一、混凝土的凝結時間
根據(ju)水(shui)泥(ni)的具體(ti)性(xing)質及混(hun)凝(ning)(ning)(ning)(ning)土所摻(chan)外加劑的性(xing)能不同,混(hun)凝(ning)(ning)(ning)(ning)土的初(chu)凝(ning)(ning)(ning)(ning)時(shi)(shi)(shi)間(jian)(jian)(jian)及終(zhong)凝(ning)(ning)(ning)(ning)時(shi)(shi)(shi)間(jian)(jian)(jian)會有(you)差別。為(wei)便于(yu)施工,常態混(hun)凝(ning)(ning)(ning)(ning)土的初(chu)凝(ning)(ning)(ning)(ning)時(shi)(shi)(shi)間(jian)(jian)(jian)不得小(xiao)于(yu)3~4小(xiao)時(shi)(shi)(shi);終(zhong)凝(ning)(ning)(ning)(ning)時(shi)(shi)(shi)間(jian)(jian)(jian)不得大于(yu)12小(xiao)時(shi)(shi)(shi)。一(yi)般(ban)控制在(zai)6~10小(xiao)時(shi)(shi)(shi)。根據(ju)施工需要,選擇適(shi)合的外加劑,可以在(zai)一(yi)定(ding)的范(fan)圍(wei)內改變混(hun)凝(ning)(ning)(ning)(ning)土的初(chu)、終(zhong)凝(ning)(ning)(ning)(ning)時(shi)(shi)(shi)間(jian)(jian)(jian)。國家(jia)標準(zhun)規定(ding)水(shui)泥(ni)初(chu)凝(ning)(ning)(ning)(ning)時(shi)(shi)(shi)間(jian)(jian)(jian)不得早(zao)于(yu)45分(fen)鐘,一(yi)般(ban)為(wei)1~3小(xiao)時(shi)(shi)(shi);終(zhong)凝(ning)(ning)(ning)(ning)時(shi)(shi)(shi)間(jian)(jian)(jian)不得遲于(yu)12小(xiao)時(shi)(shi)(shi),一(yi)般(ban)為(wei)5~8小(xiao)時(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等(deng)級高(gao)為宜。
三、混凝土配合比
混(hun)凝(ning)(ning)(ning)土(tu)(tu)施(shi)工(gong)配(pei)合比是(shi)指(zhi)混(hun)凝(ning)(ning)(ning)土(tu)(tu)中各組成材料之間(jian)的(de)比例關系(xi),混(hun)凝(ning)(ning)(ning)土(tu)(tu)配(pei)合比設計(ji)是(shi)混(hun)凝(ning)(ning)(ning)土(tu)(tu)工(gong)程中很重(zhong)要(yao)的(de)一項工(gong)作,它直接影響到混(hun)凝(ning)(ning)(ning)土(tu)(tu)的(de)順利施(shi)工(gong)、混(hun)凝(ning)(ning)(ning)土(tu)(tu)工(gong)程的(de)質量和混(hun)凝(ning)(ning)(ning)土(tu)(tu)工(gong)程的(de)成本。設計(ji)混(hun)凝(ning)(ning)(ning)土(tu)(tu)配(pei)合比的(de)基本要(yao)求(qiu)(qiu)(qiu)是(shi)滿(man)足(zu)混(hun)凝(ning)(ning)(ning)土(tu)(tu)設計(ji)的(de)強度等級、施(shi)工(gong)要(yao)求(qiu)(qiu)(qiu)的(de)混(hun)凝(ning)(ning)(ning)土(tu)(tu)和易性、混(hun)凝(ning)(ning)(ning)土(tu)(tu)使用要(yao)求(qiu)(qiu)(qiu)的(de)耐久性,在滿(man)足(zu)以(yi)上要(yao)求(qiu)(qiu)(qiu)的(de)基礎上降(jiang)低成本。
四、混凝土強度低怎么辦
混(hun)凝土(tu)強(qiang)(qiang)度(du)(du)(du)(du)低可(ke)通(tong)(tong)(tong)過(guo)提(ti)(ti)高水(shui)泥強(qiang)(qiang)度(du)(du)(du)(du)等級來(lai)增(zeng)大混(hun)凝土(tu)強(qiang)(qiang)度(du)(du)(du)(du);施工時,一(yi)般通(tong)(tong)(tong)過(guo)降低水(shui)灰比(bi)來(lai)提(ti)(ti)高混(hun)凝土(tu)強(qiang)(qiang)度(du)(du)(du)(du)。適當降低水(shui)灰比(bi),可(ke)有效(xiao)控制漿集比(bi)和(he)水(shui)泥漿層厚度(du)(du)(du)(du),使集料的骨架(jia)作用得到(dao)充(chong)分發(fa)揮,最終能(neng)增(zeng)強(qiang)(qiang)混(hun)凝土(tu)強(qiang)(qiang)度(du)(du)(du)(du)。此外,還可(ke)以通(tong)(tong)(tong)過(guo)優(you)化(hua)設計工藝流程、選擇級配優(you)良、砂率(lv)適中的高強(qiang)(qiang)度(du)(du)(du)(du)碎石(shi)、采用濕熱處理(li)養護(hu)混(hun)凝土(tu)、適量添(tian)加(jia)外加(jia)劑和(he)摻(chan)合(he)料等方法(fa)來(lai)增(zeng)加(jia)強(qiang)(qiang)度(du)(du)(du)(du)。