17. Sem enttoshdagi hajmiy o'zgarishlar 192 18. Portlandsementning m ustahkam ligi..................................................................193 19. Sem enttosh va betonlam ing kimyoviy hamda fizik yemiruvchi omillar ta’siriga chidam liligi................................................................................................ 200 V bob. M axsus portlandsementlar 20. Portlandsement turlari.......................................................................................... 213 21. Tez qotuvchan portlandsem ent.......................................................................... 213 22. Plastifikatsiyalangan va gidrofob portlandsem entlar.................................... 216 23. Sulfatga chidamli portlandsem ent...................................................................... 217 24. Oq va rangli portlandsementlar........................................................................... 220