Cementitious boards

1. A reinforced cementitious board comprising:

(a) a cementitious core; and

(b) a reinforcing fabric disposed on at least one face of said cementitious core while imbedded into a portion of the cementitious core; said reinforcing fabric including:

(i) a plurality of warp yams having a first twist (turns/inch);

(ii) a plurality of weft yams having a second twist which is greater than said first twist; and

(c) a resinous coating applied to said reinforcing fabric in a coating weight distribution ratio of less than about 2.0:1 based upon the weight of the resinous coating on the weft yams, over the weight of the resin on the warp yams.

2. The cementitious board of claim 1 wherein said cementitious core comprises Portland cement.

3. The cementitious board of claim 1 wherein said reinforcing fabric comprises a woven, braided, nonwoven mesh-type or knitted fabric.

4. The cementitious board of claim 1 wherein said first twist of said warp yams is about 0-0.3 turns/inch.

5. The cementitious board of claim 4 wherein said second twist of said weft yarns is about 0.7-1.0 turns/inch.

6. The cementitious board of claim 1 wherein said resinous coating comprises an alkali-resistant resin.

7. A reinforced cementitious board comprising:

(a) a cementitious core comprising Portland cement; and

(b) a reinforcing fabric disposed around and embedded into a portion of said cementitious core; said reinforcing fabric being composed of a multifilament yarn-based woven, braided, nonwoven mesh-type, or knitted fabric which includes:

(i) a plurality of warp yarns having a first twist (turns/inch);

(ii) a plurality of weft yarns having a second twist, said second twist being greater than said first twist; and

(c) an alkali resistant resinous coating applied to said plurality of warp and said plurality of weft yarns after they have been assembled or laid together, such as to produce a coating weight distribution ratio of less than about 2.0:1 based upon the weight of the resinous coating on the weft yarns over the weight of the resinous coating on the warp yarns.

8. The cementitious board of claim 7 wherein said reinforcing fabric comprises sized glass fibers.

9. The cementitious board of claim 7 wherein said warp yarns have a twist of about 0-0.3 turns/inch.

10. The cementitious board of claim 9 wherein said weft yarns have a twist of about 0.7-1 turns/inch.

11. The cementitious board of claim 7 wherein said alkali resistant coating provides alkali resistance to said reinforcing fabric in a Portland cement board.

12. The cementitious board of claim 11 wherein said resinous coating comprises a pvc matrix having an oil phase distributed therein.

13. The reinforced cement board of claim 7 , wherein the reinforcing fabric is disposed on at least one face of the cementitious core.

14. A method of making the cementitious board of claim 1 , comprising:

(a) providing a cementitious slurry;

(b) depositing said cementitious slurry onto a moving reinforcing fabric, said reinforcing fabric comprising a plurality of warp yarns having a first twist (turns/inch), a plurality of weft yarns having a second twist which is greater than said first twist; and a resinous coating applied to said reinforcing fabric in a coating weight distribution ratio of less than about 2.0:1, based upon the weight of the resinous coating on the weft yarns, over the weight of the resinous coating on the warp yarns;

(c) shaping said cementitious slurry and said reinforcing fabric into a board, whereby said reinforcing fabric is disposed on at least one face thereof, and

(d) permitting said cementitious slurry to set.

15. The method of claim 14 wherein said step of shaping said cementitious slurry and said reinforcing fabric into a board is continuous or discontinuous.