AASHTO HB-17 DIVISION II SEC 15-2002 Division II Construction - Concrete Block and Brick Masonry《混凝土砌块和砖砌体》.pdf

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1、Section 15 CONCRETE BLOCK AND BRICK MASONRY 15.1 DESCRIPTION Concrete block and brick masonry shall consist of con- crete blocks or brick laid in cement mortar and may be un- reinforced or reinforced with steel reinforcing. Block or brick pavements are not included under this designation. 15.2 MATER

2、IALS 15.2.1 Concrete Block Unless otherwise specified in the special provisions or approved in writing by the Engineer, all concrete block for masonry construction shall be Type I moisture controlled units (Grade N-I) that meet the requirements of ASTM C 90. The value off,!, shall be as shown on the

3、 plans or as specified in the special provisions. Concrete block units should be protected from rain, snow, or other moisture during storage on or off the job site to assure that they will meet the Type I moisture re- quirements at the time they are placed in the construction. 15.2.2 Brick Brick for

4、 masonry construction shall conform to the Specification for Building Brick (solid masonry units made from clay or shale) AASHTO M 114 (ASTM C 62), Concrete Building Brick (ASTM 55), or Solid Load-Bear- ing Concrete Masonry Units (ASTM 145). The type and grade of brick to be furnished shall be as sh

5、own on the plans or as specified in the special provisions. The bricks shall have a fine-grained uniform, and dense structure, free from lumps of lime, laminations, cracks, checks, soluble salts, or other defects which may in any way impair their strength, durability, appearance, or usefulness for t

6、he purpose intended. Bricks shall emit a clear, metallic ring when struck with a hammer. 15.2.3 Reinforcing Steel Reinforcing steel used in the construction of concrete block or brick masonry structures shall conform to the re- quirements for uncoated reinforcing in Section 9, “Rein- forcing Steel.”

7、 15.2.4 Mortar Mortar used shall conform, as regards materials, pro- portions and mixing, to the mortar specified in Articles 14.2.3 and 14.4.2. 15.2.5 Grout Grout for filling voids in hollow masonry units shall ei- ther conform to the requirements of ASTM C 476 or to the requirements of the followi

8、ng paragraph. As an alternative to the requirements of ASTM C 476, the materials for grout shall conform to the requirements of Section 8, “Concrete Structures,” for cement, aggre- gates, water and admixtures and to the requirements of Ar- ticle 14.2.3 for lime. Coarse aggregate shall be of either %

9、- inch or %-inch maximum gradation. For fine grout, if proportioned by volume, the cementitious materials shall consist of one part Portland cement to no more than %O part hydrated lime or lime putty and the aggregates shall con- sist of sand in the amount of 21/4 to 3 times the total volume of ceme

10、ntitious materials. For coarse grout, the propor- tions shall be the same as for fine grout except that coarse aggregate in the amount of 1 to 2 times the total volume of cementitious materials shall be added. If proportioned by weight, the weights used shall be equivalent to those which would be ob

11、tained by volumetric methods. Adjustments in mix proportions, within the limits al- lowed, shall be made as necessary to satisfy workability and strength requirements. Admixtures shall be used only when specified or ap- proved by the Engineer. 15.2.6 Sampling and Testing 15.2.6.1 Mortar Unless other

12、wise specified in the special provisions, mortar shall have a minimum 28-day compressive 603 604 HIGHWAY BRIDGES 15.2.6.1 strength of 1,800 psi based on the average of three spec- imens tested in accordance with the requirements of ASTM C 780. Field samples shall be obtained as follows: (a) Spread Y

13、2 inch or the thickness of the mortar joint of mortar on masonry units. (b) After 1 minute remove mortar and compress into 2 x 4 inch cylinder in two layers using flat end of a rod or fingers, being sure to see that mold is solidly filled. (c) Lightly tap cylinder immediately and maintain in damp co

14、ndition. (d) After 48 hours remove mold and store in fog room until testing. 15.2.6.2 Grout When required by the special provision or requested by the Engineer, the Contractor shall manufacture grout prisms for testing. Prisms shall be manufactured at the site during construction using the following

15、 procedure: (a) Place masonry units, having same moisture condi- tion as those being placed, on nonabsorptive base to form a void for a square prism with a height twice the side and a minimum side of 3 inches. (b) Line the side faces of the prism with permeable paper or porous separator to allow wat

16、er passage through liner into masonry units. (c) Fill prism with a fully representative grout sample in two layers. Puddle each layer to eliminate air voids. (d) Level off specimen and maintain in a damp condi- tion. (e) Remove prisms from masonry units after 48 hours and deliver to Engineer. Grout

17、prisms will be tested in accordance with the pro- visions of ASTM C 39. Grout shall have attained a com- pressive strength of 2,000 psi at 28 days unless otherwise specified in the special provisions. 15.3 CONSTRUCTION 15.3.1 Weather Conditions Block or brick masonry shall not be constructed in free

18、zing weather or when the block or brick contains frost, except by written permission of the Engineer and subject to such conditions as he or she may require. “shove-joint method; “buttered” or plastered joints will not be permitted. All clay or shale brick must be thor- oughly saturated with water b

19、efore being laid. Dampen- ing of concrete masonry units before or during construc- tion shall not be permitted unless approved by the Engineer. The arrangement of headers and stretchers shall be such as will thoroughly bond the mass and, unless oth- erwise specified, work shall be of alternate heade

20、rs and stretchers with consecutive courses breaking joints. Other types of bonding, as for ornamental work, shall be as specified on the plans. All joints shall be completely filled with mortar. They shall not be less than Y4 inch and not more than 5/s inch in thickness and the thickness shall be un

21、iform throughout. All joints shall be finished properly as the work progresses and on exposed faces they shall be neatly struck, using the “weather” joint. No spalls or bats shall be used except for shaping around irregular openings or when unavoidable to finish out a course, in which case full bric

22、ks shall be placed at the corners, the bats being placed in the interior of the course. Each masonry unit shall be adjusted to its final position while mortar is still soft and plastic. Units which are dis- turbed after mortar has stiffened shall be removed and re- layed in fresh mortar. Vertical ce

23、lls to be filled with grout shall be aligned to provide a continuous unobstructed opening. Piers and walls may be built of solid brick work, or may consist of a brick or block shell backed with concrete or other suitable material as specified on the plans. All details of the construction shall be in

24、 accor- dance with approved practice and to the satisfaction of the Engineer. 15.3.3 Placement of Reinforcement Prior to and during grouting the reinforcing steel shall be securely held in position at the top and bottom and at intermediate points not exceeding 200 bar diameters or 10 feet apart. Bar

25、s shall be maintained clear of the cell walls and within plus or minus Y2 inch of their planned position transverse to the wall and within plus or minus 2 inches of their planned position longitudinal to the wall. 15.3.4 Grouting of Voids 15.3.2 Laying Block and Brick The blocks or bricks shall be l

26、aid in such manner as will thoroughly bond them into the mortar by means of the Grouted masonry shall be constructed in such a man- ner that all elements of the masonry act together as a struc- tural element. 15.3.4 DIVISION II-CONSTRUCTION 605 Prior to grouting, the grout space shall be clean so th

27、at all spaces to be filled with grout do not contain mortar pro- jections greater than 5 inch, mortar droppings or other foreign material. Grout shall be placed so that all spaces to be grouted do not contain voids. Grout materials and water content shall be controlled to provide adequate fluidity f

28、or placement, without segre- gation. Size and height limitations of the grout space or cell on the average shall not be less than shown in Table 15.1. Higher grout pours or smaller cavity widths or cell size than shown in Table 15.1 may be used when approved by the Engineer, if it is demonstrated th

29、at grout spaces are properly filled. When required by Table 15.1, cleanouts shall be pro- vided in the bottom course at every vertical bar but shall not be spaced more than 32 inches on center for solidly grouted masonry. Cleanouts shall be of sufficient size to allow removal of debris. Units may be

30、 laid to the full height of the grout pour and grout shall be placed in a continuous pour in grout lifts not exceeding 6 feet. If construction joints are used in columns of grout, they shall be located at least 1% inches below the level of a mortar bed joint. Segregation of the grout materials and d

31、amage to the masonry shall be avoided during the grouting process. Grout shall be consolidated before loss of plasticity in a manner to fill the grout space. Grout pours greater than 12 inches in height shall be mechanically reconsolidated to minimize voids due to water loss. Grout not mechani- call

32、y vibrated shall be puddled. In nonstructurai elements, mortar of pouring con- sistency may be substituted for grout when the masonry is constructed and grouted in pours of 12 inches or less. Vertical barriers of masonry may be built across the grout space. The grouting of any section of wall betwee

33、n barriers shall be completed in 1 day with no interruption longer than 1 hour. 15.3.5 Copings, Bridge Seats, and Backwalls The tops of retaining walls, abutment wingwalls, and similarly exposed brick or block work shall be provided, in general, with either a stone or concrete coping. The un- dersid

34、e of the coping shall have a batter or drip bead, at least 1 inch beyond the face of the block or brick work wall. The coping upon an abutment backwall will com- monly have no projection beyond its bridge seat face. When concrete is used, it shall conform to the require- ments for Class A concrete s

35、pecified in Section 8, “Con- crete Structures.” For thin copings, mortar of the same proportions as used for laying the block or brick may be used to produce precast sections not less than 3 feet nor more than 5 feet in length. No coping shall be less than 4 inches thick. Copings of piers and abutme

36、nt bridge seats shall be of Ashlar stone work or of Class A concrete and shall con- form to the requirements for “Ashlar Masonry” specified in Section 14, “Stone Masonry,” or for concrete as speci- fied in Section 8, “Concrete Structures,” as the plans may TABLE 15.1 Grouting Limitations Least Clear

37、 Dimensions Grout Pour Width of Cell Maximum Height Grout Space Dimensions Cleanouts Grout Qpe (feet) (in.) (in. x in.) Required3 Fine 1 314 1-112 x 2 No Fine 5 1-112 1-112 x 2 No Fine 8 1-112 1-112 x 3 Yes Fine 12 1-1/2 1-314 x 3 Yes Fine 24 2 3x3 Yes Coarse Coarse Coarse Coarse Coarse 1 5 8 12 24

38、1-112 2 2 2-112 3 1-112 x 3 2-112 x 3 3x3 3x3 3x4 No No Yes Yes Yes The clear dimension is the cell or grout space width less mortar projects. Groutspace width shall be increased by the horizontal projection of the diameters of the horizontal bars within the cross section of the grout space. Cleanou

39、ts may be omitted if approved provisions are made to keep the grout space clean prior to grouting. 606 HIGHWAY BRIDGES 15.3.5 indicate. Unless otherwise shown on the plans, concrete shall be used. 15.4 MEASUREMENT AND PAYMENT Concrete block and brick masonry will be measured by the number of cubic y

40、ards or the number of square feet of the type of masonry actually placed in the structure in ac- cordance with the plans or as modified by written instruc- tions from the Engineer. The units of measure for the var- ious types of masonry shall be as listed in the schedule of bid items. Concrete block

41、 and stone masonry, as measured above, will be paid for by the contract price per cubic yard or square foot. Such payment shall be considered to be full compensation for the cost of all labor, equipment, materi- als, and other expenses incidental to the satisfactory com- pletion of the work. Filling material for the interior of the wall, reinforcing steel, and concrete or mortar copings, shall be considered as included in the price paid for num- ber of cubic yards or square feet of block or brick masonry actually placed.