The Birmingham age-herald., 1924-11-27
EXCLUSIVE USE OE nONTnDETE I'M UT UUINUnEIE IN
 CITY'S PROJECTS
Designated After Extend ed Tests And Observa-
 tion Of Old Paving

TUSCALOOSA, Ala, Nov. 26.- (Special. )-The concrete paving pro gram of the city of Tuscaloosa is one of the most striking illustrations in Alabama of the rapidly growing pop ularity of concrete for paving projects. After making extended investigations and acting under recommendations Of City Engineer W. H. Nicol. the city commissioners of Tuscaloosa are desig- mating concrete as the most desirable of all street paving. ,>
 The first concrete paving was i'll 1922 when 31 ,932 yards were laid. Since that time the city has put down 22o,- no yards. Previously asphalt and gravel were used, but they have not given general satisfaction. Petitions are before the commission from prop erty owners asking that about two miles of concrete be laid in several parts of the city, and it is understood that others will petition for concrete paving.
 Mayor D. E. Robertson, as well as the other commissioners, are strong advocates of concrete paving, bellev- ing after giving the matter close study, that concrete is the most practical, per manent and best paving that can be used..
 Not "a single complaint has been re- ceived from property owners where concrete has been laid. Many owners have expressed themselves as favorable to all of the streets Ill the future being paved with concrete.
 Tuscaloosa county, few months ago, voted a $6OOOO0 bond issue to pave four roads with concrete. The vote was overwhelmingly in favor of concrete as the paving material. The word concrete was placed on the ballots.
 The county commissioners made n close study of road material and after making investigations in other states were convinced that concrete was the best and most desirable road building material and would stand up better under heavy traffic.
 Why City Chose Concrete
 City Engineer Nichol explains why Tuscaloosa chose concrete for its ex- tensive street improvement program in the following statement:
 Largely as the result of the. good wearing qualities shown by concrete pavement in this city ten years ago. the city officials of Tuscaloosa adopted portland cement concrete as the mate rial to be used when the citys present program of street improvement was started. Today, there are completed or under construction i'll Tuscaloosa about 300,0O0 square yards of concrete pavement.
 Though it was not built according to present standards of constructlon- the concrete pavement laid on UnlVer- sity avenue in 1913, through the ~c 4I n+n IS in excellent condition. The pavement is half mile in length and consists of two 17-fool toadways, one on each side of a 10-foot park area enclosing the street ear tra @Is. This paving was laid in Tuscalor-a by county convict labor. Two small, One-sack mixers mixed the concrete which was propor- tioned one part cement, one and one half parts sand and three parts gravel. The fine and coarse aggregates con sisted of bank run sand and gravel which was hauled from neighboring pit. The materials were screened but not washed. Concrete was placed to a uniform. thickness of 9 inches.
 Paving Stands Traffic
 To-day this pavement shows little wear except surface pittings where gravel particles have become dislodged due to the film of clay which coats them. Most of the slabs have developed transverse cracks and some show longi- tudinal cracks, but with proper main tenance this street will last indefinite ly. A patented metal joint was used and most of the joints are high.
 With the inauguration of the pres ent street improvement program Tn 1920, the specifications were changed kIo has m crete street construction. Present city specifications require the use of washed sand for fine aggregate and washed pebbles, crushed stone or furnace slag for coarse aggregate. Proportions of one part cement, two parts fine aggre- gate and three parts course aggregate.
 "A standard thickness of seven inches is used. except in lightly travelled residential sections where a thickness of six inches is sometimes used. Integral curb is constructed on all streets where curbs are not already in place. Par ticular attention is paid to the con- sistensy of the concrete and the time of mixing. A 2-inch slump governs the amount of water used and the time of mixing is controlled by a batch meter which is set for a one-minute mix. Joints are made with prepared asphalt filler which is one inch wider than The depth of the pavement. Trans verse joints are placed every 30 feet and longitudinal joints are placed along the cilrbs in roadways up to 30 feet in width. On wider roadways, the pave ment is built in two trips separated by expansion joints. In future con- struction the prepared joint filler will be used also in the longitudinal center hn in