1.裂缝

1. Cracks

水泥稳定碎石裂缝是水泥稳定碎石基层混合料水泥固化以及水分散发后在表面产生的细微开裂，然后向深部与横向扩展，贯通整个基层。裂缝的宽度约为1cm~3cm，严重可达4cm~5cm，裂缝的产生一定程度导致上破坏基层的板的整体受力状态，如果裂缝进一步发展会产生发生反射裂缝，造成路面面层也相应产生裂缝或者断板情况的出现。

Cement stabilized crushed stone cracks refer to the subtle cracks that occur on the surface of the cement stabilized crushed stone base mixture after cement solidification and moisture dissipation, and then extend deep and horizontally, penetrating the entire base layer. The width of the cracks is about 1cm~3cm, and the severity can reach 4cm~5cm. The generation of cracks to a certain extent leads to the overall stress state of the board that damages the base layer. If the cracks further develop, reflection cracks will occur, causing cracks or broken boards in the road surface layer.

水稳层产生裂缝原因有：

The causes of cracks in the water stable layer include:

1）水泥稳定碎石混合料含水量高于佳含水量很多，水泥稳定碎石基层干缩应变随混合料的含水量增加而增大；

1) The moisture content of cement stabilized crushed stone mixture is much higher than the optimal moisture content, and the dry shrinkage strain of cement stabilized crushed stone base increases with the increase of moisture content of the mixture;

2）水泥品种的选择；

2) Selection of cement varieties;

3）水泥剂量用量偏大与级配不好；

3) Excessive cement dosage and poor grading;

4）水泥稳定碎石养生不及时或养生不规范化；

4) The curing of cement stabilized crushed stone is not timely or standardized;

5）温差原因。

5) Reason for temperature difference.

预防措施：

Preventive measures:

1）重视原材料的选用以保证有良好的级配，在满足设计强度的前提下，降低水泥剂量；

1) Pay attention to the selection of raw materials to ensure good gradation, and reduce cement dosage while meeting the design strength;

2）水泥的选择：不同品种的水泥干缩性不同，普通硅酸盐水泥干缩性很小，火山灰质硅酸水泥次之，矿渣水泥较大。因此，选用合适的水泥在一定程度上能减少干缩裂缝；

2) Selection of cement: Different types of cement have different dry shrinkage properties. Ordinary Portland cement has very low dry shrinkage, followed by volcanic ash silicate cement, and slag cement has a larger dry shrinkage. Therefore, selecting appropriate cement can to some extent reduce dry shrinkage cracks;

3）控制细集料量，细集料＜0.075mm颗粒的含量尽量小于5%~7%；

3) Control the amount of fine aggregate, and try to minimize the content of particles with fine aggregate<0.075mm to less than 5%~7%;

4）控制含水量，要严格按水泥稳定碎石配合比设计控制含水量，使其与佳含水量接近，减少用水量不当而人为造成裂缝；

4) To control the water content, it is necessary to strictly follow the design of the cement stabilized crushed stone mix ratio to control the water content, making it close to the optimal water content and reducing the risk of cracks caused by improper water use;

5）合理选择施工时间，施工时间好选择在夏季高温季节来临之前，如在夏季高温季节施工，尽量在上午或夜间施工；

5) Reasonably choose the construction time, preferably before the arrival of the summer high temperature season. If construction is carried out during the summer high temperature season, it is advisable to do so in the morning or at night;

6）加强养生，因为干燥收缩的破坏发生在早期，所以及时的采用土工布，麻袋布或薄膜覆盖进行良好的养生，可以防止水泥稳定碎石层混合料内部发生水化作用和水分的过分蒸发引起表面的干缩裂缝现象。如施工条件许可，及时铺筑沥青面层是减少干缩裂缝的一种好的办法；

6) Strengthening health preservation, as the damage caused by dry shrinkage occurs in the early stages, timely use of geotextile, burlap cloth or film covering for good health preservation can prevent hydration and excessive evaporation of water inside the cement stabilized crushed stone layer mixture, which can cause surface dry shrinkage cracks. If construction conditions permit, timely laying of asphalt surface layer is a good way to reduce dry shrinkage cracks;

7）在水稳层碎石基层中掺加粉煤灰（占集料重量的10%~20%），可以延缓水稳层混合料的凝结，增加混合料的搞冻能力和改善混合料的形变性能。

7) Adding fly ash (accounting for 10% to 20% of the aggregate weight) to the water stable layer crushed stone base can delay the setting of the water stable layer mixture, increase the freezing ability of the mixture, and improve the deformation performance of the mixture.

2.取不出完整的芯样

2. Unable to extract complete core samples

按照技术规范要求，水泥稳定碎石层龄期7d~10d，应能取出完整的钻件，可实际情况是部分路段因为松散，不能取出完整的芯样。其原因是：

According to the technical specifications, the age of the cement stabilized crushed stone layer should be between 7d and 10d, and complete drilling pieces should be able to be taken out. However, in reality, some sections of the road cannot take out complete core samples due to looseness. The reason is:

1）水泥用量偏少造成骨料之间胶结不好，达不到强度；

1) Insufficient cement usage results in poor bonding between aggregates and inability to achieve strength;

2）没有完全按照规范要求进行养护，按规范要求每一段碾压完成并经压实度检查合格后，应立即养生，宜采用湿砂进行养生，砂层厚度为7cm~10cm.也可采用沥青乳液进行养生，无述条件时，也可用洒水车结常洒水进行养生。养生期不宜少于7天；

2) The curing is not carried out in full accordance with the requirements of the specification. After each section of rolling is completed according to the requirements of the specification and the compactness is checked to be qualified, it should be cured immediately. Wet sand should be used for curing. The thickness of the sand layer is 7cm~10cm. Asphalt lotion can also be used for curing. If there is no such condition, the watering cart can also be used for curing. The health period should not be less than 7 days;

3）水泥稳定碎石层原材料级配不好；

3) Poor grading of raw materials for cement stabilized crushed stone layer;

4）含水量不合适，以至于水泥不能在混合料中完全水化和水解，水泥对碎石的稳定作用没发挥，影响水泥稳定碎石的强度；

4) The moisture content is inappropriate, so that cement cannot fully hydrate and hydrolyze in the mixture, and the stabilizing effect of cement on crushed stone is not fully exerted, which affects the strength of cement stabilized crushed stone;

5）水泥选用不当，普通硅酸盐水泥，矿渣硅酸盐水泥和火山灰质硅酸盐水泥都可用水泥稳定碎石，但应选用初凝时间3h以上和终凝时间较长（宜在6h以上）。不宜使用快硬水泥，早强水泥以及已受潮变质的水泥；

5) Improper selection of cement. Ordinary Portland cement, slag Portland cement, and volcanic ash Portland cement can all be stabilized with cement crushed stone, but the initial setting time should be more than 3 hours and the final setting time should be longer (preferably more than 6 hours). It is not advisable to use fast hardening cement, early strength cement, and cement that has been damp and deteriorated;

6）拌合得不均匀，且没在佳含水量下充分压实，以及施工碾压时间拖的过长，破坏了已结硬的水泥胶凝，使其强度下降。

6) Uneven mixing and insufficient compaction at optimal moisture content, as well as prolonged construction compaction time, have damaged the hardened cement binder and reduced its strength.