几种矿物掺合料对混凝土脆性及早期开裂性能影响比较

Comparison of Effects of Several Kinds of Mineral Admixtures on Brittleness and Early-age Cracking Performance of Concrete

将矿粉、粉煤灰、垃圾焚烧飞灰、垃圾焚烧底渣以单掺或1:1二元复掺替代部分水泥后,配制掺合料混凝土,测定其力学强度和拉压比,并利用平板法研究比较各掺合料混凝土的早期抗开裂性能。研究表明,粉煤灰具有适当降低混凝土的脆性和抑制早期开裂的性能,而矿粉的作用与其相反;飞灰对混凝土的早期开裂性能极为不利,在飞灰中复合部分粉煤灰或矿粉,可大大改善混凝土的早期抗裂性能;底渣混凝土因强度太低早期未出现明显的开裂,但在底渣中引入部分矿粉或粉煤灰后,混凝土的抗压强度能比单掺底渣混凝土明显提高,同时该底渣基复合掺合料混凝土的抗裂性能优异。

Admixture concrete was prepared with slag, fly ash, waste incineration fly ash and waste incineration bottom ash replacing parts of cement singly or mixed both with the rate of 1：1. Mechanical strength and tension strength/ compressive strength of corresponding concrete were tested. Plate method was used to study the early cracking resistance of every admixture concrete. The results showed that fly ash can appropriately reduce the brittle and restrain the early cracking of concrete, but slag plays an opposite function. The effect of waste incineration fly ash on early cracking of admixture concrete may be extremely unfavorable. Parts of fly ash or slag mixed into waste incineration fly ash can improve the early cracking resistance of corresponding concrete greatly. Because of poor strength of waste incineration bottom ash concrete, no obvious cracking phenomenon appear. But when parts of fly ash or slag were mixed into waste incineration bottom ash, compressive strength of corresponding concrete was significantly improved and its early cracking resistance was excellent, comparing with that of waste incineration bottom ash.