Show j I R R SURFACE OF ROADS 1 nillo A Methods to Be Employed in Construction Construction Construction Con Con- Depends on Conditions Conditions Conr Con- Con r to Be Met r 11 l. f-l. r r 1 N r va I FOUR SETS ARE SUMMARIZED jI- jI I Location Design Drainage Grading Etc Are Important Important Each Each Feature Fea Fea- Feature ture Described Separately and In Full The proper method to employ in constructing a sand sand clay clay road surface depends on the conditions to be metIn metIn metIn met In general there are four distinct sets of conditions all of which may occur In the same locality or even on different different dif dlf- ferent terent sections of the same road I These are Case 1 I where the Ule original roadbed Is s sandy and it is desired to construe construct the surface b by admixing clay Case 2 where the original roadbed Ss Is composed of clay and it is desired to construct the surface by admixing sand Case 3 3 where it is desired to conI construct construct con con- I the surface of topsoil or other sand-clay sand mixture without admixing admixing ad ad- mixing any of the roadbed material Case 4 where it is desired to supply the clay and sand separately and mix the two materials together In place to form fonn the surface Before discussing the different cases separately the general ends which all should bo be thoroughly and Intimately mixed together In all aU cases In makIng makIng making mak mak- I ing artificial mixtures therefore much plowing plo and harrowing are re rel required aired I tk 5 O 6 No matter what method Is s s followed fol- fol followed fol I n sand clay surface sur sur- lowed In constructing A sand clay face tace traffic usually must u k p a n c aged l J to find ij cI c. c pa t the s i 1 nl f tig t d t the Ie road n never never- ver vert t m T Ve e c ed Cl c complete mp e until after It l has asb been subjected to traffic for a considerable period During this period the surface should be kept In shape shupe h by repeated dragging drugging and If necessary additional sand or cla clay be supplied at points which show weakness owing to the these e materials materials materials ma ma- not having haYing been mixed in proper proportions Other features of of the construction can best be described separately for each of the four sets of conditions conditions conditions' mentioned above Case 1 To I.-To To construct a sand clay surface by admixing cla clay with sand from the roadbed first grade the roadbed roadbed roadbed road road- bed in is the manner already described for earth bed construction but keep leep the crown flat fiat on the portion to be surfaced Then spread clay over oyer that part of or the roadway which the surface surface sur sur- face is to cover coyer to such depth that when it I Is mixed with the sand of the roadbed a surface about eight Inches thick after compacting will be ob ob- The loose depth of cla clay sary t to to- secure a finished surface eight Inches thick usually will vary from four Inches to six Inches according to the amount of sand the clay contains After the clay has been spread plow up sand from beneath In sufficient quantity to make male the net proportion of sand to clay about 2 to 1 ly lv the plow furrows should extend exten I I g FUt Fht sli tiff w crowned crowned- s sI SJ I. I cr or slightly crox 1 W t. t s s1 j j i r i f I Y iii 1 i. i f Cross coss Section section ready to receive the su surfacing ma material te VS Xvi I I rr v r rv s w s sSu i i Su tent for this I I II II I II I fir C Cross section showing material spread on the road vv j for I r rea y mixing I W S 8 to 10 inches to inch finches s i. i N I W i ross Cross section of completed road road 4 j I TYPICAL CROSS SECTIONS SHOWING METHOD OF CONSTRUCTING I 1 SAND SAND ClAY SAND CLAY ROAD BY MIXING SAND OR CLAY WITH THE ROAD BED MATERIAL 1 vr should be at least IZ lt feet for sin single le fr track ck road and generally not less than than for or double track should W should be not less than a and S not less than I vari varies from j r to th the foot for I level vel grade rade to I r 1 0 to fo the foot for a grade trad F. F 1 i 1 I of or the construction methods should aim to attain will be summarized briefly 1 The questions of location degn design de- de sign drainage grading etc are if anything more important in the case of sand day roads than in the case of earth roads 2 The amount of clay day contained In Ina ina a 8 finished sand-clay sand road surface be only slightly more than sufficient sufficient sufficient suf suf- to fill the voids in the sand Ordinarily about one part of clay to two parts of sand gives satisfactory results though the proper proportion for tor any particular case can cnn be determined determined determined deter deter- mined best by experiment 3 For average road country traffic and a stable stable roadbed the tile depth of a asand sand clay Band surface should be about eight Inches after it is compacted I If clean sand and pure clay were used to tomake tomake tomake make the mixture the respective I depths of the sand layer and the clay layer kayer required would be approximately approximate approxImate- ly 11 eight inches and four Inches measured measured meas meas- loose It Is customary to decrease the surface thickness from center to 0 std tides sides with a n feather edge extending out over oyer the shoulders but this practice practice practice tice makes It necessary for most of the traffic to use the center of the yond Toad and heavy vehicles using the edge ge of the surface are liable Hable to break breakthrough breakthrough through the surfacing material 4 In constructing a sand-clay sand surface ur- ur f face the two constituent materials down Into the sand from four tour to six Inches depending on the compactness of the roadbed and the amount of sand originally present In the clay But It is better to have too little than too much sand because it is easier to add sand from the roadbed than to haul additional clay Next harrow the surface surface surface sur sur- face with a disk harrow Repeat the I operations of plowing and harrowing until the sand and clay are mixed thoroughly thoroughly thoroughly thor thor- and uniformly Then shape up the surface with a grading machine or road drag and permit traffic upon it After the first soaking rain plow and andi i harrow the surface again until the surfacing material practically becomes mud after which shape up the surface and keep it in shape by repeated dragging dragging dragging drag drag- ging until it has dried out and is thoroughly compacted Watch the road carefully for several months after atter ItIs it itis itis is first constructed to correct deficiencies deficiencies of sand or clay and to keep the surface In shape Case 2 To To construct a sandy-clay sandy road surface by admixing sand with clay from the roadbed the process is exactly similar to that described for Case 1 except that sand Is spread over the graded roadbed and clay is plowed I up from beneath to mix with it |