surrounding air is below 40º F., all concrete placed in the forms shall have a temperature of 45º F. or higher after placement.

(c) 

Adequate means shall be provided for maintaining this temperature for four days. When high-early-strength concrete is used, a temperature of 45º F. shall be maintained for three days. In either case, any additional time necessary to ensure proper curing of the concrete shall be provided as directed by the Town.

(d) 

The housing, covering or other protections used in connection with curing shall remain in place and intact at least 24 hours after the artificial heating is discontinued. No dependence shall be placed on salt or other chemicals for the prevention of freezing.

(7) 

Hot-weather concreting.

(a) 

In hot weather, suitable precautions shall be taken to avoid drying of the concrete prior to finishing operations. Use of windbreaks, sunshades, fog sprays or other devices shall be provided as directed by the Town.

(b) 

Concrete deposited in hot weather shall not have a placing temperature that will cause difficulty from loss of slump, flash set or cold joints. Concrete temperatures shall be less than 90º F.

(8) 

Forms.

(a) 

Forms shall conform to shapes, lines and dimensions of the members as called for in the subdivision final submission and shall be sufficiently tight to prevent leakage of mortar. They shall be properly braced or tied together so as to maintain position and shape.

(b) 

Forms shall be removed in such a manner as to ensure the complete safety of the structure. Where the structure is supported on shores, the removable floor forms, beams and girder sides and column and similar vertical forms may be removed after 24 hours, provided that the concrete is sufficiently hard. In no case shall the supporting forms or shoring be removed until members have acquired sufficient strength to support their weight and imposed loads safely.

(9) 

Placing and splicing of reinforcements. The reinforcement shall be protected by the thickness of the concrete indicated in the subdivision final approval. Where not otherwise shown, the thickness of concrete over the reinforcement shall be as follows:

(a) 

Where concrete is deposited against the ground without the use of forms: not less than three inches.

(b) 

Where concrete is exposed to the weather or to the ground but placed in forms: not less than two inches for bars larger than No. 5 and 1 1/2 inches for No. 5 bars or smaller.

(c) 

In slabs and walls not exposed to the ground or to the weather: not less than three-fourths (3/4) inch.

(d) 

In beams, girders and columns not exposed to the ground or to the weather: not less than one and one-half (1 1/2) inches.

(e) 

In all cases: at least equal to the diameter of bars or 1 1/2 times the side dimension of a square bar.

Amended 5-1-1995 by L.L. No. 2-1995