Hnub Kawg: 27, Kaum Ib Hlis, 2023 Retarder yog ib qho khoom siv feem ntau siv hauv kev tsim kho engineering. Nws lub luag haujlwm tseem ceeb yog txhawm rau ncua qhov tshwm sim ntawm qhov kub siab ntawm cov cement hydration, uas muaj txiaj ntsig zoo rau kev thauj mus los ntev, qhov kub thiab txias thiab lwm yam kev mob ntawm concret ...
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