Tam sim no tib neeg tseem ceeb heev rau cov kev ua si rau lawv txoj kev noj qab haus huv, yog li qhov kev siv ntau ntawm kev ncaws pob yeej tseem tuaj yeem siab zog thiab siab, uas ua rau qee xyoo ntawm kev ua si ntawm qhov chaw kub nyhiab tau raug puas tsuaj rau ntau qib. Qhov no, nws yog ib qho tsim nyog yuav kho cov kev kho kom tsis txhob raug mob rau cov neeg ncaws pob.
Lub hnub nyoog khoom cuav qoob loo yuav tsum tau muab tshem tawm ua ntej muab cov khoom nyom tshiab rau ntawm kev ncaws pob, uas yog qhov tseem ceeb heev rau kev ua haujlwm ntxiv. Tshem cov qoob loo qub thaum uas tsim nyog yuav tsum tau them, tsis txhob ua rau thawj cov khoom cuav qoob loo, feem ntau cov cement, asphalt, txiv qaub thiab av lub ncoo, thiab lwm yam.
Secondly, vim tias qhov khoom neeg tsim nyom yog cov nplaum rau hauv pem teb, cov nqes, cov ntaub, cov ntaub qhwv, ces tshem tawm ntawm lub sijhawm ntev npaum li cov cuab yeej siv yuav yog qhov tseeb cov nyom thiab cov txheej txheem ua ke yuav raug tshem tawm. Tsis txhob poach lub hauv paus ntawm cov khoom neeg tsim nyom.
Tom qab tshem tawm, thawj qhov khoom neeg ua si ncaws pob nyob rau ntawm cov khoom nyom, quartz xuab zeb, roj hmab cov khoom thiab lwm cov ntaub ntawv muab tawm, cov ntaub ntawv no yuav tsis siv tau. Tsis yog vim lawv tau poob lawv qhov kev ua tau zoo, tab sis nws yuav tsum muaj ntau hom impurities, tsis haum rau cov khoom nyom tshiab.
Tom qab ntawd pib paving tus tshiab dag cov nyom ntsuab. Ua ntej ntawd, nco ntsoov ntxuav lub teb, ntxuav nws kom ntau li ntau tau, thiab tshem cov hmoov av hauv av. Lub casses dag ntawm football teb tsis tuaj yeem ua raws li kev pov thawj kom txog rau thaum tus qauv tau tsim.
