科研团队自主研发出了一种新型高分子溶液型混凝土养护剂X730,通过与两种市售MT和WP养护剂进行试验对比,研究了三种养护剂的有效保水率、憎水性和吸水性等基本性能及其对养护后混凝土强度的影响.结果表明:①采用X730和MT养护剂处理得到的养护膜表面均呈憎水性,而WP养护剂呈亲水性;②三种养护剂均能够有效减小水泥砂浆试件的吸水量与毛细吸水高度,其中X730的防水效果最佳;③采用浸泡法进行养护处理时,X730有效保水率达到80.9％,MT和WP有效保水率分别为62.5％和52.3％;④与水养护相比,采用X730、MT和WP进行浸泡处理的试件,3 d、7 d和28 d的抗压强度均有所下降.但是,X730与MT、WP相比,对混凝土的养护效果最好,28 d抗压强度比达到91.2％,能够满足建材行业标准对养护剂强度比的要求.

综合评述了混凝土搅拌站废弃塑性混凝土再生利用的研究与应用进展,总结了目前国内外对废弃塑性混凝土的再生利用方法,包括用于生产非重要预制构件、自然硬化后生产再生骨料、水洗后砂石分离回收、泥浆水、沉淀或压滤污泥再生利用、废弃塑性混凝土的无水清理与再生利用、添加水化稳定外加剂实现未水化水泥颗粒高效再生利用以及作为预水化水泥基材料抑制超高性能混凝土自收缩等,并提出当前研究与应用存在的问题和今后的发展方向.

随着我国经济的发展,工程建设规模不断扩大.鉴于此,本文针对人防工程主体结构土建施工技术展开研究.在实际的施工过程中,主体结构土建施工技术水平决定者整体人防工程的最终质量,因此相关人员必须对其加以重视,加大技术性的支持力度,保障施工的顺利进行.

Defects and shortcomings of Hansen and Pedersen's equivalent age equation based on Arrhenius' s principle for estimating temperature-age dependence of concrete properties are shortly discussed.In order to improve accuracy of estimation,a modified equivalent age equation is proposed.The equation includes a regression function considering age and temperature correlation of apparent activation energy of hydration reaction.Furthermore,the validity of the modified equation is testified by a series of experiment data on autogenous shrinkage of high performance concrete under 3 different curing temperatures.The result showed that shrinkage-equivalent age curves transformed by the modified equation coincide with each other well.

In this paper,with 3 kinds of mixture proportions whose water-binder ratio are 0.30,0.40 and 0.50,and 3 kinds of curing temperatures at 5,20 and 35 ℃,the effects of curing temperature on autogenous shrinkage of high strength/performance concrete are experimentally investigated based on an improved testing method.The results show that the higher the curing temperature,the faster the increasing rate and the higher magnitude of autogenous shrinkage,especially at earlier ages and for mixtures with a lower water-binder ratio.A similar characteristic is existed on compressive strength and elastic modulus.Temperature dependence of autogenous shrinkage indirectly reflects interplay between cement hydration and self-desiccation in terms of environmental temperature and/or concrete temperature.

Concrete segments are the main structures of shield tunnel,they are also the comprehensive performance guarantees of waterproof,fireproof and durability.Therefore,the overall performance of the segment has a high requirment.But the large-diameter concrete segment in the production sometimes happens more bubble,thus it is easy to form leakage channels,which affects the durability.In this paper,concrete materials,mix design,mould,mold release agents,vibration technology and other aspects attempt to reduce the segment bubble,as a result,good results are gotten in the practice production.

Technological and economical feasibility through scatter-filling the recycled aggregate (RA) into the high fluidity concrete to realize recycling and reusing the waste concrete in worksite has been investigated in this paper.The results showed that the uniformity and the compressive strength of the hardened concrete at 3 and 28 days is obviously improved through scatter-filling the RA with higher compressive strength than that of the hardened high-fluidity concrete.While the compressive strength of the origin concrete is obviously lower than that of the hardened high-fluidity concrete and the volume percent of the RA scatter-filled is less than 30% ,compressive strength at 3 days and autogenous shrinkage of the highfluidity concrete can also be obviously enhanced,and the strength at 28 days is also improved.However,scatter-filling more than 40% of the RA will result in decrease of the strength at 28 days.It is also found that it is economic by scatterfilling the RA into the high-fluidity concrete,as compared to that without scatter-filling or scatter-filling with the natural aggregate.