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盧玲霞

（廣東冠粵路橋有限公司，廣東 廣州511400）

摘  要：針對低水膠比高強機制砂泵送混凝土早期收縮開裂嚴重易造成建筑物耐久性急劇衰退的問題，通過試驗研究粉煤灰、礦粉、硅灰在單摻、雙摻和三摻時對混凝土工作性能、力學性能、早期收縮和開裂性能的影響規律，以低場核磁共振儀（NMR）通過孔結構對早期收縮開裂性能的規律進行分析。結果表明：粉煤灰和礦粉的摻入提高了混凝土的工作性能，但硅灰的摻入降低了混凝土的工作性能；礦物摻合料的摻入對混凝土早期強度影響較大，隨著養護齡期的延長，后期強度隨著水化程度的增加有所升高；粉煤灰、礦粉、硅灰三摻時，高強機制砂混凝土具有最小的早期收縮率和開裂面積；摻入礦物摻合料使混凝土內部孔隙率減小，混凝土內部致密度提高，減小了早期收縮開裂。

關鍵詞：混凝土；礦物摻合料；機制砂；力學性能；早期收縮；早期開裂

中圖分類號：TU528  

文獻標志碼：A        

文章編號：1005-8249（2024）02-0017-06

DOI：10.19860/j.cnki.issn1005-8249.2024.02.004

LU Lingxia

(Guangdong Guanyue Road and Bridge Co., Ltd., Guangzhou 511400, China)

Abstract: Aiming at the problem of severe early shrinkage and cracking of concrete pumped with low water-binder ratio and high strength sand which is easy to cause a sharp decline in the durability of buildings,the effects of fly ash mineral powder and silica fume on the working performance,mechanical properties,early shrinkage and cracking properties of concrete under single,double and triple mixing were studied through experiments. The behavior of early shrinkage cracking was analyzed by low field nuclear magnetic resonance (NMR) through pore structure .The results show that the addition of fly ash and mineral powder can improve the working performance of concrete, but the addition of silica fume can reduce the working performance of concrete. The addition of mineral admixture has a great influence on the early strength of concrete, and with the extension of curing age, the later strength increases with the increase of hydration degree. When fly ash, mineral powder, and silica fume are mixed , the high-strength machine-made sand concrete has the smallest early shrinkage rate and cracking area.The addition of mineral admixtures can reduce the internal porosity of concrete,increase the internal density of concrete, and reduce the early shrinkage cracking.

Keywords:concrete; mineral admixture; machine-made sand; mechanical properties; early contraction; early cracking

 

 

 

作者簡介：盧玲霞（1992—），女，本科，工程師，主要研究方向：公路橋梁施工。

收稿日期：2023-11-10