Te awenga o te hydroxyethyl cellulose ether i runga i te hydration wawe o te CSA ciment

Nga hua ohydroxyethyl cellulose (HEC)me te hydroxyethyl methyl cellulose whakakapi teitei, iti ranei (H HMEC, L HEMC) i runga i te tukanga hydration moata me nga hua hydration o te sulfoaluminate (CSA) ciment i akohia. I kitea e nga hua ka taea e nga ihirangi rereke o L-HEMC te whakatairanga i te whakamakuku o te CSA ciment i roto i te 45.0 min~10.0 h. Ko nga etera cellulose e toru i whakaroa i te whakamaaramatanga o te whakakorenga ciment me te wahanga huringa o te CSA i te tuatahi, katahi ka whakatairanga i te whakamaarama i roto i te 2.0~10.0 h. Ko te whakaurunga o te roopu methyl i whakarei ake i te painga whakatairanga o te hydroxyethyl cellulose ether i runga i te hydration o te CSA ciment, a ko te L HEMC te kaha whakatairanga kaha; Ko te painga o te cellulose ether me nga momo whakakapinga rereke me nga nekehanga o te whakakapi i runga i nga hua hydration i roto i te 12.0 h i mua i te hydration he tino rerekee. He kaha ake te whakatairanga o te HEMC ki nga hua whakamakuku i te HEC. L HEMC whakarerekē CSA slurry sima hua te nuinga konupūmā-vanadite me te konumohe kāpia i 2.0 me te 4.0 h o te hydration.
Kupu matua: sulfoaluminate ciment; Ether Cellulose; Whakakapi; Te tohu whakakapinga; Te tukanga whakamahana; Hua whakamahana

Sulfoaluminate (CSA) ciment ki te konupūmā sulfoaluminate anhydrous (C4A3) me te boheme (C2S) i te mea ko te kohuke clinker matua me nga painga o te whakapakeke tere me te kaha wawe, anti-tio me te anti-permeability, iti alkalinity, me te kai wera iti i roto i te tukanga whakaputa, me te huri ngawari o te clinker. Kei te whakamahia nuitia i roto i te whakatikatika tere, anti-permeability me etahi atu kaupapa. Ko te Cellulose ether (CE) e whakamahia nuitia ana ki te whakarereke i te kumete na te mea he pupuri i te wai me te matotoru. He uaua te tauhohenga o te CSA ciment hydration, he poto rawa te wa whakaurunga, he maha nga waahanga o te waa whakatere, a ko tona whakamaarama he ngawari ki te awe o te whakauru me te whakamahana i te pāmahana. Zhang et al. i kitea ka taea e te HEMC te whakaroa i te wa whakauru o te hydration o te CSA ciment me te hanga i te tihi matua o te whakahekenga o te wera wera. Sun Zhenping et al. i kitea ko te whakangao wai a HEMC i pa ki te whakamakuku moata o te slurry ciment. Wu Kai et al. i whakapono ko te ngoikoretanga ngoikore o te HEMC i runga i te mata o te CSA ciment kaore i ranea ki te pa ki te tere o te tuku wera o te hydration ciment. Ko nga hua rangahau mo te paanga o te HEMC ki runga i te CSA ciment hydration kaore i rite, tera pea na nga waahanga rereke o te clinker ciment i whakamahia. Wan et al. i kitea he pai ake te pupuri wai o HEMC i tera o te hydroxyethyl cellulose (HEC), me te kaha o te kaha me te mata o te mata o te otinga poka o HEMC-whakarerekehia te CSA ciment slurry me te tohu whakakapinga teitei. Li Jian et al. i aro turuki i nga huringa pāmahana o roto moata o nga kumete ciment CSA kua whakarerekehia e te HEMC i raro i te wai whakapumau ka kitea he rereke te awe o te HEMC me nga nekehanga rereke o te whakakapi.
Heoi, ko te rangahau whakatairite mo nga paanga o te CE me nga momo whakakapinga rereke me nga nekehanga o te whakakapi i te whakamakuku moata o te CSA ciment kaore i te rawaka. I roto i tenei pepa, i akohia nga paanga o te hydroxyethyl cellulose ether me nga mea rereke, nga roopu whakakapi me nga nekehanga o te whakakapi i te wa tuatahi o te whakamakuku CSA ciment. Ko te ture tuku wera whakamahana o te 12h CSA ciment me te hydroxyethyl cellulose ether i tino wetewetehia, a ko nga hua whakamakuku i tātarihia ine.

1. Whakamatau
1.1 Rawa Rawa
Sima ko 42.5 kōeke nohopuku pakeke CSA sima, te wa tautuhinga tuatahi me te whakamutunga ko 28 min me 50 min, aua. Ko tona hanganga matū me te hanganga kohuke (te hautau papatipu, te inenga me te wai-ciment ōwehenga e whakahuahia ana i roto i tenei pepa he hautanga papatipu, tauwehenga papatipu ranei) te whakakē CE kei roto i te 3 hydroxyethyl cellulose ethers he rite te pokey: Hydroxyethyl cellulose (HEC), teitei o te whakakapi hydroxyethyl methyl cellulose (H HEMC), tohu iti o te whakakapi hydroxyethyl methyl fibrin (L HEMC), te viscosity o 32, 37, 36 Pa · s, te tohu o te whakakapi o 2.5, 1.9, 1.6 te whakaranu i te wai mo te wai whakaheke.
1.2 Whāranu ōwehenga
Ko te tauwehenga wai-ciment pumau o 0.54, ko te ihirangi o te L HEMC (ko te ihirangi o tenei tuhinga ka tatauhia e te kounga o te paru wai) wL=0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, HEC me H HEMC ihirangi o 0.5%. I roto i tenei pepa: L HEMC 0.1 wL=0.1% L HEMC huri CSA ciment, me etahi atu; CSA he parakore CSA sima; HEC CSA ciment, L HEMC CSA ciment, H HEMC kua whakarereketia CSA ciment e kiia ana ko HCSA, LHCSA, HHCSA.
1.3 Tikanga whakamatautau
I whakamahia he moroiti weariki e waru nga hongere me te awhe ine 600 mW hei whakamatautau i te wera o te wai. I mua i te whakamatautau, i whakapumauhia te taputapu ki te (20±2) ℃ me te haumākū whanaunga RH= (60±5) % mo te 6.0~8.0 h. Ko te CSA ciment, te CE me te ranunga wai i konatunatua kia rite ki te tauwehenga whakauru me te whakauru hiko i mahia mo te 1min i te tere o te 600 r / min. Me pauna tonu (10.0±0.1) g slurry ki roto i te ampoule, hoatu te ampoule ki roto i te taputapu ka timata te whakamatautau taima. Ko te mahana whakamahana he 20 ℃, ka tuhia nga raraunga ia 1min, ka roa te whakamatautau ki te 12.0h.
Thermogravimetric (TG) tātaritanga: I whakaritea te slurry ciment i runga i te ISO 9597-2008 Cement - Nga tikanga whakamatautau - Te whakatau i te waa whakarite me te pai. Ko te slurry sima whakauru i hoatu ki roto i te pokepokea ai whakamatautau o 20 mm × 20 mm × 20 mm, a i muri i wiri horihori mo 10 wa, i whakanohoia te reira i raro i (20±2) ℃ me RH= (60±5) % mo te whakaora. I tangohia nga tauira i te tau t=2.0, 4.0 me te 12.0 haora. I muri i te tangohanga o te paparanga mata o te tauira (≥1 mm), ka wahia ki nga wahi iti, ka rukuhia ki te waipiro isopropyl. Ka whakakapihia te waipiro Isopropyl ia 1d mo nga ra 7 karapīpiti hei whakarite i te whakatārewatanga katoa o te tauhohenga hydration, ka maroke i te 40 ℃ ki te taumaha tonu. Paunatia (75±2) mg tauira ki roto i te ipu, whakamahana i nga tauira mai i te 30 ℃ ki te 1000 ℃ i te tere pāmahana o te 20 ℃/min i roto i te hau hauota i raro i te ahua adiabatic. Ko te waiariki o te CSA ciment hydration hua te nuinga ka puta i te 50 ~ 550 ℃, a ka taea te whiwhi te ihirangi o te wai herea matū ma te tatau i te reiti mate papatipu o nga tauira i roto i tenei awhe. AFt ngaro 20 wai tioata me AH3 ngaro 3 wai tioata i te waiariki pirau i te 50-180 ℃. Ko nga ihirangi o ia hua whakamakuku ka taea te tatau i runga i te pihi TG.

2. Nga hua me te matapaki
2.1 Te tātaritanga o te tukanga whakamakuku
2.1.1 Te awenga o te ihirangi CE ki runga i te tukanga whakamakuku
E ai ki te hydration me exothermic ānau o te ihirangi rerekē L HEMC whakarerekē CSA slurry sima, i reira e 4 tihi exothermic i runga i te hydration me ānau exothermic o parakore CSA slurry sima (wL=0%). Ka taea te wehea te tukanga hydration ki te waahi whakakore (0 ~ 15.0min), te waahi whakarereke (15.0 ~ 45.0min) me te waahi whakatere (45.0min) ~ 54.0min), te waahi whakaheke (54.0min ~ 2.0h), te waahi o te taurite hihiri ( 2.0~4.0h), te reacceleration stage (4.0~5.0h), te redeceleration stage (5.0~10.0h) me te waahi whakapumau (10.0h~). I roto i te 15.0min i mua i te whakamakuku, ka tere te rewa o te kohuke sima, a, ko te tuatahi me te tuarua o te hydration exothermic peaks i tenei waahanga me te 15.0-45.0 min e rite ana ki te hanganga o te wahanga metastable AFt me tona huringa ki te monosulfide calcium aluminate hydrate (AFm), ia. Ko te tuatoru o nga tihi o waho i te 54.0min o te whakamakuku i whakamahia hei wehewehe i nga waahanga whakatere me te whakaheke, a ko nga reiti whakangao o te AFt me te AH3 i tango i tenei hei waahi hurihuri, mai i te pupuhi ki te heke, katahi ka uru ki te waahi o te taurite hihiri mo te 2.0 haora. . I te 4.0h te hydration, ka uru ano te hydration ki te waahi o te whakatere, ko te C4A3 he tere te whakakore me te whakatipuranga o nga hua o te hydration, a, i te 5.0h, ka puta mai te tihi o te hydration exothermic wera, ka uru ano ki te waahi o te whakaheke. Ka tau te whakamakuku i muri i te 10.0h.
Te awe o te ihirangi L HEMC ki te CSA ciment hydration dissolutiona he rereke te waahi o te huringa: ina he iti te ihirangi L HEMC, L HEMC whakarereke CSA ciment whakapiri te tuarua o te hydration te tihi tuku wera i puta paku i mua atu, ko te tere o te tuku wera me te uara teitei o te wera he tino teitei ake i te parakore CSA whakapiri sima; Na te pikinga o te ihirangi L HEMC, ka heke haere te reiti tuku wera o L HEMC kua whakarereketia te CSA ciment slurry, me te iti iho i te parakore CSA ciment slurry. Ko te maha o nga tihi exothermic i roto i te hydration exothermic curve o L HEMC 0.1 he rite tonu ki tera o te CSA ciment whakapiri parakore, engari ko te 3 me te 4th hydration exothermic peaks kua piki ki te 42.0min me te 2.3h, ia, ka whakataurite ki te 33.5 me te 9.0 mW/g o parakore CSA whakapiri sima, kua piki o ratou tihi exothermic ki te 36.9 me te 10.5 mW/g, ia. E tohu ana tenei ko te 0.1% L HEMC te whakatere me te whakarei ake i te whakamakuku o te L HEMC kua whakarerekehia te CSA ciment i te waahi e rite ana. Na L HEMC ihirangi ko 0.2% ~ 0.5%, L HEMC whakarerekē CSA whakatere sima me te atamira whakapōreareatanga āta ngā, e ko, te tuawha tihi exothermic i mua, me te ngā ki te tuatoru tihi exothermic, te waenganui o te atamira toenga hihiri kore puta ake. , L HEMC i runga i CSA ciment hydration pānga whakatairanga he nui ake.
L HEMC tino whakatairanga i te hydration o CSA ciment i roto i 45.0 min ~ 10.0 h. I roto i te 45.0min ~ 5.0h, he iti te painga o te 0.1% L HEMC ki te hydration o te ciment CSA, engari ka piki ake te ihirangi o te L HEMC ki te 0.2% ~ 0.5%, kaore he mea nui. He rereke tenei ki te paanga o te CE mo te whakamakuku o Portland ciment. Kua whakaatuhia e nga rangahau tuhinga ko te CE kei roto te maha o nga roopu hydroxyl i roto i te ngota ngota ka uru ki runga i te mata o nga matūriki ciment me nga hua hydration e tika ana ki te taunekeneke waikawa-papa, na reira ka whakaroa i te hydration wawe o Portland ciment, me te kaha o te adsorption. ka tino kitea te whakaroa. Heoi, i kitea i roto i nga tuhinga ko te kaha adsorption o te CE i runga i te mata AFt he ngoikore ake i tera i runga i te konupūmā silicate hydrate (C‑S‑H) gel, Ca (OH) 2 me te konupūmā aluminate hydrate mata, i te kaha adsorption o HEMC i runga i nga matūriki ciment CSA he ngoikore ano i tera i runga i nga matūriki ciment Portland. I tua atu, ka taea e te ngota hāora i runga i te ngota ngota CE te whakatika i te wai kore utu i roto i te ahua o te here hauwai hei wai adsorbed, te huri i te ahua o te wai whakaeto i roto i te slurry ciment, a ka pa ki te hydration sima. Heoi, ko te ngoikore o te whakaurunga me te whakauru wai o te CE ka ngoikore haere me te roanga o te wa whakamakuku. Whai muri i etahi wa, ka tukuna te wai kua whakahiatohia, ka mahi ano ki nga matūriki ciment kore wai. I tua atu, ka taea hoki e te hua o te CE te whakarato waahi roa mo nga hua whakamakuku. Koinei pea te take e whakatairanga ana a L HEMC i te CSA ciment hydration i muri i te 45.0 min hydration.
2.1.2 Te awenga o te whakakapinga CE me tona tohu ki runga i te mahi whakamakuku
Ka kitea mai i nga kurupae tuku wera whakamahana o nga slurries CSA e toru kua whakarereketia e te CE. Ka whakatauritea ki te L HEMC, ko nga pihi reiti tuku wera o te HEC me te H HEMC kua whakarereketia nga slurries CSA e wha ano nga tihi tuku wera whakamahana. Ko te katoa o nga CE e toru kua whakaroa i nga paanga ki te whakakore me te hurihanga o te CSA ciment hydration, me te HEC me te H HEMC he kaha ake nga paanga whakaroa, e whakaroa ana i te putanga o te waahi whakaheke tere. Ko te taapiri o te HEC me te H‑HEMC i whakaroa paku te 3rd hydration exothermic peak, i tino piki ake te 4th hydration exothermic peak, me te whakanui ake i te tihi o te 4th hydration exothermic peak. I te mutunga, ko te tukunga wera whakamahana o nga slurries CSA e toru kua whakarereketia he nui ake i tera o nga slurries CSA parakore i roto i te waa hydration o 2.0 ~ 10.0 h, e tohu ana ko nga CE e toru e whakatairanga ana i te whakamahana o te CSA ciment i tenei waahanga. I roto i te wa o te hydration o 2.0 ~ 5.0 h, ko te tukunga wera o te L HEMC kua whakarereketia te CSA ciment ko te mea nui rawa atu, a ko te H HEMC me te HEC te tuarua, e tohu ana ko te kaha o te whakatairanga o te iti o te HEMC whakakapi i runga i te wai o te CSA ciment he kaha ake. . Ko te kaha o te kaha o te HEMC he kaha ake i te HEC, e tohu ana ko te whakauru o te roopu methyl i whakarei ake i te painga o te CE i runga i te wai o te CSA ciment. Ko te hanganga matū o te CE he nui te awe ki runga i tana whakauru ki runga i te mata o nga matūriki ciment, ina koa te tohu o te whakakapi me te momo whakakapi.
He rereke te aukati o te CE me nga momo whakakapinga rereke. He hydroxyethyl anake te HEC i te mekameka taha, he iti ake i te HEMC kei roto te roopu methyl. Na reira, HEC te kaha adsorption pānga i runga i CSA matūriki sima me te awe nui i runga i te tauhohenga whakapā i waenganui i matūriki sima me te wai, na reira te tino kitea pānga whakaroa i runga i te tuatoru hydration exothermic tihi. Ko te whakauru wai o te HEMC me te whakakapi teitei he tino kaha ake i te HEMC me te iti o te whakakapi. Ko te mutunga, ko te wai kore utu e uru ana ki roto i te tauhohenga hydration i waenga i nga hanganga flocculated ka iti ake, he nui te awe ki te hydration tuatahi o te ciment CSA whakarereke. Na tenei, kua roa te tuatoru o te tihi waiariki. Ko nga HEMC whakakapi iti he ngoikore te whakauru wai me te wa mahi poto, ka puta wawe te tukunga o te wai adsorbent me te whakamakuku ano o te maha o nga matūriki ciment kore. Ko te ngoikoretanga ngoikore me te whakauru wai he rereke nga paanga whakaroa i runga i te whakakorenga o te wai me te waahi huringa o te CSA ciment, ka puta te rereketanga o te whakatairanga o te waiu ciment i te waahanga o muri mai o te CE.
2.2 Te tātaritanga o nga hua whakamakuku
2.2.1 Te awe o te ihirangi CE ki runga i nga hua wai
Hurihia te pihinga TG DTG o te slurry wai CSA na roto i nga mea rereke o te L HEMC; Ko nga ihirangi o te wai herea matū ww me nga hua whakamakuku AFt me AH3 wAFt me wAH3 i tatauhia i runga i nga pihi TG. Ko nga hua tatau i whakaatu ko nga pihi DTG o te whakapiri CSA parakore sima i whakaatu i nga tihi e toru i te 50 ~ 180 ℃, 230 ~ 300 ℃ me te 642 ~ 975 ℃. E rite ana ki te AFt, AH3 me te pirau dolomite. I te hydration 2.0 h, TG ānau o L HEMC whakarerekē CSA slurry he rerekē. Ka tae ki te 12.0 haora te tauhohenga o te wai, karekau he rereketanga nui o nga pihinga. I te 2.0h hydration, te ihirangi wai here matū o wL = 0%, 0.1%, 0.5% L HEMC whakarerekē CSA whakapiri ciment ko 14.9%, 16.2%, 17.0%, me te ihirangi AFt ko 32.8%, 35.2%, 36.7%, ia. Ko te ihirangi o te AH3 he 3.1%, 3.5% me te 3.7%, e tohu ana ko te whakaurunga o L HEMC i pai ake te tohu o te hydration o te slurry hydration ciment mo te 2.0 h, me te whakanui ake i te hanga o nga hua hydration AFt me AH3, ara, whakatairanga. te hydration o CSA ciment. Ko tenei pea na te mea kei roto i te HEMC nga roopu hydrophobic methyl me te roopu hydrophilic hydroxyethyl, he nui te mahi o te mata, a ka taea te whakaiti i te mata o te wahanga wai i roto i te slurry ciment. I te wa ano, ka whai hua ki te whakauru i te hau ki te whakangawari i te whakatipuranga o nga hua whakamakuku sima. I te 12.0 h o te whakamakuku, ko nga ihirangi AFt me te AH3 i roto i te L HEMC kua whakarereketia te CSA ciment slurry me te parakore CSA ciment slurry kaore he rereketanga nui.
2.2.2 Te awe o nga whakakapinga CE me o raatau tohu whakakapinga i runga i nga hua hydration
Ko te pihi TG DTG o CSA ciment slurry i whakarerekehia e te toru CE (ko te ihirangi o te CE ko te 0.5%); Ko nga hua tatau o te ww, wAFt me te wAH3 e whai ake nei: i te hydration 2.0 me te 4.0 h, he tino rereke nga pihi TG o nga momo slurries sima. Ka tae te hydration ki te 12.0 h, karekau he rereketanga nui o nga pihi TG o nga momo slurries sima. I te 2.0 h hydration, te ihirangi wai matū herea o parakore CSA sima slurry me HEC, L HEMC, H HEMC whakarerekē CSA slurry sima he 14.9%, 15.2%, 17.0%, 14.1%, aua. I te 4.0 h o te hydration, te TG ānau o parakore CSA slurry sima heke te iti. He nui ake te tohu whakamakuku o nga slurries CSA e toru i whakarerekehia e te CE i tera o nga slurries CSA parakore, a ko te ihirangi o te wai here matū o nga slurries CSA whakarereke HEMC he nui ake i tera o nga slurries CSA whakarereke HEC. L HEMC whakarerekē CSA sima slurry matū here ihirangi wai ko te nui rawa. Hei mutunga, ko te CE me nga momo whakakapinga me nga nekehanga o te whakakapinga he rerekeetanga nui ki nga hua whakamakuku tuatahi o te CSA ciment, a ko te L-HEMC te painga whakatairanga nui rawa atu mo te hanganga o nga hua whakamakuku. I te 12.0 h hydration, karekau he rereketanga nui i waenga i te reiti mate papatipu o nga slurps ciment CSA e toru kua whakarereketia e CE me nga parapara CSA ciment slurps, i rite tonu ki nga hua tuku wera whakahiato, e tohu ana ko te CE anake i tino pa ki te hydration o CSA ciment i roto i te 12.0 h.
Ka kitea hoki ko te AFt me te AH3 te kaha teitei o te L HEMC whakarereke CSA slurry te mea nui rawa atu i te hydration 2.0 me te 4.0 h. AFt ihirangi o parakore CSA slurry me HEC, L HEMC, H HEMC whakarerekē CSA slurry i 32.8%, 33.3%, 36.7% me 31.0%, aua, i 2.0h hydration. Ko te ihirangi AH3 he 3.1%, 3.0%, 3.6% me te 2.7%. I te 4.0 h o te hydration, ko te ihirangi AFt ko 34.9%, 37.1%, 41.5% me te 39.4%, me te ihirangi AH3 ko 3.3%, 3.5%, 4.1% me 3.6%. Ka taea te kite ko te L HEMC te kaha o te whakatairanga i te hanganga o nga hua hydration o te CSA ciment, a, ko te painga o te HEMC he kaha ake i te HEC. Ka whakatauritea ki te L-HEMC, ko te H-HEMC te whakapai ake i te pokey hihiko o te otinga pore, na reira ka pa ki te kawe wai, ka heke te tere o te kuhu slurry, me te pa ki te whakaputanga hua wai i tenei wa. Ka whakatauritea ki nga HEMC, ka tino kitea te awenga hononga hauwai i roto i nga ngota ngota HEC, a, ka kaha ake, ka roa ake te awe o te whakauru wai. I tenei wa, kua kore e kitea te painga o te whakauru wai o nga HEMC whakakapi teitei me nga HEMC iti-whakakapi. I tua atu, ka hangahia e te CE he "koropiko kati" o te kawe wai i roto i te rohe moroiti i roto i te slurry ciment, a ka taea e te wai tuku ata e CE te tauhohenga tika ki nga matūriki ciment huri noa. I te 12.0 haora o te whakamakuku, kua kore e tino nui nga paanga o te CE ki te hanga AFt me te AH3 o te CSA ciment slurry.

3. Whakamutunga
(1) Ko te hydration o te sulfoaluminate (CSA) sludge i roto i te 45.0 min ~ 10.0 h ka taea te whakatairanga me te rereke rereke o te iti o te hydroxyethyl methyl fibrin (L HEMC).
(2) Hydroxyethyl cellulose (HEC), hydroxyethyl methyl cellulose whakakapinga nui (H HEMC), L HEMC HEMC, enei e toru hydroxyethyl cellulose ether (CE) kua whakaroa i te wahanga whakakore me te huringa o te CSA ciment hydration, me te whakatairanga i te hydration o 2.0 ~ 10.0 h.
(3) Ko te whakauru o te methyl i roto i te hydroxyethyl CE ka taea te whakanui ake i tana painga whakatairanga i runga i te hydration o te CSA ciment i te 2.0 ~ 5.0 h, me te kaha o te whakatairanga o te L HEMC i runga i te hydration o te CSA ciment he kaha ake i te H HEMC.
(4) I te mea ko te ihirangi o te CE ko te 0.5%, ko te nui o te AFt me te AH3 i hangaia e L HEMC kua whakarereketia te CSA slurry i te hydration 2.0 me te 4.0 h ko te teitei rawa atu, a ko te painga o te whakatairanga i te hydration ko te mea tino nui; H HEMC me HEC whakakē CSA slurries hua AFt me AH3 slurries teitei ake i slurries CSA parakore anake i te 4.0 h o te hydration. I te 12.0 h o te whakamakuku, ko nga paanga o te 3 CE i runga i nga hua whakamakuku o te CSA ciment kua kore e tino nui.