OCR Text |
Show Cement Qun. There Is a cemont gun which Is used to apply a mortar covorlng to structural struc-tural steel work. A mtxturo ot dry saud and cement Is shot from a noi-tlo noi-tlo by compressed air. A socond hoso delivers to tho same nozzle a supply of water under pressuro, and tho mtxturo mtx-turo of sand, cement and water It shot out with a velocity ot about 3S0 foct a second. Tho nozzlo Is nrrangod to produce a thorough wotting ot tho matorlal. As tho mixture strlkos tho surface to bo covered, tho coarso sand grains rebound until tho ftno cemont mortar, which adhores Immediately, has formed a plastic baso In which the coarso partlclos bocomo Imbedded. A covering of any required thickness Is then rapidly built up. Ono of thoso guns has been used on the Panama canal In covering tho sides of tho Culebra cut with coraent, to provent tho unstable- earth from sliding Into tho canal. |