Show GRAVEL ROAD TYPES constitute about one third of surfaced roas roads in the united states BEST SELECTION OF GRAVEL quality of material Is next tn in importance to proper drainage clay Is poorest cementing matei material I 1 we have prepared by the united states department ot of agriculture roads that are artificially surfaced with gravel or 01 with earthy material laithe composition of which gravel predominates are called gravel roads this designation covers a variation in type w aich ranges from roads surfaced with a natural sand clay mixture containing a considerable percentage of gravel to having so called gravel macadam surfaces con composed I 1 posed almost wholly of pebbles and constructed ted in practically the same manner as first class macadam roads gravel roads constitute about one third the total mileage of surfaced roads in the united states and are confined to no especial section of the country in the following discussion of gravel roads it is convenient to consider the subject under the two general heads selection of gravel and construction methods selection of gravel ordinarily the selection of gravel for use in road surfacing sur faung must be confined to local materials which are or can be made suitable for that purpose because of high freight costs it seldom happens that road gravel of even the very best quality is transported by rail a greater distance than about miles from the source of supply and in the vast majority of cases it is hauled directly from pit to road in wagons since the quality of gravel varies to a considerable extent sometimes in different parts of the same pit it Is essential that local road officials who frequently are charged with the selection of such material should have some knowledge of the relation between the physical characteristics of gravel and its wearing qualities when placed in a road surface while such knowledge can best be gained by actual experience with different kinds ot of gravel there are certain general requirements quire ments which may be stated for the guidance of the inexperienced for example the following excerpt from bulletin no 2 of the michigan state highway department presents in very concise form the characteristics which gravel tor for road surf surfacing acing should possess in the judgment of the state highway commissioner in order to meet the michigan conditions next to proper drainage the most important thing thin in building gravel roads Is to secure a good quality of gravel authorities have differed as to the requirements of suitable road gravels most of them in my opinion placing too much stress on the immediate packing qualities indeed the average township commissioner and farmers generally have become so imbued with the idea that it is necessary to use a gravel that will pack quickly that they have almost lost sight of the fact that the only thing which makes a gravel road better than an earth road is the pebbles real rea I 1 stones that it contains and Is dependent upon to bear up traffic and resist wear gravels that come from the pit with the pebbles cemented together even though they hey contain no clay will in the road and become harder than they were in the pit tests of specimens of this kind always show that there Is ciuch lime present and usually ome iron both of which are excellent cementing materials briefly the experience of the state highway department warrants the statement that there are few if any bank grovels gravels in michigan that do not con tale enough limestone and other soft pebbles which grind up under traffic to furnish sufficient binder to cause them to consolidate in a few months time if separated from the surplus sand and earth and properly treated after applying to the road in accordance with these suggestions gravels are considered valuable for road purposes in the following order 1 L almost in direct proportion to the percentage of pebbles constituting the mass 2 in direct proportion to the value as road metal of the rock fragments constituting the pebbles 3 in direct proportion to the value as a cementing material under fill all conditions Alit ions of weather of the finer particles of earthy matter constituting the filler or binder in general the physical characteristics of gravel which determine its suitability for use in surfacing a road ro ad are 1 the durability of the pebbles or rock fragments 2 the quality of the binder 8 3 the grading of tile the pebbles pebble and 4 the proportion in which tile tinder binder material 1 Is 13 3 present while the influence each of these factors factor should exert r t in fixing the selection of gravel for a particular road depends upon loal cal conditions and necessarily la Is a question for individual judgment to decide nevertheless EL a few points mints in connection with each factor that may ald aid materially in reaching a decision will bo be summarized in the following paragraphs durability of pebbles the principal qualities which deter allne lne tile durability of pebbles or stone 0 of f any wi ednd when placed lit 1 a road surface are hardness tou toughness glines and resistance to wear the extent to which pebbles possess these qualities depends very largely on the clina acter of the parent stone from which they were origin originally ally produced and a accordingly varies over a wide ran range ge since nearly all gravel deposits contain pebbles which bavo been formed from many diff different crent kinds ot of stone it lias has not been considered practicable t to 0 apply the ordinary laboratory tests for determining hardness toughness mid and per cent of wear to gravel and the matter of comparing these qualities as possessed by the pebbles from different gravel deposits usually d depends e on visual inspection not infrequently a very casual inspection will reveal which deposit among a great number contains the largest percentage of hard durable pebbles there are comparatively tow few cases where this point cannot be determined with sufficient accuracy by sorting out the pebbles contained in representative samples sample s from the different deposits testing the various kinds kind s with a hand ham hammer nier and determining the relative proportions in which the more durable materials are pre present sent in the sample by means of a weighing device ordinarily the most durable pebbles which occur la in gravel deposits are those composed of either quartzite or chert though many deposits contain fragments of limestone or trap rock either or of which may make an excellent road surfacing material for example the so called blue gravel which occurs in certain sections of the country usually is composed largely of trap rock fragments and generally ranks high as a road material materi il while limestone tone pebbles usually are less iless resistant to wear than those of trap rock they hey possess the advantage of a relatively high cementing value and their presence in gravel may aid greatly in securing a well bonded surface without tin an excess of clay the binder no matter how durable nay may be the pebbles contained in a given gravel deposit they cannot be used successfully in a road surface unless they cart can be well bonded together so as to present a combined resistance to the disturbing action of traffic to accomplish this bond requires that the gravel contain some cementing or binding agent such as iron oxide carbonate of lime or clay As already explained certain pebbles such as those composed of limestone possess the property of becoming firmly bonded together by virtue of their own cementing value the principal cementing agent or binder present in most gravel deposits is clay and in case of deposits illich do not carry sufficient binder clay usually Is the material added to correct the deficiency while there are many exceptions to this rule it Is sufficiently general to warrant treating as special cases those deposits in which chich the binder is not clay the suitability of clay for use as a binder for a granel grael surface depends on exactly the same characteristics as its suitability tor for use in sand clay construction that Is a quality of clay which could be used satisfactorily la in a sand band clay surface also should make a satisfactory binder I 1 for a gravel surface provided it Is used in proper proportion and Is properly mixed with sand grading and proportions for gr gravel avel to make a satisfactory road surface the stone particles should be graded in size so that the amount of binder required will be reduced to a minimum the reason for this Is that the binder usually la is much less resistant to wear than the stone particles and therefore it Is desirable that the latter form ag aa largo large a part of the wearing surface P as la Is practicable most gravel deposits as they occur in nature satisfy this requirement qui rement in so far as grading of the pebbles is concerned but they nearly always contain pebbles of a size larger than it is desirable to incorporate in a road surface natural deposits also not infrequently contain too barkr lar gf it proportion of sand or clay to produce satisfactory results it Is desirable therefore that specifications covering gravel for use in road construction should limit the proportions sri in which the fine and coarse materials shall hall be present and a maximum limiting size for the pebbles as wella definite requirements regarding flie file quality of the pebbles and of the binder in general it has been found that satisfactory gravel will conform tho the following limits as to percentages of fine and coarse material 1 material retained on a A inch leve t 55 5 i to 75 per cent 2 material Stat erial retained on a inch steve sieve not less than 15 per der cent 3 material clay passing a mesh steve sieve for the surface course 8 to 13 15 per cent 4 material clay passing a mesh bleve for the foundation coar chirse 10 to 15 p pr per r cent the sand should be at least awl twice ca as groat great as the lie clay content and tile the sand and clay when thoroughly mixed hould be sufficient to fill the voids between the larger gravel particles tho the percentages given above usually nill vi conform with this requirement A satisfactory mechanical analysis of it a gravel sample along the lines indicated above frequently may be made mad in the geld field by first separating the coarse material from the fine by meana mean of a at me inch screen L ind ild then washing the clay out of the fine material as described in the discussion of sand clay roads both the coarse and fine materials obtained from the sample may be further farther separated into different sizes by means of suitable screens screen 3 if tor for any reason tills this Is in ds in milking making the test as sg y R Y Z rat ff f ad 44 ca c N A e A WW y PM L 1 11 1 k aa aj j 1 11 if aft i tv arta eq i TO j TI Y L 14 1 4 T 7 I 1 1 I felga feL gj new dairy and animal husbandry building for utah agricultural college when the his big dairy anti and animal Ilus husbandry bandry building shown above now being erected at logan utah Is finished the utah agricultural college will have the best equipped and most modern building in the ex exclusively elusively to animal husbandry the building will be three stories and a basement high the first floor will house a large and modern dairy manufacturing fac turing plant which will include rooms for the making of butter cheese cottage cheese and ice cream A model farm dairy Is located on the first floor equipped for demonstration where the farmer fanner can see sea in operation the dairy he should have on its his farm A large ice room coolers refrigerator plant meat curing room and cheese curing room will be located partly on this floor and partly in the basement the rest of the first floor will be given over to offices and a roomy ampi theatre where large blasses can meet and where farm ers rs and housekeepers may assemble in their 1111 nual roundup round up gatherings the second floor Is to be given over to offices class rooms and experimental and student laboratories here will be located milk testing rooms boora separator rooms and churning laboratories the third floor Is to be given over to work in forestry here problems in range management ma na gement will be worked out and the care of cattle and sheep on the range taught the care of 0 our national forests will also be part of 0 tile the work with the completion of this splendid building the utah agricultural college will be in a position to further emphasize its work in dairying and animal husbandry with enlarged and newly equipped laboratories at hand it will be able to carry on experimental work on an enlarged scale and to offer its students even better opportunities for study than it has been able to offer in the past |