附:混凝土冬期施工热工计算
(依据《建筑工程冬期施工规程JGJ104-97》计算,C25混凝土) 1.混凝土搅拌、运输、浇筑温度计算 1.1 混凝土拌合物温度:
设室外温度5℃~-15℃,水温60℃,骨料温度大于0℃(砂子2℃,石子1℃)
T0 = [0.92(mceTce+msaTsa+mgTg)+4.2Tw(mw-wsamsa-wgmg)+c1
(wsamsaTsa+ wgmgTg )-c2(wsamsa + wgmg)]÷[4.2mw+0.9(mce+msa+mg)]
= [0.92×(331×6+716×2+1088×1)+4.2×60×(195-716×5.26%-1088×4.17%)+4.2×(716×5.26%×2+1088×4.17%×1)] ÷[4.2×195+0.9×(331+716+1088)] = 11.99℃
1.2 混凝土拌合物出机温度:
设搅拌机棚内温度为3℃ T1 = T0-0.16(T0-Ti) = 11.99-0.16(11.99-3) = 10.55℃
1.3 混凝土拌合物经运输到浇筑时温度:
设混凝土运输中(泵管)温度损失系数为0.1,混凝土拌合物运输时周围环境温度为-10℃,混凝土拌合物运转2次,混凝土拌合物自运输到浇筑的时间为0.5小时。
1
T2 = T1-(αt1+0.032n)(T1- Ta)
= 10.55-(0.1×0.5+0.032×2)(10.55+10) = 8.21℃
1.4 考虑模板和钢筋的吸热影响,混凝土浇筑成型完成时的温度:
CcmcTc+CfmfTf+CsmsTsT3=
Ccmc+Cfmf+Csms
1×2400×8.21+2.51×32.24×(-10)+95×0.48×(-10)=
1×2400+2.51×32.24+95×0.48= 7.30℃
2.混凝土蓄热养护过程中的温度计算
2.1混凝土蓄热养护开始到任一时刻t的温度:
设室外温度0℃~-10℃,取平均-5℃,t=2 T = ηe-θ·Vce·t-φe -Vce·t+Tm,a
其中:
ω ·K·Mθ =
Vce·Cc·ρc
1.5×15.52×5.86=
0.013×1×2400= 4.37
Vce·Qce·mce
φ =
Vce·Cc·ρc-ω ·K·M
0.013×330×430
= 0.013×1×2400-1.5×15.52×5.86= -17.53
2
η = T3-Tm,a+φ
= 7.3-(-5)+(-17.53) = -5.23 M =
A(混凝土结构表面积)
V(混凝土结构的体积)
5.86 =
1 = 5.86
3.6
K = di0.04+ΣK (n,i=1)
i
3.6
=
0.003+0.01+0.010.04+ 0+0.06+0.06 = 15.52 故:
T = ηe-θ·Vce·t-φe -Vce·t+Tm,a
= -5.23×e-4.37×0.013×2-(-17.53)e-0.013×2-5 = 7.41℃
2.2混凝土蓄热养护开始到任一时刻t的平均温度:
1ηη
T = Vt (φe -Vce·t- θ e-θ·Vce·t+ θ -φ)+Tm,a
ce
=
15.235.23
(-17.53×e -0.013×2+ 4.37 ×e-4.37×0.013×2- 4.37 +17.53)
0.013×2-5
= 7.36℃
3
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