XI. A. 5 



Witt: Philippine Paving-brick Materials 



213 



Table IV. — Porosity of clays at various cones.' 



[Numbers give percentages.] 



Clay No. 



Porosity at cone No.— 



010. 



09. 



08.' 



07. 



06. 



05. 



04. 



03. 



02. 



01. 



1 

 1. 



1 



2 



5 



35.04 

 36.87 



21.25 

 36.15 



36.20 

 35.88 



35.84 



32.67 





35.36 

 31.25 





27.85 

 31.56 



19.10 

 28.41 



29.02 

 28.41 

 18.32 







19.49 

 35.92 





18.89 

 34.22 



20.76 

 29.33 



9 













Clay No. 



Porosity at cone No. — 



2. 



3. 



4. 



5. 



6. 



7. 



8. 



9. 



11. 



1 

 13. 



1 







3.13 

 10.91 



27.68 







10.96 

 17.71 





18.24 

 24.41 



15.22 b 





2 













5 





17.72 



13.77 



27.11 









9 



28.21 



26.7.'; 



1.97 



8.97 





















1 



' Clays not given here did not show burning qualities suitable for these data. 



" Specimen very soft at cone 11. 



' Commences to soften at cone 7 ; fuses at cone 0. 



" Cracks to pieces at cone 7. 



« Commences to vitrify at cone 9. 



DISCUSSION OF RESULTS OF PHYSICAL TESTS 



The behavior of the clays in all the tests except porosity is 

 as follows. All comments are based on the behavior of the 

 small test bricks and pats. It is planned to carry on tests on 

 full-size bricks made from all clays which show any promise as 

 paving-brick material. 



No. 1. This clay is one of the most favorable of those which 

 have been tested in this laboratory. It is easily molded 

 and dries without cracking or excessive shrinkage or distortion. 

 When placed in the kiln, all of the specimens from cone 010 

 to cone 11 are in good condition. It commences to vitrify 

 at about cone 4 and does not begin to soften until cone 11 is 

 reached. Two test bricks burned at cone 4 showed a crushing 

 strength of 880 kilograms per square centimeter. The clay burns 

 to a medium dark red up to the point of vitrification and then 

 becomes a dark brown. The raw clay briquettes show a strength 

 of 24.2 kilograms per square centimeter. 



No. 2. This material should produce good building brick 

 under the proper conditions of molding and firing, although 

 higher in water of plasticity and drying shrinkage than clay 1. 

 It dries well without cracks or distortion. The test bricks are 

 a dark red until vitrification begins, then become almost black. 

 It is likely that this clay would cause trouble in a large kiln, 



