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KANSAS ACADEMY OF SCIENCE. 



sand containing various proportions, from two to twenty per cent., of 

 clay or loam. 



The cement experimented with was the lola brand of Portland 

 cement, a cement much used in engineering construction in this part 

 of the country. The sand used was the standard Ottawa sand adopted 

 for cement testing by the American Society of Civil Engineers. The 

 clay was the ordinary reddish clay commonly found on the hillsides 

 west of the University campus and the loam was from the top soil of 

 a corn-field. 



In making the mortar briquettes for testing, the proportion of one 

 part of cement to three parts of sand was used. When clay or loam 

 was added, it was taken as a certain percentage of the sand, and thus 

 the ratio of cement to sand, or of cement to clay or loam and sand, 

 was maintained constant. All proportions were by weight. 



At the end of three, seven, twenty-eight and ninety days sets of 

 briquettes of the various proportions of clay and loam were broken in 

 a late model Falkenau-Sinclair automatic cement-testing machine. 

 The results for the clay mixtures are given in table 1 and shown 

 graphically in diagram 1, while those for the loam mixtures are 

 shown in table 2 and diagram 2. Each set consisted of six briquettes, 

 the mean of the three strongest briquettes in each set being taken. 

 Each number in the tables and each point in the diagrams represents 

 one set. The small discrepancy between the results in the two col- 

 umns headed "0 %" in the two tables is due to slight differences in 

 manipulation by the two operators. 



Table 1.— Showing strength of mortar with clay added. 



Table 2.— Showing strength of mortar with loam added. 



These tests indicate clearly that the presence of clay or loam in the 

 small amounts usually found in dirty sand (say from two to ten per 

 cent.) does not detract from the strength of the mortar, but rather 



