tiu chun vit namtcvn 3118 : 1993 Nhm H B tng nng Ph|ng php xc nh c|ng nn Heavyweight concrete - Method for determinatien of compressive strength Tiu chun ny quy nh ph|ng php xc nh c|ng chu nn ca b tng nng. 1.Thit b th.My nn;Th|c l kim loi;mtruynti(sdngkhnnccnavinmu m sau khi un gy).1.1My nn |c lp t ti mt v tr c nh.Saukhilp,myphinhklnmmtlnhoc saumilnsacha|ccquanol|ngNh n|c kim tra v cp giy chng thc hp l.1.2m truyn ti (hnh 1) |c lm bng thp dy 20 2mmcrnhcchumu302mm.Phn truyntivomuckchth|cbngkchth|ctitdincaccvinmum (100 x 100 ; 150 x 150 ; 200 x 200mm).2.Chun b mu th2.1Chun b mu th nn theo nhm mu. Mu nhm mu gm 3 vin. Khi s dng b tng khoan ct t kt cu, nu khng c 3 vin th |c php ly 2 vin lm mt nhm mu th.2.2Vic ly hn hp b tng, c bo d|ng, khoan ct mu b tng v chn kch th|c vin mu th nn phi |c tin hnh theo TCVN 3105: 1993.2.3Vin chun xc nh c|ng nn ca b tng l vin mu lp ph|ng kch th|c 150x150x150mm.Ccvinmulpph|ngkchth|ckhcvinchunvcc vin mu tr sau khi th nn phi |c tnh i kt qu th v c|ng vin chun. 2.4Kt cu sn phm yu cu th mu nghim thu thi cng hoc |a vo sa dng tui trng thi no th phi th nn cc vin mu ng tui v trng thi . 2.5Kim tra v chn hai mt chu nn ca cc vin mu th sao cho: a.Khehlnnhtgiachngvith|cthngtpstxoaytheoccph|ng khng v|t qu 0,05mm trn l00mm tnh t im t th|c.h. Khe h ln nht gia chng vi thnh th|c k gc vung khi t thnh kia p st cc mt k bn ca mu lp ph|ng hoc cc |ng sinh ca mu tr khng v|t qu 1mm trn 100nm tnh t im t th|c trn mt kim tra.c. i vi cc vin mu lp ph|ng v cc vin na dm un khng ly mt to bi y khun c v mt h c mu lm hai mt chu nn. 2.6Trong tr|ng hp cc mu th khng tho mn cc yu cu ghi iu 2.3 mu phi |c gia cng li bng cch mi bt hoc lm phng mt bng mt lp h xi mng cng anh khng dy qu 2mm. C|ng ca lp xi mng ny khi th phi khng |c thp hn mt na c|ng d kin s t ca mu b tng. 3.Tin hnh th tiu chun vit namtcvn 3118 : 1993 FPR o =3.1Xc nh din tch chu lc ca mu 3.1.1.o chnh xc ti 1mm cc cp cnh song song ca hai mt chu nn (i vi mu lpph|ng)cccp|ngknhvunggcvinhautngimttrntngmt chu nn (i vi mu tr), xc nh din tch hai mt chu nn trn v d|i theo cc gi tr trung bnh ca cc cp cnh hoc cc cp |ng knh o. Din tch chu lc nn ca mu khi chnh l trung bnh s hc din tch ca hai mt. 3.1.2.Din tch chu lc khi th cc na vin dm un gy |c tnh bng trung bnh s hc din tch cc phn chung gia cc mt chu nn pha trn v pha d|i vi cc m thp truyn lc t|ng ng. 3.2Xc nh ti trng ph hoi mu 3.2.1.Chn thang lc thch hp ca my khi nn ti trng ph hoi nm trong khong 20 - 80% ti trng cc i ca thang lc nn chn. Khng |c nn mu ngoi thang lc trn. 3.2.2.t mu vo my nn sao cho mt mt chu nn chn nm ng tm tht d|i ca my. Vn hnh my cho mt trn ca mu nh nhng tip cn vi tht trn ca my. Tip tng ti lin tc vi vn tc khng i v bng 6 4 daN/cm2 trong mt giy cho ti khi mu b ph hoi. Dng tc gia ti nh i vi cc mu b tng c c|ng thp, tc gia ti ln i vi cc mu b tng c|ng cao. 3.2.3.Lc ti a t |c l gi tr ti trng ph hoi mu. 4.Tnh kt qu 4.1C|ngnntngvinmubtng(R)|ctnhbngdaN/cm2(KG/cm2)theo cng thc: Trong : P - Ti trng ph hoi, tnh bng daN; . F - Din tch chu lc nn ca vin mu, tnh bng cm2; o - Hstnhiktquthnnccvinmubtngkchth|ckhcvin chun v c|ng ca vin mu chun kch th|c 150 x 150 x 150mm. Gi tr o ly theo bng 1. Bng 1 Hnh dng v kch th|c ca mu (mm)H s tnh i Mu lpph|ng 100 x 100 x 100 150 x 150 x 150 200 x 200 x 200 300 x 300 x 300 Mu tr 71,4 x 143 v 100 x 200 150 x 300 200 x 400 0,91 1,00 1,05 1,10 1,16 1,20 1,24 Ch thch: tiu chun vit namtcvn 3118 : 1993 1.Khng |c php s dng cc gi tr o thp hn cc gi tr ghi trong bng 1. 2.Chophpsdngccgitrolnhnccgitrghibng1khio|cxcnhbng thc nghim theo ph|ng php ghi ph lc ca tiu chun ny.3.Khi nn cc mu na dm gi tr h s chuyn i cng |c ly nh| mu lp ph|ng cng tit din chu nn.4.2Khi th cc mu tr khoan ct t cc cu kin hoc sn phm m t s chiu cao vi |ng knh ca chng nh hn 2 th kt qu cng tnh theo cng thc v h s o ghi iu 4. 1 nh|ng |c nhn thm vi h s | ly theo bng 2.Bng 2 H/d1,91,81,71,61,51,41,31,21,11,0 0,990,980,970,950,940,930,920,910,900,89 4.3C|ngchunncabtng|cxcnhtccgitrc|ngnncacc vin trong t mu b tng nh| sau:4.3.1.So snh cc gi tr c|ng nn ln nht v nh nht vi c|ng nn ca vin mu trung bnh. Nu c hai gi tr o u khng lch qu 15% so vi c|ng nn ca vin mu trung bnh th c|ng nn ca b tng |c tnh bng trung bnh s hc ca ba ktquthtrnbavinmu.Numttronghaigitrlchqu15%sovi c|ng nn ca vin mu trung bnh th b c hai kt qu ln nht v nh nht. Khi c|ng nn ca b tng l c|ng nn ca mt vin mu cn li.4.3.2.Trongtr|nghptmubtngchichaivinthc|ngnncabtng |c tnh bng trung bnh s hc kt qu th ca hai vin mu .5.Bin bn thTrong bin bn th ghi r:-K hiu mu; -Ni ly mu;-Tui b tng, iu kin bo d|ng, trng thi mu lc th;-Mc b tng thit k;-Kch th|c tng vin mu;-Din tch chu nn ca tng vin;-Ti trng ph hoi tng vin;-C|ng chu nn ca tng vin v c|ng chu nn trung bnh,-Ch k ca ng|i th. tiu chun vit namtcvn 3118 : 1993 niniiRR0= oPh lc Xc nh h s tnh i bng thc nghim 1.H s tnh i |c xc nh ring cho tng mc b tng, tng loi b tng, tng my nn v tng l khun c mu kch th|c khc vin chun. 2. xc nh h s tnh i cn th 8 t mu (mi t 3 vin) kch th|c chun v 8 t mu t|ng ng cho mi loi khun kch th|c khc vin chun. 3.Ccmukchth|cchunvkchth|ckhcvinchunphi|cchtotmt mu hn hp bo d|ng, ng rn trong cng mt iu kin v th cng mt tui. Khith,ccmukchth|cchunvkhcchunphickhil|ngthtchchnh lch nhau khng qu 2%. 4.Sau khi nn mu, tin hnh cc tnh ton sau: 4.1.H s tnh i cho tng cp t mu kch th|c chun v khng chun. (1) Trong : 0niR v niR -C|ngbtngtrungbnhcatmukchth|cchunvkhc chun th i. 4.2.H s tnh i trung bnh: (2) 4.3.Ph|ng sai S. (3) 4.4.Gi tr t V phn bit ra theo gi tr t ba tr|ng hp sau: a.Nu t > 1,4 th s dng h s o xc nh bng thc nghim; b.Nu t < l,4 th s dng h s o tra theo bng l ca tiu chun ny; c.Khng ph thuc vo t nu o < o tra bng th phi s dng o tra theo bng 1 ca tiu chun ny. 5.Gi tr ca h s tnh i |c xc nh cc phng th nghim c s c s tham gia ca cc phng th nghim chuyn v b tng ca cc B. Sau |c cc t chc c thm quyn thng qua. 881==iiooSto o = 83 , 2( )7812==iiSo oo tiu chun vit namtcvn 3118 : 1993 6.Vic kim tra cc h s tnh i bng thc nghim cn |c tin hnh t nht mt ln trong hai nm.