碱激发矿渣混凝土的补偿收缩性能试验研究

以硫铝酸钙-氧化钙类膨胀剂(EA)作为掺合料,通过改变EA的掺量(0%,2%,4%,6%和8%),采用自制收缩架对自由条件下和半密封约束条件下的碱激发矿渣混凝土的收缩性能进行测试.在此基础上,对EA分别与水,NaOH溶液及水玻璃溶液反应净浆及不同EA掺量碱激发矿渣净浆进行微观分析.收缩性能测试结果显示:两种不同养护制度条件下的试件掺入EA后干缩量均有所降低,且降低程度随EA掺量的增加而增大.当EA掺量达8%时,自由条件养护下的试件补偿收缩量约为3.0×10-4με,而半密封约束条件下的试件补偿收缩量可达4.0×10-4με.表明:该类EA对碱激发矿渣混凝土具有较好的补偿收缩性能,且在半密封约束条件下补偿收缩效果更为显著.微观分析显示:EA分别与水,NaOH溶液及水玻璃溶液反应净浆中均检出钙矾石与氢氧化钙两种水化产物,但在掺EA碱激发矿渣净浆中仅检出氢氧化钙一种水化产物.表明:EA在碱激发矿渣混凝土中起到补偿收缩作用的主要是水化产物氢氧化钙.

Experimental Study on Shrinkage Compensation Performance of Alkali-activated Slag Concrete

The shrinkage compensation performance of alkali-activated slag concrete ( AASC ) with lime and cacium sulphoaluminate expansive admixture ( EA ) of different content ( 0%, 2%, 4%, 6% and 8%) under the condition of free and semi sealed constraints was texted .On this basis , microstructural analysis of hardened pastes of EA react with water , NaOH solution and water glass solution individually and alkali-activated slag with diferent EA content was invtstigate .Shrinkage performance test results show that the AASC specimens'shrinkage are all reduce under two conditions , and the reduction degree increases with the increase of EA content .When the content of EA is 8%the shrinkage is 3.0 ×10 -4μεunder free condition and 4.0 ×10 -4 με under semi sealed conditon .Indicated that the EA has a good shrinkage-compensation capability , and the effection is more significant under the semi sealed condition . Microstructural analysis results show that the hydration products of ettringite and calcium hydroxideare are all tested in the EA pastes , but in the alkali-activated slag past only tested calcium hydroxideare . Indicated that in the AASC with EA play the role of shrinkage-compensation capability is main because the hydration products of Ca ( OH) 2 .