Concrete Materials CIVL

Transcription

1 Concrete Materials CIVL

2 Concrete Ingredients Portland Cement Water Fine Aggregate Coarse Aggregate Supplementary Cementitious Materials Chemical Admixtures CIVL

3 Important Aggregate Properties Crushing strength Deleterious substances Shape and texture Hardness Soundness Chemical stability Gradation / Fineness Modulus Relative density and absorption Dry-rodded unit weight CIVL

4 Important Aggregate Properties Crushing strength Deleterious substances Shape and texture Hardness Soundness Chemical stability Gradation / Fineness Modulus Relative density and absorption Dry-rodded unit weight CIVL

5 Important Aggregate Properties Crushing strength Deleterious substances Shape and texture Hardness Soundness Chemical stability Gradation / Fineness Modulus Relative density and absorption Dry-rodded unit weight CIVL

6 Deleterious Substances Organic Coatings Dust Coatings Soft Particles Lightweight Particles (e.g., coal) Friable Particles (e.g., shale) Clay Lumps Reactive Particles CIVL

7 Important Aggregate Properties Crushing strength Deleterious substances Shape and texture Hardness Soundness Chemical stability Gradation / Fineness Modulus Relative density and absorption Dry-rodded unit weight CIVL

8 Particle Shape Source: CIVL

9 Important Aggregate Properties Crushing strength Deleterious substances Shape and texture Hardness Soundness Chemical stability Gradation / Fineness Modulus Relative density and absorption Dry-rodded unit weight CIVL

10 Important Aggregate Properties Crushing strength Deleterious substances Shape and texture Hardness Soundness Chemical stability Gradation / Fineness Modulus Relative density and absorption Dry-rodded unit weight CIVL

11 Soundness (Resistance to Weathering) Resistance to Wetting/Drying Resistance to Freezing/Thawing Resistance to Heating/Cooling CIVL

12 Freeze-Thaw Problems Popouts D Cracking CIVL

13 Specifications TDOT Specs for Concrete Coarse Aggregate Dust Shape Clay Lumps Lightweight Hardness Soundness Material Passing No. 200 Sieve < 1% Flat and Elongated Particles (5:1) < 10% Clay Lumps < 0.25% Coal and Lignite < 1% L.A. Abrasion Loss < 40% Sodium Soundness Loss < 9% CIVL

14 Important Aggregate Properties Crushing strength Deleterious substances Shape and texture Hardness Soundness Chemical stability Gradation / Fineness Modulus Relative density and absorption Dry-rodded unit weight CIVL

15 Reactive Aggregate (ASR) Map Cracking CIVL

16 What is ASR? Na + OH Na + OH K + K + Na + Ca ++ Ca ++ OH K + CIVL

17 What is ASR? Na + OH Na + OH K + K + Na + Ca ++ Ca ++ OH K + Hydroxl ions are attracted to the reactive silica CIVL

18 What is ASR? Na + Na + K + K + Na + Ca ++ Ca ++ K + C-N-S-H and C-K-S-H gel forms from alkali in the cement CIVL

19 What is ASR? H 2 O H 2 O H 2 O H 2 O Ca ++ Ca ++ H 2 O C-N-S-H and C-K-S-H gel attracts water CIVL

20 ASR Requirements Reactive Silica Sufficient Alkali Sufficient Moisture CIVL

21 Important Aggregate Properties Crushing strength Deleterious substances Shape and surface texture Hardness Soundness / Durability Chemical stability Gradation / Fineness Modulus Relative density and absorption Dry-rodded unit weight CIVL

22 Coarse Aggregate TDOT Specs for Concrete Coarse Aggregate Application Size No. Concrete Pavement 467 Concrete Base Course 467 Cement Treated Base Course 57 Structural Concrete 57 Prestressed Concrete 57 or 67 Precast Concrete 57 or 67 CIVL

23 Coarse Aggregate TDOT Specs for Concrete Coarse Aggregate Application Size NMAS No. Concrete Pavement 467 2" Concrete Base Course 467 2" Cement Treated Base Course 1½" 57 Structural Concrete 1½" 57 Prestressed Concrete 1½" 57 or 67 1" Precast Concrete 1½" 57 or 67 1" CIVL

24 Coarse Aggregate NMAS depth of slab 3 NMAS narrowest dimension 5 3 NMAS clear space 4 CIVL

25 Fine Aggregate Source: Design and Control of Concrete Mixtures (PCA, 2007)

26 ASTM C-33 Sand 100 1½" ¾" 3 / 8 " Percent Passing Coarse Sand Fine Sand Opening Size (mm) CIVL

27 Fineness Modulus Fineness modulus (n.) an index of the coarseness or fineness of an aggregate; it is computed as the sum of the fraction retained on each full series sieve starting from the No. 100 sieve. CIVL

28 Gradation Example FM 3.72 CIVL

29 Fineness Modulus 100 1½" ¾" 3 / 8 " Percent Passing FM Opening Size (mm) CIVL

30 Fineness Modulus 100 1½" ¾" 3 / 8 " Percent Passing FM Opening Size (mm) CIVL

31 Fineness Modulus 100 1½" ¾" 3 / 8 " Percent Passing FM 2.74 FM Opening Size (mm) CIVL

32 ASTM C-33 Sand 100 1½" ¾" 3 / 8 " Percent Passing Coarse Sand Fine Sand Opening Size (mm) CIVL

33 ASTM C-33 Coarse Sand 100 1½" ¾" 3 / 8 " Percent Passing Coarse Sand FM Opening Size (mm) CIVL

34 ASTM C-33 Fine Sand Percent Passing ½" ¾" 3 / 8 " Fine Sand FM Opening Size (mm) CIVL

35 Important Aggregate Properties Crushing strength Deleterious substances Shape and texture Hardness Soundness Chemical stability Gradation / Fineness Modulus Relative density and absorption Dry-rodded unit weight CIVL