Covering for sports ground - having two layers formed by clay soil, coarse sand, slaked line, and pozzuolana aggregate

摘要

Covering consists of a base layer (a) contg. by wt. 10-50, esp. 10-20% clay soil; 1-10% slaked lime fixed to the clay; 10-30, esp. 10-20% coarse sand; and 30-80, esp. 60-80% of a coarse grained aggregate of pozzuolana, schist, clinker or slag. Layer(a) is covered by an intermediate layer(b) with the same compsn. as layer(a) except that the aggregate has a smaller grain size. On top of layer (b) is a surface layer of baked powdered clay or brick dust mixed with a small amt. of slaked lime. Layer(c) is not essential. In an example, layers(a,b) each contained 15% clay soil, 10% sand, and 75% pozzuolalana with grain size 5/20 in layer(a) and size 0/2 in layer(b). Layer(a) also contained 4.5 pts.wt. slaked lime, and layer(b) 6 pts.wt. slaked lime.