XI, A, 1 Kiyig: Pozzuolanic Properties of Meycauayan Tuff 



21 



PRELIMINARY WORK 



For the purpose of ascertaining whether or not the Tayawanak 

 tuff possessed any hydraulic properties, the fragments remaining 

 after the compression test were dried in the sun, reduced in a 

 crusher, and ground in a ball mill until 100 per cent passed 

 through a sieve having an average of 22,500 meshes per square 

 inch. Dry slaked lime, containing 96.98 per cent calcium 

 hydroxide, and the pulverized tuff were mixed in equal parts 

 by weight. The lime had the same fineness as the tuff. The 

 resulting mixture, after being tempered with water in the usual 

 way and allowed to harden, was tested for compressive and 

 tensile strengths and setting time. In the test pieces 27 per 

 cent of water was used. After two days in moist air the speci- 

 mens were stored in water until broken. 



The approximate setting time was determined by the Gilmore 

 needle. 



In Table II are tabulated the results obtained. 



Table II. — Tensile strengths of briquettes and compressive strengths of 

 2-inch cubes made from tuff fragments.^ 



TENSILE STRENGTH OP BRIQUETTES. 





Kilo- 

 grams 



per 

 square 

 centi- 

 meters. 



Pounds 



per 

 square 

 inch. 



7 days neat (2 days in moist air, 5 days in water) _-. .. _ 



11.60 

 17.58 

 18.71 

 9.98 

 2L45 

 26.72 



165 

 250 

 266 

 142 

 305 

 380 





180 days neat (2 days in moist air, 178 days in water) 





90 days mortar (2 days in moist air)!) . 



180 days mortar (2 days in moist air)b 





COMPRESSIVE STRENGTH OF 2-INCH CUBES. 





Kilo- 

 grams 



per 

 square 



centi- 

 meter. 



Pounds 



per 

 square 

 inch. 





71.52 



78.69 



218.28 



268.42 



1017 

 1119 

 3104 

 3817 



28 days neat (2 days in moist air) 









■ Initial setting time, 23 hours. 



* Briquettes were made from one part by weight of the tuff -lime mixture and three parts 

 by weight of standard Ottawa sand. 



