一、混凝土的凝結時間
根(gen)據水(shui)(shui)泥的(de)具體(ti)性(xing)質(zhi)及混(hun)凝(ning)土所(suo)摻(chan)外加劑(ji)的(de)性(xing)能不(bu)同,混(hun)凝(ning)土的(de)初(chu)(chu)凝(ning)時(shi)(shi)(shi)(shi)間及終(zhong)凝(ning)時(shi)(shi)(shi)(shi)間會有差別(bie)。為(wei)便于(yu)(yu)施工,常(chang)態混(hun)凝(ning)土的(de)初(chu)(chu)凝(ning)時(shi)(shi)(shi)(shi)間不(bu)得(de)小(xiao)于(yu)(yu)3~4小(xiao)時(shi)(shi)(shi)(shi);終(zhong)凝(ning)時(shi)(shi)(shi)(shi)間不(bu)得(de)大于(yu)(yu)12小(xiao)時(shi)(shi)(shi)(shi)。一(yi)般(ban)控制在(zai)6~10小(xiao)時(shi)(shi)(shi)(shi)。根(gen)據施工需(xu)要,選擇(ze)適合的(de)外加劑(ji),可以在(zai)一(yi)定(ding)的(de)范圍內改變混(hun)凝(ning)土的(de)初(chu)(chu)、終(zhong)凝(ning)時(shi)(shi)(shi)(shi)間。國家標準(zhun)規定(ding)水(shui)(shui)泥初(chu)(chu)凝(ning)時(shi)(shi)(shi)(shi)間不(bu)得(de)早于(yu)(yu)45分(fen)鐘,一(yi)般(ban)為(wei)1~3小(xiao)時(shi)(shi)(shi)(shi);終(zhong)凝(ning)時(shi)(shi)(shi)(shi)間不(bu)得(de)遲于(yu)(yu)12小(xiao)時(shi)(shi)(shi)(shi),一(yi)般(ban)為(wei)5~8小(xiao)時(shi)(shi)(shi)(shi)。
二、混凝土一方多少噸
普通混凝土因為強度和等級的不同,在重量上也有一定的差異,常規的混凝土一般有C10、C15、C20、C25、C30、C35、C40等級,最高的能達到C80。以C10為例,一立方C10混凝土通常需要用到水泥100公斤,砂石780公斤,碎石1025公斤,水160公斤,摻合料220公斤,總重量2285公斤。通常混凝土的等級越高,重量約大,選擇的混凝土品牌以強度(du)等級高為宜(yi)。
三、混凝土配合比
混(hun)(hun)(hun)凝(ning)(ning)土(tu)(tu)(tu)(tu)施工(gong)配合(he)比(bi)是(shi)指(zhi)混(hun)(hun)(hun)凝(ning)(ning)土(tu)(tu)(tu)(tu)中(zhong)各組成(cheng)(cheng)材料之間的比(bi)例關系,混(hun)(hun)(hun)凝(ning)(ning)土(tu)(tu)(tu)(tu)配合(he)比(bi)設(she)計是(shi)混(hun)(hun)(hun)凝(ning)(ning)土(tu)(tu)(tu)(tu)工(gong)程(cheng)(cheng)中(zhong)很重(zhong)要(yao)(yao)(yao)(yao)的一項工(gong)作,它直(zhi)接(jie)影響到混(hun)(hun)(hun)凝(ning)(ning)土(tu)(tu)(tu)(tu)的順利施工(gong)、混(hun)(hun)(hun)凝(ning)(ning)土(tu)(tu)(tu)(tu)工(gong)程(cheng)(cheng)的質(zhi)量(liang)和(he)混(hun)(hun)(hun)凝(ning)(ning)土(tu)(tu)(tu)(tu)工(gong)程(cheng)(cheng)的成(cheng)(cheng)本。設(she)計混(hun)(hun)(hun)凝(ning)(ning)土(tu)(tu)(tu)(tu)配合(he)比(bi)的基(ji)本要(yao)(yao)(yao)(yao)求(qiu)(qiu)是(shi)滿足(zu)(zu)混(hun)(hun)(hun)凝(ning)(ning)土(tu)(tu)(tu)(tu)設(she)計的強度等級(ji)、施工(gong)要(yao)(yao)(yao)(yao)求(qiu)(qiu)的混(hun)(hun)(hun)凝(ning)(ning)土(tu)(tu)(tu)(tu)和(he)易性、混(hun)(hun)(hun)凝(ning)(ning)土(tu)(tu)(tu)(tu)使(shi)用(yong)要(yao)(yao)(yao)(yao)求(qiu)(qiu)的耐(nai)久性,在滿足(zu)(zu)以上(shang)要(yao)(yao)(yao)(yao)求(qiu)(qiu)的基(ji)礎上(shang)降(jiang)低成(cheng)(cheng)本。
四、混凝土強度低怎么辦
混(hun)凝土(tu)(tu)強度(du)(du)(du)低可(ke)通過提(ti)高(gao)水(shui)泥強度(du)(du)(du)等級來增(zeng)大(da)混(hun)凝土(tu)(tu)強度(du)(du)(du);施工(gong)時,一般(ban)通過降(jiang)低水(shui)灰比來提(ti)高(gao)混(hun)凝土(tu)(tu)強度(du)(du)(du)。適當降(jiang)低水(shui)灰比,可(ke)有效控(kong)制漿(jiang)集(ji)比和水(shui)泥漿(jiang)層厚度(du)(du)(du),使集(ji)料的骨架作用(yong)得到充分發揮(hui),最終能(neng)增(zeng)強混(hun)凝土(tu)(tu)強度(du)(du)(du)。此(ci)外,還可(ke)以通過優化(hua)設計工(gong)藝流(liu)程、選(xuan)擇(ze)級配優良、砂率適中(zhong)的高(gao)強度(du)(du)(du)碎石、采用(yong)濕(shi)熱處理養護混(hun)凝土(tu)(tu)、適量添加外加劑和摻合(he)料等方(fang)法(fa)來增(zeng)加強度(du)(du)(du)。